Updated on 2024/10/30

Information

 

写真a

 
POKHAREL RAMESH
 
Organization
Faculty of Information Science and Electrical Engineering Department of I&E Visionaries Professor
Center for Japan-Egypt Cooperation in Science and Technology(E-JUST Center) (Concurrent)
School of Engineering Department of Electrical Engineering and Computer Science(Concurrent)
Graduate School of Information Science and Electrical Engineering Department of Electrical and Electronic Engineering(Concurrent)
Title
Professor
Profile
We are investigating the feasibility of a paradigm shift from battery-dependent systems to battery-free wireless and embedded sensor systems. This research focuses on developing ultra-low power and low voltage analog/high frequency integrated circuits using CMOS technology. Additionally, we are exploring the utilization of 5G and beyond 5G (B5G) networks to transfer both signals/data and power. Our aim is to realize a wire/battery-free and self-powered system that can replace conventional batteries in future wireless and embedded sensor systems.
Homepage
  • http://rfic.ed.kyushu-u.ac.jp/en.html

    We are investigating the possibility of a paradigm shift from a battery-inherent to a battery-free wireless and embedded sensor system.
    The core techniques include the development of the ultra-low power and low voltage analog/high frequency integrated circuits in CMOS technology,
    and on the other hand, efforts are going to apply 5G carrier frequency to transfer not only the signal/data but also the power to realize a wire/battery-free
    and self-powered system to replace the conventional batteries in the future wireless and embedded sensor systems.

Research Areas

  • Manufacturing Technology (Mechanical Engineering, Electrical and Electronic Engineering, Chemical Engineering) / Electron device and electronic equipment

Degree

  • Dr. Eng.

Research History

  • Nepal Telecomminication Corporation, Kathamandu, Nepal 期間:1995年1月1日〜1997年3月21日

    Nepal Telecomminication Corporation, Kathamandu, Nepal 期間:1995年1月1日〜1997年3月21日

  • 青山学院大学電気電子工学科 期間:2003年4月1日〜2005年3月31日

Research Interests・Research Keywords

  • Research theme:EM Energy Harvesting

    Keyword:EM Energy Harvesting

    Research period: 2024

  • Research theme:Wireless Power Transfer

    Keyword:Wireless Power Transfer

    Research period: 2024

  • Research theme:Millimeter wave and terahertz CMOS signal source

    Keyword:Millimeter wave and terahertz CMOS signal source

    Research period: 2024

  • Research theme:Millimeter wave and Terahertz interconnects

    Keyword:Millimeter wave and Terahertz interconnects

    Research period: 2024

  • Research theme:Sensor Interface System

    Keyword:Sensor Interface System

    Research period: 2024

  • Research theme:CMOS Front ends Circuits and Systems

    Keyword:CMOS Front ends Circuits and Systems

    Research period: 2024

  • Research theme:Development of beamforming, phase-array technology for 5G, B5G, SATCOM

    Keyword:Phase noise, above 100GHz oscillators, post-5G, low cost, CMOS

    Research period: 2023.5 - 2026.3

  • Research theme:Development of compact and highly efficient wireless power transfer system

    Keyword:WPT system, efficiency, compact

    Research period: 2020.5 - 2023.5

  • Research theme:Development of CMOS PA (Power Amplifer) for beyond 5G (B5G) applications

    Keyword:Phase noise, above 100GHz oscillators, post-5G, low cost, CMOS

    Research period: 2020.4 - 2026.3

  • Research theme:Development of above-100GHz CMOS Oscillators for post-5G applications

    Keyword:Phase noise, above 100GHz oscillators, post-5G, low cost, CMOS

    Research period: 2018.4 - 2022.3

  • Research theme:Development of compact and highly efficient wireless power transfer system

    Keyword:WPT system, efficiency, compact

    Research period: 2014.5 - 2020.5

  • Research theme:Low power CMOS system of sensor network applications

    Keyword:low power, sensor network, CMOS circuits

    Research period: 2013.4 - 2015.3

  • Research theme:CMOS Front-End for TV White space applications.

    Keyword:TV White space, CMOS front end

    Research period: 2012.4 - 2016.3

  • Research theme:Ultra-low power CMOS transmitter

    Keyword:CMOS, Ultra low power

    Research period: 2012.4 - 2013.3

  • Research theme:Development of low power Digital to Analog converter

    Keyword:low power, fibonacci series, DAC

    Research period: 2008.4 - 2010.3

  • Research theme:Development of ADPLL in 0.18 um CMOS process

    Keyword:PLL(phase locked loop), ADPLL(all-digital phase-locked loop),DCO (digitally-controlled oscillator), WLAN

    Research period: 2007.4 - 2010.3

  • Research theme:IEEE802.11b規格の無線LAN用オンチップCPW線路整合回路付き一体型RFフロント・エンドの開発

    Keyword:System LSI,無線LAN,IEEE802.11b,マイクロ波回路

    Research period: 2006.4 - 2007.3

  • Research theme:(i) マイクロ波伝送線路およびそれを用いた小型受動デバイスの開発

    Keyword:マイクロ波回路、電磁界解析、マイクロ波計測

    Research period: 2003.3 - 2005.3

Awards

  • 2022 Asian Wireless Power Transfer Workshop (Student Award)

    2022.12   IEICE (The Institute of Electronics, Information and Communications Engineers)   This award was given to the best paper presented by the students supervised by me at the workshop.

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    A self-impedance matching which reduces the circuit size and losses is proposed for a 5G rectifier by using a voltage doubler and a half-wave rectifier where the later operates as a virtual dc source to cancel out the junction capacitance of the voltage doubler. Furthermore, an inductance of 2 nH was realized by Defected Ground Structure (DGS) topology which is loaded between these two elements for further improvement of the rectifier’s performance. Without any external matching circuits, the proposed rectifier provides more than 65% flat efficiency in the frequency band of 3.5 GHz to 4.5 GHz with an overall circuit size of 0.756 cm2 only.

  • 3nd Thailand Japan Microwave Student Workshop (Presentation Award)

    2022.11   IEICE (The Institute of Electronics, Information and Communications Engineers)   This award was given to the best paper presented by the students supervised by me at a symposium jointly organized by Japan and Thailand side named as Thailand-Japan Microwave Workshop.

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    For next-generation wireless communication, sub-terahertz band targeting more than 100Gbps is
    already started to get explored. To meet the stringent requirement of high-performance and low-loss systems, both active and passive components are necessary to be researched for the on-chip
    applications. At high frequencies, Substrate Integrated Waveguide (SIW) outperforms
    transmission lines, but for on-chip implementation, the size becomes too bulky. In this work, the
    possibility of implementing a miniaturized high-Q SIW resonator is explored in CMOS
    technology. Measurement results at the 200GHz band show the promising future of such cavities
    to design on-chip filters, antennas, low-phase noise VCO, and other components for sub-THz
    applications.

  • 3nd Thailand Japan Microwave Student Workshop (Best Presentation Award)

    2022.11   IEICE (The Institute of Electronics, Information and Communications Engineers)   This award was given to the best paper presented by the students supervised by me at a symposium jointly organized by Japan and Thailand side named as Thailand-Japan Microwave Workshop.

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    We developed a low magnetic loss metamaterial by proposing a multi-ring-resonator (MRR).
    Then, we employed it to build a highly efficient WPT system with a 7×7 mm2 compact receiver
    (RX) for biomedical applications. The transmitter (TX) consists of a feeding inductive loop and
    three-stacked layers of the proposed MRR metamaterial forming a meta-TX. The achieved high
    coupling by the proposed MRR metamaterial enabled the realization of a matching-less rectifier
    that was integrated on the backside of the RX substrate without any additional area. The measured
    WPT system's RF-RF and RF-dc efficiencies were 51% and 39%, respectively.

  • 2nd Thailand Japan Microwave Student Workshop (Best Presentation Award)

    2021.12   IEICE (The Institute of Electronics, Information and Communications Engineers)   This award was given to the best paper presented by the students supervised by me at a symposium jointly organized by Japan and Thailand side named as Thailand-Japan Microwave Workshop.

  • 2021(第18)年度無線電力伝送コンテスト(ユニークなWPTコンテスト)(最優秀賞)

    2021.12   電子情報通信学会   電子情報通信学会 無線電力伝送研究専門委員会(IEICE WPT 研究会)では、2021年12 月研究会に「ユニーク」をテーマにした、WPT 技術・アイデアのショートプレゼンコンテ ストを開催した。主な評価項目は「ユニークさ・斬新さ」であり、何にも縛られない自由な発想の技術・アイデアを募集した。通常の研究会とは趣旨が異なるため、実現に至っていないアイデアまで、幅広い内容が投稿された。厳正なる審査の結果、WPT 研究会より 1チーム、コンテスト委員会より 1 チームを表彰された。その最優秀賞を受賞したのポカレルがリードしているチームでした。

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    電子情報通信学会 無線電力伝送研究専門委員会(IEICE WPT 研究会)では、2021年12 月研究会に「ユニーク」をテーマにした、WPT 技術・アイデアのショートプレゼンコンテ
    ストを開催した。主な評価項目は「ユニークさ・斬新さ」であり、何にも縛られない自由な発想の技術・アイデアを募集した。通常の研究会とは趣旨が異なるため、実現に至っていないアイデアまで、幅広い内容が投稿された。厳正なる審査の結果、WPT 研究会より 1チーム、コンテスト委員会より 1 チームを表彰された。その最優秀賞を受賞したのポカレルがリードしているチームでした。

  • 2019 IEEE Excellent Stuent Award of the IEEE Fukuoka Section (指導学生と共同)

    2020.2  

  • 2019年度電子情報通信学会無線電力伝送研究会WPTコンテスト~目の前の壁を越えろ!!(最優秀賞)

    2019.3   IEICE (電子情報通信学会 無線電力伝送研究会)   無線電力伝送コンテストにおいて、最優秀賞を受賞しました。

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    この賞は、国内で開催された無線電力伝送コンテストで受賞したものである。魏業、大学から多くのチームが参加していたた、
    新規性、将来性をもとに審査され、最優秀賞を受賞した。このコンテストで、無線で体内への電力を伝送する技術を提案し、
    今後ペースメーカーや体内埋め込みセンサー、医療機器をバッテリー無しで動作させる技術を提案した。

  • BEST ELEX AWARD 2016

    2017.9   This best paper award is awarded to the authors of those paper which was selected as the best one of those published in the previous year of ELEX journal.

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    本賞、電子通信学会誌ELEX詩で2016.1-12までの一年間の期間で掲載された学術論文の中で最優秀の1件の論文に報奨するものであるであるため。

  • 感謝賞

    2008.6   在日エジプト大使館   感謝賞

  • LETTER OF APPRECIATION

    2008.6   Letter of Appreciation

  • Travel Grant

    2004.8  

  • 優勝発表賞

    2003.2   東京大学   2002度東京大学21世紀COE研究拠点形成アシスタント(RA)発表会でも優勝発表賞

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Papers

  • An Efficient Inverse Modeling Method Using Translator-inspired Neural Network and Dual-annealing for a Compact WPT System Reviewed International journal

    Xin Jiang; Ramesh K. Pokharel; Adel Barakat

    IEEE Transactions on Antennas and Propagation   72 ( 4 )   3282 - 3291   2024.4   ISSN:0018-926X eISSN:1558-2221

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    This article proposes a novel prediction method for efficient inverse modeling of a compact wireless power transfer (WPT) system. Impedance matching circuit analysis with admittance (J-) inverter theory is used for coupling analysis. Then, a simple translator-inspired neural network is proposed to predict scattering (S-) parameters from 100 MHz to 1 GHz for each coupling case. The training dataset comprises 2900 randomly generated dimensions and the corresponding S-parameters via full-wave simulation. Consequently, the power transfer efficiency (PTE) can be figured out using the S-parameter, which varies from different coupled modes. Then, a dual-annealing algorithm is leveraged to find the best dimensions. The predicted dimensions, including the transmitter (Tx) and receiver (Rx) layouts, values of the etched capacitors, and WPT distances, meet the design purposes. Compared to the state-of-the-art approaches, the proposed method can efficiently optimize the WPT system with desired frequencies. The proposed inverse model reveals new insights and understanding of the prediction and optimization of inductively coupled WPT.

    DOI: 10.1109/TAP.2024.3372149

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    Other Link: https://ieeexplore.ieee.org/abstract/document/10462915

  • Reliable Multiple Cascaded Resonators WPT System Using Stacked Split-Ring Metamaterial Passive Relays Reviewed International journal

    Mohamed Aboualalaa; Ramesh K. Pokharel

    IEEE Transactions on Instrumentation and Measurement   72 ( xx )   xx - xx   2023.10   ISSN:0018-9456 eISSN:1557-9662

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    DOI: 10.1109/TIM.2023.3324672

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    Other Link: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10285869

  • Low Pass Filtering Admittance Inverter for High out-of-band Rejection Millimeter-Wave on-Chip BPF Reviewed International journal

    Adel Barakat and Ramesh K. Pokharel

    IEEE Transactions on Circuits and Systems II: Express Brief   70 ( 11 )   3963 - 3967   2023.8   ISSN:1549-7747 eISSN:1558-3791

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    DOI: 10.1109/TCSII.2023.3283532

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    Other Link: https://ieeexplore.ieee.org/abstract/document/10146024

  • Hybrid SRR-based Stacked Metamaterial for Miniaturized Dual-band Wireless Power Transfer System Reviewed International journal

    Xin Jiang, Ramesh K. Pokharel, Adel Barakat, Kuniaki Yoshitomi

    IEEE Transactions on Antennas and Propagation   71 ( 6 )   5014 - 5024   2023.7   ISSN:0018-926X eISSN:1558-2221

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/TAP.2023.3262977

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    Other Link: https://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=10091755

  • Design of a K-Band VCO Implementing T-Type LC Network in 0.18-um CMOS Technology Reviewed International journal

    N. Jahan and R. K. Pokharel

    IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS   33 ( 7 )   1039 - 1042   2023.7   ISSN:2771-957X eISSN:2771-9588

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/LMWT.2023.3266315

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    Other Link: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=10109110

  • Energy Harvesting Rectenna Using High-gain Triple-band Antenna for Powering Internet-of-Things (IoT) Devices in a Smart Office Reviewed International journal

    M. Ali and Ramesh K. Pokharel

    IEEE Trans. on Instrumentation and Measurement   72 ( 1 )   2001312   2023.1   ISSN:0018-9456 eISSN:1557-9662

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/TIM.2023.3238050

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    Other Link: https://ieeexplore.ieee.org/document/10021985

  • High PAE CMOS power amplifier with 44.4% FBW using superimposed dual-band configuration and DGS inductors Reviewed International journal

    O. Algnar, A. Barkat, and R. K. Pokharel

    IEEE Microwave and Wireless Components Letters   32 ( 7 )   1423 - 1426   2022.12   ISSN:1531-1309 eISSN:1558-1764

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    A two-stage 180-nm CMOS wideband (14&#x2013;22 GHz) power amplifier (PA) with a superimposed staggered technique and defected-ground-structure (DGS) inductors is introduced, where a wideband peaking main stage is designed at the center frequency; then, a superimposed dual-band (SDB) driver stage is proposed to obtain the optimally flat gain response over the whole bandwidth (BW). Also, DGS inductors are used to enhance the power added efficiency (PAE) of the implemented PA by decreasing the matching circuits&#x2019; insertion losses. The proposed PA achieved a power gain of 12 dB at a total chip area of 0.564 mm<inline-formula> <tex-math notation="LaTeX">$^{2}$</tex-math> </inline-formula>. Also, at the center frequency, it achieved a saturated output power of 16.6 dBm exhibiting the smallest reported amplitude-to-phase (AM-PM) distortion (2.1<inline-formula> <tex-math notation="LaTeX">$^{\circ})$</tex-math> </inline-formula> and group delay (GD) variations (<inline-formula> <tex-math notation="LaTeX">$\pm$</tex-math> </inline-formula>66 ps). Finally, it gives among the highest fractional bandwidth (FBW) (44.4%) and the PAE (18.7%) so far. Also, it achieves an error vector magnitude of <inline-formula> <tex-math notation="LaTeX">$-$</tex-math> </inline-formula>25 dB at 9.3-dBm output power for a 400-MHz 5G-NR signal.

    DOI: 10.1109/LMWC.2022.3189347

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    Other Link: https://ieeexplore.ieee.org/abstract/document/9829838

  • Capacitive Feedbacked Cold-Phase Compensator Analog Pre-Distorter and PAE Enhancer for 5G-NR K-Band CMOS PAs Reviewed International journal

    O. Algnar, A. Barkat, and R. K. Pokharel

    IEEE Transactions on Circuits and Systems I: Regular Papers.   69 ( 12 )   4969 - 4980   2022.12   ISSN:1549-8328 eISSN:1558-0806

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    A K-band two-stage power amplifier (PA) with capacitive-feedbacked cold-phase compensator (cold-PC) linearizer and power-added-efficiency (PAE) enhancer is introduced in 180-nm CMOS technology. This cold-PC consists of two parts. First, a cold-FET analog pre-distorter (APD) with a new capacitive-feedbacked technique is proposed to improve the linear behavior of the PA by enhancing the corresponding APD&#x2019;s compensation slope. The proposed implementation has a reduced insertion loss and a minimal chip area overhead. Second, a low-pass two-tunable inductive and capacitive PC is proposed to solve the phase shift problem at intermediate nodes that would enhance the PAE of the stacked-transistors configuration. The implemented PA achieves, at 23.5-GHz, a maximum measured PAE of 21.2%, output power at the 1-dB compression point (OP<inline-formula> <tex-math notation="LaTeX">$_{\text{1dB } }$</tex-math> </inline-formula>) of 13.4-dBm, and saturated output power of 15-dBm using a total chip area of 0.58 mm<inline-formula> <tex-math notation="LaTeX">$^{\text{2 } }$</tex-math> </inline-formula>. Employing the proposed cold-PC results in a decrease of the measured error vector magnitude (EVM) of the 400-MHz 5G-NR of 64-QAM modulated signal and an increase of the OP<inline-formula> <tex-math notation="LaTeX">$_{\text{1dB } }$</tex-math> </inline-formula> and its PAE by 2.5-dB and 7%, respectively (enhancement by 78% and 72% from the original case, respectively), which, to the best of authors&#x2019; knowledge, is the highest reported enhancement of the linearizers of k-band PAs.

    DOI: 10.1109/TCSI.2022.3205367

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    Other Link: https://ieeexplore.ieee.org/document/9894111

  • Experimental Study of Effectiveness of Metasurface for Efficiency and Misalignment Enhancement of Near-Field WPT System Reviewed International journal

    M. Ali, Islam Mansour, and R. K. Pokharel

    IEEE Antennas and Wireless Propagation Letters   21 ( 10 )   2010 - 2014   2022.10   ISSN:1536-1225 eISSN:1548-5757

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    DOI: 10.1109/LAWP.2022.3188297

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    Other Link: https://ieeexplore.ieee.org/document/9815525

  • Dual-Band VCO Using High Quality Factor Two Orthogonally Located Inductors in 0.18-m CMOS Technology Reviewed International journal

    Islam Mansour, Marwa Mansour, Mohamed Aboualalaa, Ahmed Allam, Adel B Abdel-Rahman, Ramesh K Pokharel, Mohammed Abo-Zahhad

    IEEE Microwave and Wireless Components Letters   32 ( 12 )   1431 - 1434   2022.7   ISSN:1531-1309 eISSN:1558-1764

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    DOI: 10.1109/LMWC.2022.3179002

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    Other Link: https://ieeexplore.ieee.org/abstract/document/9791101

  • On-Chip Millimeter-Wave DGS Based Bandstop Filter in 0.18-mu m CMOS Process Invited Reviewed International journal

    #Samundra K Thapa, Ramesh K Pokharel, #Baichuan Chen, Adel Barakat

    IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS   69 ( 6 )   2732 - 2736   2022.6   ISSN:1549-7747 eISSN:1558-3791

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    Defected Ground Structure (DGS) based on-chip bandstop filter (BSF) design is proposed for millimeter-wave applications. In the proposed structure, a capacitively loaded T-shape resonator is embedded in the original DGS resonator, which forms two high quality ( ${Q}$ -) factor small loop resonators. Moreover, this structure, in combination with the feedline and series capacitor, independently realizes the position of two transmission poles: one at each side of the parallel resonance without increasing the layout size. The proposed BSF presents a sharp scattering (S-) parameter response due to the appearance of two transmission poles. As a result, the loaded ${Q}$ -factor and negative group delay of the BSF are improved. The prototype of the proposed BSF is fabricated in 0.18- $\mu \text{m}$ Complementary Metal-Oxide-Semiconductor (CMOS) process and measured. The measurement result shows a return loss of 1.78 dB at 53.2 GHz center stopband frequency with the negative group delay of 161 pS. The measurement results also agree well with the electromagnetic simulation results. Without pads, the active area of the prototyped BSF is only 0.024 mm2.

    DOI: 10.1109/TCSII.2022.3158995

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    Other Link: https://ieeexplore.ieee.org/abstract/document/9733395

  • Design of 50-GHz Low Phase Noise VCO Employing Two-Branches DGS Resonator in 0.18-mu m CMOS Technology Reviewed International journal

    #Baichuan Chen, Ramesh K Pokharel, #Samundra K Thapa, Nusrat Jahan, Adel Barakat

    IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS   32 ( 10 )   1203 - 1206   2022.5   ISSN:1531-1309 eISSN:1558-1764

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    This letter presents a $V$ -band low phase noise voltage-controlled oscillator (VCO) design using a novel integrated two-branches defected ground structure (DGS) resonator in 0.18- $\mu \text{m}$ complementary metal-oxide-semiconductor (CMOS) technology. The proposed DGS resonator is realized in the top metal layer (M6) which has not only a higher quality factor than its predecessors but is also effective to reduce the length of interconnects. The measured carrier frequency and phase noise are 49 GHz and -122.05 dBc/Hz (-102.58 dBc/Hz) at 10-MHz (1-MHz) offset frequencies, respectively. The VCO core consumes 5.5 mW of dc power from the dc supply, which results in a figure of merit (FoM) of -189 dBc/Hz. The proposed VCO using the two-branches DGS resonator may give an alternative low-cost solution for designing a high-performance VCO or frequency synthesizer at $V$ -band and beyond.

    DOI: 10.1109/LMWC.2022.3171405

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    Other Link: https://ieeexplore.ieee.org/abstract/document/9773303

  • Ku-Band Low Phase Noise VCO Using High-Quality Factor Transformer in 0.18-mu m CMOS Technology Reviewed International journal

    Islam Mansour, Marwa Mansour, Mohamed Aboualalaa, Ahmed Allam, Adel B Abdel-Rahman, Ramesh K Pokharel, Mohammed Abo-Zahhad

    IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS   32 ( 10 )   1207 - 1210   2022.5   ISSN:1531-1309 eISSN:1558-1764

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/LMWC.2022.3167705

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    Other Link: https://ieeexplore.ieee.org/abstract/document/9781797

  • A W-Band Compact Substrate Integrated Waveguide Bandpass Filter With Defected Ground Structure in CMOS Technology Reviewed International journal

    Baichuan Chen, Samundra K Thapa, Adel Barakat, Ramesh K Pokharel

    IEEE Transactions on Circuits and Systems II: Express Briefs   69 ( 3 )   889 - 893   2022.3   ISSN:1549-7747 eISSN:1558-3791

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Institute of Electrical and Electronics Engineers ({IEEE})  

    This brief proposes the first on-chip bandpass filter (BPF) based on substrate integrated waveguide (SIW) for W-band applications. Slot-loaded, folded ridge and quarter mode technology is used to reduce the cavity size. The coupling characteristic of two folded ridged quarter mode substrate integrated waveguide (QMSIW) cavities implemented in CMOS technology is investigated. A simplified equivalent lumped-element circuit model of the proposed wide-band BPF approach is provided and applied to study the coupling characteristic of slot-loaded folded ridged QMSIW cavity. Then, a novel coupling method using a defected ground structure is proposed to realize a proper coupling intensity for BPF design. Finally, the proposed BPF design is implemented in a commercial complementary metal-oxide-semiconductor (CMOS) technology, fabricated, and measured. The active size of the proposed cavity resonator is only 405 μ m ×185μ m (0.22λ g × 0.1 λ g), and the measured insertion loss ( |S 21) is 3.15 dB with a central frequency of 85.5 GHz.

    DOI: 10.1109/TCSII.2021.3123655

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    Other Link: https://ieeexplore.ieee.org/abstract/document/9592631

  • Compact and Efficient WPT System to Embedded Receiver in Biological Tissues Using Cooperative DGS Resonators Reviewed International journal

    Shimaa Alshhawy, Adel Barakat, Kuniaki Yoshitomi, Ramesh K Pokharel

    IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS   69 ( 3 )   869 - 873   2022.3   ISSN:1549-7747 eISSN:1558-3791

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    Language:English   Publishing type:Research paper (scientific journal)   Publisher:Institute of Electrical and Electronics Engineers ({IEEE})  

    This brief presents a compact and efficient resonance-shift insensitive wireless power transfer (WPT) system. This is possible by using a small electrical length defected ground structure (DGS) resonator, which is found effective against the resonance-shift phenomenon resulted from the higher permittivity of the tissue. Tissue has two undesired effects on a WPT system: (i) reduced coupled quality factor, and (ii) self-resonance shifting that leads to mismatch loss. So, the efficiency of a WPT system degrades in a tissue environment. Then, using the small electrical length DGS, we build a WPT transmitter (TX) using three cooperative DGS resonators to mitigate both issues. The fabricated prototype operates at 49 MHz in the air and tissue. This shows no change in operating frequency when the same receiver (Rx) is kept in the air or embedded inside tissues, which proves the effectiveness of the proposed cooperative DGS-WPT system against the resonance shift. The measured efficiency is 62% when the RX is embedded inside the tissue and is 68% in the air.

    DOI: 10.1109/TCSII.2021.3123954

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  • A W-Band 0.01 mm2 Cavity Resonator Employing Slot-Loaded Shielded Folded Ridged Quarter-Mode in CMOS Technology Reviewed International journal

    #Baichuan Chen, #Samundra K Thapa, Adel Barakat, Ramesh K Pokharel

    IEEE Microwave and Wireless Components Letters   32 ( 2 )   113 - 116   2022.2   ISSN:1531-1309 eISSN:1558-1764

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    This letter proposes a W -band compact cavity resonator for future applications of on-chip bandpass filters (BPFs), oscillators, phase shifters, and so on. To mitigate the leakage from the open sides of a folded ridged quarter-mode substrate integrated waveguide (SIW) cavity, shielding structures made of vias are employed. Two parallel inductive slots are etched on the top metal layer for further size reduction. Later, the one-port cavity is converted to a two-port cavity resonator and utilized in the design of W -band BPF. The proposed design is implemented in a commercial complementary metal-oxide-semiconductor (CMOS) technology, fabricated, and measured. The active size of the proposed cavity resonator is only 99 mu text{m},,boldsymbol {times },,99,,mu text{m} ( 0.054 boldsymbol {lambda }-{mathbf {g } },,{ boldsymbol {times } },,0.054{} boldsymbol {lambda }-{mathbf {g } } ), and the measured insertion loss ( vert S-{21}vert ) is 2.26 dB.

    DOI: 10.1109/LMWC.2021.3122149

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  • A multimode metamaterial for a compact and robust dualband wireless power transfer system Reviewed International journal

    Xin Jiang, Ramesh K Pokharel, Adel Barakat, Kuniaki Yoshitomi

    Scientific Reports   11 ( 1 )   2021.12

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    DOI: 10.1038/s41598-021-01677-6

    Other Link: https://www.nature.com/articles/s41598-021-01677-6

  • Analysis and design of diode physical limit bandwidth efficient rectification circuit for maximum flat efficiency, wide impedance, and efficiency bandwidths Reviewed International journal

    Babita Gyawali, Samundra K Thapa, Adel Barakat, Kuniaki Yoshitomi, Ramesh K Pokharel

    SCIENTIFIC REPORTS   11 ( 1 )   2021.10

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    DOI: 10.1038/s41598-021-99405-7

    Other Link: https://www.nature.com/articles/s41598-021-99405-7

  • A multiband VCO using a switched series resonance for fine frequency tuning sensitivity and phase noise improvement Reviewed International journal

    Islam Mansour, Marwa Mansour, Mohamed Aboualalaa, Ahmed Allam, Adel B Abdel-Rahman, Ramesh K Pokharel, Mohammed Abo-Zahhad

    IEEE Transactions on Very Large Scale Integration (VLSI) Systems   29 ( 12 )   2163 - 2171   2021.10

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    DOI: 10.1109/TVLSI.2021.3115050

    Other Link: https://ieeexplore.ieee.org/document/9559736

  • Design of Low Phase Noise VCO Considering C/L Ratio of LC Resonator in 0.18-μm CMOS Technology Reviewed International journal

    2021.5

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    A voltage-controlled oscillator (VCO) is usually designed by maximizing the quality (Q-) factor of the LC-tank resonator to realize a low phase noise. For the same frequency, the ratio of C/L affects the loaded Q-factor (QL) and then phase noise of the VCO. This affect has not been considered so far in the design of VCO because the conventional on-chip spiral inductor cannot be optimized for C/L ratio. This brief first investigates the effects of C/L ratio on the phase noise, and a design methodology for optimized C/L ratio using defected ground structure (DGS) resonator is presented. Then, the resonators were further evaluated based on LgL-product simulation for a fixed Ibias. Employing the proposed resonator, a very low phase noise KUband VCO is designed and implemented in 0.18-lm CMOS technology. The measurement result shows that the proposed VCO has a phase noise of -110.77 dBc/Hz at 1 MHz offset of 17.5 GHz carrier frequency and a frequency tuning range of 8.7%. The VCO consumes 2.3 mW power, which results in a figure of merit (FoM) of -191.95 dB.

    DOI: 10.1109/TCSII.2021.3079309

    Other Link: https://ieeexplore.ieee.org/abstract/document/9428594/authors#authors

  • X-Band Feedback Type Miniaturized Oscillator Design With Low Phase Noise Based on Eighth Mode SIW Bandpass Filter Invited Reviewed International journal

    Samundra K Thapa, Baichuan Chen, Adel Barakat, Kuniaki Yoshitomi, Ramesh K Pokharel

    IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS   31 ( 5 )   485 - 488   2021.5

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    DOI: 10.1109/LMWC.2021.3064602

    Other Link: https://ieeexplore.ieee.org/abstract/document/9373441

  • Wireless power transfer system rigid to tissue characteristics using metamaterial inspired geometry for biomedical implant applications Invited Reviewed International journal

    Ramesh K Pokharel, Adel Barakat, Shimaa Alshhawy, Kuniaki Yoshitomi, Costas Sarris

    Scientific Reports   11:5868 ( 11:5868 )   1 - 10   2021.3

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    DOI: /10.1038/s41598-021-84333-3

    Other Link: https://www.nature.com/articles/s41598-021-84333-3

  • Simultaneous Wireless Power and Information Transfer Using Coupled Co-Existing Defected Ground Structure Resonators Invited Reviewed International journal

    Adel Barakat, Shimaa Alshhawy, Kuniaki Yoshitomi, Ramesh K Pokharel

    IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS   68 ( 2 )   632 - 636   2021.2

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    DOI: 10.1109/TCSII.2020.3016385

    Other Link: https://ieeexplore.ieee.org/abstract/document/9166524

  • Improvement of Magnetic Field for Near-Field WPT System Using Two Concentric Open-Loop Spiral Resonators Invited Reviewed International journal

    Mohamed Aboualalaa, Islam Mansour, Adel Barakat, Kuniaki Yoshitomi, Ramesh K Pokharel

    IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS   30 ( 10 )   993 - 996   2020.10

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    DOI: 10.1109/LMWC.2020.3016136

    Other Link: https://ieeexplore.ieee.org/abstract/document/9173565

  • Dual-band CPW rectenna for low input power energy harvesting applications Invited Reviewed International journal

    Mohamed Aboualalaa, Islam Mansour, Adel B Abdelrahman, Ahmed Allam, Mohamed Abo-zahhad, Hala Elsadek, Ramesh K Pokharel

    IET CIRCUITS DEVICES & SYSTEMS   14 ( 6 )   892 - 897   2020.9

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    DOI: 10.1049/iet-cds.2020.0013

    Other Link: https://digital-library.theiet.org/content/journals/10.1049/iet-cds.2020.0013

  • Analysis and Implementation of High-Q CT Inductor for Compact and Wide-Tuning Range Ku-Band VCO Invited Reviewed International journal

    Islam Mansour, Mohamed Aboualalaa, Adel Barakat, Ahmed Allam, Adel B Abdel-Rahman, Mohammed Abo-Zahhad, Ramesh K Pokharel

    IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS   30 ( 8 )   802 - 805   2020.8

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    DOI: 10.1109/LMWC.2020.3004753

    Other Link: https://ieeexplore.ieee.org/abstract/document/9134404

  • Utilization of Multi-Resonant Defected Ground Structure Resonators in the Oscillator Feedback for Phase Noise Reduction of K-Band VCOs in 0.18-μ m CMOS Technology Reviewed International journal

    67 ( 4 )   1115 - 1125   2020.4

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    This work proposes a new theory to reduce the phase noise of K-band Voltage-Controlled Oscillators (VCOs) in Complementary Metal Oxide Semiconductor (CMOS) process by introducing one or more transmission poles around the parallel resonance of an LC-tank circuit. Introduction of transmission poles beside the parallel resonance of the LC-tank circuit sharpens the skirt characteristics of the Scattering (S) parameters of the resonators. In return, sharp S-parameters slope enhances the resonator loaded quality (Q) factor without compromising the unloaded Q-factor. In addition, the transmission pole can be realized near the second harmonic of the oscillation. This allocation of the transmission pole leads to the cancellation of this second harmonic and a further reduction of the phase noise. The proposed theory is verified by three different designs based on defected ground structure (DGS) resonators. These designs realized a low-band transmission pole before the parallel resonance, a high-band transmission pole after the parallel resonance, and dual-band transmission poles around the parallel resonance. First, each design is verified and compared to the others using circuit and electromagnetic simulations to establish the Q-factor improvement. Then, each of the resonators is utilized in a differential VCO topology and the phase noise reduction in post-layout simulations is confirmed. Finally, two chips are fabricated in 0.18-μ m CMOS technology and measured. The measurement results are in good agreement with the simulations, which confirm our claim about the proposed theory.

    DOI: 10.1109/TCSI.2020.2965007

  • A −192.7-dBc/Hz FOm Ku-band VCO using a DGS resonator with a high-band transmission pole in 0.18-μm CMOS technology Reviewed International journal

    29 ( 12 )   814 - 817   2019.12

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    This letter presents the improvement of the phase noise (PN) of a voltage-controlled oscillator (VCO) by using a defected ground structure (DGS) resonator with a high-band transmission pole. The proposed DGS resonator has two loops in a coplanar stripline topology. The outer loop is loaded by a series capacitance, which produces the high-band transmission pole. The overall combination has a parallel capacitor to generate the necessary parallel resonance for the VCO operation. This proposed DGS resonator has a sharper impedance and frequency response slope, which results in an improved quality factor. In return, utilization of this DGS resonator into a KU-Band VCO reduces its PN. The prototyped VCO in 0.18-µm CMOS oscillates at 15.52 GHz and shows a PN of −111.27 and −134.07 dBc/Hz at 1- and 10-MHz offset, respectively, while consuming 3.3-mW power. The VCO has a frequency tuning range of 9.5%, which results in a figure of merit (FoM) of −192.7 dB.

    DOI: 10.1109/LMWC.2019.2950525

  • Separation-Misalignment Insensitive WPT System Using Two-Plane Printed Inductors Reviewed International journal

    Shimaa Alshhawy, Adel Barakat, Kuniaki Yoshitomi, Ramesh K. Pokharel

    IEEE Microwave and Wireless Components Letters   29 ( 10 )   683 - 686   2019.10

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    DOI: 10.1109/LMWC.2019.2935621

  • High Efficiency and Small Group Delay Variations 0.18-μ m CMOS UWB Power Amplifier Reviewed International journal

    66 ( 4 )   592 - 596   2019.4

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    A new staggered tuning technique, by optimizing the inter-stage matching circuit, is proposed to realize a power amplifier (PA) with small group delay (GD) variations and excellent gain flatness across the full bandwidth of ultra-wideband (UWB) system. The proposed PA consists of two stages where the first stage is constructed by a current-reuse with shunt RC feedback topology to realize gain flatness and low power consumption. The design is implemented in 0.18 μ m commentary metal-oxide semiconductor (CMOS) technology, fabricated, and tested. The proposed PA has a measured power gain (|S 21 |) of 11.5 ± 0.7 dB, maximum power-added efficiency (PAE) of 26% and an output 1-dB compression point of 9 dBm, respectively, and this is the maximum PAE among CMOS PAs that cover the full bandwidth of UWB system. Besides, the PA has a small GD variations of ± 68 ps which is the lowest till date.

    DOI: 10.1109/TCSII.2018.2870165

  • Design and Implementation of Dual-Mode Inductors for Dual-Band Wireless Power Transfer Systems Reviewed International journal

    Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    IEEE Transactions on Circuits and Systems II: Express Briefs   2018.12

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    DOI: 10.1109/TCSII.2018.2883671

  • Design of Low-Loss Coplanar Transmission Lines Using Distributed Loading for Millimeter-Wave Power Divider/Combiner Applications in 0.18-μm CMOS Technology Reviewed International journal

    66 ( 12 )   5221 - 5229   2018.12

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    This paper presents a new type of a low-loss miniaturized coplanar-waveguide (CPW) transmission line (TL) by employing distributed loading, capacitors and inductors, in 0.18-μm complementary metal-oxide-semiconductor (CMOS) technology. The capacitors are realized by vertical parallel plates made of vias, and a group of open stubs inserted to the signal line, whereas the inductors are realized by high impedance lines. Then, the proposed CPW-TL is employed to design a miniaturized millimeter wave ultra-wideband low-loss Wilkinson power divider/combiner (WPD/C). The proposed distributed loading results in reducing each WPD/C arm length by more than 50% without changing its characteristic impedance and insertion loss (IL). The design is fabricated in 0.18-μm CMOS technology and tested. The measured results show a wideband performance from dc to 67 GHz with 1-dB IL and isolation greater than 15 dB from 36 to 67 GHz. In addition, the fabricated WPD/C achieves an excellent amplitude imbalance and phase imbalance of less than 0.16 dB and 0.45°, respectively. The core chip size is 336 × 165 μm 2 , which is almost 32.8% compact compared to the recently proposed WPD in the same technology.

    DOI: 10.1109/TMTT.2018.2873381

  • Ultra Compact 60 GHz Tapped Line Combline BPF with Two Transmission Zeros Using Defected Ground Structures Reviewed International journal

    Elsayed Elsaidy, Adel Barakat, Member, Adel B. Abdel, Rahman, Ahmed Allam, and Ramesh K. Pokharel

    IEEE TRANSACTIONS ON COMPONENTS, PACKAGING AND MANUFACTURING TECHNOLOGY   1 - 7   2018.12

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  • Design Approach for Efficient Wireless Power Transfer Systems during Lateral Misalignment Reviewed International journal

    Adel Barakat, Kuniaki Yoshitomi and Ramesh K. Pokharel

    IEEE Transactions on Microwave Theory and Techniques   (In press)   2018.12

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  • Design Approach for Efficient Wireless Power Transfer Systems during Lateral Misalignment Reviewed International journal

    Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    IEEE Transactions on Microwave Theory and Techniques   66 ( 9 )   4170 - 4177   2018.9

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    DOI: 10.1109/TMTT.2018.2852661

  • 22-GHz-Band Oscillator Using Integrated H-Shape Defected Ground Structure Resonator in 0.18-μ m CMOS Technology Reviewed International journal

    28 ( 3 )   233 - 235   2018.3

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    A novel 22-GHz-band oscillator using an integrated defected ground structure (DGS) resonator is presented for quasi-millimeter waveband applications. The DGS is etched on the first metal layer (M1) below a 50-Ω microstrip line on the top metal layer (M6) of 0.18-μm one-poly six-metal (1P6M) complementary metal-oxide-semiconductor (CMOS) technology. The proposed oscillator is fabricated using 0.18-μm CMOS technology, and the measured carrier frequency and phase noise are 22.88 GHz and-129.21 dBc/Hz (-108.05 dBc/Hz) at 10-MHz (1 MHz) offset frequency, respectively. The power dissipation is 6 mW that results in a figure of merit to be-188.8 dB. As the DGS resonator could be designed at any high frequency, it may give an alternative design approach of high performance voltage controlled oscillator and frequency synthesizers at K-band and beyond, thus alleviates the problem of self-resonance that a spiral inductor usually encounters at higher frequency.

    DOI: 10.1109/LMWC.2018.2801031

    Other Link: https://ieeexplore.ieee.org/abstract/document/8298526/

  • Dual Band VCO based on High Quality factor Switched Interdigital Resonator for Ku band using 180 nm CMOS Technology Reviewed International journal

    IEEE Transactions on Circuits and Systems II: Express Briefs   2018.3

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    A dual band and low phase noise Ku-band voltage-controlled oscillator (VCO) using 180 nm CMOS technology is presented in this brief. The proposed VCO employs a switched notch filter that can operate in the low and high band depends on the state of nmos transistor and has a quality factor that is higher than that of a conventional inductor-capacitor (LC) resonator. The proposed resonator doubles the quality factor compared to LC in the technology and reduces the total die area. The first band is realized by the switched interdigital resonator when nmos transistor is in the off state. Furthermore, the second band is realized by turning nmos transistor to the on state which is located between two fingers in the proposed resonator. The chip is implemented in 180nm CMOS technology, and found that the proposed VCO operates from 15.5 16.7Hz (low band) and 16.6 17.4 GHz (high band). At 1.8 V power supply, the power consumption of the oscillator core is 5.4mW and 7.2mW in the low and high-frequency bands respectively. The measured phase noise is &#x2013;107 dBc/Hz at 1MHz offset from 16.7 GHz carrier frequency.

    DOI: 10.1109/TCSII.2018.2817499

    Other Link: https://ieeexplore.ieee.org/abstract/document/8320300/

  • Design of compact frequency agile filter-antenna using reconfigurable ring resonator bandpass filter for future cognitive radios Reviewed International journal

    International Journal of Microwave and Wireless Technologies   83   22 - 31   2018.1

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    In this paper, a new miniaturized frequency agile filter-antenna with a wide reconfigurable frequency band is proposed for interweave cognitive radios (CRs). A tunable bandpass filter (BPF) composed of a symmetrical ring resonator is cascaded to the feed line of an ultra-wideband planar antenna. The structure of the proposed ring resonator BPF is simple and compact so that the total size of the proposed filter-antenna is smaller than that of a conventional system made of a separate antenna and BPF. The reconfigurability of the proposed filter-antenna is achieved by changing the operating frequency of the BPF by loading the ring resonator with a single varactor diode at its center. The fabricated prototype has successfully achieved a wide operational bandwidth of 1.43 GHz which covers continuous narrow bands from 4.65 to 6.08 GHz. Moreover, the operating tunable narrow bands have stable radiation characteristics. Good agreement between measurement and simulation results is demonstrated.

    DOI: DOI: 10.1017/S1759078717001556

    Other Link: https://www.cambridge.org/core/journals/international-journal-of-microwave-and-wireless-technologies/article/design-of-compact-frequency-agile-filterantenna-using-reconfigurable-ring-resonator-bandpass-filter-for-future-cognitive-radios/BC3CF90E7F2DE1293F

  • Dual-Band Defected Ground Structures Wireless Power Transfer System with Independent External and Inter Resonator Coupling Reviewed International journal

    #Fairus Tahar, Adel Barakat, #Redzuan Saad, Kuniaki Yoshitomi, Ramesh Pokharel

    IEEE Transactions on Circuits and Systems II: Express Briefs   64 ( 12 )   1372 - 1376   2017.12

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    This brief proposes a design methodology based on the admittance (J-) inverters for a dual-band wireless power transfer (WPT) system that employs two cascaded circulars defected ground structure (DGS) resonators with different capacitive loading to guarantee distinct resonances. A single microstrip line excites the two DGSs, and when two DGS resonators are coupled back to back, it transforms to a dual band pass filter leading to wireless power transfer at both bands. Each of the DGS resonators has independent coupling. Thus, the realized J-Inverters are designed independently. Also, we employ a single stub for the matching. This stub appears with a different length according to the operating frequency; hence, an independent external coupling is achieved at both frequencies. A compact size of 30 mm &#x00D7; 15 mm is fabricated achieving a WPT efficiency of more than 71% at a power transfer distance of 16 mm for both bands (0.3 GHz and 0.7 GHz).

    DOI: 10.1109/TCSII.2017.2740401

    Other Link: https://ieeexplore.ieee.org/abstract/document/8010857/

  • 1.06 FoM and Compact Wireless Power Transfer System Using Rectangular Defected Ground Structure Resonators Reviewed International journal

    F. Tahar, R. Saad, A. Barakat, Ramesh Pokharel

    IEEE Microwave and Wireless Components Letters   27 ( 11 )   1025 - 1027   2017.11

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    DOI: 10.1109/LMWC.2017.2750032

    Other Link: https://ieeexplore.ieee.org/abstract/document/8059822/

  • Ultracompact 60-GHz CMOS BPF Employing Broadside-Coupled Open-Loop Resonators Reviewed International journal

    IEEE Microwave and Wireless Components Letters   27 ( 9 )   818 - 820   2017.9

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    This letter presents a 60-GHz ultracompact on-chip bandpass filter (BPF). The designed filter is based on a unique structure, which consists of two overlapped broadside-coupled open-loop resonators, achieving a high level of miniaturization. Moreover, each resonator is loaded by a metal-insulator-metal capacitor to get further miniaturization. Defected ground structure pattern is constructed under the filter structure to enhance the insertion loss (IL). This BPF is designed and fabricated using a standard 0.18- μ complementary metal-oxide-semiconductor technology for millimeter-wave applications. The fabricated BPF chip size is 240 × 225-μ 2 including pads. The measured results agree well with the simulation ones and show that the BPF has an IL of 3.3 dB at 59.5-GHz center frequency, and a bandwidth of 12.9 GHz.

    DOI: 10.1109/LMWC.2017.2734771

    Other Link: https://ieeexplore.ieee.org/abstract/document/8010799/

  • Design and Application of Virtual Inductance of Square-Shaped Defected Ground Structure in 0.18-$\mu \text{m}$ CMOS Technology Reviewed International journal

    #Nusrat Jahan, #Siti Amalina Enche Ab Rahim, Adel Barakat, Takana Kaho, Ramesh Pokharel

    IEEE Journal of the Electron Devices Society   5 ( 5 )   299 - 305   2017.9

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    This paper investigates a possibility of application of a virtual inductor realized by an integrated defected ground structure (DGS) to design a front-end circuit in CMOS technology. Two types of DGS are analyzed and found that the inductance realized by a square-shaped DGS achieves smaller size and higher quality factor than an H-shaped DGS. Then, a 15-GHz low phase noise voltage-controlled oscillator (VCO) employing the proposed square-shaped DGS in 0.18-$\mu \text{m}$ 1P6M CMOS technology is designed. The fabricated VCO operates from 15.2 to 16.12 GHz and consumes 5-mW power. The measured phase noise is-132.08 dBc/Hz at 10-MHz offset frequency, and this results in the figure of merit (FoM) and FoM taking account of the area to be 189.1 and 199.9 dB, respectively.

    DOI: 10.1109/JEDS.2017.2728686

    Other Link: https://ieeexplore.ieee.org/abstract/document/7984797/

  • A CMOS ultrawideband pulse generator for 3-5 GHz applications Reviewed International journal

    IEEE Microwave and Wireless Components Letters   27 ( 6 )   584 - 586   2017.6

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    A low-power ultrawideband (UWB) pulse generator based on pulsed oscillator architecture for 3-5 GHz applications is proposed. The pulsed oscillator is improved, so it realizes binary phase shift keying (BPSK) modulation. Unlike ON-OFF keying or pulse-position modulation (PPM), BPSK can scramble the spectrum, so it can be used in high pulse rate applications without having spectral line problem. The signal structure in this design is burst mode of PPM+BPSK. The proposed UWB pulse generator was successfully implemented on 0.18-μm CMOS technology. The peak-to-peak amplitude of output pulse is about 220 mV with 50-ω load, the maximum power consumption is 4 mW at a raw data rate of 7.8 Mbps and the energy consumption is 32 pJ/pulse at a pulse rate of 125 Mpulses/s.

    DOI: 10.1109/LMWC.2017.2701306

    Other Link: https://ieeexplore.ieee.org/abstract/document/8010799/

  • A 1.9 GHz low-phase-noise complementary cross-coupled FBAR-VCO without additional voltage headroom in 0.18 μm CMOS technology Reviewed

    #Guoqiang Zhang, #Awinash Anand, Kousuke Hikichi(その他), Shuji Tanaka(その他), Masayoshi Esashi(その他), Ken Ya Hashimoto(その他), Shinji Taniguchi(その他), Ramesh Pokharel

    E100C ( 4 )   363 - 369   2017.4

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    A 1.9 GHz film bulk acoustic resonator (FBAR)-based low-phase-noise complementary cross-coupled voltage-controlled oscillator (VCO) is presented. The FBAR-VCO is designed and fabricated in 0.18 μ m CMOS process. The DC latch and the low frequency instability are resolved by employing the NMOS source coupling capacitor and the DC blocked cross-coupled pairs. Since no additional voltage headroom is required, the proposed FBAR-VCO can be operated at a low power supply voltage of 1.1 V with a wide voltage swing of 0.9 V. An effective phase noise optimization is realized by a reasonable trade-off between the output resistance and the trans-conductance of the cross-coupled pairs. The measured performance shows the proposed FBAR-VCO achieves a phase noise of-148 dBc/Hz at 1 MHz offset with a figure of merit (FoM) of-211.6 dB.

    DOI: 10.1587/transele.E100.C.363

    Other Link: https://search.ieice.org/bin/summary.php?id=e100-c_4_363

  • Class-C architecture for cross-coupled FBAR oscillator to further improve phase noise Reviewed

    POKHAREL RAMESH KUMAR

    IEICE Electronics Express   14 ( 5 )   1 - 5   2017.3

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

    DOI: 10.1587/elex.14.20170056

    Other Link: https://www.jstage.jst.go.jp/article/elex/14/5/14_14.20170056/_pdf

  • 60 GHz CMOS Circular Patch Antenna-on-Chip Reviewed International journal

    Adel Barakat, Ahmed Allam, Ramesh Kumar Pokharel

    Microwave Journal   60 ( 2 )   90 - 100   2017.2

  • A Novel Technique for Compact Size Wireless Power Transfer Applications Using Defected Ground Structures Reviewed International journal

    Hekal Sherif, Adel Barakat, Ahmed Allam, Adel B. Abdel-Rahman, Hongting Jia, Ramesh Kumar Pokharel

    IEEE Transactions on Microwave Theory and Techniques.   65 ( 2 )   591-599 - 599   2017.2

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    DOI: 10.1109/TMTT.2016.2618919

    Other Link: http://ieeexplore.ieee.org/abstract/document/7731202/

  • Design of Dual Band Microstrip Antenna with Enhanced Gain for Energy Harvesting Applications Reviewed International journal

    Mohamed Ali, Ahmed Allam, Adel B. Abdel-Rahman, Ramesh Kumar Pokharel

    IEEE Antennas and Wireless Propagation Letters   2017.1

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    DOI: 0.1109/LAWP.2017.2654353

    Other Link: http://ieeexplore.ieee.org/abstract/document/7731202/

  • Compact Wireless Power Transfer System Using Defected Ground Bandstop Filters Reviewed International journal

    Sherif Hekel, Adel Barakat, Ahmed Allam, Adel B. Adel-Rahman, Hongting Jia, Ramesh Kumar Pokharel

    IEEE Microwave and Wireless Components Letters   99 ( 10 )   2016.10

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    DOI: 10.1109/LMWC.2016.2601300

  • A 12 to 24 GHz High Efficiency Fully Integrated 0.18 μm CMOS Power Amplifier Reviewed International journal

    13 ( 14 )   20160551   2016.10

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    This letter presents a high efficiency, and small group delay variations 12–24GHz
    fully-integrated CMOS power amplifier (PA) for quasi-millimeter wave applications.
    Maximizing the power added efficiency (PAE), and minimizing the group delay variations in
    a wideband frequency range are achieved by optimizing the on-chip input, output, and inter-
    stage matching circuits. In addition, stagger tuning is employed for realizing excellent gain
    flatness. A two-stage CMOS PA using the proposed methodology is designed and ...

  • Compact Size On-Chip 60 GHz H-Shaped Resonator BPF Invited Reviewed International journal

    Nessim Mahmoud, Adel Barakat, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Kumar Pokharel

    IEEE Microwave and Wireless Components Letters   26 ( 9 )   681 - 683   2016.9

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    DOI: 10.1109/LMWC.2016.2597219

  • Compact frequency reconfigurable filtennas using varactor loaded T-shaped and H-shaped resonators for cognitive radio applications Reviewed International journal

    Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Ramesh Kumar Pokharel

    IET Microwaves Antennas & Propagation   4 ( 4 )   2016.3

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    DOI: 10.1049/iet-map.2015.070

    Other Link: http://digital-library.theiet.org/content/journals/10.1049/iet-map.2015.0700

  • Improved Gain 60 GHz CMOS Antenna with N-well Grid Reviewed

    ADEL TAWFIK MOHAMED MOHAMED BARAKAT, Hala Elsadek, Adel Abdelrahma, POKHAREL RAMESH KUMAR, Takana Kaho

    2016.3

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    Other Link: https://www.jstage.jst.go.jp/article/elex/advpub/0/advpub_13.20151115/_article

  • 60 GHz on-chip mixed coupled BPF with H-shaped defected ground structures Invited Reviewed International journal

    Adel Barakat, Ramesh Kumar Pokharel

    Electronics Letters   2016.3

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    DOI: 10.1049/el.2015.4465

    Other Link: http://digital-library.theiet.org/content/journals/10.1049/el.2015.4465

  • Performance Analysis of Multicode OCDM Networks Supporting Elastic Transmission With QoS Differentiation Reviewed International journal

    Ramesh Kumar Pokharel

    IEEE TRANSACTIONS ON COMMUNICATIONS   64 ( 2 )   741 - 752   2016.2

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    DOI: 10.1109/TCOMM.2015.2512922

    Other Link: http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=7368162&tag=1

  • Compact Modeling of Phase-Locked Loop Frequency Synthesizer for Transient Phase Noise and Jitter Simulation Reviewed International journal

    Lechang Liu, POKHAREL RAMESH KUMAR

    IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS   35 ( 1 )   166-170   2016.1

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    DOI: 10.1109/TCAD.2014.2354291

    Other Link: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6926919

  • Miniaturized low loss 60 GHz CMOS mixed coupled BPF with patterned ground shield Reviewed International journal

    Adel Barakat, Ramesh Kumar Pokharel

    Microwave and Optical Technology Letters   58 ( 3 )   697-699   2016.1

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  • 60 GHz CMOS Circular Patch AoC Modified Asymmetric AMC Reviewed International journal

    Adel Barakat, A. B. Adel, Ahmed Allam, POKHAREL RAMESH KUMAR

    Microwave Journals   (In Press) (採録決定)   2015.12

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  • Optical Code-Division Multiplexing (OCDM) Networks Adopting Code-Shift Keying/Overlapping PPM Signaling: Proposal and Performance Analysis Reviewed International journal

    Ahmed E. Farghal, Hossam M. H. Shalaby, Kazutoshi Kato, Ramesh Kumar Pokharel

    IEEE Transactions on Communications   63 ( 10 )   3779 - 3788   2015.10

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  • Monolithic Integration of BST Thin Film Varactors and Au Electroplated Thick Film Inductors above IC Reviewed

    Sho Asano, ANAND AWINASH, Ramesh Kumar Pokharel, Hideki Hirano, Shuji Tanaka

    138 ( 8 )   323 - 329   2015.8

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    Other Link: http://ci.nii.ac.jp/naid/130005090447

  • Strong resonant coupling for short-range wireless power transfer using defected ground structures International journal

    Proc. 3rd International Japan-Egypt Conference on Electronics, Communications and Computers   100 - 101   2015.3

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  • Design of High Performance of Oscillator using Film Bulk Acoustic Resonator Invited Reviewed

    POKHAREL RAMESH KUMAR, G. Zhang, S. A. Enche Ab Rahim

    2014 Korea-Japan Microwave Workship   1 - 2   2014.12

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  • Post-Layout Simulation Time Reduction for Phase-Locked Loop Frequency Synthesizer Using System Identification Techniques Reviewed International journal

    Lechang Liu, POKHAREL RAMESH KUMAR

    IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS   33 ( 11 )   1751 - 1755   2014.11

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    DOI: 10.1109/TCAD.2014.2354291

    Other Link: http://ieeexplore.ieee.org/stamp/stamp.jsp?tp=&arnumber=6926919

  • A 0.18 CMOS Current Reuse Ultra-Wideband Low Noise Amplifier (UWB-LNA) with Minimized Group Delay Variations Reviewed

    Proc. 44th European Microwave Conference   1392 - 1392   2014.10

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  • Small Size 60 GHz CMOS Antenna-on-Chip Reviewed

    Proc. 44th European Microwave Conference   104 - 107   2014.10

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  • A 1.9 GHz Low Phase Noise Complementary Cross-coupled FBARVCO in 0.18 um CMOS Technology Reviewed

    Proc. 44th European Microwave Conference   253 - 256   2014.10

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  • Back radiation reduction of 60 GHz CMOS slot Antenna-on-Chip (AoC) using Artificial Dielectric Layer (ADL) for Area Reuse Reviewed

    Proc. 2014 IEEE International Symposium on Antennas and Propagation and USNC-URSI National Radio ScienceMeeting   1 - 1   2014.7

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  • A Low Power 2.4GHz LNA Operated in Subthreshold Region Reviewed International journal

    Future Information Engineering Volume I, WIT Transactions on Communications and Information Technologie   199 - 196   2014.5

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  • A 10-bit 50MS/s 350 μW Small Die Area Capacitive Digital-to-Analog Converter for Bluetooth Applications Reviewed International journal

    兼本 大輔, POKHAREL RAMESH KUMAR, 吉田 啓二, 金谷 晴一, Keigo Oshiro

    134 ( 2 )   328 - 329   2014.2

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  • A low phase noise FBAR based multiband VCO design Reviewed

    IEICE Electronics Express   10 ( 13 )   1 - 6   2013.7

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  • Energy Harvesting Circuit on a One-Sided Directional Flexible Antenna Reviewed International journal

    IEEE Microwave and Wireless Components Letters   23 ( 3 )   164 - 166   2013.3

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  • Low Phase Noise 14-Bit Digitally Controlled CMOS Quadrature Ring Oscillator Reviewed

    IEICE Trans. on Electronics   Vol E-96 ( No. 2 )   262 - 269   2013.2

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  • A 0.9-3.5 GHz high linearity, good efficiency CMOS broadband power amplifier using stagger tuning technique Reviewed International journal

    Microwave and Optical Technology Letters   Vol. 54 ( Issue: 12 )   2881 - 2884   2012.12

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  • Analytical method to determine optimal out-of-band gain in multi-bit delta-sigma modulator Reviewed

    IEICE Electronics Express   vol. 9 ( no. 20 )   1598 - 1603   2012.10

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  • Low phase noise, 18 kHz frequency tuning step, 5 GHz, 15 bit digitally controlled oscillator in 0.18 um CMOS technology Reviewed

    R. K. Pokharel, K. Uchida, A. Tomar, H. Kanaya, and K. Yoshida

    IEICE Trans. on Electronics   Vol. E93-C ( no. 7 )   2010.7

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  • Design and evaluation of -117dBc/Hz phase noise voltage-controlled oscillator using on-chip CPW resonator for 5 GHz-band WLAN Reviewed International journal

    R. K. Pokharel, H. Kanaya, and K. Yoshida

    Microwave and Optical Technology Letters.   52 ( 3 )   2010.3

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  • Low noise wide tuning range quadrature ring oscillator for multi-standard transceiver Reviewed International journal

    O. Nizhnik, R. K. Pokharel, H. Kanaya, and K. Yoshida

    IEEE Microwave and Wireless Components Letters   vol. 19 ( no. 7 )   2009.7

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  • Linearization Technique using Bipolar Transistor at 5GHz Low Noise Amplifier Reviewed International journal

    A. I. A. Galal, R. K. Pokharel, H. Kanaya, and K. Yoshida

    2009.7

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    DOI: (2009), doi: 10.1016/j.aeue.2009.07.008.

  • A 2.4 GHz 0.18µm CMOS Class E Single-Ended Switching Power Amplifier with Self Biased Cascode Reviewed International journal

    Int. Journal of Electronic and Communications (AEU), (Elsevier publication)   2009.6

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    DOI: doi: 10.1016/j.aeue.2009.06.002.

  • Design of 5GHz-band power amplifier with on-chip matching circuits using CPW impedance (K) inverters Reviewed International journal

    Ramesh K. Pokharel, H. Kanaya and K. Yoshida

    Trans. of IEICE   2008.11

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  • Design of Power Amplifier with On-Chip Matching Circuits using CPW Line Impedance (K) Inverters Reviewed International journal

    Haruichi Kanaya, Ramesh K. Pokharel, Sangtae Kim, Akihiro Imada, and Keiji Yoshida

    11th WSEAS CSCC, Crete island, Greece, July 2007.   2007.7

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    Other Link: http://www.wseas.org/

  • Design and Verification of On-Chip Impedance-Matching Circuit Using Transmission-Line Theory for 2.4 GHz-Band Wireless Receiver Front-End Reviewed International journal

    Haruichi KANAYA, Ramesh K. POKHAREL, Fuminori KOGA, Keiji YOSHIDA

    IEICE Trans. On Electronics.   2006.12

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  • Fundamental characteristics of microstrip resonators loaded with dielectric rods for suppression of spurious responses Reviewed International journal

    R. K. Pokharel, K. Wada, O. Hashimoto, and T. Takahashi

    IEE Proc. Microwaves, Antennas, & Propagation   2006.8

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    Other Link: www.iee.org

  • Analysis of EM environment for DSRC system on express highway with wave absorbers on sidewalls and pavement Reviewed International journal

    R. K. Pokharel, O. Hashimoto, and M. Toyota

    IEICE Trans. Electron.,   2006.1

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    Other Link: www.ieice.org

  • Out-of-band improvement by BPFs with multiple attenuation poles using a condition of variable coupling length of a parallel partially coupled-line section Reviewed International journal

    Ramesh K. Pokharel, K. Wada and O. Hashimoto

    Microwave and optical Technology Letters   vol. 47 ( no. 1 )   2005.9

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  • Improvement of spurious responses of coupled-line BPFs using interdigital-type resonators Reviewed International journal

    Ramesh K. Pokharel, K. Wada and O. Hashimoto

    Microwave and optical Technology Letters   vol. 44 ( no. 2 )   2005.1

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  • A method for LTCC resonators to improve spurious responses on reduced-size microstrip structure Reviewed

    R. K. Pokharel, K. Wada, O. Hashimoto, and T. Takahashi

    Trans. of IEICE   2004.9

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  • A method for LTCC resonators to improve spurious responses on reduced-size microstrip structure Reviewed

    R. K. Pokharel, K. Wada, O. Hashimoto and T. Takahashi

    IEICE Trans. on Electronics   Vol. E87-C ( no. 9 )   2004.9

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  • Improvement of spurious responses with attenuation poles in stopband by microstrip resonator Reviewed International journal

    R. K. Pokharel, K. Wada, O. Hashimoto, and T. Takahashi

    IEE Electronics Letters   2004.4

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    Other Link: www.iee.org

  • Analysis of EM wave absorbers for improvement of DSRC EM environment on express highway Reviewed International journal

    Ramesh K. Pokharel, M. Toyota and O.Hashimoto

    IEEE Trans. on Microwave Theory and Techniques   vol. 53 ( no. 9 )   1900

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  • High-Efficiency Platinum-Band CMOS Rectifier Using Modified Body-Biasing Technique

    Jordan, W; Barakat, A; Gyawali, B; Pokharel, RK

    IEEE MICROWAVE AND WIRELESS TECHNOLOGY LETTERS   2024.9   ISSN:2771-957X eISSN:2771-9588

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    This letter introduces a novel approach to achieve high efficiency in high-power rectification using 180-nm complementary metal-oxide-semiconductor (CMOS) technology. The proposed rectifier targets the utilization of electromagnetic waves within the platinum band, operating within the frequency range of 0.6-0.9 GHz. Unlike conventional body-biasing techniques using pMOS transistors, where the output terminal is used for biasing, the proposed method employs biasing through the drain voltage of respective transistor. This approach results in higher output voltage for increased input power. Measurement results demonstrate outstanding power conversion efficiency (PCE) exceeding 60% and an output voltage surpassing 9 V across the 0.6-0.9 GHz range at 16-dBm input power ( P). Furthermore, the peak PCE of 67.5% was achieved at a carrier frequency of 0.7 GHz.

    DOI: 10.1109/LMWT.2024.3461799

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  • High Quality Factor Miniaturized CMOS Transmission Lines Using Cascaded T-Networks for 60 GHz Millimeter Wave Applications

    Barakat, A; Pokharel, RK

    ELECTRONICS   13 ( 18 )   2024.9   eISSN:2079-9292

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    This work presents an on-chip 60 GHz lumped element transmission line (TL) using cascaded T-networks with a high Quality factor. Each T-network consists of a series inductance with a shunt capacitance at its center. We have derived the design equations for this TL configuration and proved that a TL whose electrical length ≥ 60° achieves additional miniaturization when implemented with three or more cascaded T-networks. The inductance is implemented using a straight wire model with no ground below it, while the capacitance is implemented using a parallel plate model with a grounding pedestal. Both configurations guarantee maximum inductance per unit length and capacitance per unit area to further improve the miniaturization level. A quarter wavelength TL with three cascaded T-networks is fabricated as proof of concept. The measured and simulated results of the fabricated TL have good agreement, and the measured quality factor is 17 at 60 GHz.

    DOI: 10.3390/electronics13183748

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  • Design of Miniaturized Sub-6 GHz Rectifier With Self-Impedance Matching Technique

    Gyawali, B; Aboualalaa, M; Barakat, A; Pokharel, RK

    IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS   71 ( 7 )   3413 - 3422   2024.7   ISSN:1549-8328 eISSN:1558-0806

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    This work presents a novel concept of self-impedance matching in rectifier design by integrating a driving rectifier in parallel with a conventional voltage doubler circuit. The input impedance of the wideband rectifier is perfectly matched with the use of driving rectifier, which consists of a half-wave rectifier, a series stub line, and a grounding capacitor. The series stub adjusts the operating frequency and the efficiency bandwidth (EBW) of the proposed rectifier. This approach streamlines the rectifier design by eliminating additional input impedance matching networks and offers simultaneous control of EBW and operating bandwidth. Instead of a conventional lossy microstrip line, a Defected Ground Structure (DGS) is employed to design a high-impedance series stub line which makes the proposed circuit compact with improved quality factor. The experimental results highlight the effectiveness of the proposed rectifier, achieving more than 50% power conversion efficiency (PCE) for the frequency range of 3 GHz to 5.8 GHz, covering entire sub-6 GHz band of the 5G network with minimal variation. The fabricated prototype is the most compact design, with a circuit size of only 0.756 cm2.

    DOI: 10.1109/TCSI.2024.3397810

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  • Efficient and Low Leakage WPT System With Integrated Uncomplicated Matching Circuit Rectifier Using Metamaterial Director and Isolator for Biomedical Application

    Alshhawy, S; Barakat, A; Pokharel, RK

    IEEE JOURNAL OF ELECTROMAGNETICS RF AND MICROWAVES IN MEDICINE AND BIOLOGY   8 ( 2 )   144 - 154   2024.6   ISSN:2469-7257 eISSN:2469-7249

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    Publisher:IEEE Journal of Electromagnetics, RF and Microwaves in Medicine and Biology  

    Supplying wireless power to biomedical implants presents numerous challenges, including the compactness, efficiency, and biomedical safety of the receiver (RX). In this work, we propose several solutions to overcome these challenges. Firstly, we designed a metamaterial-inspired transmitter (TX) based on a multi-ring resonator (MRR). This transmitter achieves low magnetic loss and is used as a director to supply power to the RX, featuring an integrated uncomplicated matching circuit rectifier. Secondly, to realize the rectifier, we leverage the high coupling achieved through the proposed MRR metamaterial. The rectifier is integrated on the backside of the RX substrate without requiring additional area for further compactness. Additionally, we introduce a metamaterial-based isolator designed to reduce magnetic field leakage on the back side of the system. Importantly, this isolator has been proven to have no adverse effects on the original wireless power transfer (WPT) system's performance. A prototype was successfully fabricated, and both RF-dc simulation and measurements indicate a peak efficiency of 43% and 39%, respectively, at 50 MHz for a 9 mm embedded RX in chicken breast tissue. The TX size is 20 mm × 20 mm, while the integrated RX/rectifier has dimensions of 7 mm × 7 mm.

    DOI: 10.1109/JERM.2024.3395572

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  • New Rectification Technique Employing Auxiliary Rectifier for Resonance Control Achieving Compact Size and High Efficiency in CMOS

    Babita Gyawali, Ramesh K. Pokharel, Samundra K. Thapa, Adel Barakat, Naoki Shinohara

    IEEE Solid-State Circuits Letters   7   187 - 190   2024   eISSN:2573-9603

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    DOI: 10.1109/LSSC.2024.3409710

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  • Improvement of Data Rate of SWIPT System in Phantom by Integrated Metamaterial-Inspired Absorber for Biomedical Applications

    Xin Jiang, Ramesh K. Pokharel, Adel Barakat

    IEEE MTT-S International Microwave Symposium Digest   10 - 13   2024   ISSN:0149-645X ISBN:979-8-3503-7505-3 eISSN:2576-7216

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    This paper proposes a metamaterial-inspired absorber designed to enhance isolation in a simultaneous wireless information and power transfer (SWIPT) system through biological tissue. The study delves into the metamaterial perspective, focusing on the characteristics of split-ring resonators (SRRs) within the proposed absorber unit cells. The absorber exhibits a significant real part near -1 and an imaginary part close to 0 in permeability. A 10-mm-thick human body equivalent phantom is used for the SWIPT system's evaluation. Experimental results indicate that embedding this absorber between power and signal ports in both Tx and Rx of a SWIPT system results in a 3 dB improvement in isolation performance. Concurrently, with the assistance of the proposed absorber, the datarate improves by 3.6 Mb/s, allowing signals to be transmitted with 5 dBm weaker power than the original system.

    DOI: 10.1109/IMS40175.2024.10600186

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  • Experimental Study on Transition Loss of on-chip SIW Interconnects and Transmission Lines using Two De-embedding Reference Planes in 200 GHz Band Frequency

    Thapa, SK; Pokharel, RK; Barakat, A; Amakawa, S; Mubarak, MH; Hara, S; Watanabe, I; Kasamatsu, A

    2024 IEEE/MTT-S INTERNATIONAL MICROWAVE SYMPOSIUM, IMS 2024   694 - 697   2024   ISSN:0149-645X ISBN:979-8-3503-7505-3 eISSN:2576-7216

  • Experimental Study on Transition Loss of On-Chip SIW Interconnects and Transmission Lines Using Two De-Embedding Reference Planes in 200 GHz Band Frequency

    Samundra K. Thapa, Ramesh K. Pokharel, Adel Barakat, Shuhei Amakawa, Mohamed H. Mubarak, Shinsuke Hara, Issei Watanabe, Akifumi Kasamatsu

    IEEE MTT-S International Microwave Symposium Digest   694 - 697   2024   ISSN:0149-645X ISBN:9798350375046

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    A method for calculating transition loss in long lowloss substrate integrated waveguide (SIW)-based transmission lines fabricated using commercial complementary metal-oxidesemiconductor (CMOS) technology is presented. To quantify the accurate transition loss, the proposed approach employed twostep de-embedding technique besides normal measurement setup calibration using impedance standard substrate (ISS) at two distinct reference points: the first mitigates measuring pad effects, and the second removes both pads and transition structures. By using the attenuation constants calculated from these reference planes, the intrinsic transition loss is estimated. From the experiment, a low transition loss is observed in the proposed SIW design, which varies between 0.2 dB and 1.3 dB over a wide measurement bandwidth of 120 to 220 GHz. The experimental results underscore the efficacy of the proposed method and suggest the potential for consistent performance above the current measurement threshold of 220 GHz, which could be pivotal for terahertz (THz) applications.

    DOI: 10.1109/IMS40175.2024.10600291

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  • Compact and low phase noise LC-VCO design using novel V-shaped inductor in 0.18-μm CMOS technology for Ku-band applications Reviewed International journal

    Taha, MA; Mansour, I; Allam, A; El Dessouky, M; Pokharel, RK; Abdel-Rahman, AB

    INTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS   61 ( 12 )   5604 - 5616   2023.12   ISSN:0098-9886 eISSN:1097-007X

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    An innovative, high-quality factor, and small-area V-shaped inductor is presented in this article to improve the performance of voltage-controlled oscillators (VCOs). The differential inductance of the suggested V-shaped inductor in the resonator and the buffer is 280 pH and 630 pH, respectively. The inductor area is compacted by 42% and 76% compared to the conventional inductor with the same inductance value. Using 0.18- μ CMOS technology, the proposed V-shaped inductor is employed to design a compact VCO operating at Ku-band. The proposed VCO has a simulated phase noise range of −114 to −114.6 dBc/Hz, which is relatively constant. Also, its simulated frequency tuning range (FTR) is 5.6 % from 14.03 to 14.74 GHz. The power consumption is 2.2 mW. The simulated figure of merit (FoM) ranges from −193.5 to −194.2 dBc/Hz, which is enhanced by 6%. The designed VCO core area is 0.034 mm2, which is compacted by 35% compared to using a conventional spiral inductor. The achieved area-included figure of merit ( ) is −208.7 dBc/Hz. The VCO has an output power of −6.8 dBm and a good harmonic suppression of 29.4 dB between the fundamental and the second harmonic.

    DOI: 10.1002/cta.3747

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    Other Link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/cta.3747

  • A new rectangular dielectric resonator sensor for glucose measurement: Design, modeling, and experimentalvalidation Reviewed International journal

    Hala M. Marzouk, Anwer S. Abd El- Hameed, Ahmed Allam, Ramesh K. Pokharel, Adel B. Abdel- Rahman

    International Journal of Circuit Theory and Applications   xx ( xx )   xx - xx   2023.12   ISSN:0098-9886 eISSN:1097-007X

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    DOI: 10.1002/cta.3903

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    Other Link: https://onlinelibrary.wiley.com/doi/epdf/10.1002/cta.3903

  • Substrate Integrated Waveguide Sensor for Noninvasive Glucose Measurement

    Marzouk H.M., El-Hameed A.S.A., Allam A., Pokharel R.K., Abdel-Rahman A.B.

    Proceedings of the 11th International Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2023   46 - 49   2023   ISBN:9798350369328

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    Publisher:Proceedings of the 11th International Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2023  

    This paper explores utilizing a substrate-integrated waveguide (SIW) sensor for noninvasive glucose measurement at 3.73 GHz. The design considerations and performance evaluation are presented specifically tailored for glucose measurement. The proposed SIW resonator was designed using two narrow slots on the top patch with an inset feed. The ground plane is etched with a split ring resonator to enhance the sensitivity. The suggested glucose resonant sensor is simulated for glucose levels ranging from 100 to 2000 mg/dL. The loading process is done in two categories: containers with varied glucose levels and finger layers. The frequency detection for this range of glucose-level fluctuations is 3.43 GHz. The suggested sensor has a sensitivity of approximately 0.42% for detecting glucose levels, which is higher than other relatives. The obtained results demonstrate the feasibility of the proposed SIW sensor as a promising candidate for noninvasive glucose monitoring.

    DOI: 10.1109/JAC-ECC61002.2023.10479616

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  • Implementation of SIW Cavity in Commercial CMOS Technology for Sub-Terahertz Band Applications

    Samundra K. Thapa, Ramesh K. Pokharel, Adel Barakat, Ruibing Dong, Shuhei Amakawa, Shinsuke Hara, Issei Watanabe, Akifumi Kasamatsu

    IEEE MTT-S International Microwave Symposium Digest   2023-June   493 - 496   2023   ISSN:0149-645X ISBN:9798350347647

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    For sub-terahertz band applications, two compact and low-loss on-chip substrate integrated waveguide (SIW) cavities are designed in CMOS technology. Compact size cavity is achieved by utilizing the folded ridge structure in the quarter mode SIW (QMSIW) structure which is loaded with complementary split-ring resonators (CSRRs). Two prototypes of the proposed QMSIW cavities with and without CSRR are fabricated in 1P6M CMOS technology. From the measurement, both cavities present return losses higher than 27 dB and external Q-factors higher than 140. The proposed work shows that even at such high frequencies, compact and low-loss SIWs can be fabricated in commercial CMOS technology and opens a window to utilizing such cavities for other low-loss components such as oscillators, on-chip bandpass filters and on-chip antennas for sub-terahertz band applications.

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  • Implementation of Low-Loss Sub-Terahertz Band Substrate Integrated Waveguide-based Interconnects and Cavities in CMOS Technology

    Thapa S.K., Pokharel R.K., Barakat A., Amakawa S., Dong R., Hara S., Watanabe I., Kasamatsu A.

    2023 35th General Assembly and Scientific Symposium of the International Union of Radio Science, URSI GASS 2023   2023   ISBN:9789463968096

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    Sub-terahertz (sub-THz) band low-loss on-chip substrate integrated waveguide (SIW)-based transmission line interconnects, and cavities are presented and implemented in complementary metal oxide semiconductor (CMOS) technology. SIW cavities are designed with standard and half-mode (HM) SIW structures. Similarly, low-loss SIW interconnect design is implemented by introducing complementary split ring resonators (CSRR) in HMSIW interconnects. The prototypes of the proposed SIW cavities and the interconnects structures are fabricated and experimented in 1P6M CMOS at 200 GHz band. The measurement results of designed SIW cavities present return loss better than 25 dB and the external quality (Q-) factor better than 130 from both designs. Similarly, the HMSIW interconnect presents a measured attenuation constant of less than 1.6 dB/mm at the frequency range of 130-220 GHz band. This works shows that on-chip low-loss SIW-based designs can be implemented in frequency bands like sub-THz and above and can find application for designing transmission lines, filters, oscillators, antennas, etc., for THz applications.

    DOI: 10.23919/URSIGASS57860.2023.10265470

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  • Frequency Switching Dual Power Band Rectifier with Load-Modulation Technique

    Babita Gyawali, Samundra Kumar Thapa, Mohamed Aboualalaa, Adel Barakat, Ramesh Kumar Pokharel

    2023 IEEE Wireless Power Technology Conference and Expo, WPTCE 2023 - Proceedings   2023   ISBN:979-8-3503-3737-2

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    The frequency switching dual power band rectifier is proposed to achieve both low-power and high-power applications from a single circuit. Two different operating frequencies f1 = 900 MHz and f2 = 2.4 GHz are selected for low-power and high-power applications, respectively. The proposed rectifier fulfills stable operation at two levels of input power by making frequency switching. The Schottky diodes HSMS 2850 and HSMS 2860 are selected for f1 and f2, respectively, based on their performance with respect to the input power. Instead of conventional lumped inductors, defected ground structure (DGS)-based inductors are employed in matching circuits. For maximum RF-to-dc conversion efficiency in both low and high-power conditions, two different optimal loads are required, which is achieved from the load-modulation technique by using Bipolar Junction Transistor (BJT). The measurement result of the proposed rectifier shows more than 50% conversion efficiency for the power range -18 dB to 2 dBm and 8 dBm to 20 dBm with circuit size of 35 mm × 30 mm.

    DOI: 10.1109/WPTCE56855.2023.10216256

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  • Extended Embedded Depth Using Cascaded Resonators Near-field WPT System with High Efficiency for Biomedical Implants

    Aboualalaa M., Pokharel R.K., Kaho T.

    IEEE MTT-S International Microwave Symposium Digest   2023-June   887 - 890   2023   ISSN:0149645X ISBN:9798350347647

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    A novel multiple cascaded resonators wireless power transfer (WPT) design is proposed to provide an extended implanted depth for biomedical implants. Symmetrical four cascaded resonators are utilized in Tx/Rx to obtain high power transfer efficiency (PTE); each resonator consists of two concentric rectangular loops. KQ-product is calculated for a single resonator and compared with the four resonators WPT; four cascaded resonators achieve higher KQ-product value and produce a maximum measured PTE of 89.5% at a transfer distance of 20 mm. Then, the proposed WPT is tested with human tissue to provide a measured PTE of 76% and 63% at a transfer distance of 15 and 20mm, respectively. Specific absorption rate (SAR) is calculated to estimate the maximum operating power of the source and receiver that guarantees working within the safety standard levels of RF exposure.

    DOI: 10.1109/IMS37964.2023.10187972

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  • Comparator-less ASK-PWM CDR Circuit for Forward Data Communication Over A Single Channel Wireless Power and Data Transfer System

    Adel Barakat, Mohd Khairi Bin Zulkalnain, Ramesh Pokharel

    2023 IEEE Wireless Power Technology Conference and Expo, WPTCE 2023 - Proceedings   2023   ISBN:979-8-3503-3737-2

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    In this work, a new clock and data recovery (CDR) scheme is proposed for amplitude shift keying (ASK) with pulse width modulation (PWM) encoding. Such a technique can fully recover the clock as well as the encoded data without the need for any comparator. The clock is recovered by passing the ASK-PWM encoded data to the frequency divider and frequency multiplier. Then, the data sampler can recover the data by sampling the ASK-PWM modulated data using a delayed version of the recovered clock with no additional processing. This technique is intended for a data transfer system over an inductively coupled wireless power transfer system (WPT) system for biomedical implants where the data will modulate the power carrier without the need for a dedicated data channel. A prototype example implementation of the CDR scheme on a 180 nm Complementary-Metal-Oxide-Semiconductor (CMOS) technology with a data rate of 2 Mbps is provided as a proof-of-concept. This CDR prototype has an area of 8000 μm2 and consumes a power of 129 microwatts from a 1.4 Voltage dc supply.

    DOI: 10.1109/WPTCE56855.2023.10215978

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  • Circular DGS Resonator for Non-Invasive Sensing of Diabetes

    Marzouk, HM; El-Hameed, ASA; Allam, A; Pokharel, RK; Abdel-Rahman, AB

    2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP   2023   ISSN:2164-3342 ISBN:978-88-31299-07-7

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    A millimeter wave defected ground structure (DGS) resonator is introduced for noninvasive blood glucose concentrations detection. The unloaded sensor is designed to operate at 16 GHz. The sensing process is carried out by measuring the variations in the resonant frequency, and S-parameters phase and magnitude. The planned resonator is justified by time domain and frequency domain measurements. Several glucose solution concentrations are considered through experiments from 0 to 1000 mg/dL, providing high sensitivity of 1.4 dB/ (100mgdL-1) and quality factor of 61.08. Three volunteers assisted to check the potential sensor sensitivity by measuring their blood glucose levels. The actual permittivity of the human body affects the measurements and shifts down the frequency from 16 GHz to 5 GHz, while in simulation the frequency of the loaded sensor is 12 GHz. The presented sensor reveals high sensitivity levels in both simulations and measurements.

    DOI: 10.23919/EuCAP57121.2023.10133446

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  • A Simulation Study on Triple-Square Complementary Split-Ring Resonator for Non-Invasive Blood and Aqueous Solutions Measurements

    Mansour E., Ahmed M.I., Allam A., Pokharel R.K., Abdel-Rahman A.B.

    Proceedings of the 11th International Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2023   13 - 16   2023   ISBN:9798350369328

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    In the current study, we introduce an innovative triple square cell sensor, precisely angled at 45 degrees, mounted on a Roger RT/Duroid 3210 substrate for the non-invasive monitoring of glucose levels. Utilizing advanced computational simulations, including a 3D full-wave electromagnetic analysis facilitated by CST software, the sensor identifies minor changes in the dielectric properties of glucose solutions. The triple square cell design distinguishes itself with significantly heightened sensitivity, evidenced by three distinct resonant peaks, surpassing the single-cell design. Achieving a notable sensitivity measure of 0.38812 dB for each mg/dL change in glucose concentration, this sensor demonstrates promising capabilities for continuous, non-invasive glucose surveillance, which is an essential component in diabetes care.

    DOI: 10.1109/JAC-ECC61002.2023.10479602

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  • A Novel Biosensor for Non-Invasive Blood Glucose Measurement Based on Double Square Complimentary Split Ring Resonator

    Mansour, E; Ahmed, MI; Allam, A; Pokharel, RK; Abdel-Rahman, AB

    2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP   2023   ISSN:2164-3342 ISBN:978-88-31299-07-7

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    Planar microwave sensors are considered a promising solution to measure blood glucose levels non-invasively. A novel metamaterial microwave biosensor is presented, consisting of a double square complementary split-ring resonator (CSRR) over the frequency range (0-7 GHz). This unique structure is novel in this application. The main concept of the proposed sensor is the concentrated, confined electric field over the sensing region, which results in sensitivity enhancement. The double CSSR sensor is theoretically studied and numerically modelled using Computer Simulation Technology (CST) software. The sensor's sensitivity is illustrated through simulation in the range of 40-500 mg/dL. In-vitro, experiments are held using de-ionized water glucose solutions within the clinical diabetic range. Results show a high sensitivity performance up to 0.0056 dB/(mg/dL). Hence, our sensor ensures the capability of monitoring the glucose changes either for hypo (40 mg/dL) or hyperglycemia (500 mg/dL) cases non-invasively.

    DOI: 10.23919/EuCAP57121.2023.10133252

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  • A Microwave Sensor Based on Double Complementary Split-Ring Resonator Using Hexagonal Configuration for Sensing Diabetics Glucose Levels

    Mansour, E; Ahmed, MI; Allam, A; Pokharel, RK; Abdel-Rahman, AB

    2023 17TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION, EUCAP   2023   ISSN:2164-3342 ISBN:978-88-31299-07-7

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    In this article, we propose a compact microwave sensor for monitoring the blood glucose level of diabetes patients. The presented sensor utilizes eight cells of hexagonal-shaped complementary split-ring resonators (CSRRS), lined up in honey-cell configuration, fabricated on Rogers RO3210 substrate, and fed by a 50 Ohm microstrip line. For sensing glucose, the index and middle figures are placed on the sensing area. The biosensor can detect the small changes in the dielectric properties (relative permittivity and dielectric dissipation (Tan Delta)) of the blood's glucose across the signal path. This design's main concept is the strong interaction with electromagnetic fields concentrated in the sensing area. The resonator exhibits higher sensitivity performance than the single counterpart demonstrated by simulations in a 3D full-wave EM simulator CST. Along with theoretical estimations, the sensor is validated experimentally using a convenient setup of a vector network analyzer (VNA) that operated in measuring the transmission coefficient S21 and the phase. The sensor showed a shift in the resonant frequency by around 3 MHz/(mg/dL) of blood glucose concentration, which is significantly better sensitivity compared to previous studies. This sensor concept is a promising candidate for wearable non-invasive blood glucose monitoring devices.

    DOI: 10.23919/EuCAP57121.2023.10133248

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  • 200 GHz-band Low-loss Half-Mode SIW CMOS Interconnects and Transmission Lines for Sub-Terahertz Frequency Band Applications

    Ramesh K. Pokharel, Tomoki Fukuda, Samundra K. Thapa, Adel Barakat, Ruibing Dong, Shinsuke Hara, Issei Watanabe, Akifumi Kasamatsu

    IEEE MTT-S International Microwave Symposium Digest   2023-June   497 - 500   2023   ISSN:0149-645X ISBN:9798350347647

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    Low-loss half-mode substrate integrated waveguide (HMSIW)-based interconnects and transmission lines are designed and implemented in Complementary Metal-Oxide Semiconductor (CMOS) technology. In HMSIW interconnects, complementary split ring resonators (CSRR) whose self-resonance is much higher than the cut-off frequency of the SIW are etched on, due to which matching is improved. By controlling the parameters of the CSRRs, the losses due to microstrip to SIW transition are substantially improved, and no extra external matching circuit is required. A prototype was fabricated in 1P6M CMOS technology and tested. The measured cut-off frequency of the proposed HMSIW transmission line is 110 GHz, and the measured attenuation constant at frequencies of 175-220 GHz is less than 1.4 dB/mm. This work confirms a significant performance improvement of the CMOS interconnects in the sub-terahertz frequency band.

    DOI: 10.1109/IMS37964.2023.10188034

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  • Frequency-reconfigurable dielectric resonator antenna using metasurface

    Abdalrazik, A; Abdel-Rahman, AB; Allam, A; Abo-Zahhad, M; Yoshitomi, K; Pokharel, RK

    INTERNATIONAL JOURNAL OF MICROWAVE AND WIRELESS TECHNOLOGIES   14 ( 7 )   832 - 838   2022.9   ISSN:1759-0787 eISSN:1759-0795

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    Publisher:International Journal of Microwave and Wireless Technologies  

    In this paper, we propose a frequency-reconfigurable antenna structure consisting of a dielectric resonator (DR) topped by a superstrate material. Two metasurfaces (MSs) are placed upon the DR and the superstrate, where these two MSs are utilized to synthesize a localized reduction of the dielectric constant of the DR. By placing switches into one of the MSs, the distribution of dielectric constant of the DR can be switched to one of two predefined distributions, which is equivalent to switching the DR length to two different lengths. Consequently, the frequency response of the proposed structure can be tuned to one of two operating bands. The excited modes inside the proposed antenna were obtained analytically and through simulations. Also, the dielectric constant value of substrates topped by MSs was analyzed. The antenna was fabricated and measured, and good agreement between simulation and measurement was attained. The antenna bandwidths are 7-8.1 GHz (14.7%) and 8.5-9.2 GHz (8%) and the gains are 5.1 and 7.8 dB, in the cases of having switches off and on, respectively.

    DOI: 10.1017/S1759078721001215

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  • Design of low phase noise K-band VCO using high quality factor resonator in 0.18 μm CMOS technology

    Mansour, I; Mansour, M; Aboualalaa, M; Pokharel, RK

    INTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING   32 ( 4 )   2022.4   ISSN:1096-4290 eISSN:1099-047X

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    A novel resonator to improve the phase noise of a Voltage-Controlled Oscillator (VCO) utilizing double series resonances or two attenuation zeros to improve the susceptance slope parameter of the resonator circuit is proposed, and its effectiveness is demonstrated by designing a low phase noise K-band VCO. The first series resonance is created by an additional inductor (L) in series to the capacitor (C) in the parallel branch of a conventional LC-tank circuit, and the second one is realized by an additional capacitor in series to the whole resonator circuit. The additional L is realized by defected ground structures (DGS) so that there is no additional burden in the chip size. The proposed resonator is fabricated in 0.18 μm CMOS technology and has active quality factor of 101 and a compact size of 0.009 mm2 (0.00046 λ2). The measured return loss |S11| and insertion loss |S21| of the fabricated prototype resonator are 2.8 and 11 dB, respectively, at a center frequency of 37 GHz with 8 GHz of bandwidth. The resulting active quality (QK-) factor of the proposed resonator is enhanced significantly that, in returns, improves the phase noise. The design is implemented in 0.18 μm CMOS technology, and the post-layout simulation shows that VCO has a tuning range of 3.8% and phase noise of −114.4 dBc/Hz @1 MHz offset at 19.5 GHz oscillation. The VCO consumes 2.96 mW power resulting in a Figure of Merit (FoM) of −195.5 dB. The proposed resonators improve the VCO FoM by more than 5.5 dB compared to conventional LC resonator.

    DOI: 10.1002/mmce.23045

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  • Wideband Stacked Metamaterial for a Compact and Efficient Dual-band Wireless Power Transfer

    Xin Jiang, Ramesh K. Pokharel, Adel Barakat, Kuniaki Yoshitomi

    IEEE MTT-S International Microwave Symposium Digest   2022-June   198 - 201   2022   ISSN:0149-645X ISBN:978-1-6654-9613-1 eISSN:2576-7216

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    A novel wideband stacked metamaterial is proposed for a dual-band wireless power transfer (WPT) system. Firstly, two types of split-ring resonators (SRRs) of different self-resonance frequencies are proposed. Then we sandwiched each type of the unit cell. Consequently, the proposed metamaterial exhibits wideband near-zero characteristics on both the real part and imaginary part of the permeability. Also, compared with conventional 1-D metamaterial [2], the proposed metamaterial can significantly empower both bands simultaneously of the dual-band WPT system. An experiment shows that the proposed metamaterial of size (20 mm x 20 mm 5.468 mm) has improved the efficiencies of both bands from 18.6%, 22.9% to 51.8% and 47.8%, respectively, at a wireless power transfer distance of 20 mm.

    DOI: 10.1109/IMS37962.2022.9865455

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  • Study of Metamaterial on Efficiency of DGS-based MISO-WPT system

    Sun, MQ; Jiang, X; Aboualalaa, M; Barakat, A; Yoshitomi, K; Pokharel, RK

    2022 WIRELESS POWER WEEK (WPW)   344 - 348   2022   ISBN:978-1-6654-8445-9

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    In this paper, we propose a multiple-input single-output (MISO) wireless power transfer (WPT) system using a stacked meta-surface structure for achieving a high transmission distance. We started by studying two coupled DGS resonators one is a transmitter and the other is a receiver, each resonator is excited by a microstrip line to transfer power at a frequency of 670 MHz. In order to improve the power transfer efficiency, five extra DGS transmitters are employed. Therefore, the proposed multiple-input transmitter is composed of six DGS resonators printed on one layer of a single substrate. On the other side, the receiver is a single DGS resonator. The size of the transmitter and receiver are 46.4mm × 30.7 mm and 15mm × 15 mm, respectively. The stacked meta-surface is in three layers. And the size of it is 25.4mm × 25 mm. In measurement, the WPT efficiency of the MISO system with meta-surface is a maximum of 31.1% higher than that of the MISO system without meta-surface.

    DOI: 10.1109/WPW54272.2022.9853985

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  • Millimeter-Wave High Q-factor Sixteenth Mode SIW Cavity Resonator Implemented in 0.18-μm CMOS Technology

    Samundra K. Thapa, Ramesh K. Pokharel, Baichuan Chen, Tomoki Fukuda, Adel Barakat

    IEEE MTT-S International Microwave Symposium Digest   2022-June   560 - 563   2022   ISSN:0149-645X ISBN:978-1-6654-9613-1 eISSN:2576-7216

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    Millimeter-wave miniaturized Substrate Integrated Waveguide (SIW) cavity resonator is proposed in 0.18-μm CMOS technology. Miniaturization of the SIW cavity resonator is achieved first by taking 1/16thparts of the standard SIW and employing folded ridge structure. Later this folded ridge sixteenth mode SIW cavity is inductively loaded by a complementary split-ring resonator, which provides internal matching within the cavity resonator. This improved matching enhances the return loss, the external Q-factor, and ultimately, the loaded Q-factor of the proposed cavity resonator. At 60 GHz resonance frequency, the fabricated prototype of the proposed cavity resonator presents a measured reflection coefficient of -33.42 dB, with the external Q- factor 112. Moreover, the active area of the fabricated cavity without measuring pads is only 0.019 mm2.

    DOI: 10.1109/IMS37962.2022.9865522

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  • Low Magnetic Loss Metamaterial Based Miniaturized WPT System for Biomedical Implants

    S. Alshhawy, Adel Barakat, Ramesh K. Pokharel, Kuniaki Yoshitomi

    IEEE MTT-S International Microwave Symposium Digest   2022-June   275 - 278   2022   ISSN:0149-645X ISBN:978-1-6654-9613-1 eISSN:2576-7216

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    We propose a low magnetic loss multi-ring resonator (MRR) metamaterial. Then, we utilize this MRR metamaterial in a stacked configuration as the WPT transmitter (TX) for a miniaturized receiver (RX) embedded in biomedical tissue. A prototype is fabricated, and the measurement shows an efficiency of 51% at 50 MHz when the TX/RX separation distance is 9 mm. The TX/RX sizes are 20 mm × 20 mm and 7 mm × 7 mm, respectively. Hence, the proposed system has a figure-of- merit of 0.42, which is a significant improvement over the previously reported WPT systems. Also, the simulated specific absorption rate is within the recommended level when the input power is 21 dBm.

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  • Experimental Study on the Effect of Feeding Topology of 60 GHz Sixteenth Mode SIW Cavity Resonator in CMOS Technology

    Thapa, SK; Chen, BC; Barakat, A; Pokharel, RK

    2022 ASIA-PACIFIC MICROWAVE CONFERENCE (APMC)   384 - 386   2022   ISBN:978-4-902339-56-7

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  • Experimental Study on the Effect of Feeding Topology of 60 GHz Sixteenth Mode SIW Cavity Resonator in CMOS Technology

    Thapa S.K., Baichuan C., Barakat A., Pokharel R.K.

    Asia-Pacific Microwave Conference Proceedings, APMC   2022-November   384 - 386   2022   ISBN:9784902339567

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    Millimeter-wave compact, high quality (Q-) Substrate Integrated Waveguide (SIW) cavity is proposed in 0.18-µm CMOS technology. Compact size of the SIW cavity resonator is achieved first by taking 1/16th parts of the standard SIW and employing folded ridge structure. Two prototypes of the proposed cavity resonator with different feeding structures were fabricated and measured. The measurement results present a reflection coefficient lower than -22 dB and the external Q-factor greater than 60 in both cases. Experimentally, it is verified that due to the low losses associated with the top feed structure, it presents better return losses and Q-factor than the transition feed structure. Moreover, the active area of the fabricated cavity resonators without measuring pads are only 0.024 mm2, which is only 0.563% when compared to the standard SIW cavity.

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  • Efficacy of Transmission Poles Characteristics on K-Band VCOs Phase Noise Reduction

    Jahan, N; Barakat, A; Pokharel, R

    2022 ASIA-PACIFIC MICROWAVE CONFERENCE (APMC)   668 - 670   2022   ISBN:978-4-902339-56-7

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  • Efficacy of Transmission Poles Characteristics on K-Band VCOs Phase Noise Reduction

    Jahan N., Barakat A., Pokharel R.

    Asia-Pacific Microwave Conference Proceedings, APMC   2022-November   668 - 670   2022   ISBN:9784902339567

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    In this paper, effectiveness of multi-resonance around the parallel resonance of an LC-tank circuit on the reduction of K-band Voltage-Controlled Oscillators (VCOs) phase noise is proposed. The skirt characteristics of the Scattering (|S|) parameters of the resonators is sharpened by introducing transmission poles beside the parallel resonance of the LC-tank circuit. In return, an enhanced the resonator loaded quality (Q) factor without compromising the unloaded Q-factor is obtained. Three designs are realized, verified and compared to the others in a differential VCO topology and the phase noise reduction in post-layout simulations is confirmed. Finally, two chips are fabricated in 0.18-µm CMOS technology and measured.

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  • Dual-band Split-ring Antenna with High-gain Endfire Radiation Characteristics for 5G mm-wave Applications

    Aboualalaa M., Mansour I., Pokharel R.K.

    2022 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, AP-S/URSI 2022 - Proceedings   1050 - 1051   2022   ISBN:9781665496582

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    A dual-frequency band high-gain split-ring antenna is proposed for 5G mm-wave applications. The antenna consists of three split ring resonators (SRRs), one is the main SRR which radiates at the first resonant frequency (f1=24.5 GHz). The other two resonators are parasitic SRRs which act as directors to get end-fire radiation characteristics for the proposed antenna at f1. In addition, the two parasitic SRRs are fed by capacitive coupling with the main SRR to radiate at the second resonant frequency (f2=28.5 GHz). The antenna has better radiation characteristics. It has high gain values of 7.9, and 7.5 dBi with radiation efficiencies of 92% and 95% at f1, and f2, respectively. The proposed antenna is a good candidate for MIMO array at 5G frequency bands utilizing the antenna high gain to improve the system performance.

    DOI: 10.1109/AP-S/USNC-URSI47032.2022.9887224

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  • Design of Self-Impedance Matching Ultra-Wideband Rectification Circuit

    Gyawali, B; Thapa, SK; Aboualalaa, M; Barakat, A; Yoshitomi, K; Pokharel, RK

    2022 ASIA-PACIFIC MICROWAVE CONFERENCE (APMC)   671 - 673   2022   ISBN:978-4-902339-56-7

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  • Design of Self-Impedance Matching Ultra-Wideband Rectification Circuit

    Gyawali B., Thapa S.K., Aboualalaa M., Barakat A., Yoshitomi K., Pokharel R.K.

    Asia-Pacific Microwave Conference Proceedings, APMC   2022-November   671 - 673   2022   ISBN:9784902339567

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    An ultrawideband rectifier without an external impedance matching circuit offers many benefits, such as compact circuit size and lower losses. Generally, the rectifier is designed using the conventional voltage doubler circuit, which has varying input impedance for the operating frequency. But, to achieve the wideband rectification, the input impedance of the proposed circuit must be matched with 50 O impedance throughout the desired frequency band. For varying impedance, it is challenging to design the impedance matching network. In [11], the idea of a virtual DC battery is utilized to achieve ultra-wideband rectification without using any external matching at input section. For the further improvement of rectification efficiency, in this work, parallel diode connection is proposed instead of single diode. The proposed design achieved maximum flat conversion efficiency for energy harvesting and wireless power transfer applications.

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  • Design of an Ultra-Wideband Antenna for Ambient Radio Frequency Energy Harvesting in 10.88-33.66 GHz

    Elbendera S.A., Allam A., Mohamed A.M., Pokharel R., Abdel-Rahman A.B.

    2022 16th European Conference on Antennas and Propagation, EuCAP 2022   2022   ISBN:9788831299046

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    This paper aims at exploiting the expected massive deployment of RF signals by proposing a low-cost ultrawideband (UWB) planar antenna with a bandwidth of approximately 23 GHz ranging from 10.9 to more than 33.66 GHz. Using different slots on the patch and ground planes and through feedline transitions the UWB requirements are achieved. Simulation results show that a proposed antenna with optimized dimensions can enhance the impedance matching and increase the bandwidth with minor effects on the antenna performance. The antenna is fabricated, and the simulated results are validated by the experimental measurements.

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  • Design of an Ultra-Wideband Antenna for Ambient Radio Frequency Energy Harvesting in 10.88-33.66 GHz

    Elbendera, SA; Allam, A; Mohamed, AM; Pokharel, R; Abdel-Rahman, AB

    2022 16TH EUROPEAN CONFERENCE ON ANTENNAS AND PROPAGATION (EUCAP)   2022   ISSN:2164-3342 ISBN:978-88-31299-04-6

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  • Broadband and Compact 3-Bit Digitally-Controlled Reconfigurable Rectification Circuit

    Gyawali B., Pokharel R.K., Thapa S.K., Aboualalaa M., Barakat A., Yoshitomi K.

    2022 Wireless Power Week, WPW 2022 - Proceedings   2022-January   780 - 783   2022   ISBN:9781665484459

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    Publisher:2022 Wireless Power Week, WPW 2022 - Proceedings  

    A broadband rectification circuit is usually designed with complex matching circuits to achieve decade and octave impedance which result is the bulkiness of the layout and increases the losses. To mitigate these problems, an ultra-wideband high-efficiency rectification circuit without any inductors and transmission lines at the input section [1] is utilized and employed with 3-bit digitally controlled signals to vary the length of a short stub at the grounding so that reconfigurable operation of the proposed rectifier is obtained in the frequency range of 60 MHz to 3.8 GHz. The proposed compact rectification circuit offers reconfigurable operation over a wide bandwidth and is best suitable for the applications in wirelessly powered multiband and software-defined radios or other portable devices.

    DOI: 10.1109/WPW54272.2022.9901332

    Scopus

  • A High PAE Stacked K-band Power Amplifier Using π-Phase Compensation Technique

    Omar Z. Alngar, Adel Barakat, Ramesh K. Pokharel

    RFIT 2022 - 2022 IEEE International Symposium on Radio-Frequency Integration Technology   42 - 44   2022   ISBN:978-1-6654-6649-3

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    A three-Tunable low-pass π-phase compensator technique is proposed and employed in a K-band CMOS power amplifier (PA) to solve the phase shift problem at intermediate nodes of stacked transistor configurations (STCs). Also, it reduces the effects of harmonic signals that in turns, enhances the overall power added efficiency (PAE) of the PA. The PA consists of two stages i.e. driver and main stages, designed using 2-STCs in 180-nm CMOS technology. The fabricated PA achieved a power gain of 12.8 dB at 23 GHz, a maximum PAE of 18.3%, an output power of 1 dB compression point \left(\mathrm{P}{1 \mathrm{~dB } }\right) of 14.1 1 dBm, and saturated output power \left(\mathrm{P}{\text {sat } }\right) of 16.0 dBm while it consumes chip area of 0.604 mm2 including pads.

    DOI: 10.1109/RFIT54256.2022.9882403

    Web of Science

    Scopus

    researchmap

  • A Compact Millimeter-Wave On-chip DGS-based Bandstop Filter with Two Transmission Poles in CMOS Technology

    Thapa S.K., Chen B., Barakat A., Pokharel R.K.

    2022 52nd European Microwave Conference, EuMC 2022   564 - 567   2022   ISBN:9782874870699

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    Publisher:2022 52nd European Microwave Conference, EuMC 2022  

    A compact size millimeter-wave on-chip defected ground structure (DGS)-based bandstop filter (BSF) is proposed and implemented in 0.18-μm CMOS technology. The proposed BSF is realized with T-shape DGS. In combination with the series resonance circuits, the proposed design realizes two transmission poles: one at either side of parallel resonance. Despite the compact size, the proposed BSF still maintains higher quality (Q) factors and group delay. The proposed BSF optimized at 52 GHz frequency is fabricated and tested. The active area of the fabricated prototype without pads is 0.0129 mm2 which is only 50% of the size of a wideband BSF recently proposed in a similar technology [8] and [16]. The measured loaded and unloaded Q-factors are 4.57 and 20.55, respectively.

    DOI: 10.23919/EuMC54642.2022.9924382

    Scopus

  • A Compact Millimeter-Wave On-chip DGS-based Bandstop Filter with Two Transmission Poles in CMOS Technology

    Thapa, SK; Chen, BC; Barakat, A; Pokharel, RK

    2022 52ND EUROPEAN MICROWAVE CONFERENCE (EUMC)   564 - 567   2022   ISSN:2325-0305 ISBN:978-2-8748-7069-9

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  • A Compact Millimeter-Wave On-Chip DGS-Based Bandstop Filter with Two Transmission Poles in CMOS Technology

    Thapa, SK; Chen, BC; Barakat, A; Pokharel, RK

    2022 52ND EUROPEAN MICROWAVE CONFERENCE (EUMC)   2022   ISSN:2325-0305 ISBN:978-2-8748-7069-9

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  • A Compact Millimeter-Wave On-Chip DGS-Based Bandstop Filter with Two Transmission Poles in CMOS Technology

    Thapa, SK; Chen, BC; Barakat, A; Pokharel, RK

    2022 52ND EUROPEAN MICROWAVE CONFERENCE (EUMC)   2022   ISSN:2325-0305 ISBN:978-2-8748-7069-9

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  • General silicon-on-insulator higher-order mode converter based on substrip dielectric waveguides Reviewed

    Basma E. Abu-Elmaaty, Mohammed S. Sayed, Ramesh Pokharel, Hossam M.H. Shalaby

    Applied Optics   58 ( 7 )   1763 - 1771   2019.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1364/AO.58.001763

  • Performance enhancement of 60 GHz CMOS band pass filter employing oxide height virtual increase Reviewed

    Nessim Mahmoud, Adel Barakat, Mohamed E. Nasr, Ramesh Pokharel

    Progress In Electromagnetics Research M   77   125 - 134   2019.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.2528/pierm18101608

  • Independent Matching Dual-Band Compact Quarter-Wave Half-Slot Antenna for Millimeter-Wave Applications Reviewed

    Mohamed Aboualalaa, Islam Mansour, Hala Elsadek, Adel B. Abdel-Rahman, Ahmed Allam, Mohammed Abo-Zahhad, Kuniaki Yoshitomi, Ramesh K. Pokharel

    IEEE Access   7   130782 - 130790   2019.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/ACCESS.2019.2940273

  • A DC-2.5 GHz high linearity CMOS attenuator in a 0.18 µm technology Reviewed International journal

    22   591 - 597   2018.11

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    Language:Japanese   Publishing type:Research paper (scientific journal)  

    A CMOS attenuator with high linearity has been designed and measured in a 0.18-µm
    CMOS process, to be used for a variable gain amplifier of RF wireless transceiver. The
    design is based on four cascaded Bridge-T attenuator stages that are consecutively
    activated to adjust the attenuation level and improve linearity. The design operates in the
    frequency band of DC-2.5 GHz with 2-3.5 dB insertion loss and 14 dB maximum attenuation
    in the entire frequency range. Measured and simulated results are in good agreement over
    the frequency band of interest. Measured worst case S11 and S22 are–10 and-8.8 dB,
    respectively, across the frequency band. The measured 1-dB compression point is+ 22 dBm
    at maximum-attenuation.

    Other Link: https://www.sciencedirect.com/science/article/pii/S2351978918303822

  • Photonic crystal-based compact hybrid WDM/MDM (De)multiplexer for SOI platforms Reviewed

    Omnia M. Nawwar, Hossam M.H. Shalaby, Ramesh Pokharel

    Optics Letters   43 ( 17 )   4176 - 4179   2018.9

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1364/OL.43.004176

  • High-Efficiency CMOS RF-to-DC Rectifier Based on Dynamic Threshold Reduction Technique for Wireless Charging Applications Reviewed

    Manal M. Mohamed, Ghazal A. Fahmy, Adel B. Abdel-Rahman, Ahmed Allam, Adel Barakat, Mohammed Abo-Zahhad, Hongting Jia, Ramesh Pokharel

    IEEE Access   6   46826 - 46832   2018.8

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1109/ACCESS.2018.2866457

  • Design of compact frequency agile filter-antenna using reconfigurable ring resonator bandpass filter for future cognitive radios Reviewed

    Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Ramesh Pokharel

    International Journal of Microwave and Wireless Technologies   10 ( 4 )   487 - 496   2018.5

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1017/S1759078717001556

  • CPW-Fed UWB antenna with sharp and high rejection multiple notched bands using stub loaded meander line resonator Reviewed

    Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Ramesh Pokharel

    AEU - International Journal of Electronics and Communications   83   22 - 31   2018.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1016/j.aeue.2017.08.022

  • Modeling, simulation, and fabrication of bi-directional mode-division multiplexing for silicon-on-insulator platform Reviewed

    Omnia M. Nawwar, Hossam M.H. Shalaby, Ramesh Pokharel

    Applied Optics   57 ( 1 )   42 - 51   2018.1

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1364/AO.57.000042

  • Mutual Coupling Reduction in MIMO Patch Antenna Array Using Complementary Split Ring Resonators Defected Ground Structure Reviewed International journal

    Atallah, Hany A, Ahmed Allam, Kuniaki Yoshitomi, Ramesh Kumar Pokharel

    APPLIED COMPUTATIONAL ELECTROMAGNETICS SOCIETY JOURNAL   31 ( 7 )   737 - 743   2016.7

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  • Miniaturized low loss 60 GHz CMOS mixed coupled BPF with patterned ground shield Invited Reviewed International journal

    Adel Barakat, Ramesh Kumar Pokharel

    MICROWAVE AND OPTICAL TECHNOLOGY LETTERS   58 ( 3 )   697 - 699   2016.3

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1002/mop.29650

  • Design of a Tunable CMOS PA for TV White Space Application Reviewed International journal

    2014 Korea-Japan Microwave Workshop.   1   1 - 4   2014.12

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    Language:English   Publishing type:Research paper (international conference proceedings)  

  • A design methodology for SAR ADC optimal redundancy bit Reviewed

    IEICE Electronics Express   Vol. 11 (2014) ( No. 10 )   1 - 6   2014.4

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    Language:English   Publishing type:Research paper (scientific journal)  

  • 60 GHz Millimeter-Wave CMOS Integrated On-Chip Open Loop Resonator Bandpass Filters on Patterned Ground Shields Reviewed International journal

    IEICE TRANSACTIONS on Electronics   Vol E-96 ( No. 2 )   270 - 276   2013.2

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    Language:English   Publishing type:Research paper (scientific journal)  

  • Realization of attenuation poles, spurious resonance Suppression and size reduction by microstrip SIR loaded with dielectric rods Reviewed

    R. K. Pokharel, K. Wada, O. Hashimoto and T. Takahashi

    IEICE Trans. on Electronics   vol. E88-C ( no. 12 )   2302 - 2309   2005.12

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    Language:English   Publishing type:Research paper (scientific journal)  

    DOI: 10.1093/ietele/e88-c.12.2302

  • Analysis of temperature distribution and absorption characteristics of single layer radio wave absorber Reviewed International journal

    K. Suga, O. Hashimoto, R. K. Pokharel, and K. Wada

    IEEE Trans on Electromagnetic Compatibility   2005.11

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  • Analysis of error due to exclusion of higher modes on complex permittivity measurement using waveguide with flange Reviewed

    O. Hashimoto and R. K. Pokharel

    Trans. of IEICE   2005.1

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    Language:English   Publishing type:Research paper (scientific journal)  

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Books

Presentations

  • Implementation of SIW Cavity in Commercial CMOS Technology for Sub-Terahertz Band Applications International conference

    #S.K. Thapa, R.K. Pokharel, A. Barakat, Ruibing Dong; Shuhei Amakawa; Shinsuke Hara; I. Watanabe, and A. Kasamatsu

    2023 International Microwave Symposium (IMS)  2023.6 

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    Event date: 2023.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://ieeexplore.ieee.org/abstract/document/10188161/

  • Extended Embedded Depth Using Cascaded Resonators Near-field WPT System with High Efficiency for Biomedical Implants International conference

    M. Ali, R.K. Pokharel, and T. Kaho

    2023 International Microwave Symposium (IMS)  2023.6 

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    Event date: 2023.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://ieeexplore.ieee.org/abstract/document/10187972

  • 200 GHz-band Low-loss Half-Mode SIW CMOS Interconnects and Transmission Lines for Sub-Terahertz Frequency Band Applications International conference

    Ramesh K. Pokharel, T. Fukuda, Samundra K. Thapa, Adel Barakat, Ruibing Dong, Shinsuke Hara, Issei Watanabe, and A. Kasamatsu

    2023 International Microwave Symposium (IMS)  2023.6 

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    Event date: 2023.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://ieeexplore.ieee.org/abstract/document/10188034

  • MetaTx-introduction of metamaterial-assisted WPT system for biomedical implants Invited International conference

    Ramesh K. Pokharel

    2022Asian Wireless Power Transfer Workshop  2022.12 

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    Event date: 2022.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

    Other Link: https://www.ieice.org/~wpt/international/AWPT2022/keynote1.html

  • A Compact Millimeter-Wave On-chip DGS-based Bandstop Filter with Two Transmission Poles in CMOS Technology International conference

    S. K. Thapa, B. Chen, A. Barakat, and R. K. Pokharel

    2022 European Microwave Conference (EuMW)  2022.9 

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    Event date: 2022.9

    Language:English   Presentation type:Oral presentation (general)  

    Country:Italy  

    Other Link: https://ieeexplore.ieee.org/document/9924382

  • Dual-band split-ring antenna with high-gain end-fire radiation characteristics for 5G MM-wave applications International conference

    M. Ali and Ramesh K. Pokharel

    2022 IEEE International Symposium on Antennas and Propagation & USNC-URSI Radio Science Meeting  2022.7 

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    Event date: 2022.7

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://ieeexplore.ieee.org/document/9887224

  • Millimeter-Wave High Q-factor Sixteenth Mode SIW Cavity Resonator Implemented in 0.18-µm CMOS Technology International conference

    2022.6 

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    Event date: 2022.6

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Denver (USA)   Country:United States  

    Millimeter-wave miniaturized Substrate Integrated Waveguide (SIW) cavity resonator is proposed in 0.18-µm CMOS technology. Miniaturization of the SIW cavity resonator is achieved first by taking 1/16 th parts of the standard SIW and employing folded ridge structure. Later this folded ridge sixteenth mode SIW cavity is inductively loaded by a complementary split-ring resonator, which provides internal matching within the cavity resonator. This improved matching enhances the return loss, the external Q-factor, and ultimately, the loaded Q-factor of the proposed cavity resonator. At 60 GHz resonance frequency, the fabricated prototype of the proposed cavity resonator presents a measured reflection coefficient of −33.42 dB, with the external Q- factor 112. Moreover, the active area of the fabricated cavity without measuring pads is only 0.019 mm2 .

    Other Link: https://ieeexplore.ieee.org/abstract/document/9865522

  • Low Magnetic Loss Metamaterial Based Miniaturized WPT System for Biomedical Implants International conference

    #S. Alshhawy, A. Barakat, R.K. Pokharel, K. Yoshitomi

    2022 International Microwave Symposium (IMS)  2022.6 

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    Event date: 2022.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  • Wideband Stacked Metamaterial for a Compact and Efficient Dual-Band Wireless Power Transfer International conference

    #X. Jiang, R.K. Pokharel, A. Barakat, K. Yoshitomi

    2022 International Microwave Symposium (IMS)  2022.6 

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    Event date: 2022.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  • Design Methodology of Wide Tuning Range DGS-based VCO for K-band Applications in 0.18-µm CMOS Technology International conference

    2022.4 

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    Event date: 2022.4

    Language:English   Presentation type:Oral presentation (general)  

    Venue:London (UK) and online   Country:United Kingdom  

    Recently, defected ground structure (DGS) resonators have been employed to design a low phase noise Voltage-Controlled Oscillator (VCO) for quasi-millimeter wave applications [10]. A few advantages of such VCOs are that a DGS resonator has a higher Q-factor than an on-chip spiral inductor, and it has a higher self-resonance frequency compared to a conventional LC resonator so that a stable inductance value with respect to the frequency can be realized. However, one of its drawbacks is that the tuning range of DGS-based VCOs is limited. In this paper, a method to realize a wide tuning range of DGS-based VCOs has been proposed using two interconnected DGS resonators. As a result, the designed VCO implemented in 0.18-µm 1P6M CMOS technology achieves a 19.8% tuning range with the best phase noise performance of -109.43dBc/Hz at 1-MHz offset frequency in simulations. The experiment result shows that the fabricated VCO has a phase noise of -108.41dBc/Hz at 1-MHz offset frequency with the carrier frequency of 18.51GHz, which exhibits good agreement with the simulation.

    Other Link: https://ieeexplore.ieee.org/abstract/document/9783689

  • A 100GHz Bandpass Filter Employing Shielded Folded Ridged Quarter-Mode SIW Resonator in CMOS Technology International conference

    #Baichuan Chen, Samundra K Thapa, Adel Barakat, Ramesh K Pokharel

    2021 51st European Microwave Conference (EuMC)  2022.4 

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    Event date: 2022.4

    Language:English   Presentation type:Oral presentation (general)  

    Country:United Kingdom  

    Other Link: https://scholar.google.com/citations?view_op=view_citation&hl=en&user=yP5mW0gAAAAJ&sortby=pubdate&citation_for_view=yP5mW0gAAAAJ:CdxZDUztZiMC

  • Stacked Metasurfaces for Misalignment Improvement of WPT System Using Spiral Resonators International conference

    #Yutaro Ikeda, Xin Jiang, Mohamed Aboualalaa, Adel Barakat, Kuniaki Yoshitomi, Ramesh K Pokharel

    2021 51st European Microwave Conference (EuMC)  2022.4 

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    Event date: 2022.4

    Language:English   Presentation type:Oral presentation (general)  

    Country:United Kingdom  

    Other Link: https://ieeexplore.ieee.org/abstract/document/9784281

  • Design of Compact and High Q-Factor W-Band Cavity in 0.18-µm CMOS Technology International conference

    2022.4 

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    Event date: 2022.4

    Language:English   Presentation type:Oral presentation (general)  

    Venue:London (UK) and online   Country:United Kingdom  

    This paper proposes a compact, high-quality (Q-) factor cavity in commercial CMOS technology for terahertz band applications. The proposed cavity consists of a folded quarter-mode substrate integrated waveguide (QMSIW) topology. It also outlines some guidelines for creating layouts with specific foundries, particularly for building vertical walls using an array of vias. The cavity was implemented in 0.18 µm CMOS technology and measurements were taken. The measurements showed that the resonant frequency and reflection coefficients were 96.9 GHz and -30.14 dB, respectively, in good agreement with the simulation results. The area of the proposed cavity was 0.0506 mm2 without measurement pads, which is only 2.4% and 8.9% when compared to the standard full-mode SIW cavity and the recently proposed 87 GHz.

    Other Link: https://ieeexplore.ieee.org/abstract/document/9784193

  • Broadband and Compact 3-Bit Digitally-Controlled Reconfigurable Rectification Circuit International conference

    B. Gyawali, Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    2022 IEEE Wireless Power Transfer Conference, WPTC 2022  2022.7 

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    Event date: 2021.7

    Language:English   Presentation type:Oral presentation (general)  

    Country:France  

    Other Link: https://www.wpw2022.org/detailed-program/

  • STUDY OF METAMATERIAL ON EFFICIENCY OF DGS-BASED MISO-WPT SYSTEM International conference

    X. Sun, Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    2022 IEEE Wireless Power Transfer Conference, WPTC 2022  2022.7 

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    Event date: 2021.7

    Language:English   Presentation type:Oral presentation (general)  

    Country:France  

    Other Link: https://www.wpw2022.org/detailed-program/

  • Efficient and Compact Dual-band Wireless Power Transfer System through Biological Tissues Using Dual-Reference DGS Resonators International conference

    X. Jiang, Adel Barakat, Kuniaki Yoshitomi, Ramesh K. Pokharel

    2021 IEEE MTT-S International Microwave Symposium, (IMS 2021)  2021.6 

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    Event date: 2021.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://ims-ieee.org/ims2021

  • Design of Three Layers-stacked Metasurface and its Application to Compact Dual-band WPT System International conference

    X. Jiang, Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    2021 IEEE Wireless Power Transfer Conference, WPTC 2021  2021.6 

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    Event date: 2021.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  • Miniaturized Slot-Loaded SIW Resonator and Its Application to C-band Low Phase Noise Oscillator International conference

    S. Thapa, B. Chen, Adel Barakat, and Ramesh Pokharel

    2020 50th European Microwave Conference, EuMC 2020  2021.1 

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    Event date: 2021.1

    Language:English   Presentation type:Oral presentation (general)  

    Country:France  

    Other Link: https://ieeexplore.ieee.org/abstract/document/9338129

  • Experimental Study of the Effect of Interconnects on Phase Noise of K-Band VCO in CMOS Technology International conference

    Baichuan Chen, Nusrat Jahan, Adel Barakat, Ramesh K Pokharel

    2019 IEEE Asia-Pacific Microwave Conference (APMC)  2019.12 

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    Event date: 2020.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:Singapore  

    Other Link: https://ieeexplore.ieee.org/abstract/document/9038781/

  • High Isolation Simultaneous Wireless Power and Information Transfer System Using Coexisting DGS resonators and Figure-8 Inductors International conference

    Adel Barakat, Shimaa Alshhawy, Kuniaki Yoshitomi, Ramesh K. Pokharel

    2020 IEEE MTT-S International Microwave Symposium, (IMS 2020)  2020.8 

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    Event date: 2020.8

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9223866

  • Triple-Band Near-Field Wireless Power Transfer System Using Coupled Defected Ground Structure Band Stop Filters International conference

    Adel Barakat, Shimaa Alshhawy, Kuniaki Yoshitomi, Ramesh K. Pokharel

    2019 IEEE MTT-S International Microwave Symposium, IMS 2019  2019.6 

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    Event date: 2019.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  • 45% RF-to-DC Conversion Efficiency Wireless Power Transfer System Through Biological Tissues Using Complex Conjugate Impedance Matching Taking Account of Tissue's Properties International conference

    Sumin Chalise, Mitsuki Nakao, Fairus Tahar, Adel Barakat, Kuniaki Yoshitomi, Ramesh K. Pokharel

    2019 IEEE MTT-S International Microwave Symposium, IMS 2019  2019.6 

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    Event date: 2019.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  • Analysis and application of dual series resonances for low phase noise K-band VCO design in 0.18-μm CMOS technology International conference

    2019.1 

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    Event date: 2019.5

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Sapporo   Country:Japan  

    This work proposes a new theory to improve the phase noise of a Voltage-Controlled Oscillator (VCO) by introducing dual series resonances around the parallel resonance of an LC-tank circuit. The overall circuit has an improved susceptance slope parameters, which results in the improvement of quality (Q-) factor. Later, its effectiveness is demonstrated to design a low phase noise K-band VCO. The proposed characteristics are realized by a compact defected ground structure (DGS) resonator in a coplanar strip line (CPS) topology. The DGS is loaded by a capacitor, and this combination introduces the parallel resonance. The CPS signal line is implemented with high characteristic impedance to introduce a series inductance. Then, a gap in the CPS is introduced with a loading series capacitance forming a series resonance circuit with the CPS inductance. The overall combination of the series and parallel resonance circuits allowed the targeted two series resonances before and after the parallel resonance. The design is implemented in 0.18-μm CMOS technology, and the post-layout simulation shows that the VCO has a phase noise of -112.31 dBc/Hz @1 MHz offset of 22.07 GHz oscillation, which is 2.3 dB improvement compared to single series resonance VCO. The VCO consumes 4 mW power resulting in a figure of merit (FoM) of -193.2 dB.

  • Silicon-on-insulator first-order mode converter based on binary phase plate International conference

    Basma E. Abu-Elmaaty, Omnia M. Nawwar, Mohammed S. Sayed, Hossam M.H. Shalaby, Ramesh Pokharel

    2018 Japan-Africa Conference on Electronics, Communications, and Computations, JAC-ECC 2018  2018.12 

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    Event date: 2018.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:Egypt  

  • 70% Improvement in Q-factor of spiral inductor and its application in switched K-band VCO using 0.18 um CMOS technology International conference

    Islam Mansour, Marwa Mansour, Mohamed Aboualalaa, Ahmed Allam, Adel B. Abdel-Rahman, Mohammed Abo-Zahhad, Ramesh Pokharel

    30th Asia-Pacific Microwave Conference, APMC 2018  2018.11 

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    Event date: 2018.11

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

  • Dual Resonance Circuits by Defected Ground Structure Resonators for Low Phase Noise K-Band CMOS VCO Invited International conference

    Ramesh Pokharel, Nusrat Jahan, Adel Barakat

    2018 IEEE International Symposium on Radio-Frequency Integration Technology, RFIT 2018  2018.8 

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    Event date: 2018.8

    Language:English   Presentation type:Oral presentation (general)  

    Country:Australia  

  • Design of multi-layers DGS resonator for phase noise improvement of K-Band VCOs in 0.18 µm CMOS technology International conference

    2018.8 

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    Event date: 2018.8

    Language:English  

    Venue:Windsor   Country:Canada  

    A novel technique for a low phase noise and compact K-band Voltage-Controlled Oscillator (VCO) using multi-layers DGS resonator is proposed. The proposed DGS resonator realizes an additional series resonance at the higher side of parallel resonance frequency, and this results in improving both the active and loaded quality factor of the resonator. The proposed resonator has active quality factor of 130 and a compact size of 0.009 mm
    2
    (0.000459 ?
    2
    ). Using the proposed DGS resonator in the VCO causes 9 dB improvement in the phase noise compared the VCO implemented using the conventional LC resonator. Two VCOs are designed using the method to illustrate the effect of the series resonance. The first VCO is designed three layers DGS resonator and the other VCO using two layers DGS resonator. The designs are implemented in 0.18 µm CMOS technology and consume 2.9 mW power, and from the post layout results, the first proposed VCO oscillates from 19.6 to 21.3 GHz (8.3 %) and has a phase noise of -113.2 dBc/Hz at 1 MHz offset frequency, and this results in the figure of merit (FoM) and FoM taking account of the tuning range to be -194.4 and -192.7 dB, respectively. The second VCO has a tuning range of 6.1 % and phase noise of -114 dBc/Hz @ 1 MHz offset at 19.6 GHz oscillation.

  • High FOM Dual Band Wireless Power Transfer using Bow-tie Defected Ground Structure Resonators International conference

    M. R. Saad, Fairus Tahar, Sumin Chalise, Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    2018 IEEE Wireless Power Transfer Conference, WPTC 2018  2018.6 

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    Event date: 2018.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:Canada  

  • Compact Dual-Band Wireless Power Transfer Using Overlapped Single Loop Defected Ground Structure International conference

    Fairus Tahar, Sumin Chalise, Kuniaki Yoshitomi, Adel Barakat, Ramesh Pokharel

    2018 IEEE Wireless Power Transfer Conference, WPTC 2018  2018.6 

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    Event date: 2018.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:Canada  

  • A K-Band VCO Employing High Active Q-factor Defected Ground Structure Resonator in 0.18 pm CMOS Technology International conference

    Nusrat Jahan, Chen Baichuan, Ramesh K Pokharel, Adel Barakat

    2018 IEEE International Conference in Circuits and Systems (ISCAS2018)  2018.5 

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    Event date: 2018.5

    Language:English   Presentation type:Oral presentation (general)  

    Country:Italy  

    In this paper, a new theory to improve the phase noise of a Voltage-Controlled Oscillator (VCO) utilizing dual series and parallel resonance to improve the susceptance slope parameter of the resonator circuit is proposed, and its effectiveness is demonstrated to design a low phase noise K-band VCO. The proposed dual resonance is realized using a compact defected ground structure (DGS) resonator, which achieve the additional series resonance by loading its transmission line by a series capacitor. The resulting susceptance slope, and active quality (Qk-) factor of the resonator circuit enhance that, in returns, improves the phase noise by 3.2dB of the same circuit without the series resonance. The design is implemented in 0.18 μm CMOS technology, and the post-layout simulation results show that VCO has a tuning range of 3.4%, and low phase noise with − 111.9 dBc/Hz @1 MHz offset at 21.04 GHz oscillation. The VCO consumes 7.5 mW power resulting in a FoM of −188.7 dB

    Other Link: http://www.iscas2018.org/

  • Compact 24GHz half-slot antenna for energy combining International conference

    M Aboualalaa, Adel B Abdel-Rahman, A Allam, Ramesh K Pokharel, Kuniaki Yoshitomi, H Elsadek

    2018 International Applied Computational Electromagnetics Society Symposium (ACES)  2018.3 

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    Event date: 2018.3

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Compact 24GHz half-slot antenna for energy combining

    Other Link: http://www.aces-society.org/

  • K and Q Factors in Near-Field Wireless Power Transfer: A Case Study of DGS Resonators Invited International conference

    Ramesh K. Pokharel, Adel Barakat, and Fairus Tahar

    2017 IEEE MTT-S International Microwave and RF Conference  2017.12 

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    Event date: 2017.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:India  

    This paper discusses the probability of improving the degree of freedom in implementing wireless power transfer (WPT) systems. This is possible by utilizing the defected ground structures (DGSs). The WPT efficiency can be increased by optimizing the coupling coefficient (K) between the transmitter and the receiver, and the quality (Q-) factor of them. DGSs can be implemented in different shapes; hence, the K and Q-factor of these DSGs are realized with different values depending on the DGS shape. In return, the achievable WPT efficiency can be maximized by careful selection of the DGS shape and dimensions depending on the system efficiency and distance requirements.

    Other Link: https://imarc-ieee.org/

  • Dual-Band Wireless Power Transfer System Using Circular Defected Ground Structure Resonators for Biomedical Applications International conference

    F. Tahar, A. Barakat, R. Saad, K. Yoshitomi, and R. K. Pokharel

    2017 International Conference in Circuits and Systems (ISCAS2017)  2017.5 

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    Event date: 2017.5

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    In this paper, we proposed and developed a compact dual-band wireless power transfer system for future wireless power supply to embedded sensors and implants. This was fabricated in the commercial substrate, so it is low cost but it has high efficiency.

    Other Link: http://iscas2017.org/

  • Low insertion loss 60 GHz CMOS H-shaped resonator BPF International conference

    ADEL Barakat, N Mahmoud, POKHAREL RAMESH KUMAR

    2017 IEEE Radio and Wireless Symposium (RWS)  2017.1 

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    Event date: 2017.1

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: https://scholar.google.com/citations?view_op=view_citation&hl=ja&user=BVZNhYYAAAAJ&sortby=pubdate&citation_for_view=BVZNhYYAAAAJ:GFxP56DSvIMC

  • Simple design approach for asymmetric resonant inductive coupled WPT systems using J-inverters International conference

    Adel Barakat, Sherif Hekal, Ramesh Kumar Pokharel

    2016 Asia Pacific Microwave Conference  2016.12 

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    Event date: 2016.12 - 2017.5

    Language:English   Presentation type:Oral presentation (general)  

    Country:India  

    Other Link: http://ieeexplore.ieee.org/abstract/document/7931382/

  • Performance enhancement of 0.18 um CMOS on chip bandpass filters using H-shaped parasitic element International conference

    Nessim Mahmoud, Adel B Abdel-Rahman, Adel Barakat, Ramesh Kumar Pokharel

    2015 27th International Conference on Microelectronics (ICM)  2015.12 

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    Event date: 2015.12

    Language:English   Presentation type:Oral presentation (general)  

    Country:Morocco  

    Other Link: http://www.ieeeicm2015.org/

  • Comparative Design of Extremely Low Phase Noise Oscillator in Class-B and Class-C by Integrating Film Bulk Acoustic Resonator (FBAR) on CMOS Wafer for Low Power Applications Invited International conference

    Ramesh Kumar Pokharel, B. Amalina

    2015 IEEE MTT-S International Microwave and RF Conference (IMaRC)  2015.12 

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    Event date: 2015.12

    Language:English   Presentation type:Oral presentation (invited, special)  

    Country:India  

  • A gain enhanced 60 GHz CMOS antenna-on-chip using off-chip Mu near zero metamaterial lens International conference

    M. Hanif, ADEL TAWFIK MOHAMED MOHAMED BARAKAT, POKHAREL RAMESH KUMAR

    , 2015 IEEE 4th Asia-Pacific Conference on Antennas and Propagation (APCAP)  2015.7 

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    Event date: 2015.6 - 2015.7

    Language:English   Presentation type:Oral presentation (general)  

    Country:Indonesia  

  • 5.0 to 10.6 GHz 0.18 µm CMOS power amplifier with excellent group delay for UWB applications International conference

    2015.5 

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    Event date: 2015.5

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Phoenix   Country:United States  

    The optimization technique to realize the minimum group delay (GD) of a 5-10.6 GHz, two stages CMOS Ultra Wideband power amplifier (UWB-PA) is presented and implemented in 0.18 μm CMOS technology. The fabricated UWB-PA has a power gain (|S21|) of 14± 1 dB, maximum power added efficiency and an output 1-dB compression of 10 %, and 2 dBm, respectively at 6 GHz. In addition, the PA has an excellent small group delay variation of 147± 40 ps with power consumption of 20 mW and this is the smallest variations among CMOS PAs so far reported.

    Other Link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7167082&action=search&sortType=&rowsPerPage=&searchField=Search_All&matchBoolean=true&queryText=((%22Authors%22:Mosalam)%20AND%20%22Authors%22:Pokharel)

  • Strong resonant coupling for short-range wireless power transfer applications using defected ground structures International conference

    H. Hekel, A. B. Abdel-Rahman, M. Hanif, Ramesh Kumar Pokharel

    2015 IEEE Wireless Power Transfer Conference (WPTC)  2015.5 

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    Event date: 2015.5

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: http://www.wptc2015.org/

  • Miniaturized 60 GHz triangular CMOS Antenna-on-Chip using asymmetric artificial magnetic conductor International conference

    Adel Barakat, A. B. Abdel-Rahman, M. Hanif, Ramesh Kumar Pokharel

    2015 IEEE 15th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF)  2015.1 

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    Event date: 2015.1

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: http://www.silicon-rf.org/sirf2015/

  • A DC-2.5GHz voltage variable attenuator in 0.18-μm CMOS technology International conference

    2014.11 

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    Event date: 2014.11

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Ishigaki   Country:Japan  

    A CMOS variable voltage attenuator(VVA) with wide bandwidth has been designed and fabricated in a 0.18-μm CMOS process. Four bridge-T stages are cascaded to achieve 12 dB of dynamic range attenuation over a frequency range from DC up to 2.5 GHz. Cascaded bridge-T stages can be programmed to achieve the full scale attenuation and ensure good input and output matching. The design operates with 1.5-dB step size and with a maximum input power of -13 dBm in the entire frequency DC-2.5 GHz range. Worst case S11 is -11.5 dB across the frequency band. The design achieves an input third order intercept point (IIP3) of+31 dBm at maximum-attenuation

    Other Link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=7032792&action=search&sortType=&rowsPerPage=&searchField=Search_All&matchBoolean=true&queryText=((%22Authors%22:Abdalla)%20AND%20%22Authors%22:Pokharel)

  • Small size 60 GHz CMOS Antenna-on-Chip: Gain and efficiency enhancement using asymmetric Artificial Magnetic Conductor International conference

    Adel Barakat, Ramesh Kumar Pokharel, Haruichi Kanaya

    2014 44th European Microwave Conference (EuMC)  2014.10 

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    Event date: 2014.10

    Language:English   Presentation type:Oral presentation (general)  

    Country:Italy  

    Other Link: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=6986380&abstractAccess=no&userType=inst

  • An eight-phase CMOS injection locked ring oscillator with low phase noise International conference

    Khalil Yousef, A. B. Abdel-Rahman, Ramesh Kumar Pokharel, Hongting Jia

    2014 IEEE International Conference on Ultra-WideBand (ICUWB)  2014.9 

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  • Design Technique for a High-speed SAR ADC Using Non-binary Search Algorithm and Redundancy International conference

    2013 Asia-Pacific Microwave Conference Proceedings  2013.11 

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    Event date: 2013.11

    Language:English   Presentation type:Oral presentation (general)  

    Country:Korea, Republic of  

    Other Link: http://www.apmc2013.org/

  • Development of Circularly Polarized Planar Slot Antenna for 5.8 GHz-DSRC Application International conference

    2013 Asia-Pacific Microwave Conference Proceedings  2013.11 

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    Event date: 2013.11

    Language:English   Presentation type:Oral presentation (general)  

    Country:Korea, Republic of  

    Other Link: http://www.apmc2013.org/

  • CMOS Ultra-Wideband Low Noise Amplifier (UWB-LNA) Using Symmetric 3D RF Integrated Inductor International conference

    IEEE International Conference on Ultra-Wideband  2013.9 

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    Event date: 2013.9

    Language:English   Presentation type:Oral presentation (general)  

    Country:Australia  

    Other Link: http://www.icuwb2013.org/index.php

  • A 5–9 GHz CMOS Ultra-wideband power amplifier design using load-pull International conference

    2013.8 

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    Event date: 2013.8

    Language:English   Presentation type:Oral presentation (general)  

    Venue:Abu Dhabi   Country:United Arab Emirates  

    The design of 5-9 GHz, two stages CMOS power amplifier (PA) for Ultra-wideband (UWB) is presented in this paper. Post-layout simulation results indicated a power gain S21 of 16± 0.5dB, an input return loss S11 less than -4 dB and an output return loss S22 less than -5 dB over the frequency range of interest. Source-pull contours were used to design the inter stage matching of the PA. The proposed two stages PA achieves an average Power Added Efficiency (PAE) of 12.4% and an output 1-dB compression above 0 dBm over the same frequency band. Moreover, the proposed UWB PA achieves group delay of 170±20 ps with power consumption of 25 mW from a 1.8V supply voltage. The UWB PA is designed in TSMC 0.18 μm CMOS technology.

    Other Link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=6815333&action=search&sortType=&rowsPerPage=&searchField=Search_All&matchBoolean=true&queryText=((%22Authors%22:Mosalam)%20AND%20%22Authors%22:Pokharel)

  • A Low Power 8-bit Digitally Controlled CMOS Ring Oscillator International conference

    Proc. of 2012 European Microwave Conference  2012.10 

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    Event date: 2012.10 - 2012.11

    Language:English   Presentation type:Oral presentation (general)  

    Country:Netherlands  

    Other Link: http://www.eumweek.com/2012/

  • Digitally Controlled CMOS Quadrature Ring Oscillator with Improved FoM for GHz Range All-Digital Phase-Locked Loop Applications International conference

    POKHAREL RAMESH KUMAR, Prapto Nugroho, ANAND AWINASH, Haruichi Kanaya, Keiji Yoshida

    Dig. of 2012 IEEE International Microwave Symposium (IMS)  2012.6 

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    Event date: 2012.6

    Language:English   Presentation type:Oral presentation (general)  

    Country:Canada  

    Other Link: www.ims2012.org

  • Ultra-wideband Low Noise Amplifier with Shunt Resistive Feedback in 0.18um CMOS Process International conference

    A. I. A. Galal, R. K. Pokharel, K. Uchida, H. Kanaya, and K. Yoshida

    IEEE 10th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems  2010.1 

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    Event date: 2010.1

    Presentation type:Oral presentation (general)  

    Country:United States  

  • Low Phase Noise 18 kHz Frequency Tuning Step 5 GHz DCO Using Tiny Capacitors Based on Transmission Lines International conference

    R. K. Pokharel, K. Uchida, H. Kanaya, and K. Yoshida

    IEEE 10th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems  2010.1 

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    Event date: 2010.1

    Presentation type:Oral presentation (general)  

    Country:United States  

  • A 2.4 GHz 0.18 um CMOS Class E Single-Ended Power Amplifier without Spiral Inductors International conference

    S. A. Z. Murad, R. K. Pokharel, K. Uchida, H. Kanaya, and K. Yoshida

    IEEE 10th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems  2010.1 

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    Event date: 2010.1

    Presentation type:Oral presentation (general)  

    Country:United States  

  • Low Flicker-Noise and Low Leakage Direct Conversion CMOS Mixer for 5GHz Application International conference

    H. Kanaya, N. Koga, M. A. Abdelghany, R. K. Pokharel, and K. Yoshida

    Proc. of 2009 Asia Pacific Microwave Conference (APMC), Singapore, December 2009.  2009.12 

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    Event date: 2009.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

  • 10 Bit 2/5 GHz Dual Band Digitally-Controlled LC-Oscillator in 0.18 um CMOS Process International conference

    R. K. Pokharel, K. Uchida, H. Kanaya, and K. Yoshida

    Proc. of 2009 Asia Pacific Microwave Conference (APMC), Singapore, December 2009.  2009.12 

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    Event date: 2009.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

  • An UWB Bandpass Filter with Large Notch Suppression International conference

    R. Dong, R. K. Pokharel, H. Kanaya, and K. Yoshida

    Proc. of 2009 Asia Pacific Microwave Conference (APMC), Singapore, December 2009.  2009.12 

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    Event date: 2009.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

  • Design and performance of 800MHz/2GHz dual band small planar antenna International conference

    H. Urabe, R. K. Pokharel H. Kanaya, K. Yoshida, A. Ishikawa, S. Fukagawa, A. Tahira

    Proc. of 2009 Asia Pacific Microwave Conference (APMC), Singapore, December 2009.  2009.12 

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    Event date: 2009.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

  • Development of a One-Sided Directional Thin Planar Antenna with Quarter Wavelength Top Metal International conference

    H. Kanaya, K. Tsumura, R. K. Pokharel, H. Kanaya, K. Yoshida, A. Ishikawa, S. Fukagawa, and A. Tahira

    Proc. of 2009 Asia Pacific Microwave Conference (APMC), Singapore, December 2009.  2009.12 

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    Event date: 2009.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

  • A Low Flicker Noise Direct Conversion Receiver for the IEEE 802.11a Wireless LAN Standard International conference

    M. A. Abdelghany, R. K. Pokharel, H. Kanaya, and K. Yoshida

    Proc. of 2009 Asia Pacific Microwave Conference (APMC), Singapore, December 2009.  2009.12 

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    Event date: 2009.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

  • A 3.0-7.5 GHz CMOS UWB PA for Group 1~3 MB-OFDM Application Using Current-Reused and Shunt-Shunt Feedback International conference

    S. A. Z. Murad, R. K. Pokharel, H. Kanaya, and K. Yoshida

    the first International Conference on Wireless Communications & Signal Processing, WCSP2009.  2009.11 

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    Event date: 2009.11

    Presentation type:Oral presentation (general)  

    Country:China  

  • Low Phase Noise 10 bit 5 GHz DCO Using On-Chip CPW Resonator in 0.18 mm CMOS Technology International conference

    R. K. Pokharel, H. Kanaya, and K. Yoshida

    First Asian Himalayas International Conference on Internet AH-ICI2009, The next generation of mobile, wireless and Optical communications networks  2009.11 

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    Event date: 2009.11

    Presentation type:Oral presentation (general)  

    Country:Nepal  

  • Wide Tuning Range CMOS Quadrature Ring Oscillator of Lowest Figure of Merit International conference

    R. K. Pokharel, O. Nizhinik, H. Kanaya, and K. Yoshida

    2009 IEEE European Microwave Integrated Circuits (EuMIC)  2009.9 

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    Event date: 2009.9

    Presentation type:Oral presentation (general)  

    Country:Italy  

    Other Link: http://www.eumweek.com/

  • A 3.1 - 4.8 GHz CMOS UWB Power Amplifier Using Current Reused Technique International conference

    S. A. Z. Murad, R. K. Pokharel, H. Kanaya, and K. Yoshida

    the 5th International conference on wireless communications, networking, and mobile computing networks  2009.9 

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    Event date: 2009.9 - 2009.11

    Presentation type:Oral presentation (general)  

    Country:China  

  • Development of one-sided thin planner antenna for 5GHz wireless communication applications International conference

    H. Kanaya, R. K. Pokharel, Y. Nakamura, and K. Yoshida

    20009 IEEE Symposium on Antenna and Propagation  2009.6 

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    Event date: 2009.6

    Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: http://www.apsursi2009.org/

  • A low flicker noise high conversion gain RF-CMOS mixer with differential active inductor International conference

    2009.4 

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    Event date: 2009.4

    Presentation type:Oral presentation (general)  

    Venue:Jeju   Country:Korea, Republic of  

  • Design of Digitally Controlled LC Oscillator with Wide Tuning Range in 0.18um TSMC CMOS Technology International conference

    Abhishek Tomar, R. K. Pokharel, Haruichi Kanaya, Keiji Yoshida

    Design of Digitally Controlled LC Oscillator with Wide Tuning Range in 0.18um TSMC CMOS Technology  2008.12 

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    Event date: 2008.12

    Presentation type:Oral presentation (general)  

  • Design of VCO Using On-Chip CPW Resonator for 5 GHz-Band Wireless Applications International conference

    R. K. Pokharel, S. Sasaki, O. Nizhnik, H. Kanaya, and K. Yoshida

    Proc. of 2008 Asia-Pacific Microwave Conference (APMC)  2008.12 

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    Event date: 2008.12

    Presentation type:Oral presentation (general)  

  • Design and performance of electrically small planar antennas with matching circuit at 2.4GHz band International conference

    Y. Nakamura, H. Kanaya, R. K. Pokharel, and Keiji Yoshida

    Proc. of 2008 Asia-Pacific Microwave Conference (APMC)  2008.12 

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    Event date: 2008.12

    Presentation type:Oral presentation (general)  

  • Comparison between Bipolar and NMOS Transistors in Linearization Technique at 5GHz Low Noise Amplifier International conference

    A. I. A. Galal, R. K. Pokharel, H. Kanaya, and K. Yoshida

    Proc. of 2008 Asia-Pacific Microwave Conference (APMC)  2008.12 

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    Event date: 2008.12

    Presentation type:Oral presentation (general)  

  • Design of Highly linear, 1GHz 8-bit digitally controlled ring oscillator with wide turning range in 0.18um CMOS process International conference

    R. K. Pokharel, A. Tomar, H. Kanaya, and K. Yoshida

    The Proc. of China-Japan Microwave conference (CJMW)  2008.9 

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    Event date: 2008.9

    Presentation type:Oral presentation (general)  

    Country:China  

  • Design of flat gain and low noise figure LNA for 3.1-10.2GHz band UWB applications in 0.18um CMOS process International conference

    R. K. Pokharel, A. I. A. Galal, O. Nizhnik, H. Kanaya and K. Yoshida

    The 2008 IEEJ international workshop on AVLSI  2008.7 

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    Event date: 2008.7 - 2008.8

    Presentation type:Symposium, workshop panel (public)  

    Country:Turkey  

  • Design of Power Amplifier with On-Chip Matching Circuits using CPW Line Impedance (K) Inverters International conference

    H. Kanaya, R. K. Pokharel, S. Kim, A. Imada, K. Yoshida

    11th WSEAS International Conference on CIRCUITS  2007.7 

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    Event date: 2008.7

    Presentation type:Oral presentation (general)  

    Country:Greece  

    Design of Power Amplifier with On-Chip Matching Circuits using CPW Line Impedance (K) Inverters

  • CPWインピーダンス回路を用いたRFフロントエンドLSIの設計・評価

    電子情報通信学会技術研究報告  2007.4 

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    Event date: 2008.4 - 2007.4

    Presentation type:Oral presentation (general)  

    Country:Japan  

  • 片面指向性をもつ整合回路一体型平面アンテナの開発

    中村優太・鍋嶋隆介・ポカレル ラメシュ・金谷晴一・吉田啓二

    電子情報通信学会技術研究報告  2008.4 

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    Event date: 2008.4

    Presentation type:Oral presentation (general)  

    Venue:東京   Country:Japan  

  • 5.2GHz帯VCOの開発と高性能化の検討

    佐々木慎一・今田明寛・ポカレル ラメシュ・金谷晴一・吉田啓二

    電子情報通信学会技術研究報告  2008.4 

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    Event date: 2008.4

    Presentation type:Oral presentation (general)  

    Venue:東京   Country:Japan  

  • High Dynamic Range Mixer in 0.18 um Technology for WLAN Direct Conversion Receiver International conference

    Oleg Nizhnik, Ramesh Pokharel, Haruichi Kanaya, Keiji Yoshida

    Proceedings of 2008 International Conference on Microwave and Millimeter Wave Technology (ICMMT 2008)  2008.4 

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    Event date: 2008.4

    Presentation type:Oral presentation (general)  

    Country:China  

    High Dynamic Range Mixer in 0.18 um Technology for WLAN Direct Conversion Receiver

  • Development of an Electrically Small One-Sided Directional Antenna with Matching Circuit International conference

    Haruichi Kanaya, Ryusuke Nabeshima, Ramesh Pokharel, Keiji Yoshida, Masato Tsujii, and Ryoichi Iino

    2008 IEEE Radio and Wireless Symposium Proceedings  2008.1 

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    Event date: 2008.1

    Presentation type:Oral presentation (general)  

    Country:United States  

    Development of an Electrically Small One-Sided Directional Antenna with Matching Circuit

  • Study of A CPW-Fed Slot Dipole One-Sided Directional Antenna for UWB Systems International conference

    H. Kanaya, T. Hashiguchi, R. K. Pokharel, and K. Yoshida

    2007APMC (2007 Asia-Pacific Microwave Conference) Proceedings  2007.12 

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    Event date: 2007.12 - 2012.12

    Presentation type:Oral presentation (general)  

    Country:Thailand  

    Study of A CPW-Fed Slot Dipole One-Sided Directional Antenna for UWB Systems

  • Design of VCO for 2.4GHz Wireless Applications Using Transmission Line Resonators International conference

    R. K. Pokharel, A. Imada, S. Sasaki, H. Kanaya, and K. Yoshida

    2007APMC (2007 Asia-Pacific Microwave Conference) Proceedings  2007.12 

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    Event date: 2007.12

    Presentation type:Oral presentation (general)  

    Country:Thailand  

    Design of VCO for 2.4GHz Wireless Applications Using Transmission Line Resonators

  • Design of High-Linearity Amplifier for Wireless LAN Transceiver International conference

    O. Nizhnik, R.K. Pokharel, H. Kanaya, and K. Yoshida

    2007APMC (2007 Asia-Pacific Microwave Conference)  2007.12 

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    Event date: 2007.12

    Presentation type:Oral presentation (general)  

    Country:Thailand  

    Design of High-Linearity Amplifier for Wireless LAN Transceiver

  • Design and Performance of an Electrically Small Antenna with Matching Circuit International conference

    H. Kanaya, R. Nabeshima, R. K. Pokharel, and K. Yoshida

    2007APMC (2007 Asia-Pacific Microwave Conference)  2007.11 

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    Event date: 2007.12

    Presentation type:Oral presentation (general)  

    Country:Thailand  

    Design and Performance of an Electrically Small Antenna with Matching Circuit

  • Design of 1.1 GHz Highly Linear Digitally-Controlled Ring Oscillator with Wide Tuning Range International conference

    A. Tomar, R. K. Pokharel, O. Nizhnik, H. Kanaya, and K. Yoshida

    IEEE International Workshop on Radio-Frequency Integration Technology  2007.12 

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    Event date: 2007.12

    Presentation type:Oral presentation (general)  

    Country:Singapore  

    Design of 1.1 GHz Highly Linear Digitally-Controlled Ring Oscillator with Wide Tuning Range

  • Compact size high gain AoC using rectangular AMC in CMOS for 60 GHz millimeter wave applications International conference

    2013 IEEE MTT-S International Microwave Symposium  2013.6 

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    Language:English  

    Country:Japan  

    This paper presents a compact size, high gain triangular Antenna-on-Chip (AoC), designed and fabricated using a 0.18 μm CMOS process and optimized over different cells' configurations of rectangular artificial magnetic conductor (R-AMC). An AMC acts as a shield plane between the AoC and the lossy CMOS substrate. R-AMC shows better shielding characteristics than previously reported AMCs. Measurement results confirm the wide impedance bandwidth of the AoC.

    Other Link: http://ieeexplore.ieee.org/xpl/articleDetails.jsp?tp=&arnumber=6697475&matchBoolean%3Dtrue%26searchField%3DSearch_All%26queryText%3D%28%28p_Authors%3ABarakat%29+AND+p_Authors%3APokharel%29

  • “Design of CMOS design circuit connected to a transmission line for high speed and low power optical switch,” China-Japan Joint Microwave Conferrence, 23-25 Aug, 2006. International conference

    2006.8 

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    Presentation type:Symposium, workshop panel (public)  

    Venue:Chengdu   Country:China  

  • Development of high conversion gain double balanced mixer for high performance direct conversion receiver

    R. K. Pokharel, H. Kanaya, and K. Yoshida

    2006.8 

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    Presentation type:Oral presentation (general)  

    Country:Japan  

    Development of high conversion gain double balanced mixer for high performance direct conversion receiver

  • Accuracy and Applications of Time-Domain Numerical Electromagnetic Code to Lightning Surge Analysis: Survey and Comparative Study in Time- and Frequency-Domain Codes International conference

    R. K. Pokharel and M. Ishii

    International Conference on Lightning Protection (ICLP), 2006  2006.8 

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    Presentation type:Oral presentation (general)  

    Country:Japan  

  • Design of Coplanar Waveguide on-chip impedance matching circuit for wireless receiver front-end International conference

    H. Kanaya, R. K. Pokharel, , F. Koga, D. Arima, S. Kim, and K .Yoshida

    IEEE Radio Frequency Integrated Circuit Conference (2006)  2006.6 

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    Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: www.rfic2006.org

  • Metamaterial Inspired Geometries for Wireless Power Transfer to Biomedical Implants Invited International conference

    Ramesh Pokharel, Adel Barakat, Costas Sarris

    2021 51st European Microwave Conference (EuMC)  2022.4 

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    Event date: 2022.4

    Language:English   Presentation type:Oral presentation (invited, special)  

    Country:United Kingdom  

    Other Link: https://ieeexplore.ieee.org/abstract/document/9784207

  • Enhancing Dynamic Range of RF-to-DC Rectifier using Leakage Current Reduction Technique

    M. Mahmoud, G. Fahmy, A. B. Abdel-Rahman, A. Allam, M. Abo-Zahhad, H. Jia, R. K. Pokharel

    7th International Japan-Africa Conference on Electronics, Communications and Computations, JAC-ECC 2019  2019.12 

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    Event date: 2019.12

    Language:English  

    Country:Egypt  

  • Dual-Band Defected Ground Structure Resonators Wireless Power Transfer System Connected to Voltage-Doubler Circuit

    Fairus Tahar, Sumin Chalise, Adel Barakat, Kuniaki Yoshitomi, Ramesh K. Pokharel

    2019 IEEE Topical Conference on Wireless Sensors and Sensor Networks, WiSNet 2019  2019.5 

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    Event date: 2019.1

    Language:English  

    Country:United States  

  • First-Order Mode Compact Focusing Grating Coupler for SOI Interconnect International conference

    Omnia M. Nawwar, Hossam M.H. Shalaby, Ramesh Pokharel

    2018 IEEE Photonics Society Summer Topicals Meeting Series, SUM 2018  2018.7 

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    Event date: 2018.7

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

  • High efficiency wireless power transfer system using spiral DGS resonators through biological tissues

    Sumin Chalise, F. Tahar, M. R. Saad, A. Baraket, Kuniaki Yoshitomi, Ramesh Pokharel

    2018 IEEE/MTT-S International Microwave Biomedical Conference, IMBioc 2018  2018.8 

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    Event date: 2018.6

    Language:English  

    Country:United States  

  • Dual-band Rectenna Using Voltage Doubler Rectifier and Four-Section Matching Network

    Mohamed Aboualalaa, Islam Mansour, Mohamed Mansour, Adel Bedair, Ahmed Allam, Mohammed Abo-Zahhad, Hala Elsadek, Kuniaki Yoshitomi, Ramesh Pokharel

    2018 IEEE Wireless Power Transfer Conference, WPTC 2018  2019.2 

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    Event date: 2018.6

    Language:English  

    Country:Canada  

  • A K-Band VCO Employing High Active Q-factor Defected Ground Structure Resonator in 0.18pm CMOS Technology

    Nusrat Jahan, Chen Baichuan, Ramesh Pokharel, Adel Barakat

    2018 IEEE International Symposium on Circuits and Systems, ISCAS 2018  2018.4 

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    Event date: 2018.5

    Language:English  

    Country:Italy  

  • Compact 24GHz half-slot antenna for energy combining

    M. Aboualalaa, Adel B. Abdel-Rahman, A. Allam, Ramesh Pokharel, Kuniaki Yoshitomi, H. Elsadek

    2018 International Applied Computational Electromagnetics Society Symposium in Denver, ACES-Denver 2018  2018.5 

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    Event date: 2018.3

    Language:English  

    Country:United States  

  • Broadband printed-dipole antenna for future 5G applications and wireless communication

    Anwer S.Abd El-Hameed, Adel Barakat, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Pokharel, Kuniaki Yoshitomi

    2018 IEEE Radio and Wireless Symposium, RWS 2018  2018.2 

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    Event date: 2018.1

    Language:English  

    Country:United States  

  • A high-efficiency, low-power 2.4 GHz class AB PA for WBAN applications using load pull

    A. Gadallah, A. Allam, A. B. Abdel-Rahman, Hongting Jia, Ramesh Pokharel

    2017 Japan-Africa Conference on Electronics, Communications, and Computers, JAC-ECC 2017  2018.3 

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    Event date: 2017.12

    Language:English  

    Country:Egypt  

  • Degree of freedom to select coupling coefficent and quality factor in near-field wireless power transfer A case study of using DGS Structures

    Ramesh Pokharel, Adel Barakat, Fairus Tahar, Sherif Hekal

    2017 IEEE MTT-S International Microwave and RF Conference, IMaRC 2017  2018.8 

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    Event date: 2017.12

    Language:English  

    Country:India  

  • Study of phase noise improvement of K-band VCO using additional series resonance realized by DGS resonator on CMOS technology

    Nusrat Jahan, Adel Barakat, Ramesh Pokharel

    2017 IEEE Asia Pacific Microwave Conference, APMC 2017  2018.1 

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    Event date: 2017.11

    Language:English  

    Country:Malaysia  

  • Analysis of near field wireless power transfer using bow-tie defected ground structure

    M. R. Saad, Fairus Tahar, Adel Barakat, Kuniaki Yoshitomi, Ramesh Pokharel

    2017 IEEE Asia Pacific Microwave Conference, APMC 2017  2018.1 

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    Event date: 2017.11

    Language:English  

    Country:Malaysia  

  • Ku-band oscillator using integrated defected ground structure resonator in 0.18μm CMOS technology

    2017.12 

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    Event date: 2017.10

    Language:English  

    Venue:Nuremburg   Country:Germany  

    In the paper, we propose a novel voltage-controlled oscillator (VCO) employing defected ground structure (DGS) band stop filter (BSF). The VCO operates from 15.24 GHz to 15.86 GHz. A square shaped DGS etched at the lowest metal layer (M1) below 50-Ohm microstrip line on the top metal layer (M6) of 0.18 μm 1P6M CMOS process. The proposed square-shaped DGS resonator achieves smaller size and higher quality factor than those of a conventional spiral inductor resonator at Ku band frequency. The power dissipation of the VCO is 4 mW. The measured carrier frequency and phase noise are 15.76 GHz and-127.57 dBc/Hz (104.25 dBc/Hz) at 10 MHz (1 MHz) offset frequency, respectively. The measured figure of merit (FoM) is 182.9 dB. The fabricated chip core VCO size is only 0.084mm2 which increases figure of merit (FoMa) to 194 dB.

  • A DC-2.5 GHz high linearity CMOS attenuator in a 0.18μm technology

    2018.1 

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    Event date: 2017.10

    Language:English  

    Venue:Tirgu Mures   Country:Romania  

    A CMOS attenuator with high linearity has been designed and measured in a 0.18-μm CMOS process, to be used for a variable gain amplifier of RF wireless transceiver. The design is based on four cascaded Bridge-T attenuator stages that are consecutively activated to adjust the attenuation level and improve linearity. The design operates in the frequency band of DC-2.5 GHz with 2 - 3.5 dB insertion loss and 14 dB maximum attenuation in the entire frequency range. Measured and simulated results are in good agreement over the frequency band of interest. Measured worst case S11 and S22 are -10 and -8.8 dB, respectively, across the frequency band. The measured 1-dB compression point is +22 dBm at maximum-attenuation.

  • Design and fabrication of a Bi-directional Mode-Division Multiplexer (BMDM) for optical interconnects

    Omnia M. Nawwar, Hossam M.H. Shalaby, Ramesh Pokharel

    30th Annual Conference of the IEEE Photonics Society, IPC 2017  2017.11 

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    Event date: 2017.10

    Language:English  

    Country:United States  

  • Design and fabrication of a Bi-directional Mode-Division Multiplexer (BMDM) for optical interconnects

    Omnia M. Nawwar, Hossam M.H. Shalaby, Ramesh Pokharel

    30th Annual Conference of the IEEE Photonics Society, IPC 2017  2017.11 

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    Event date: 2017.10

    Language:English  

    Country:United States  

  • Low insertion loss 60 GHz CMOS H-shaped resonator BPF

    Adel Barakat, Nessim Mahmoud, Ramesh Pokharel

    2017 IEEE Radio and Wireless Symposium, RWS 2017  2017.3 

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    Event date: 2017.1

    Language:English  

    Country:United States  

  • A new compact wireless power transfer system using C-shaped printed resonators

    Ramy Sharaf, Sherif Hekal, Anwer Abd El-Hameed, Adel B. Abdel-Rahman, Ramesh Pokharel

    23rd IEEE International Conference on Electronics, Circuits and Systems, ICECS 2016  2017.2 

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    Event date: 2016.12

    Language:English  

    Country:Monaco  

  • Simple design approach for asymmetric resonant inductive coupled WPT systems using J-inverters

    Adel Barakat, Sherif Hekal, Ramesh Pokharel

    2016 Asia-Pacific Microwave Conference, APMC 2016  2017.5 

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    Event date: 2016.12

    Language:English  

    Country:India  

  • Low phase noise high switching ring VCO with quadrature output

    Ankit Goel, Abhishek Tomar, Navneet Kumar, Ramesh Pokharel

    2016 Asia-Pacific Microwave Conference, APMC 2016  2017.5 

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    Event date: 2016.12

    Language:English  

    Country:India  

  • Design of 5.5GHz LC oscillator using distributed grid of N-well in P-substrate inductor

    S. A.Enche Ab Rahim, Adel Barakat, Ramesh Pokharel

    2016 IEEE Asia Pacific Conference on Circuits and Systems, APCCAS 2016  2017.1 

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    Event date: 2016.10

    Language:English  

    Country:Korea, Republic of  

  • Dynamic threshold compensated, low voltage CMOS energy harvesting rectifier for UHF applications

    Manal Mahmoud, Adel B. Abdel-Rahman, Ghazal A. Fahmy, Ahmed Allam, Hongting Jia, Ramesh Pokharel

    59th IEEE International Midwest Symposium on Circuits and Systems, MWSCAS 2016  2017.3 

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    Event date: 2016.10

    Language:English  

    Country:United Arab Emirates  

  • A high-efficiency good linearity 21 to 26.5 GHz fully integrated power amplifier using 0.18 μm CMOS technology

    2017.3 

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    Event date: 2016.10

    Language:English  

    Venue:Abu Dhabi   Country:United Arab Emirates  

    This paper presents the design and implementation of a 21- 26.5 GHz broadband, two stages CMOS power amplifier (PA) for quasi-millimeter wave band wireless communication systems. The proposed PA is designed using staggered tuning method [1], which is employed for the first time in quasi-millimeter wave band. Moreover, source and load-pull simulation, in addition to, impedance analysis are employed to optimize the input, output, and inter-stage impedance matching circuits for maximum power added efficiency (PAE) and better linearity. The measurement results on a chip fabricated using 0.18 μm CMOS technology shows a power gain of 10.2 ± 0.8 dB, a maximum PAE and output gain compression point (POut1dB ) of 10.5 dBm and 18 %, respectively, at 24 GHz while consuming 42 mW only. In addition, the PA achieved excellent low measured group delay variations of 75 ± 22 ps.

  • Radiation performance enhancement of a 60 GHz CMOS Quasi-Yagi antenna

    Elsayed Elsaidy, Adel Barakat, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Pokharel

    17th IEEE Annual Wireless and Microwave Technology Conference, WAMICON 2016  2016.6 

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    Event date: 2016.4

    Language:English  

    Country:United States  

  • Design of frequency tunable CPW-Fed UWB antenna using varactor diodes for cognitive radio and future software defined radio

    Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Sherif Hekal, Ramesh Pokharel

    17th IEEE Annual Wireless and Microwave Technology Conference, WAMICON 2016  2016.6 

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    Event date: 2016.4

    Language:English  

    Country:United States  

  • A 60-GHz on-chip tapered slot Vivaldi antenna with improved radiation characteristics

    Anwer S.Abd El-Hameed, Nessim Mahmoud, Adel Barakat, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Pokharel

    10th European Conference on Antennas and Propagation, EuCAP 2016  2016.5 

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    Event date: 2016.4

    Language:English  

    Country:Switzerland  

  • New compact tunable filter-antenna using varactor loaded ring resonator for cognitive radio front end system

    Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Ramesh Pokharel

    IEEE/ACES International Conference on Wireless Information Technology, ICWITS 2016 and System and Applied Computational Electromagnetics, ACES 2016  2016.5 

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    Event date: 2016.3

    Language:English  

    Country:United States  

  • Compact frequency tunable filtenna with wide continuous tuning range using capacitively loaded folded arms open loop resonator for interweave cognitive radio applications

    Hany A. Atallah, Adel B. Abdel-Rahman, Kuniaki Yoshitomi, Ramesh Pokharel

    33rd National Radio Science Conference, NRSC 2016  2016.4 

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    Event date: 2016.2

    Language:English  

    Country:Egypt  

  • A broadband high linearity inductorless CMOS variable gain amplifier for square kilometer array International conference

    I. L. Abdalla, A. Allam, JIA HONGTING, Ramesh Kumar Pokharel

    2015 International Conference on Synthesis, Modeling, Analysis and Simulation Methods and Applications to Circuit Design (SMACD)  2015.9 

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    Event date: 2015.9

    Language:English   Presentation type:Oral presentation (general)  

    Country:Turkey  

    Other Link: http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=7301683&abstractAccess=no&userType=inst

  • A High Efficiency 3-7 GHz Class AB CMOS Power Amplifier for WBAN Applications

    A. Gadallah, A. B. Abdel-Rahman, Ramesh Kumar Pokharel, Hongting Jia

    2014 IEEE International Symposium on Radio-Frequency Integration Technology  2015.8 

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    Event date: 2015.8

    Language:English   Presentation type:Oral presentation (general)  

    Country:Japan  

    Other Link: http://www.rfit2014.org/

  • Multi-Band Miniaturized Slot Antenna with Two-Stage Bandpass Filter, International conference

    IEEE International Symposium on Antennas and Propagation and USNC-URSI National Radio ScienceMeeting  2013.7 

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    Event date: 2013.7

    Language:English   Presentation type:Oral presentation (general)  

    Country:United States  

    Other Link: http://www.2013apsursi.org/

  • Comparative study of 5.8 GHz DSRC EM environment in a rectangular and semi-circular tunnel International conference

    R. K. Pokharel, M. Toyota, and O. Hashimoto

    2005 IEEE International EMC Symposium  2005.8 

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    Presentation type:Symposium, workshop panel (public)  

    Country:United States  

  • Experimental study on LTCC resonators loaded with dielectric rods International conference

    R, K. Pokharel, K. Wada, O. Hashimoto, and T. Takahashi

    2005 IEEE International Symposium on AP-S/USRI  2005.6 

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    Country:United States  

  • Improvement of out-of band characteristics of BPFs using partially coupled lines International conference

    R. K. Pokharel, K. Wada, and O. Hashimoto

    Asia Pacific Microwave Conference (APMC'04)  2004.12 

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    Presentation type:Symposium, workshop panel (public)  

    Country:India  

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MISC

Industrial property rights

Patent   Number of applications: 2   Number of registrations: 2
Utility model   Number of applications: 0   Number of registrations: 0
Design   Number of applications: 0   Number of registrations: 0
Trademark   Number of applications: 0   Number of registrations: 0

Professional Memberships

  • 電気学会

  • The Institute of Electronics, Information and Communication Engineers

  • The Institute of Electrical and Electronics Engineers

Academic Activities

  • Screening of academic papers

    Role(s): Peer review

    2024

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:20

    Number of peer-reviewed articles in Japanese journals:0

    Proceedings of International Conference Number of peer-reviewed papers:8

    Proceedings of domestic conference Number of peer-reviewed papers:0

  • Screening of academic papers

    Role(s): Peer review

    2023

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:12

    Number of peer-reviewed articles in Japanese journals:0

    Proceedings of International Conference Number of peer-reviewed papers:6

    Proceedings of domestic conference Number of peer-reviewed papers:2

  • Screening of academic papers

    Role(s): Peer review

    2022

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:13

    Number of peer-reviewed articles in Japanese journals:0

    Proceedings of International Conference Number of peer-reviewed papers:4

    Proceedings of domestic conference Number of peer-reviewed papers:0

  • Screening of academic papers

    Role(s): Peer review

    2021

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:15

    Number of peer-reviewed articles in Japanese journals:0

    Proceedings of International Conference Number of peer-reviewed papers:8

    Proceedings of domestic conference Number of peer-reviewed papers:0

  • Screening of academic papers

    Role(s): Peer review

    2019

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:11

    Number of peer-reviewed articles in Japanese journals:0

    Proceedings of International Conference Number of peer-reviewed papers:3

    Proceedings of domestic conference Number of peer-reviewed papers:0

  • TPC International contribution

    International Japan-Africa Conference on Electronics, Communications and Computers (JAC-ECC2018)  ( Alexandaria Egypt ) 2018.12

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    Type:Competition, symposium, etc. 

    Number of participants:70

  • TPC International contribution

    2018 IEEE International Symposium on Radio-Frequency Integration Technology (RFIT2018)  ( Melbourn Australia ) 2018.8

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    Type:Competition, symposium, etc. 

    Number of participants:200

  • Screening of academic papers

    Role(s): Peer review

    2018

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:18

    Number of peer-reviewed articles in Japanese journals:0

    Proceedings of International Conference Number of peer-reviewed papers:3

    Proceedings of domestic conference Number of peer-reviewed papers:0

  • TPC International contribution

    Japan-Africa Conference on Electronics, Communications and Computers (JAC-ECC2017)  ( Alexandaria Egypt ) 2017.12

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    Type:Competition, symposium, etc. 

    Number of participants:70

  • 座長(Session Chair) International contribution

    2017.12

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    Type:Competition, symposium, etc. 

    Number of participants:300

  • TPC International contribution

    2017 IEEE MTT-S International Microwave and RF Conference  ( Ahmedabad India ) 2017.12

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    Type:Competition, symposium, etc. 

    Number of participants:300

  • 座長(Session Chair) International contribution

    2017.11

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    Type:Competition, symposium, etc. 

    Number of participants:100

  • Advisory Comimittee International contribution

    International conference on Electrical, Computers and Communication Engineering  ( Cox's Bazar Bangladesh ) 2017.2

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  • Screening of academic papers

    Role(s): Peer review

    2017

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    Type:Peer review 

    Number of peer-reviewed articles in foreign language journals:10

    Number of peer-reviewed articles in Japanese journals:1

    Proceedings of International Conference Number of peer-reviewed papers:5

    Proceedings of domestic conference Number of peer-reviewed papers:0

  • Conference Chair (実行委員長) International contribution

    2016.5 - 2016.6

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    Type:Competition, symposium, etc. 

    Number of participants:80

  • 委員長(Conference Chair) International contribution

    2016 The Third International Japan-Egypt Conference on Electronics, Communications and Computers (第4回 日本エジプト電子・通信・計算機に関する国際会議)  ( カイロ ) 2016.5 - 2016.6

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  • Conference Chair (委員長) International contribution

    ( 伊都キャンパス(九州大学 ) 2015.3 - 2016.3

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    Type:Competition, symposium, etc. 

    Number of participants:33

  • Conference Chair (実行委員長) International contribution

    2015.3

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    Type:Competition, symposium, etc. 

    Number of participants:80

  • 座長(Chairmanship) International contribution

    ( ジョグジャカルタ ) 2013.10

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  • IEICE International contribution

    Role(s): Peer review

    2013.5 - 2020.4

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  • IEEE Transactions on Microwave Theory and Techniques International contribution

    Role(s): Peer review

    2012.5 - 2022.4

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  • IEEE Trans. on Circuits and Systems II: Express Brief International contribution

    Role(s): Peer review

    2012.4 - 2020.3

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  • IEEE Microwave and Components Letters International contribution

    Role(s): Peer review

    2012.4 - 2020.3

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  • プログラム編集員

    平成21年度(第62回)電気関係学会九州支部連合大会  ( 北九州 ) 2009.9

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    Type:Competition, symposium, etc. 

    Number of participants:400

  • 座長(Chairmanship) International contribution

    ( 上海 ) 2008.9

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  • 座長(Chairmanship) International contribution

    ( 愛媛大学 ) 2008.3

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  • 座長(Chairmanship) International contribution

    2007.7

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Other

  • 研究成果のプレースリリース ーーーーーーーーーーーーーーーー ポイント 従来型無線電⼒伝送システムには伝送効率、伝送距離、ミスアラインメントで電⼒伝送ができないという問題ありました。 上記の問題を対処するため、新たなメタサーフェスを開発し、それらを⽤いて磁場の制御に成功しました。 タブレット、携帯などを机に置くだけで充電可能な技術の開発が期待されます。 概要  スマートフォンや医療機器などの⼩型デバイスの普及に伴い、充電の⽅法が有線から無線へと移⾏しています。このようなシステムでは、無線電⼒伝送(※1)が不可⽋ですが、WPT システムを⼩型化することで電⼒伝送効率が低下し、遠距離での電⼒伝送に制約が⽣じていました。また、受信機と送信機の位置のずれにより、電⼒伝送が妨げられる問題も存在しました。本研究では、新たなメタサーフェス(※2)を開発し、⼩型化されたWPT システムに導⼊することで、元の伝送効率を維持しながら、最⼤300%まで伝送距離を向上させることに成功しました。具体的には、メタサーフェスを導⼊する前の40mm の伝送距離での伝送効率が8%だったものが、メタサーフェスを応⽤することで78%まで向上しました。さらに、受信機と送信機の位置ずれによるミスアラインメント(※3)の問題も、開発したメタサーフェスの応⽤により⼤幅に改善されました。このような新たなWPT システムの性能向上は、当該分野においては画期的な成果となりました。  九州⼤学⼤学院システム情報科学研究院Ramesh Pokharel(ポカレル ラメシュ)教授のグループと共同研究者のMohamed Aboualalaa(モハメド アブアララー)外国⼈特別研究員が、メタサーフェスの設計を⾏い、無線電⼒伝送システムの送信器と受信器の間の磁場を制御することにより、無線電⼒伝送距離およびミスアラインメント問題が解決されることを明らかにしました。  本研究成果は⽶国の雑誌「IEEE Transactions on Instrumentation and Measurement」に2023年10⽉17⽇(⽔)午前10時(⽇本時間)に掲載されました。

    2023.10

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    ポイント

    従来型無線電⼒伝送システムには伝送効率、伝送距離、ミスアラインメントで電⼒伝送ができないという問題ありました。
    上記の問題を対処するため、新たなメタサーフェスを開発し、それらを⽤いて磁場の制御に成功しました。
    タブレット、携帯などを机に置くだけで充電可能な技術の開発が期待されます。

    概要

     スマートフォンや医療機器などの⼩型デバイスの普及に伴い、充電の⽅法が有線から無線へと移⾏しています。このようなシステムでは、無線電⼒伝送(※1)が不可⽋ですが、WPT システムを⼩型化することで電⼒伝送効率が低下し、遠距離での電⼒伝送に制約が⽣じていました。また、受信機と送信機の位置のずれにより、電⼒伝送が妨げられる問題も存在しました。本研究では、新たなメタサーフェス(※2)を開発し、⼩型化されたWPT システムに導⼊することで、元の伝送効率を維持しながら、最⼤300%まで伝送距離を向上させることに成功しました。具体的には、メタサーフェスを導⼊する前の40mm の伝送距離での伝送効率が8%だったものが、メタサーフェスを応⽤することで78%まで向上しました。さらに、受信機と送信機の位置ずれによるミスアラインメント(※3)の問題も、開発したメタサーフェスの応⽤により⼤幅に改善されました。このような新たなWPT システムの性能向上は、当該分野においては画期的な成果となりました。
     九州⼤学⼤学院システム情報科学研究院Ramesh Pokharel(ポカレル ラメシュ)教授のグループと共同研究者のMohamed Aboualalaa(モハメド アブアララー)外国⼈特別研究員が、メタサーフェスの設計を⾏い、無線電⼒伝送システムの送信器と受信器の間の磁場を制御することにより、無線電⼒伝送距離およびミスアラインメント問題が解決されることを明らかにしました。
     本研究成果は⽶国の雑誌「IEEE Transactions on Instrumentation and Measurement」に2023年10⽉17⽇(⽔)午前10時(⽇本時間)に掲載されました。

Research Projects

  • High Efficiency WPT System Using Hybrid Metasurface and Reactive Impedance Surface

    Grant number:22KF0292  2023.3 - 2024.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for JSPS Fellows

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    Grant type:Scientific research funding

    CiNii Research

  • Research on a small phased array device using a staircase array antenna and a Butler matrix circuit

    Grant number:22K04094  2022.4 - 2025.3

    Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

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    Grant type:Scientific research funding

    CiNii Research

  • メタマテリアルとリアクティブ反射板を利用した高効率WPTシステム

    2022 - 2023

    日本学術振興会  海外特別研究員

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    Authorship:Principal investigator  Grant type:Joint research

  • メタマテリアルとリアクティブ反射板を利用した高効率WPTシステム

    Grant number:21F41046  2021.9 - 2024.3

    科学研究費助成事業  特別研究員奨励費

    Pokharel R.K., ALI MOHAMED

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    Grant type:Scientific research funding

    CiNii Research

  • メタマテリアルとリアクティブ反射板を利用した高効率WPTシステム

    Grant number:21F31046  2021.7 - 2023.3

    科学研究費助成事業  特別研究員奨励費

    Pokharel R.K., ALI MOHAMED

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    Grant type:Scientific research funding

    CiNii Research

  • メタマテリアル支援小型化効率化無線電力システムにより情報と電力の同時伝送に関する研究

    2021.4 - 2024.6

    科研費 総務省・SCOPE 

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    Authorship:Principal investigator 

  • Metamaterial-based Compact and Efficient Wireless Power Transfer System for Biomedical Implants

    2021.4 - 2024.3

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    Authorship:Principal investigator 

    In this research, a magnetic loss meta surface will be developed and with the help of that meta surface, high efficiency and compact WPT system will be developed for biomedical applications.

  • メタマテリアルとリアクティブ反射板を利用した高効率WPTシステム

    Grant number:21F21046  2021.4 - 2023.3

    科学研究費助成事業  特別研究員奨励費

    Pokharel R.K., ALI MOHAMED

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    Grant type:Scientific research funding

    CiNii Research

  • メタマテリアル支援小型・高効率無線電力伝送システムによる体内への電力と情報の無線伝送システムの研究開発

    2021 - 2024

    総務省・戦略的情報通信研究開発推進事業(SCOPE)

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    Authorship:Principal investigator  Grant type:Contract research

  • Metamaterial-based Compact and Efficient Wireless Power Transfer System for Biomedical Implants

    Grant number:21K04178  2021 - 2023

    Japan Society for the Promotion of Science  Grants-in-Aid for Scientific Research  Grant-in-Aid for Scientific Research (C)

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    Authorship:Principal investigator  Grant type:Scientific research funding

    CiNii Research

  • メタマテリアル支援小型・高効率無線電力伝送システムによる体内への電力と情報の無線伝送システムの研究開発

    2021 - 2023

    総務省・戦略的情報通信研究開発推進事業(SCOPE)

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    Authorship:Principal investigator  Grant type:Contract research

  • メタマテリアルとリアクティブ反射板を利用した高効率WPTシステム

    2021 - 2022

    日本学術振興会  海外特別研究員

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    Authorship:Principal investigator  Grant type:Joint research

  • メタマテリアル支援小型・高効率無線電力伝送システムによる体内への電力と情報の無線伝送システムの研究開発

    2021

    総務省・戦略的情報通信研究開発推進事業(SCOPE)

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    Authorship:Principal investigator  Grant type:Contract research

  • 助研究成金

    2020

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    Grant type:Donation

  • 助研究成金

    2020

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    Grant type:Donation

  • テラヘルツ波CMOSオンチップ配線に関する研究

    2019.4 - 2021.3

    公益財団電気通信普及財団 公益財団村田学術振興財団 

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    Authorship:Principal investigator 

  • 200GHz CMOS発振器の開発

    2019 - 2021

    公益財団電気通信普及財団

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    Authorship:Principal investigator  Grant type:Contract research

  • メタマテリアルダイプレクサ受信機を用いた信号と電力の同時無線転送システムの開発

    2019 - 2020

    日本学術振興会  海外特別研究員

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    Authorship:Principal investigator  Grant type:Joint research

  • 200GHz CMOS発振器の開発

    2019 - 2020

    公益財団村田学術振興及財団

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    Authorship:Principal investigator  Grant type:Contract research

  • 無線電力伝送に関する研究

    2019 - 2020

    Share-Q

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    Authorship:Principal investigator  Grant type:On-campus funds, funds, etc.

  • 助研究成金

    2019

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    Grant type:Donation

  • 助研究成金

    2019

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    Grant type:Donation

  • 第5回目:教育・研究に関する寄付金

    2018

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    Grant type:Donation

  • 第6回目:教育・研究に関する寄付金

    2018

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    Grant type:Donation

  • 第1回目:教育・研究に関する寄付金

    2017

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    Grant type:Donation

  • 第2回目:教育・研究に関する寄付金

    2017

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    Grant type:Donation

  • 第3回目:教育・研究に関する寄付金

    2017

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    Grant type:Donation

  • 第4回目:教育・研究に関する寄付金

    2017

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    Grant type:Donation

  • 第5世代準ミリ波様CMOSアナログ回路に関する研究

    2016.4 - 2018.3

    科研費 

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    Authorship:Principal investigator 

  • 第5世代移動通信対応オンチップアンテナ付き異種集積化フロントエンドの開発

    Grant number:16K06301  2016 - 2018

    日本学術振興会  科学研究費助成事業  基盤研究(C)

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • 第4回 日本エジプト電子・通信・計算機に関する国際会議

    2016

    科学研究費助成事業  国際学術研究

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • 準ミリ波帯CMOS RF回路の研究

    2015.7 - 2016.3

    共同研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • 準ミリ波帯CMOS RF回路の研究

    2014.7 - 2015.3

    受託研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • フレキシブルワイヤレスシステム用発振回路の研究

    2013.7 - 2014.3

    共同研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • 次世代無線通信用フレキシブルエレクトロニクスに関する研究

    2013.6 - 2016.3

    N(社) 

  • FBARを用いた発信器及びチューナブルPAの設計・評価

    2013.4 - 2014.3

    受託研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • FBARを用いた発振器の設計・評価

    2012.4 - 2013.3

    受託研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • ホワイトスペース対応リコンフィギュラブルPAの開発

    Grant number:23360159  2011 - 2015

    日本学術振興会  科学研究費助成事業  基盤研究(B)

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • ホワイトスペース対応コグニティブ無線用異種集積化リコンフィギュラブルPAの開発

    2010.4 - 2016.3

    科研費 

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    Authorship:Principal investigator 

    第4世代携帯端末など,移動体通信市場でのモバイル利用の拡大に伴うユビキタスネットワーク情報社会を構築するため、SDR(Softwa re defined radio:ソフトウエア無線)技術を活用したコグニティブ無線の実現が期待されている。
    本研究の目標であるチューナブルPAにおいては、これまでワイドバンドCMOS PA がいくつか報告されているが,不要の帯域も増幅してしまうため、近隣チャネルの干渉が起きやすい。本研究では、上記のような問題を解決し、コグニティブ無線用自由にチューニングできる高効率高利得チューナブルPAを開発することを目的としている。

  • ソフトウエア無線用リング型超低消費電力・リコンフィギュアラブルDCOの開発』JST地域イノベーション創出総合支援事業 重点地域研究開発推進プログラム H21年度「シーズ(B)発掘試験」(代表)

    2009.7 - 2010.3

    受託研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • フィボナッチ数列により最適化された超低消費電力・高速DACの開発

    2008.7 - 2009.3

    受託研究

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    Authorship:Principal investigator  Grant type:Other funds from industry-academia collaboration

  • フィボナッチ数列により最適化された超低消費電力・高速DACの開発

    2008.7 - 2009.3

    日本 

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    Authorship:Principal investigator 

    近年ユビキタスネットワーク情報社会の実現のための世界的にも注目されているソフトウエア無線(Software-Defined Radio)に繋がる最先端LSI回路の実現に、低消費電力化は最大の設計問題になっている。従来のデジタル回路では、CML(current mode logic)や3次元実装によりインダクタンス結合やソフトウエアからの最適化も提案されているが、消費電力がもっとも重要になるアナログ回路、例えばDAやAD変換回路の設計には低消費電力は半導体デバイスの微小化に伴い実現されている。本研究では、フィボナッチ数列を応用した新しいトランジスタ最適化手法により、次世代リコンフィギュアラブル無線通信用超低消費電力・高速DA変換回路を開発する。

  • ユビキタスネットワーク用小型平面アンテナの開発とトランシーバへの実装に関する研究

    2008.4 - 2012.3

    科研費(日本) 

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    Authorship:Coinvestigator(s) 

    本研究の目的は、ユビキタスネットワーク社会実現のためのキーテクノロジーである小型平面アンテナの開発、およびそれをトランシーバに実装することにより超小型トランシーバを開発することである。具体的実現項目は「研究計画・方法」の欄に述べている以下の項目である。(I) 整合回路一体型微小アンテナの設計(II) 指向性を有する整合回路一体型平面型アレイアンテナの設計(III) 広帯域平面型微小アンテナ一体型RFフロントエンドの開発(IV) 三次元実装による裏面遮蔽型アンテナ一体型トランシーバの開発(V) システム検証及びフィールド試験ならびに総合評価

  • 超低消費電力・超広帯域12bitリングDCOの開発

    2008.4 - 2010.3

    日本 

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    Authorship:Principal investigator 

    本研究の目的は、ユビキタスネットワーク社会実現のためのCognitive Radio(コグニティブ無線)の基盤である超消費電力・超広帯域デジタル制御発信器(DCO)を開発することである。具体的実現項目は「研究計画・方法」の欄に述べている以下の項目である。(I) トランジスタの並列的接続による低消費電力・高速インバータの設計(II) フィボナッチ数列によりトランジスタを最適化した超低消費電力・超広帯域デジタル制御リング発信器(DCO: digital controlled oscillator)の開発・評価(III) (I)(II)で開発した超低消費電力・超広帯域DCOをADPLL(All digital Phase locked loop)に応用

  • ユビキタスネットワーク用小型平面アンテナの開発とトランシーバへの実装に関する研究

    Grant number:20360173  2008 - 2012

    日本学術振興会  科学研究費助成事業  基盤研究(B)

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    Authorship:Coinvestigator(s)  Grant type:Scientific research funding

  • 超低消費電力・超広帯域12bitリングDCOの開発

    Grant number:20760224  2008 - 2010

    科学研究費助成事業  若手研究(B)

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • 無線LAN用低消費電力・低雑音を有する低コストRF フロントエンドチップの開発

    2007 - 2008

    科学研究費助成事業  特別研究

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    Authorship:Principal investigator  Grant type:Scientific research funding

  • Development of Compact Size and Low Noise RF Front-End for WLAN On-Chip Implementation

    2006 - 2007

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    Authorship:Principal investigator  Grant type:On-campus funds, funds, etc.

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Educational Activities

  • (1) Fundamentals of Electrical and Information Engineering (From 2011) (For 1st-year student of International course, this is in English)
    (2)Analog Circuits (from 2011) (For 3rd Undergraduate course, this is of course in Japanese)
    (3) Linear Circuits-I (from 2016) (For 2nd Year students of International course, this is in English)
    (4) Special Lecture on Wireless Communication System (For graduate course, I use English and Japanese both in this lecture)

Class subject

  • Analog Electronic Circuits-I

    2024.4 - 2024.9   First semester

  • Linear Circuits-I

    2023.10 - 2024.3   Second semester

  • アナログ電子回路ーI

    2023.4 - 2023.9   First semester

  • アナログ電子回路ーII

    2023.4 - 2023.9   First semester

  • Linear Circuits-I

    2022.10 - 2023.3   Second semester

  • ワイヤレス通信特論

    2022.10 - 2023.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2022.10 - 2023.3   Second semester

  • アナログ電子回路ーI

    2022.4 - 2022.9   First semester

  • Introduction of Electronics Engineering and Information Science

    2021.10 - 2022.3   Second semester

  • ワイヤレス通信特論

    2021.10 - 2022.3   Second semester

  • Linear Circuits-I

    2021.10 - 2022.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2020.10 - 2021.3   Second semester

  • ワイヤレス通信特論

    2020.10 - 2021.3   Second semester

  • Linear Circuits-I

    2020.10 - 2021.3   Second semester

  • アナログ電子回路ーI

    2020.4 - 2020.9   First semester

  • Introduction of Electronics Engineering and Information Science

    2019.10 - 2020.3   Second semester

  • Linear Circuits-I

    2018.10 - 2019.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2018.10 - 2019.3   Second semester

  • ワイヤレス通信特論

    2018.10 - 2019.3   Second semester

  • アナログ電子回路-I

    2018.4 - 2018.9   First semester

  • ワイヤレス通信特論

    2017.10 - 2018.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2017.10 - 2018.3   Second semester

  • 回路理論I

    2017.4 - 2017.9   First semester

  • アナログ電子回路-I

    2017.4 - 2017.9   First semester

  • ワイヤレス通信特論

    2016.10 - 2017.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2016.10 - 2017.3   Second semester

  • アナログ電子回路-I

    2016.4 - 2016.9   First semester

  • 回路理論I

    2016.4 - 2016.9   First semester

  • ワイヤレス通信特論

    2015.10 - 2016.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2015.10 - 2016.3   Second semester

  • ワイヤレス通信特論

    2013.10 - 2014.3   Second semester

  • アナログ電子回路-I

    2013.10 - 2014.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2013.10 - 2014.3   Second semester

  • ワイレス通信特論

    2013.10 - 2014.3   Second semester

  • ワイレス通信特論

    2012.10 - 2013.3   Second semester

  • Introduction of Electronics Engineering and Information Science

    2012.10 - 2013.3   Second semester

  • アナログ電子回路ーI

    2012.10 - 2013.3   Second semester

  • ワイレス通信特論

    2011.10 - 2012.3   Second semester

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FD Participation

  • 2019.6   Role:Participation   Title:8大学情報系研究科長会議の報告

    Organizer:[Undergraduate school/graduate school/graduate faculty]

  • 2018.1   Role:Participation   Title:「M2B(みつば)学習支援システム」

    Organizer:Undergraduate school department

  • 2018.1   Role:Participation   Title:SciVal」及び「Pure」

    Organizer:Undergraduate school department

  • 2017.8   Role:Participation   Title:学術研究・産学官連携本部における研究支援等について

    Organizer:[Undergraduate school/graduate school/graduate faculty]

  • 2017.2   Role:Participation   Title:「QRECの教育プログラムの活用法~イノベーション・マネジメントの体験的学習への誘導」

    Organizer:University-wide

  • 2016.3   Role:Participation   Title:H27年度国際的エリート・ドクター育成促進プログラム開発

    Organizer:[Undergraduate school/graduate school/graduate faculty]

  • 2015.11   Role:Participation   Title:EEP海外研修

    Organizer:University-wide

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Visiting, concurrent, or part-time lecturers at other universities, institutions, etc.

  • 2023  University of Waterloo  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2023.5.19〜2024.4.30

  • 2020  University of Toronto  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2019.9.1〜2020.8.31

  • 2018  エジプト日本科学技術大学  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2017.10-2018.09

  • 2017  エジプト日本科学技術大学  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2016.10-2017.09

  • 2015  エジプト日本科学技術大学  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2014.10-2017.09

  • 2014  エジプト日本科学技術大学  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2013.12-2014.9

  • 2013  エジプト日本科学技術大学 電子通信工学部  Classification:Affiliate faculty  Domestic/International Classification:Overseas 

    Semester, Day Time or Duration:2012年10月~2013年9月

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Participation in international educational events, etc.

  • 2015.7

    JICA

    E-JUST(エジプト日本科学技術大学)の電子通信工学研究科における学科運営、学生指導について、2015.7.22~28にアレキサンドリアに出張し、当大学学科長、当該研究科の学長と打合せし、学科運営について意見交換した。

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    Venue:エジプト・アレキサンドリア

    Number of participants:3

  • 2015.5

    JICA

    E-JUSTにおける理事会及びシンポジウム

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    Venue:エジプト

    Number of participants:150

  • 2013.2

    JICA,在ネパール日本大使館

    日本留学フェア

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    Venue:ネパール・カトマンズ

    Number of participants:600

  • 2009.9

    JICA, EJUST

    E-JUST(エジプト日本科学技術大学)の設立準備を行い、2009.9.22~30にアレキサンドリアに出張し機材の設置、9月27日のE-JUST開校式に日本の大学を九州大学の一員として出席した。

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    Venue:エジプト・アレキサンドリア

    Number of participants:30

  • 2009.3

    JICA, EJUST

    E-JUST(エジプト日本科学技術大学)の設立準備を行い、2009.3.27~4月4日にアレキサンドリアに出張し機材リストの作成及びシラバスの作成に関する会議に九大グルプの一員として参加した。

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    Venue:エジプト・アレキサンドリア

    Number of participants:20

Other educational activity and Special note

  • 2020  Class Teacher 

Outline of Social Contribution and International Cooperation activities

  • (1)委員:IEC−SC46F/WG1"Measurement Methods for Reflectivity of Electromagnetic Wave Absorbers in Millimetre Wave Frequency" に関する国際標準化を作成中.

    (2)Secretary, 国際会議 "One Day International Seminar on the Role of Japanese University Alumni in Nation Building"ネパールのカトマンズで2005年11月20日開催予定(ORGANIZER: 愛媛大学)

Social Activities

  • Vice-Chair: IEEE MTT-S Japan chapter- Education Committee

    2015

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    Vice-Chair: IEEE MTT-S Japan chapter- Education Committee

  • Vice-Chair: IEEE MTT-S Japan chapter- Education Committee

    2014

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    Vice-Chair: IEEE MTT-S Japan chapter- Education Committee

  • Associate Editor: IEICE ELEX

    2014

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    Associate Editor: IEICE ELEX

  • IEEE MTT-S Japan Chapter, Secretory

    2013

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    IEEE MTT-S Japan Chapter, Secretory

  • Associate Editor: IEICE ELEX

    2013

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    Associate Editor: IEICE ELEX

  • IEEE MTT-S Japan Chapter Secretory

    2012

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    IEEE MTT-S Japan Chapter Secretory

  • Associate Editor: IEICE ELEX

    2012

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    Associate Editor: IEICE ELEX

  • IEEE MTT-S Japan Chapter-Secretary

    2011

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    IEEE MTT-S Japan Chapter-Secretary

  • This is an international symposium organized by NESAJ (Nepalese Student Association in Japan) which was held in Ehime University on 22nd March 2008. This conferrence was opened by the President of Ehime Univesity and His Excellency Embassador of Nepal for Japan.

    NESAJ (Nepalese Students Association in Japan), Ehime University  2008.3

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    Audience: General, Scientific, Company, Civic organization, Governmental agency

    Type:Seminar, workshop

  • Secretary/'ONE DAY SEMINAR ON THE ROLE OF JAPANESE UNIVERSITY ALUMNI IN NATION BUILDING'

    2005.11

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    Audience: General, Scientific, Company, Civic organization, Governmental agency

    Type:Seminar, workshop

  • ハイレベル実験演習:「高校生対象」

    福岡県立修猷館高等学校  2005.10

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    Audience: Infants, Schoolchildren, Junior students, High school students

    Type:Seminar, workshop

  • 委員会: "Measurement methods for reflectivity of wave absorbers in millimeter wave band”IEC/SC46F/WG1 (作成中)

    委員長:橋本 修(青山学院大学}  標準化作成  2004.9

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    Audience: General, Scientific, Company, Civic organization, Governmental agency

    Type:Other

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Media Coverage

  • 九大、メタサーフェスを活用して無線電力伝送の距離や効率の向上に成功 記事:九州大学(九大)は10月26日、負やゼロと近い透磁率を有する人工誘電体「メタサーフェス」の設計を行い、無線電力伝送(Wireless Power Transfer:WPT)システムの送信器と受信器の間の磁場を制御することにより、WPT距離および「ミスアラインメント問題」を解決できることを明らかにしたと発表した。 同成果は、九大大学院 システム情報科学研究院のポカレル・ラメシュ教授、同・モハメド・アブアララー外国人特別研究員らの研究チームによるもの。詳細は、IEEEが刊行する物理現象の測定・監視・記録用機器の開発や使用に関する全般を扱う学術誌「IEEE Transactions on Instrumentation and Measurement」に掲載された。 まだ有線充電も一般的だが、スマートフォンなどの小型デバイスにおいてワイヤレス充電が実用化されている。こうした機器の有線充電からワイヤレス充電への移行は、利便性と使用可能なデバイスの設置場所の柔軟性を向上させたものの、それに伴う新たな課題も浮上している。 1つは、WPTシステムの伝送距離だ。現状のWPTシステムは近距離でしか効果的に電力を伝送できない傾向があり、長距離は困難なことが課題だった。さらに、受信機と送信機の位置のずれによるアラインメントの問題もある。WPTシステムでは、受信機と送信機のコイルやアンテナが完全に一致していない場合や、位置がずれている場合は電力伝送の効率が低下したり、さらには通信が中断される可能性があるほか熱の問題も生じてしまう。これらの課題を解決するため、研究チームはメタサーフェスを用いて新たなアプローチを追求することにしたという。 今回の研究で提案されたメタサーフェスは、メタマテリアルともいわれる人工光学物質だ(メタマテリアルのうち、平面型のものがメタサーフェスと呼ばれる)。メタサーフェス/メタマテリアルは、制御の対象とする電磁波の波長よりも小さなサイズの人工構造を表面に並べることで、自然界にはない電磁波応答を示すことを特徴とする。また、将来的には熱光学迷彩や透明マントなどのクローキング技術や、負の屈折率なども実現できる物質として研究が進められている。 メタサーフェスは特異な光学特性により、送信器と受信器の間の磁場を効果的に制御し、遠距離への電力伝送を実現する。具体的には、メタサーフェスを導入する前は40mmの距離での伝送効率がわずか8%に過ぎなかったが、メタサーフェスを活用すると78%にまで向上するという。また、この新技術の応用により、受信機と送信機の位置ずれに起因するミスアラインメント問題も大幅に改善されたとした。 今回の成果により、受信器の位置に依存しない無線電力伝送システムの開発が可能になるという。これにより、スマートフォンやタブレットなどを机などに置くだけで充電できるような、いつでもどこでも無線で電力伝送が可能な技術の開発への貢献が期待されるとした。 また、医療分野においても、ペースメーカーや人工心臓などの埋め込み型医療機器のバッテリーを体外から充電でき、バッテリー交換のための手術が不要になることも期待されるとする。このような進歩は、ワイヤレス充電技術の広範な応用可能性を開拓し、未来の技術に大きな寄与をするものと見込まれているとした。 Newspaper, magazine

    Mappionニュース  2023.10

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    九大、メタサーフェスを活用して無線電力伝送の距離や効率の向上に成功

    記事:九州大学(九大)は10月26日、負やゼロと近い透磁率を有する人工誘電体「メタサーフェス」の設計を行い、無線電力伝送(Wireless Power Transfer:WPT)システムの送信器と受信器の間の磁場を制御することにより、WPT距離および「ミスアラインメント問題」を解決できることを明らかにしたと発表した。

    同成果は、九大大学院 システム情報科学研究院のポカレル・ラメシュ教授、同・モハメド・アブアララー外国人特別研究員らの研究チームによるもの。詳細は、IEEEが刊行する物理現象の測定・監視・記録用機器の開発や使用に関する全般を扱う学術誌「IEEE Transactions on Instrumentation and Measurement」に掲載された。

    まだ有線充電も一般的だが、スマートフォンなどの小型デバイスにおいてワイヤレス充電が実用化されている。こうした機器の有線充電からワイヤレス充電への移行は、利便性と使用可能なデバイスの設置場所の柔軟性を向上させたものの、それに伴う新たな課題も浮上している。

    1つは、WPTシステムの伝送距離だ。現状のWPTシステムは近距離でしか効果的に電力を伝送できない傾向があり、長距離は困難なことが課題だった。さらに、受信機と送信機の位置のずれによるアラインメントの問題もある。WPTシステムでは、受信機と送信機のコイルやアンテナが完全に一致していない場合や、位置がずれている場合は電力伝送の効率が低下したり、さらには通信が中断される可能性があるほか熱の問題も生じてしまう。これらの課題を解決するため、研究チームはメタサーフェスを用いて新たなアプローチを追求することにしたという。

    今回の研究で提案されたメタサーフェスは、メタマテリアルともいわれる人工光学物質だ(メタマテリアルのうち、平面型のものがメタサーフェスと呼ばれる)。メタサーフェス/メタマテリアルは、制御の対象とする電磁波の波長よりも小さなサイズの人工構造を表面に並べることで、自然界にはない電磁波応答を示すことを特徴とする。また、将来的には熱光学迷彩や透明マントなどのクローキング技術や、負の屈折率なども実現できる物質として研究が進められている。

    メタサーフェスは特異な光学特性により、送信器と受信器の間の磁場を効果的に制御し、遠距離への電力伝送を実現する。具体的には、メタサーフェスを導入する前は40mmの距離での伝送効率がわずか8%に過ぎなかったが、メタサーフェスを活用すると78%にまで向上するという。また、この新技術の応用により、受信機と送信機の位置ずれに起因するミスアラインメント問題も大幅に改善されたとした。

    今回の成果により、受信器の位置に依存しない無線電力伝送システムの開発が可能になるという。これにより、スマートフォンやタブレットなどを机などに置くだけで充電できるような、いつでもどこでも無線で電力伝送が可能な技術の開発への貢献が期待されるとした。

    また、医療分野においても、ペースメーカーや人工心臓などの埋め込み型医療機器のバッテリーを体外から充電でき、バッテリー交換のための手術が不要になることも期待されるとする。このような進歩は、ワイヤレス充電技術の広範な応用可能性を開拓し、未来の技術に大きな寄与をするものと見込まれているとした。

  • どこでもいつでも無線で電⼒伝送可能な技術 | 研究成果 | 九州大学(KYUSHU UNIVERSITY) 記事:九州大学大学院システム情報科学研究院のRamesh Pokharel(ポカレル ラメシュ)教授らは2023年10月26日、新たなメタサーフェスを開発し、無線電力伝送(WPT)システムの送信器と受信器の間の磁場を制御することで、無線電力伝送距離およびミスアラインメント問題を解決したと発表した。タブレットやスマートフォンなどのデバイスを机に置くだけで充電できる技術の開発が期待される。 スマートフォンや医療機器などの小型デバイスの普及に伴って、充電の方法が有線から無線へと移行している。このようなシステムでは無線電力伝送が不可欠だが、WPTシステムは近距離でしか効果的に電力を伝送できない傾向があり、長距離への電力伝送が難しいという問題がある。また、受信機と送信機の位置のずれにより、電力伝送ができなくなる問題があった。 そこで研究グループは、人工誘電体であるメタサーフェスを新たに開発し、小型化されたWPTシステムに導入することで、もとの伝送効率を維持しながら、伝送距離を最大300%まで伸ばした。メタサーフェスは、送信器と受信器間の磁場を特異な光学特性で効果的に制御し、遠距離へ電力伝送できる。 メタサーフェスを導入する前の40mmの伝送距離での伝送効率は8%だったが、メタサーフェスの応用によって78%まで向上させた。新たな技術の応用により、受信機と送信機の位置ずれに起因するミスアラインメント問題も大幅に改善されている。 今回の研究の成果により、受信器の位置に依存しない無線電力伝送システムを開発できるようになり、どこでもいつでも無線で電力伝送が可能になることが期待される。 Newspaper, magazine

    fabcross for エンジニア  2023.10

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    どこでもいつでも無線で電⼒伝送可能な技術 | 研究成果 | 九州大学(KYUSHU UNIVERSITY)

    記事:九州大学大学院システム情報科学研究院のRamesh Pokharel(ポカレル ラメシュ)教授らは2023年10月26日、新たなメタサーフェスを開発し、無線電力伝送(WPT)システムの送信器と受信器の間の磁場を制御することで、無線電力伝送距離およびミスアラインメント問題を解決したと発表した。タブレットやスマートフォンなどのデバイスを机に置くだけで充電できる技術の開発が期待される。

    スマートフォンや医療機器などの小型デバイスの普及に伴って、充電の方法が有線から無線へと移行している。このようなシステムでは無線電力伝送が不可欠だが、WPTシステムは近距離でしか効果的に電力を伝送できない傾向があり、長距離への電力伝送が難しいという問題がある。また、受信機と送信機の位置のずれにより、電力伝送ができなくなる問題があった。

    そこで研究グループは、人工誘電体であるメタサーフェスを新たに開発し、小型化されたWPTシステムに導入することで、もとの伝送効率を維持しながら、伝送距離を最大300%まで伸ばした。メタサーフェスは、送信器と受信器間の磁場を特異な光学特性で効果的に制御し、遠距離へ電力伝送できる。

    メタサーフェスを導入する前の40mmの伝送距離での伝送効率は8%だったが、メタサーフェスの応用によって78%まで向上させた。新たな技術の応用により、受信機と送信機の位置ずれに起因するミスアラインメント問題も大幅に改善されている。

    今回の研究の成果により、受信器の位置に依存しない無線電力伝送システムを開発できるようになり、どこでもいつでも無線で電力伝送が可能になることが期待される。

  • 「激変!!アジア留学生~ベトナム・ネパール 急増の背景に迫る~」 TV or radio program

    福岡NHK放送  2014.5

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    「激変!!アジア留学生~ベトナム・ネパール 急増の背景に迫る~」

Activities contributing to policy formation, academic promotion, etc.

  • 2010.10 - 2019.3   エジプト日本科学技術大学(エジプト)

    エジプト日本科学技術大学(エジプト)における、学会運営、シラバス作成、機材リスト作成等に意見交換している。当該大学の学生達をCo-supervisorとしてえんかくで指導し、成果として数多くの国際ジャナール論文や国際学会で発表させています。

Acceptance of Foreign Researchers, etc.

  • エジプト日本科学技術大学

    Acceptance period: 2022.6 - 2023.10   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • エジプト日本科学技術大学

    Acceptance period: 2018.12 - 2019.9   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • エジプト日本科学技術大学

    Acceptance period: 2018.11 - 2019.7   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • エジプト日本科学技術大学

    Acceptance period: 2018.2 - 2018.10   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • エジプト日本科学技術大学

    Acceptance period: 2017.11 - 2018.7   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • エジプト日本科学技術大学

    Acceptance period: 2017.10 - 2018.6   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • エジプト日本科学技術大学

    Acceptance period: 2017.5 - 2018.2   (Period):1 month or more

    Nationality:Egypt

    Business entity:Other

  • ETI(エジプト)

    Acceptance period: 2016.4   (Period):2weeks to less than 1 month

    Nationality:Egypt

    Business entity:Foreign governments, foreign research institutes, international organizations

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Travel Abroad

  • 2023.5 - 2024.5

    Staying countory name 1:Canada   Staying institution name 1:University of Waterloo

  • 2019.9 - 2020.8

    Staying countory name 1:Canada   Staying institution name 1:トロント大学

  • 2018.12

    Staying countory name 1:India   Staying institution name 1:Jamia Millia Islamia大学

    Staying countory name 2:Japan  

  • 2018.7

    Staying countory name 1:Canada   Staying institution name 1:トロント大学

    Staying countory name 2:Canada   Staying institution name 2:ヨーク大学

  • 2016.3

    Staying countory name 1:Canada   Staying institution name 1:British Columbia University

    Staying institution name 2:ブリティッシュコロンビア大学

  • 2015.5 - 2016.7

    Staying countory name 1:Egypt   Staying institution name 1:日本エジプト開学技術大学

    Staying countory name 2:Egypt   Staying institution name 2:日本エジプト開学技術大学

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