| 1. |
Adel Barakat, Stacked Metamaterial Based Wireless Power Transfer System for Biomedical Implant Applications, International Japan-Africa Conference on Elctronics, Communications, and Computations (JAC_ECC 2022), 2022.12. |
| 2. |
Xin Jiang; Fairus Tahar; Takashi Miyamoto; Adel Barakat; Kuniaki Yoshitomi; Ramesh K. Pokharel, Efficient and Compact Dual-band Wireless Power Transfer System through Biological Tissues Using Dual-Reference DGS Resonators, 2021 IEEE MTT-S International Microwave Symposium (IMS), 2021.06, This paper presents a novel design for a compact dual-band wireless power transfer (WPT) system through biological tissues using dual-reference defected ground structure (DGS) resonators. Overlapping is used to minimize the size to be suitable for biomedical applications. The proposed DGS resonator exhibits bandstop characteristics at two different frequencies depending on the excitation reference-plane. Then, two coupled sets of the proposed dual-reference DGS, in a back-to-back configuration, achieves a dual-band WPT system. The sizes of the receiver and transmitter are 15 mm × 15 mm and 18 mm × 18 mm, respectively. The measured efficiencies are 60.3% at 381 MHz and 54.3% at 750 MHz when the receiver is embedded in chicken breast within a depth of 10 mm, while the overall WPT distance of 11 mm. |
| 3. |
Samundra K. Thapa; Baichuan Chen; Adel Barakat; Kuniaki Yoshitomi; Ramesh K. Pokharel, Miniaturized Slot-Loaded SIW Resonator and Its Application to C-band Low Phase Noise Oscillator, 2020 50th European Microwave Conference (EuMC), 2021.01, This paper presents a C-band low phase noise oscillator using small size low-profile substrate integrated waveguide (SIW) resonator for RF applications. A compact 6 GHz SIW resonator size is possible by introducing λ g /4 resonating slots. A size reduction of 29.87% is achieved while maintaining the quality factor. Also, the impedance of the SIW resonator is controlled by appropriate selection of the location of these introduced slots; which advantages for the conjugate matching between SIW resonator and the active device and removes the need of matching circuit between them. Then, a C-band oscillator prototype utilizing the proposed compact SIW resonator is designed, fabricated and measured. The measured results shows a phase noise of -122.11 dBc/Hz at 1 MHz offset with an output power of -4.2 dBm at 5.96 GHz oscillation frequency.. |
| 4. |
Xin Jiang; Fairus Tahar; Takashi Miyamotol; Adel Barakat; Kuniaki Yoshitomi; Ramesh K. Pokharel, Design of Three Layers-Stacked Metasurface and Its Application to Compact Dual-band WPT System, 2021 IEEE Wireless Power Transfer Conference (WPTC), 2021.06, This paper proposes a three-layers stack metasurface first, and then employed it to a compact double-band wireless power transfer (WPT) system. For the proposed dual-band WPT system, the metasurface exhibits the wide-band characteristic of the negative-near-zero permeability from 222 MHz to 889 MHz, where the transmission efficiency improves significantly at longer WPT distance at the lower band. Only a unit cell is stacked in three layers so that the size of the proposed metasurface has significantly reduced compared to a conventional metasurface where several unit cells are arranged in 1-D topology. The size of the proposed WPT system and the metasurface is 15 x15 mm and 20 x20 mm, respectively. Also, capacitors with the value of 0.1pF are etched on the gaps of the metasurface. The measured efficiencies' improvement ratios are 1.13 at 390 MHz in the air, where the WPT distance is significantly improved from 19 mm to 23 mm.. |
| 5. |
Baichuan Chen; Samundra K. Thapa; Nusrat Jahan; Adel Barakat; Ramesh K. Pokharel, Design Methodology of Wide Tuning Range DGS-based VCO for K-band Applications in 0.18-µm CMOS Technology, 2021 16th European Microwave Integrated Circuits Conference (EuMIC), 2022.04, 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.. |
| 6. |
Tomoki Fukuda; Baichuan Chen; Samundra K. Thapa; Adel Barakat; Ramesh K. Pokharel, Design of Compact and High Q-Factor W-Band Cavity in 0.18-µm CMOS Technology, 2021 51st European Microwave Conference (EuMC), 2022.04, 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 coefficient 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.. |
| 7. |
Yutaro Ikeda; Xin Jiang; Mohamed Aboualalaa; Adel Barakat; Kuniaki Yoshitomi; Ramesh K. Pokharel, Stacked Metasurfaces for Misalignment Improvement of WPT System Using Spiral Resonators, 2021 51st European Microwave Conference (EuMC), 2022.04, The conventional inductive wireless power transfer (WPT) systems have a trade-off between transmission distance and size. Furthermore, when the transmitter and receiver go away from the line of sight, the performance due to this so-called misalignment will sharply drop. In this work, a new type of metasurfaces called stacked metasurface is proposed, and its effectiveness to mitigate above problems are studied experimentally. As a result, by using the proposed metasurface, we succeeded in achieving a transmission distance between the transmitter and the receiver of 70 mm, which is more than double than its original transmission distance without the metasurface when the maximum efficiency occurs. At this enhanced transmission distance, the efficiency of the WPT system has improved from 2% to 60%.. |
| 8. |
Ramesh Pokharel; Adel Barakat; Costas Sarris, Metamaterial Inspired Geometries for Wireless Power Transfer to Biomedical Implants, 2021 51st European Microwave Conference (EuMC), 2022.04, Wireless charging of biomedical implants will make the life of patients with implants much easier. However, it is associated with significant design challenges - efficiency degradation and the need to meet standards for exposure to electromagnetic fields. Biomedical tissue dielectric and conductive properties affect the electrical performance of an inductor, which appears on increased effective inductance, reduced quality factor, and reduced self-resonance. Building a wireless power transfer (WPT) system using such inductors leads to low efficiency and low power that limit specific absorption rate. In this work, we study the characteristics of inductance in biomedical tissue and present a theory to maintain the effective inductance with the same value in the air and biomedical tissue. Finally, to overcome these issues, we propose a metamaterial inspired geometry with near-zero permeability. This metamaterial inspired geometry is stacked split ring resonator metamaterial fed by a driving inductive loop and acts as a WPT transmitter for an in-tissue implanted WPT receiver. The presented demonstrations have confirmed that the proposed metamaterial inspired WPT system outperforms the conventional one. Also, the resonance frequency of the proposed metamaterial inspired TX is negligibly affected by the tissue characteristics, which is of great interest from the design and operation prospects. Furthermore, the proposed WPT system can be used with more than twice the input power of the conventional one while complying with the safety regulations of electromagnetic waves exposure.. |
| 9. |
Baichuan Chen; Samundra K. Thapa; Adel Barakat; Ramesh K. Pokharel, A 100GHz Bandpass Filter Employing Shielded Folded Ridged Quarter-Mode SIW Resonator in CMOS Technology, 2021 51st European Microwave Conference (EuMC), 2022.04, A miniaturized shielded folded ridged quarter-mode Substrate Integrated Waveguide (FRQMSIW) resonator in 1P6M CMOS technology is presented for millimetre wave applications. By adding a capacitive ridge and folded it inside the resonator, a significant miniaturization is realized. An additional shielded structure is employed to mitigate the leakage from the effective perfect conductor of the conventional quarter-mode SIW cavity. The characteristics of the proposed resonator are investigated first and then employed to design a 100GHz bandpass filter (BPF) with two transmission zeros. Finally, the proposed filter is implemented in 1P6M CMOS technology and measured. The active size of the proposed BPF without pads is 309μm×275μm(∼0.1λ×∼0.09 λ), and the measured insertion loss (|S21|) is 2.06dB.. |
| 10. |
ADEL Barakat, POKHAREL RAMESH KUMAR, Nessim Mahmoud, Low insertion loss 60 GHz CMOS H-shaped resonator BPF, 2017 IEEE Radio and Wireless Symposium (RWS), 2017.01, This paper presents a low insertion less 60 GHz on-chip bandpass filter (BPF) on 0.18 μm standard CMOS technology. For insertion loss minimization, this BPF uses the H-shaped resonator which couples through two branches and the rectangular defected ground structures (DGS) which reduce the external quality factor. Besides, this BPF employs metal-insulator-metal capacitor to ensure size compactness. The fabricated BPF chip size is 240 μm × 650 μm. The simulation results agree well with the measured ones. The measured insertion loss is 2.1 dB at 60GHz.. |
| 11. |
ADEL Barakat, POKHAREL RAMESH KUMAR, Sherif Hekal, Simple design approach for asymmetric resonant inductive coupled WPT systems using J-inverters, 2016 Asia Pacific Microwave Conference (APMC), 2016.12, This paper presents a simple and precise design method for asymmetric resonant inductive coupled wireless power transfer (WPT) systems without the involvement of circuit or electromagnetic (EM) simulators. The design method is based on the generalized second-order band-pass filter (BPF). First, the values of the BPF's J-inverters are computed based on the mutual coupling between the transmitter (TX) and the receiver (RX). Then, the required components are extracted from the J-inverters values. We achieved good agreements between the analytical design procedure, the circuit and the EM simulations, and the measurements. The measured efficiency is 75% at a transmission distance of 38 mm, and the sizes of the TX and RX are 50×50 mm2 and 30×30 mm2, respectively.. |
| 12. |
S.A Enche Ab Rahim, Adel Barakat, Ramesh Kumar Pokharel, Design of 5.5GHz LC oscillator using distributed grid of N-well in P-substrate inductor, 2016 IEEE Asia Pacific Conference onCircuits and Systems (APCCAS), 2016.10. |
| 13. |
Anwer S. Abd El-Hameed, Nessim Mahmoud, ADEL Barakat, Adel B. Abdel-Rahman, Ahmed Allam, POKHAREL RAMESH KUMAR, A 60-GHz on-chip tapered slot Vivaldi antenna with improved radiation characteristics, 2016 10th European Conference on Antennas and Propagation (EuCAP), 2016.04, This paper presents a design of 60-GHz exponential tapered slot Vivaldi antenna-on-chip (AOC). The antenna is designed using standard 0.18μm six metal-layers CMOS technology. A double-Y balun feeding structure is used to make transition from coplanar waveguide to slot-line. Two techniques are investigated for improving antenna radiation properties. The first technique incorporates equal corrugations on the edges of exponential flaring section and other on the backed-edge of antenna to enhance the antenna gain. Second, a planar arc reflector is constructed using metal vias between M6 and M1 to inhibit the back lobe, contributing to the enhancement of gain and efficiency. The overall antenna size is compact and equal to 785μm × 930μm. The influence of the antenna position on the radiation properties is also studied. The proposed antenna offers endfire radiation pattern with a simulated peak gain and a radiation efficiency of -0.4 dBi and 32%, respectively.. |
| 14. |
Sherif hekal, Adel B. Abdel-Rahman, Ahmed Allam, ADEL Barakat, JIA HONGTING, POKHAREL RAMESH KUMAR, Asymmetric strongly coupled printed resonators for wireless charging applications, 2016 IEEE 17th AnnualWireless and Microwave Technology Conference (WAMICON), 2016.04, This paper presents a simple compact design for wireless charging applications using asymmetric strongly coupled printed resonators (SCPR). The proposed resonators are further loaded by surface mounted (SMD) capacitors for miniaturization. The system consists of two substrates. The first transmitting substrate contains a driving loop on the top layer and the high Q-resonator on the bottom layer. Similarly, the second substrate contains the high Q-resonator as the receiver and a loop as the load. An equivalent circuit model is extracted. An analytic design method is proposed to get a high wireless power transfer (WPT) efficiency. Good agreement between electromagnetic simulations, circuit simulations, and measurements was achieved. The proposed system achieves a measured WPT efficiency of 60% at 100 MHz using a receiving resonator of size 20 mm × 20 mm away for a transmission distance of 35 mm from the transmitting resonator of size 30 mm × 30 mm.. |
| 15. |
Elsayed Elsaidy, ADEL Barakat, Adel B. Abdel-Rahman, Ahmed Allam, POKHAREL RAMESH KUMAR, Radiation performance enhancement of a 60 GHz CMOS Quasi-Yagi antenna, 2016 IEEE 17th Annual Wireless and Microwave Technology Conference (WAMICON), 2016.04, This paper presents a study on 60 GHz CMOS Quasi-Yagi antenna for radiation performance enhancement. The driven element is meandered for size compactness and is fed by a coplanar waveguide to coplanar stripline transition. Moreover, the ground plan was corrugated to serve as the reflecting element. Furthermore, the director was designed from multi-element which led to gain and efficiency enhancement. Finally, the effect of the antenna location on the radiation characteristics was studied. The simulated gain and efficiency are -0.746 dBi and 21.4%, respectively at 60 GHz, and The design has an area of 1 × 0.87 mm2.. |
| 16. |
Nessim Mahmoud, Anwer S. Abd El-Hameed, ADEL Barakat, Adel B. Abdel-Rahman, Ahmed Allam, POKHAREL RAMESH KUMAR, Performance enhancement of 0.18µm CMOS on chip bandpass filters using H-shaped parasitic element, 2015 27th International Conference on Microelectronics (ICM), 2015.12, A design of an improved open loop resonator on-chip bandpass filter for 60 GHz millimeter-wave applications using 0.18 μm CMOS technology is presented. The proposed on-chip BPF employs H-shaped parasitic structure inserted between two open loop coupled resonator. The adoption of a two open loop coupled resonators BPF and the utilization of two transmissions zero located at 48 and 80 GHz permit a compact size and high selectivity of the BPF. In addition, the parasitic H-shaped structure increases the capacitance between the two resonators, which enables a further reduction of the physical length of the filter and enhances the coupling between the resonators which improve the filter insertion loss. The proposed BPF has a center frequency of 60 GHz, an insertion loss of -2 dB, a 3dB band width of 13 GHz, and a core size 160×480 μm2 with total chip size 680×280 μm2 (including bonding pads).. |
| 17. |
Nessim Mahmoud, Adel Barakat, Anwer S. Abd El-Hameed, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Kumar Pokharel, Study of SiO2 thickness effect on insertion loss of CMOS 60 GHz band pass filter, 2015 IEEE International Conference on Electronics, Circuits, and Systems (ICECS), 2015.12, This paper presents a study of the effect of the SiO2 substrate thickness on the insertion loss performance of half wavelength open loop resonator bandpass filter. It has been observed that the main reason for insertion loss degradation is the small thickness of SiO2. An insertion loss of -1.49dB is achieved with a SiO2 thickness of 24μm. Furthermore, an equivalent lumped circuit model of the filter is proposed to verify this observation. The S-parameters of lumped element circuit model are obtained using the ADS simulator and compared with the results obtained from the EM simulator showing good agreement.. |
| 18. |
Anwer S. Abd El-Hameed, ADEL Barakat, Adel B. Abdel-Rahman, Ahmed Allam, POKHAREL RAMESH KUMAR, A60-GHz double-Y balun-fed on-chip Vivaldi antenna with improved gain, 2015 27th International Conference on Microelectronics (ICM), 2015.12, A60-GHz double-Y balun-fed exponential tapered slot Vivaldi antenna-on-chip (AOC) is designed using standard 0.18μm six metal-layer CMOS technology. A double-Y balun feeding structure is used to make transition from coplanar to slot line. Three methods are developed for improving antenna radiation properties. First, an impeding longitudinal rectangular slits on the backed edge of the Vivaldi antenna are used to enhance the gain. Second, loading circular metal-strips are used as additional director into the slot area of Vivaldi antenna on M6. Finally, a planar arc reflector is used to inhibit the back lobe, contributing to the enhancement of gain and efficiency. The overall antenna size is very compact and equal to 700um×940μm. The influence of the antenna position on the radiation properties is also studied. The proposed antenna offers a simulated peak gain and a radiation efficiency of -1.9 dBi and 24%, respectively.. |
| 19. |
M. Hanif, POKHAREL RAMESH KUMAR, 吉富邦明, ADEL Barakat, Hala Elsadek, A gain enhanced 60 GHz CMOS antenna-on-chip using off-chip Mu near zero metamaterial lens, 2015 IEEE 4th Asia-Pacific Conference on Antennas and Propagation (APCAP), 2015.07, This paper presents a Mu Near Zero Metamaterial (MNZ-MM) lens to enhance the gain of a 60 GHz Antenna-on-Chip (AoC). First, a MNZ-MM unit cell is designed to ensure the near zero characteristics at the 60 GHz band. Furthermore, a 3 by 3 matrix of the MNZ-MM is placed in the desired direction of radiation such that the radiated waves are coupled and the gain is enhanced and the AoC's |S11| is negligibly affected. The simulated gain and efficiency of the AoC with MNZ-MM lens are 2.8dBi and 35%, respectively.. |
| 20. |
Adel Barakat, Ahmed Allam, Hala Elsadek, Adel B. Abdel-Rahman, S. Muhammad Hanif, Ramesh K. Pokharel, Miniaturized 60 GHz triangular CMOS Antenna-on-Chip using asymmetric artificial magnetic conductor, 2015 IEEE 15th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF), 2015.01, This paper presents a miniaturized triangular Antenna-on-Chip (AoC) designed and fabricated on a 0.18 μm CMOS process using asymmetric rectangular artificial magnetic conductor (R-AMC). An AMC acts as a shield plane between the AoC and the lossy CMOS substrate. AoC using asymmetric R-AMC presents a smaller overall area than that of the previous reported AoC with symmetric AMCs. The triangular AoC area including the asymmetric AMC cells is only 0.81mm2 with a simulated gain of -0.2 dBi at 60 GHz. Measurements confirm the wide impedance bandwidth of the AoC.. |
| 21. |
Adel Barakat, Ahmed Allam, Hala Elsadek, Haruichi Kanaya, Ramesh K. Pokharel, Small size 60 GHz CMOS Antenna-on-Chip: Gain and efficiency enhancement using asymmetric Artificial Magnetic Conductor, 2014 44th European Microwave Conference (EuMC), 2014.10, This paper presents a small size 60 GHz Antenna-on-Chip (AoC) designed and fabricated using 0.18 um TSMC Complementary Metal Oxide Semiconductor (CMOS) process. AoC performance is enhanced using asymmetric Artificial Magnetic Conductor (AMC). The AoC area including the AMC is 1715 um by 710 um. As AMC shields AoC from the lossy CMOS substrate, simulated gain of -0.25 dBi is achieved at 60 GHz for design rule compatible circular AoC with 12.8 dB front-to-back ratio (FBR) due to removal of AMC cells below the AoC. Measurements agree well with simulation results and confirm operation at the 60 GHz band with a peak measured gain of -3 dBi at 64 GHz.. |
| 22. |
Adel Barakat, Ahmed Allam, Hala Elsadek, Haruichi Kanaya, Hongting Jia, Kuniaki Yoshitomi, Ramesh Pokharel, Back radiation reduction of 60 GHz CMOS slot Antenna-on-Chip (AoC) using Artificial Dielectric Layer (ADL) for Area Reuse, 2014 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium), 2014.07, Antenna-on-Chip (AoC) integration with other radio frequency and digital circuits is a prime target for complete System-on-Chip (SoC). However, CMOS AoC integration suffers from two main disadvantages. First, AoC suffers from losses due to low resistivity CMOS substrate (σ=10S/m) which leads to reduction of the AoC efficiency (A. Barakat, et al, IEEE IMS, June2013). Second, AoC occupies a large area that cannot be reused because of the strong field below the AoC.. |
| 23. |
Adel Barakat, Ahmed Allam, Ramesh K. Pokharel, Hala Elsadek, Mohammed Ragab, Keji Yoshida, Compact size high gain AoC using rectangular AMC in CMOS for 60 GHz millimeter wave applications, 2013 IEEE MTT-S International Microwave Symposium Digest (IMS), 2013.06, 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.. |
| 24. |
Adel Barakat, Ahmed Allam, Ramesh K. Pokharel, Hala Elsadek, Mohammed Ragab, Keji Yoshida, Performance optimization of a 60 GHz Antenna-on-Chip over an Artificial Magnetic Conductor, 2012 Japan-Egypt Conference on Electronics, Communications and Computers (JEC-ECC), 2012.03, This paper presents an optimization methodology for a 60 GHz triangular monopole Antenna-on-Chip (AOC), designed using a standard 0.18 μm CMOS process and optimized over a Jerusalem Cross Artificial Magnetic Conductor (JC-AMC). The JC-AMC acts as a shield between the AOC and the lossy CMOS substrate. Different configurations of JC-AMC cells are tested to acquire best AOC performance. It has been found that increasing the number of JC-AMC cells in the feeding direction and decreasing its number of cells in the direction perpendicular to the feed can improve the antenna characteristics in terms of gain, efficiency, front-to-back ratio, and small area.. |
| 25. |
Adel Barakat, Ahmed Allam, Ramesh K. Pokharel, Hala Elsadek, Mohammed Ragab, Keji Yoshida, 60 GHz triangular monopole Antenna-on-Chip over an Artificial Magnetic Conductor, 2012 6th European Conference on Antennas and Propagation (EUCAP), 2012.03, A high-gain and small-area triangular monopole Antenna-on-Chip (AOC), designed using a standard CMOS process and optimized over a modified rectangular Artificial Magnetic Conductor (AMC). The rectangular AMC acts as a shield between the AOC and the lossy CMOS substrate. Using this configuration, a Frequency Selective Surface (FSS) is realized by the shield providing high wave impedance around 60 GHz. The AOC dimensions including the AMC are 0.86 mm by 1.76mm. The antenna gain is 0.3 to 1 dBi from 57 to 64 GHz.. |
| 26. |
Adel Barakat, Mostafa ElKhamy, Bandwidth extension of UWB planar antenna with band-notched characteristics, 2010.10, In this paper, an ultra-wideband (UWB) antenna with a band notched filter is proposed. The transmission range of this antenna covers the FCC unlicensed band from 3.1 to 10.6 GHz with a notch filter from 4.9 to 6.3 GHz to avoid interference with IEEE802.11a system. The notch filter is implemented using a U-shaped slot. To extend the impedance bandwidth of the antenna, an electroband-gap (EBG) structure is used. EBG lattice holes surrounding the radiating patch enhances the impedance bandwidth to be from 3 GHz to 12 GHz with a return loss (S11 |
