| 1. |
Barakat, Adel; Yoshitomi, Kuniaki; Pokharel, Ramesh K., Design Approach for Efficient Wireless Power Transfer Systems During Lateral Misalignment, IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, 10.1109/TMTT.2018.2852661, 66, 9, 4170-4177, 2018.09. |
| 2. |
Elsaidy, Elsayed; Barakat, Adel; Abdel-Rahman, Adel B.; Allam, Ahmed; Pokharel, Ramesh K., Ultracompact CMOS 60-GHz Tapped-Line Combline BPF With Two Transmission Zeros Using Defected Ground Structures, IEEE TRANSACTIONS ON COMPONENTS PACKAGING AND MANUFACTURING TECHNOLOGY, 10.1109/TCPMT.2018.2861411, 8, 9, 1642-1649, 2018.09. |
| 3. |
Nusrat Jahan, Siti Amalina Enche Ab Rahim, Hamed Mosalam, Adel Barakat, Takana Kaho, Ramesh K. Pokharel,, 22-GHz-Band Oscillator Using Integrated H-Shape Defected Ground Structure Resonator in 0.18-mu m CMOS Technology, IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, 10.1109/LMWC.2018.2801031, 28, 3, 233-235, 2018.03, A novel 22-GHz-band oscillator using an integrated defected ground structure (DGS) resonator is presented for quasimillimeter 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.. |
| 4. |
Fairus Tahar, Adel Barakat, Redzuan Saad, Kuniaki Yoshitomi, Ramesh K. Pokharel, Dual-Band Defected Ground Structures Wireless Power Transfer System With Independent External and Inter-Resonator Coupling, IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS II-EXPRESS BRIEFS, 10.1109/TCSII.2017.2740401, 64, 12, 1372-1376, 2017.12, 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 WPT 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 × 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 and 0.7 GHz).. |
| 5. |
Fairus Tahar, Redzuan Saad, Adel Barakat, Ramesh Kumar Pokharel, 1.06 FoM and Compact Wireless Power Transfer System Using Rectangular Defected Ground Structure Resonators, IEEE Microwave and Wireless Components Letters, 10.1109/LMWC.2017.2750032, 27, 11, 1025-1025, 2017.11, This letter proposes a wireless power transfer (WPT) system using coplanar waveguide fed rectangular defected ground structure (DGS) resonators. One of the advantages of rectangular DGS resonator is that it has higher quality (Q-) and coupling (K-) factor compared to the H-shape or semi-H-shape DGS resonators. When two DGS resonators are coupled back-to-back, it transforms to a bandpass filter with tight coupling, resulting in the transfer of power wirelessly. The fabricated WPT system of size 35.8 mm×20 mm achieves, for the first time, a figure of merit of more than one at a WPT distance from 40 to 44 mm.. |
| 6. |
Anwer S. Abd El-Hameed, Adel Barakat, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Kumar Pokharel, Ultracompact 60-GHz CMOS BPF Employing Broadside-Coupled Open-Loop Resonators, IEEE Microwave and Wireless Components Letters, 27, 9, 818-820, 2017.09, 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-μm complementary metal-oxide-semiconductor technology for millimeter-wave applications. The fabricated BPF chip size is 240 × 225 μm2 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.. |
| 7. |
Nusrat Jahan, Siti Amalina Enche Ab Rahim, Adel Barakat, Takana Kaho, Ramesh Kumar Pokharel, Design and Application of Virtual Inductance of Square-Shaped Defected Ground Structure in 0.18- μm CMOS Technology, IEEE Journal of the Electron Devices Society, 10.1109/JEDS.2017.2728686, 5, 5, 2168-6734, 2017.07, 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-μm 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.. |
| 8. |
Adel Barakat, Ahmed Allam, Hala Elsadek, Adel B. Abdel-Rahman, Ramesh Kumar Pokharel, Americ Bisognin, Cyril Luxey, 60 GHz CMOS Circular Patch Antenna on Chip, Microwave Journal, 60, 2, 90-100, 2017.02. |
| 9. |
Sherif Hekal, Adel B. Abdel-Rahman, Hongting Jia, Ahmed Allam, Adel Barakat, Ramesh Kumar Pokharel, A Novel Technique for Compact Size Wireless Power Transfer Applications Using Defected Ground Structures, IEEE Transactions on Microwave Theory and Techniques, http://dx.doi.org/10.1109/TMTT.2016.2618919, 65, 1, 591-599, 2017.02, This paper presents a novel technique for high efficiency and compact size wireless power transfer (WPT) systems. These systems are based on coupled defected ground structure (DGS) resonators. Two types of DGSs (H-shape and semi-H-shape) are proposed. The semi-H-shaped DGS realizes larger inductance value, and this results in higher WPT efficiency. Instead of using an inductive-fed resonant coupling, we propose capacitive-fed resonant coupling, which reduces the design complexity and enhances the efficiency further. The DGS resonator of both the systems is loaded by chip capacitors for miniaturization. An equivalent circuit using approximate quasi-static modeling is extracted. An analytical design procedure is developed to calculate the optimum design parameters for the proposed WPT systems. The optimized structures are fabricated and measured. The simulation and measurement results are in good agreement. The proposed semi-H-shaped DGS WPT system has a peak efficiency of 73% at a transmission distance of 25 mm. In turn, the figure of merit becomes the highest among the WPT systems proposed so far.. |
| 10. |
Sherif Hekal, Adel B. Abdel-Rahman, Ahemd Allam, Hongting Jia, Adel Barakat, Ramesh Kumar Pokharel, Asymmetric Wireless Power Transfer Systems Using Coupled DGS Resonators, IEICE Electronics Express, http://doi.org/10.1587/elex.13.20160591, 13, 21, 20160591, 2016.11, his paper presents a new design for wireless power transfer (WPT) systems using asymmetric structures for the transmitter (TX) and the receiver (RX), and the TX/RX are constructed using spiral-strips defected ground structure (DGS) resonators. The proposed spiral-strips DGS resonator overcome the problem of low self-inductance that encountered by H-shape DGS resonator in [1, 2], so that the proposed WPT system that employs the proposed spiral-strips DGS resonators has better efficiency and higher power transmission distance. Design methodology of the proposed WPT system are formulated and fabricated. The measurement results show a WPT efficiency of 78% at a transmission distance of 40 mm with the TX and RX areas of 50 x 50 mm2 and 30 x 30 mm2, respectively.. |
| 11. |
Sherif Hekal, Adel B. Abdel-Rahman, Hongting Jia, Ahmed Allam, Adel Barakat, Takano Kaho, Ramesh Kumar Pokharel, Compact Wireless Power Transfer System Using Defected Ground Bandstop Filters, IEEE Microwave and Wireless Components Letters, 10.1109/LMWC.2016.2601300, 26, 10, 2016.10, This letter presents a new design for wireless power transfer (WPT) applications using two coupled bandstop filters (BSF). The stopband is created by etching a defected structure on the ground plane, and the power is transferred through electromagnetic (EM) resonant coupling when the two BSFs are coupled back to back. An equivalent circuit model of the proposed WPT system is extracted. Verification of the proposed design is performed through a good agreement between the EM simulation, circuit simulation, and measurement results. The proposed system achieves a measured WPT efficiency of 68.5% at a transmission distance of 50 mm using a compact size (40 x 40mm²). This results in a figure of merit of the proposed system to be 0.856 and the ratio of transmission distance/lateral size is 1.25 that is the highest among the WPT systems proposed so far using planar structures.. |
| 12. |
Nessim Mahmoud, Adel Barakat, Adel B. Abdel-Rahman, Ahmed Allam, Ramesh Kumar Pokharel, Compact Size On-Chip 60 GHz H-Shaped Resonator BPF, IEEE Microwave and Wireless Components Letters, 10.1109/LMWC.2016.2597219, 26, 9, 681-683, 2016.09, In this letter, we propose a compact size, small insertion loss 60 GHz on-chip H-shaped resonator bandpass filter (BPF) using 0.18 μm standard CMOS technology. The BPF Size is miniaturized by loading the H-shaped resonator with metal-insulator-metal capacitors at its ends. Besides, two defected ground structure cells are etched under the coupled lines to improve the filter insertion loss. Furthermore, selectivity is enhanced by loading the center of the H-shaped resonator with two unsymmetrical meander line stubs generating two transmission zeroes at 50 and 70 GHz. The fabricated BPF chip size is 240×650 μm2. The measured insertion loss and fractional bandwidth are 2.5 dB at 60 GHz and 21%, respectively.. |
| 13. |
Adel Barakat, Muhammad Hanif, Ramesh Kumar Pokharel, Miniaturized Low loss 60GHz CMOS Mixed Coupled BPF with Patterned Ground shield, Microwave and Optical Technology letters, 10.1002/mop.29650, 58, 3, 697-699, 2016.03, This letter presents a miniaturized low loss mixed coupled on-chip band-pass filter using overlapped open loop ring resonators and using patterned ground shields. The fabricated prototype shows an insertion loss of 3.7 dB, a return loss > 20 dB, a bandwidth of 13 GHz, and a chip size of 700 μm × 450 μm.
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| 14. |
Adel Barakat, Ramesh Kumar Pokharel, Takana Kaho, 60 GHz on-chip mixed coupled BPF with H-shaped defected ground structures, Electronics Letters, 10.1049/el.2015.4465, 2016.03, This letter presents a 60 GHz miniaturized, low loss on-chip bandpass filter (BPF) based on open-loop resonators (OLR). Overlapping of the BPF’s resonators leads to miniaturization and introduces a mixed coupling configuration. Moreover, its resonators are folded to minimize the size and the insertion loss. H-shaped defected ground structures are also used to reduce insertion loss and to improve the out of band rejection. The measured insertion loss, return loss, centre frequency, and bandwidth are 2.85 dB, 18 dB, 59 GHz and 15.5 GHz with a chip size of 368 × 262 um2 including pads.. |
| 15. |
Adel Barakat, Ahmed Allam, Hala Elsadek, Adel Abdelrahman, Ramesh Kumar Pokharel, Takana Kaho, Improved gain 60 GHz CMOS antenna with N-well grid, IEICE Electronics Express, 10.1587/elex.13.20151115, 13, 5, 2016.03, This paper presents a novel technique to enhance Antenna-on-Chip (AoC) gain by introducing a high resistivity layer below it. Instead of using the costly ion implantation method to increase resistivity, the N-well that is available in the standard CMOS process is used. A distributed grid structure of N-well on P-type substrate is designed such that the P and N-type semiconductors are fully depleted forming a layer with high resistivity. By an electromagnetic simulation, the using depletion layers enhance the antenna gain and radiation efficiency without increasing the occupied area. The simulated and measured |S11| are in fair agreement. The measured gain is –1.5 dBi at 66 GHz.. |
