In this seminar, some advanced techniques of Doherty power amplifier for 5G/6G wireless communications will be introduced. In past decades, Doherty power amplifiers have become the best candidate for linear amplification of modulated signals with high peak-to-average power ratios (PAPRs) due to their high efficiency from back-off point to saturation (e.g., OBO range). Meanwhile, the gallium nitride (GaN) electronic devices are emerging as promising candidates for next-generation high-efficiency power converters in wireless communication owing to superior material properties, such as high electric breakdown field, high-electron saturation velocity, and high mobility in a readily available heterojunction 2-D electron gas (2DEG) channel. With the development of wireless communications, more and more strict system requirements (such as high efficiency, high linearity, and OBO range extension) have been proposed that should be satisfied by DPAs, Therefore, GaN-based DPA circuits are needed to be developed urgently for various wireless application scenarios. Dr. Zhou will demonstrate his original techniques to show how the new technologies improve the performances of DPAs circuits for 5G/6G wireless communication. Meanwhile, some MMIC works that focus on the 5G mm-wave band and space communication based on the GaN and Indium phosphide (InP) process will be presented. In addition, the impact of diamond passivation on fT and fMAX of a mm-wave GaN HEMT that is used for the design of a 5G power amplifier will be investigated. Eventually, the conclusion will be given and the future research strategies will be demonstrated.

Xinyu Zhou (S’15-M’18-SM’21) was born in Tsingtao, Shandong Province, China. He received an M.Sc. and Ph.D. degrees in electronic engineering from City University of Hong Kong, Kowloon, Hong Kong, in 2014 and 2018, respectively. From 2014 to 2015, he was a research assistant with the Sun Yat-sen University - Carnegie Mellon University (SYSU-CMU) Shunde international joint research institute, China. From 2018 to 2020, he was a postdoctoral fellow with the Department of Electrical Engineering at the City University of Hong Kong, Kowloon, Hong Kong. From 2020 to 2021, he was a postdoctoral research associate with the Department of Electrical Engineering at Princeton University, New Jersey, U.S.A. He is currently a postdoctoral research fellow with the Department of Electrical Engineering at Stanford University, California, USA. His current research interests include broadband high-efficiency and high-linearity GaN power amplifiers in RF and millimeter-wave, integrated circuits, and microwave passive circuits. Dr. Zhou was a recipient of the First Place Award of the High-Efficiency Power Amplifier Student Design Competition, IEEE Microwave Theory and Techniques Society (IEEE MTT-S) International Microwave Symposium (IMS) in 2017 and a recipient of the Second Place Award of the same Student Design Competition in 2018. He is also an affiliate member of the MTT-12 Microwave High-Power Techniques Committee and the member of IMS Technical Paper Review Committee. Dr. Zhou is currently the associate editor of IEEE Transactions on Circuits and Systems I: Regular Papers, IET Electronics Letters, and a reviewer for over ten internationally refereed journals and conferences, including IEEE JSSC, IEEE TMTT, IEEE TCAS1, and IEEE MWCL.