mm-Wave PA Design Challenges and Solutions for 6G Applications

Research towards 6G wireless networks for next-generation communication and sensing has accelerated at an incredible speed. It is envisioned that the 100GHz to 240GHz spectrum will be the major spectrum of interest due to their abundant available bandwidth to achieve the “hole grail” of 1Tb/s wireless network throughput. It is also expected that large-scale arrays with massive elements will become a necessity to provide array gains and compensate for the high-frequency path loss. However, a major challenge at the 6G network physical layer is the lack of energy-efficient, wideband, and ultra-compact front-end electronics, in particular power amplifiers, at high mm-wave/sub-THz frequencies. This is even more problematic for large-scale densely-packed arrays, where thermal management becomes a severe issue. Further, next-generation wireless links demand ultra-wideband modulations and high efficiency, while radar/imaging/sensing systems require large instantaneous bandwidth. Despite of decades of research on integrated power amplifiers, most of these efforts have focused on RF and mm-wave PAs, while high mm-wave/sub-THz frequency PAs entail distinct challenges at both device and circuit levels. In this talk, we will review the current state-of-the-art of the high mm-wave and sub-THz frequencies PAs, including PAs in both silicon and III-V technologies. A variety of challenges and performance limitations will be outlined. Then, we will present several recently published mm-wave/sub-THz PA designs as examples to showcase the present capabilities. Future technology trends and potential devices/circuits solutions will be discussed as well.