This project investigates novel architectures and circuits for sub-6GHz 5G, mm-wave 5G, and introductory 6G power amplifiers (PAs)
Research for sub-6GHz 5G systems will focus on basestation GaN-based PAs that have improved efficiency by tailoring the power supply voltage for the power level to be delivered. This strategy is known to be effective for envelope tracking (for low signal bandwidths) and average power tracking (for slow variations in power required). In this work, we will tailor the dynamic power supply response time to the symbol rate, which will allow optimization of both the power supply and the RF amplifier. With participation of Prof. Hanh-Phuc Le, a GaN-based rapid switching dc-dc converter will be developed for the high efficiency supply.
For 5G mm-wave applications, we will focus on refinement of the adaptively biased asymmetric Doherty amplifiers currently being developed in our laboratory, and investigate digitally-assisted analog predistortion techniques to maintain linearity and improve tolerance to VSWR.
For initial explorations of higher frequency bands for 6G, we will implement high efficiency CMOS amplifiers at 70-75GHz, which can be used near term in backhaul and in E band point-to-point applications. We will investigate PAs for significantly higher power (>1W) by researching the use of CMOS ICs closely-coupled to final stage PAs implemented in GaN.