Recent advances in the design of efficient-yet-linear watt-class mmWave CMOS PAs

Technology scaling, which has enabled operation at mmWave frequencies in CMOS, has also brought with it a steady decrease in the breakdown voltages of the transistors. The resulting fall in output power of power amplifiers (PAs) combined with the low efficiency due to poor device gain and lossy passive components has led to research efforts towards efficient yet linear high output PAs at mmWave. This paper discusses key advances toward this goal, namely device stacking, mmWave switch-mode operation, large-scale power combining and linearization techniques capable of supporting multi-Gbps complex modulations efficiently.