Improvement Method of Power-Added Efficiency of Multi-Stage CMOS Amplifiers in Millimeter-Wave Band

A power amplifier in the millimeter-wave band usually consists of multiple stages because the gain per stage is small. It is necessary to optimally distribute gain compression over multiple stages to improve power-added efficiency (PAE) while maintaining linearity. This paper proposes a method of gain-compression allocation that maximizes the PAE of a multistage amplifier. In an 80-GHz power amplifier designed using a 55-nm CMOS process and lossless inter-stage networks, the PAE is improved by 2 % as compared to the case where gain compression is evenly distributed to each stage.