Ku-Band CMOS Power Amplifier with Three-Stack Power Stage to Enhance Output Power and Efficiency

In this study, we proposed a power amplifier structure with improved efficiency while securing high output power. First, the characteristics of the common-source and stack structures were investigated. In particular, the output power and output impedance characteristics of the stack structure were analyzed compared with the common-source structure. A common-source structure was applied to the driver stage to minimize dc power consumption, and a stack structure was applied to the power stage to ensure high output power. In order to verify the proposed structure, a Ku-band power amplifier was designed using the 65-nm RF CMOS process that provides nine metal layers. At the operating frequency of 15 GHz, saturation output power and maximum power-added efficiency were confirmed to be 22.1 dBm and 17.2%, respectively.