The RF power amplifier (PA) is typically the most power hungry and area consuming block in a wireless transceiver system. A viable RF PA solution should offer competitive power and area efficiency while maintaining high-performance large-signal RF operations. Fully integrated RF PA in CMOS has been an area of active research and development over the past years. Recently, there has been a surge of interest to leverage the mixed-mode, analog and digital, computational and signal processing capability in CMOS to radically enhance RF CMOS PA solutions and offer unique functionalities in parallel. This paper reviews several recently reported circuit design techniques of CMOS PAs. All of these techniques take advantage of computation and integration advantages of CMOS process and can potentially lead to competitive PA solutions compared to traditional III-V HBT PA solutions.