A High-Efficiency, Broadband CMOS Power Amplifier for Cognitive Radio Applications

This paper presents a wideband power amplifier (PA) for the application of intelligent cognitive radios. Resistive feedback and transformer matching network are proposed in this PA design to enhance the broadband frequency response. The broadband load impedance match is realized using series stack topology. The limitation of stack PA in both GaAs and CMOS processes are discussed. A high-efficiency broadband PA in commercial 0.18 μm CMOS process with the best P_1dB of 20 dBm and PAE of 30% are demonstrated to verify the design concepts. This PA also shows the widest fractional bandwidth performance among CMOS PAs below 10 GHz.