A 60 GHz CMOS power amplifier using varactor cross-coupling neutralization with adaptive bias

This paper proposes the method of varactor cross-coupling with adaptive bias. The capacitive cross-coupling neutralization contributes to improve power gain and reverse isolation. The optimized capacitance of cross-coupled PA depends heavily on the input power. Thus, the varacter is used and adaptive bias is obtained by the feedback of the input power. The 2-stage differential power amplifier is fabricated in a 65nm CMOS process. It achieves the PAE at P_1dB of 7.7% and peak PAE of 12.5% from a 1.2V power supply. The effect of varactor cross-coupling neutralization with adaptive bias is validated.