A wideband supply modulator for 20MHz RF bandwidth polar PAs in 65nm CMOS

A wideband modulator for a 20 MHz bandwidth polar modulated PA is presented which achieves a maximum efficiency of 87.5% and a small signal -3 dB bandwidth of 285 MHz. Realized in 65 nm CMOS, it consists of a cascoded nested Miller compensated linear amplifier and a class D switching amplifier. It can deliver 22.7 dBm output power to a 5.3 Omega load. With a switching frequency of 118 MHz, the output switching ripple is 4.3 mVrms.