Design of CMOS Digital Power Amplifier Applied in Digital Polarized Transmitter

This paper presents a fully integrated wideband current-mode digital power amplifier (DPA) for digital polar transmitter in a 22nm RF CMOS process. Current-mode class-D configuration and differential cascode structure are used to obtain high efficiency, noise reduction and high output power with limited supply voltage. A three-coil transformer-based output passive network provides power combining and optimum load impedance transformations simultaneously at two operating frequencies. As a proof-of-concept, a 2.4–5.25 GHz wideband DPA is implemented with supply voltage of 1V for driver circuit and 2.5V for power cells. The simulated peak DPA output power is 30.0dBm/27.5dBm at 2.4GHz/5.25GHz. The simulated peak drain efficiency is 49.8% at 2.4GHz.