Wideband High-Efficiency Digital Power Amplifier in GaN

This work presents a wideband digital PA topology implemented in Gallium Nitride MMIC for a direct-digital RF transmitter. The topology employs a differential current mode driver and GaN inverter stage with active pull-up to drive an efficient switch-mode PA. By applying digital circuit design techniques in GaN, our approach enables wide-band digital drive of a switched-mode PA through pulse-width and pulse-position control. The approach is experimentally validated in a 0.2 mu m GaN on SiC foundry process at C band. The digital PA operates over a 2.5-6.0 GHz range with total drain efficiency greater than 30%, final-stage drain efficiency yielded over 40%, and peak output power of 35.2 dBm.