Broadband GaN MMIC Asymmetric Doherty Power Amplifier Employing Complex Load Impedance

This work presents the design and simulation of a broadband fully integrated asymmetric Doherty power amplifier (ADPA) that employs complex combining load impedance, the continuous operation is achieved at both output power back-off (OBO) point and saturation. A 250-nm gallium nitride (GaN) process was used in this design. The impedance inverter network (lIN) and post-matching network (PMN) were implemented using lumped components, furthermore, the parasitic parameters of transistors are also absorbed into the matching network to simplify the matching structure. Within the working frequency band of 4.3-5.1 GHz, the simulation results shows that the saturated drain efficiency (DE) of the designed DPA is between 58.9%-61.3%, with a saturated output power of 39.4-40.3 dBm. 46.7%-52.0% DE is achieved at 8 dB OBO within the working bandwidth.