An X-band 40 W power amplifier GaN MMIC design by using equivalent output impedance model

Abstract

This paper presents an X-band 40 W power amplifier with high efficiency based on 0.25 µm GaN HEMT (High Electron Mobility Transistor) on SiC process. An equivalent RC (Resistance Capacitance) model is presented to provide accurate large-signal output impedances of GaN HEMTs with arbitrary dimensions. By introducing the band-pass filter topology, broadband impedance matching networks are achieved based on the RC model, and the power amplifier MMIC (Monolithic Microwave Integrated Circuit) with enhanced bandwidth is realized. The measurement results show that this power amplifier at 28 V operation voltage achieved over 40 W output power, 44.7% power-added efficiency and 22 dB power gain from 8 GHz to 12 GHz. The total chip size is 3.20 mm × 3.45 mm.