A 50 W dual‐band high‐efficiency gallium nitride high electron mobility transistor power amplifier with three‐stage L‐type DC bias circuit at 1.8 and 2.6 GHz

Abstract

AbstractA 50 W dual‐band high‐efficiency gallium nitride (GaN) high electron mobility transistor (HEMT) power amplifier with a three‐stage L‐type DC bias circuit capable of individually adjusting second‐harmonic impedances is proposed for 1.8 and 2.6 GHz frequencies. The output network of this power amplifier is composed of an output matching network comprising five‐stage transmission lines and a three‐stage L‐type DC bias circuit with three L‐type circuits and one transmission line. The one‐stage L‐type circuit comprises a series transmission line and a quarter‐wavelength open‐ended shunt stub. For the high‐efficiency performance of the power amplifier, the output matching network is matched to the optimum impedances of the fundamental frequencies, and the DC bias circuit optimizes the impedances individually at the second‐harmonic frequencies without affecting the matched fundamental frequency impedances in the output matching network. Measured results show that the proposed dual‐band GaN HEMT power amplifier achieved gains of 15.6 and 13.8 dB as well as maximum power‐added efficiencies of 70.5% and 66.3% with 47 dBm output power at 1.8 and 2.6 GHz, respectively.