3–3.6-GHz Wideband GaN Doherty Power Amplifier Exploiting Output Compensation Stages

TLDR

The authors design, realize, and experimentally characterize a GaN‑based hybrid Doherty power amplifier for wideband operation in the 3–3.6 GHz band. The amplifier employs a novel, simple wideband compensator network and exploits second‑harmonic tuning at the upper band limit to improve gain equalization. The packaged GaN HEMT amplifier achieves >38 % drain efficiency at 6 dB back‑off, ~10 dB gain, 43–44 dBm maximum power, 55–66 % saturated efficiency, and a constant 20 W output, matching state‑of‑the‑art performance at higher frequency with a simpler design.

Abstract

We discuss the design, realization and experimental characterization of a GaN-based hybrid Doherty power amplifier for wideband operation in the 3-3.6-GHz frequency range. The design adopts a novel, simple approach based on wideband compensator networks. Second-harmonic tuning is exploited for the main amplifier at the upper limit of the frequency band, thus improving gain equalization over the amplifier bandwidth. The realized amplifier is based on a packaged GaN HEMT and shows, at 6 dB of output power back-off, a drain efficiency higher than 38% in the 3-3.6-GHz band, gain around 10 dB, and maximum power between 43 and 44 dBm, with saturated efficiency between 55% and 66%. With respect to the state of the art, we obtain, at a higher frequency, a wideband amplifier with similar performances in terms of bandwidth, output power, and efficiency, through a simpler approach. Moreover, the measured constant maximum output power of 20 W suggests that the power utilization factor of the 10-W (Class A) GaN HEMT is excellent over the amplifier band.