A 5-W GaN Doherty Amplifier for Ka-Band Satellite Downlink With 4-GHz Bandwidth and 17-dB NPR

This letter presents the design and experimental characterization of a GaN–Si monolithic Doherty power amplifier (PA) for the $Ka$ -band satellite downlink. The fabricated amplifier favorably compares with the current state of the art, achieving from 16.3 to 20.3 GHz (4 GHz, 22% relative bandwidth), a record band to date, 36.6–37.7-dBm output power, 23%–31% power-added efficiency, 18–22-dB gain at saturation, and around 20% power-added efficiency at 6-dB output back-off. At 18.8 GHz, the amplifier shows a noise-to-power ratio higher than 17 dB at all power levels, making it suitable for satellite applications where additional linearization is usually unfeasible.