A 5-W GaN Doherty Amplifier for <i>Ka</i>-Band Satellite Downlink With 4-GHz Bandwidth and 17-dB NPR
Anna Piacibello, Rocco Giofrè, Roberto Quaglia, Ricardo Figueiredo, Nuno Borges Carvalho, Paolo Colantonio, Václav Valenta, Vittorio Camarchia
Abstract
This letter presents the design and experimental characterization of a GaN–Si monolithic Doherty power amplifier (PA) for the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Ka$ </tex-math></inline-formula> -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.