A Flexible and Efficient GaN-Based SSPA for Next-Generation L-Band Reconfigurable Payloads

This article presents the design and experimental characterization of an engineering model (EM) solid-state power amplifier (SSPA) based on European 0.5-<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu $</tex-math> </inline-formula>m gallium nitride (GaN) on silicon carbide technology, conceived for next-generation flexible L-band navigation payloads. Operating in the E1 band (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1575.42\pm 25$</tex-math> </inline-formula> MHz), the unit integrates a radio frequency tray (RFT) to amplify the useful signal, and an electronic power conditioner (EPC), which provides telecommand/telemetry functions, remote mode selection, and interfaces the module with the satellite primary bus. Continuous-wave measurements demonstrate an adjustable output power range from 50.8 to 54.8 dBm with efficiency above 41%, including EPC consumption and connector/isolator losses. The amplifier also exhibits excellent thermal stability, with output power variation below 0.1 dB across −20 °C to +65 °C temperature range. Under Galileo-like modulated signals, it ensures full compliance with the spectral emission masks, thanks to an embedded analog linearizer (LIN), while delivering up to 300-W average output power with efficiencies up to 48%. The SSPA is multipaction free and fulfills all the space derating rules in terms of junction temperature and voltage/current swings for the involved GaN active devices. Compared with previously reported GaN SSPAs, the proposed design uniquely combines embedded output power flexibility and analog linearization in a compact, lightweight, space-ready unit. In particular, its power flexibility enables a reduction of more than 130 W in dc power consumption in low-power mode, easing thermal management and enhancing reliability, thus offering a valid solution for implementing high-reliability next-generation reconfigurable satellite payloads entirely based on solid-state technology.