L‐band high power solid‐state power amplifier for aerospace usage

This work presents the design, implementation, and experimental results of an L-band solid-state power amplifier (SSPA) developed for the next generation high-power transmitter for the space usage. The microwave frequency nircuit (MFC) is realized by cascading a channel amplifier, a drive power amplifier (PA) and a high PA section. By utilizing the gallium nitride (GaN) HEMTs, the efficiency of the drive PA and high PA are improved to more than 70% over the frequency range from 1.45 to 1.55 GHz, which ensures an overall efficiency of the MFC higher than 66%. Then a high efficiency power-supply based on the phase-array bridge topology is proposed for voltage conversion and output sequence control, which delivers a high efficiency of about 94% at the rated power range. In the 100-MHz operating bandwidth, the SSPA delivers more than 200 W of output power with an associated 3rd order intermodulation product (IM3) and power added efficiency (PAE) better than -18 dBc and 60%, respectively. The gain can be varied from 25 to 56 dB with a minimal step of 0.5 dB through telecommand, whereas the phase can be adjusted within 360 degrees range with a minimal step of 5.6 degrees.