Microwave Diode-based MMIC Analog Predistorter for SSPA with Independently Tunable Phase

This paper presents a reflection predistorter based on Schottky diodes. It can improve the strong correlation between the gain and phase of the traditional analog predistorter used in the solid-state power amplifier (SSPA). The predistorter operates at 25-27 GHz and is implemented using GaAs monolithic microwave integrated circuit (MMIC) process. The experimental results show that the predistorter has the opposite distortion performance of SSPA, and the function that the phase of the predistorter can be tuned independently is verified. By adjusting the bias voltage of the linear reflection branch, the phase compression can change by 31.2°, while the gain expansion only changes by 1.5dB. The results confirm the studied topology can be used flexibly for predistortion applications in SSPAs.