Stability analysis and demonstration of an X-band GaN power amplifier MMIC

High power amplifier design always requires a compromise between performance and stability. The goal is to design an amplifier that is stable under all operating conditions without sacrificing too much performance by the introduction of stability improvement measures. This paper describes the design of an X-band GaN High Power Amplifier MMIC and the performed stability analysis and measures taken. The amplifier is designed to operate over a wide range of drain bias voltages and input power levels, making the stability analysis particularly important. Using the applied analysis techniques a stable amplifier design has been realized. The measurements show a maximum pulsed output power of 20 W at 30 V drain bias and a maximum PAE of 45% at 18V drain bias. The output power can be adjusted by changing either the drain bias or drive level, while maintaining a good efficiency.