Stability and Efficiency Enhancement of a C-band Class-F Power Amplifier Using a Coupling Compensation Method

This paper presents a new method that improves the stability of the C-band GaN power amplifier (PA) while maintaining high PA gain. It is well known that the electromagnetic (EM) coupling between the PA input and output matching network (MN) can degrade the PA stability. In this paper, an iteration method is used to monitor the design of the input MN to compensate the EM coupling and stabilize the whole PA, while the output MN is designed to improve the PA efficiency by carefully controlling the drain impedances at multiple harmonic frequencies. By using the proposed method, a 5.8GHz class-F power amplifier is designed, fabricated and measured. Experimental results reveals that the proposed PA archives a saturation output power of 38.2dBm, drain efficiency of 70.7% and gain of 13.5dB while maintaining a high stability factor over the entire frequency band.