Linearity analysis of a 40 W class-G-modulated microwave power amplifier

In this paper, a class-G power amplifier is presented. It consists of a discrete class-G supply modulator, which uses a GaN-HEMT for switching, connected to a 2.65 GHz power amplifier with 40 W peak power, specifically designed for class-G supply modulation. The focus of the paper is on evaluating this system in terms of the RF and the switching signal, the switching behavior, and linearity. A combination of a complex memory polynomial digital predistorter and lookup tables as well as class-G-optimized digital predistorter models is used to improve the linearity of the power amplifier. It is found that the Class-G modulation improves overall PAE by 10-15 %. It is shown that using dedicated digital predistortion the linearity the distortions caused by the modulator can be significantly reduced.