Design and Realization of an Output Network for a GaN-HEMT Current-Mode Class-S Power Amplifier at 450MHz

This paper describes the design and realization of a hybrid lumped output network for a current-mode class-S power amplifier. It consist of a band pass filter, a balun and a broad-band constant current supply. The filter achieves a bandwidth of 300 MHz and 0.5 dB insertion loss. As a demonstrator for the class-S concept, the developed network together with a GaN MMIC switching stage and GaAs Schottky-diodes demonstrates a complete class-S power amplifier for a data rate of 1.8 Gbps for an analog signal frequency of 450 MHz. An output power of 2.7 W at 450 MHz with an efficiency of 19% and a very high power gain of 37 dB has been achieved. This is the first demonstration of class-S operation at these power levels for this frequency range.