An AlGaN/GaN class-S amplifier for RF-communication signals

A Gallium-Nitride (GaN) current switched class-S amplifier for 450 MHz RF-signals is presented. A FPGA board is used to generate a band-pass delta sigma sequence with 1800 Mbit/s. This quasi digital signal is amplified to the required gate voltage swing for the HEMTs using a commercial available preamplifier. The AlGaN/GaN-HEMTs are driven in a high efficient switch mode. Linearity is preserved using the class-S architecture. Limits of this classical amplifier architecture are shown and discussed. Simulation results are presented and the realized class-S demonstrator is shown.