Class S power amplifier based on CSCD with delta-sigma modulation

This paper presents the digital transmitter architecture using Class S power amplifier (PA) based on GaN HEMT transistor. In order to overcome the efficiency degradation problem in amplification of envelope varying signal, delta-sigma modulation scheme is used along with Class S power amplifier. The proposed Class S architecture is based on current switching Class D power amplifier which is designed and fabricated at 2 GHz. The result shows that the drain efficiency of 71.5% and gain of 11.6 dB is obtained at peak output power. LTE signal of 5 MHz band is used as an input to delta-sigma modulator for validating the functionality of Class S PA design.