Pulse width modulation of multilevel delta-sigma output for class S power amplifier

In this paper a platform that implements the digital processing and RF carrier generation for class S PA operation is presented. This implementation consists of a bandpass delta sigma modulator (DSM) with a multi-level quantizer followed by a pulse width modulator and frequency upconversion stage. The principle of operation is described and validation is provided through simulation and experimental measurements on a prototype of the modulator. It is shown that the output from the new modulator can achieve significant improvements in SNR performance compared to a two level DSM with little added computational overhead.