Low cost implementation of filterless class D audio amplifier with constant switching frequency

A new and simple configuration of filterless class D audio amplifier is proposed in this paper. The proposed filterless class D audio amplifier provides the advantages of both low total system cost and generation of synchronized 3-level pulse-width modulated (PWM) output. Moreover, as a result of hysteresis window variation, a close to constant switching frequency of PWM output is obtained. The proposed filterless class D audio amplifier is verified by the PSpice simulation and prototype circuit experiment