Clock jitter in class-D audio power amplifiers

Abstract

Many class-D audio amplifiers use a reference clock to fix the PWM carrier frequency. The jitter of the reference clock can cause significant voltage noise at the amplifier output. In this paper a simple model is presented that allows accurate prediction of the noise contribution from an integrated regenerative sawtooth oscillator to the output noise of a class-D audio amplifier. The implementation of an oscillator in a class-D amplifier is presented and the model is verified with measurements.