A Computationally-Efficient PWM Technique for Digital Class-D Amplifiers

Abstract

We describe a technique that digitally converts a pulse-code-modulated (PCM) signal to a pulse-width-modulation (PWM) signal. This technique is based on the naturally sampled PWM emulation scheme. Its computation is simplified by using empirical models. It provides sufficient accuracy with minimal computation. At 384 kHz sampling rate, the proposed technique can convert a sine wave to a PWM signal and achieve better than 92 dB total harmonic distortion (THD) for a sine wave frequency up to 20 kHz and a sine wave amplitude up to 90% of the full range.