Low frequency PWM modulation for high efficiency Class-D audio driving

This paper is focused on the necessity of developing a low frequency modulation system to convert a PCM audio signal into a binary signal with suitable properties to drive Class-D audio amplifiers. Several modulation techniques are being used to overcome the inherent distortion of PWM techniques particularly its need for a high sampling frequency and correspondingly high output switching rates with negative impact on efficiency. A full-digital click modulation system is presented along with its implementation constraints and advantages when compared with other modulation solutions. The simulation results presented suggest that this modulation can be very competitive, especially when the efficiency of the amplification system is a key target.