Architecture implementation of class-D amplifiers using digital-controlled multiphase-interleaved PWM technique

Abstract

The class-D amplifier has the advantages of having a high efficiency, a small-size and gains its wide applications in battery-powered audio systems. However, its output power is limited by the rating of its output transistors. This paper presents the development of a new architecture for the realization of a class-D audio amplifier using a digital-controlled multi-phase interleaved PWM converter to enhance its output power. This interleaved technique is widely used in DC-DC converters. A digital current control technique with interleaved PWM generation was developed to reduce the total harmonic distortion (THD) of the output current under lower PWM switching frequency. A comparative evaluation of a single-phase and a three-phase class-D amplifier structure is presented. Furthermore, the design and implementation of a digital control IC, including an ADC synchronous sampler, a digital compensator, and a phase-shift PWM generator, is introduced. Computer simulations and experimental verifications are given to illustrate the feasibility and performance of the proposed technique.