A high performance class-D amplifier with cascaded sigma-delta modulators

Abstract

A topology for high performance of a class-D amplifier is proposed. The structural design consists of two sigma-delta modulator (SDM) stages in cascade with an intermediate decimation-filter between them. Noise and high tone introduced at the first stage are filtered out through the decimation-filter. The signal is converted to a 1-bit pulse duration modulation signal by the second stage SDM. The H-bridge is made part of the SDM loop, which not only enables the shaping of quantization noise but also stabilizes the output power switching stage.