A 3.3 V/1 W class D audio power amplifier with 103 dB DR and 90% efficiency

Abstract

A single-chip Integrated circuit of 3.3 V/1 W class-D high fidelity and high efficiency audio power amplifier is presented in this paper. The design has been done using a 3.3 V/0.25 /spl mu/m CMOS process. The maximum output power is 1 W before the amplifier saturates. The THD+N at 0.5 W output power is below 0.03% and efficiency is better than 90% thanks to the careful design of the output stage. The dynamic range is more than 100 dB suitable for high fidelity audio applications. A single-loop single-bit third order sigma-delta modulator is used to generate the PWM signal from input audio signal. The PWM signal is then filtered at the output with a second order low pass filter external to the chip to regenerate the input signal.