A phase-shift self-oscillating stereo class-D amplifier for battery-powered applications

This paper presents a highly efficient stereo audio amplifier, based on a self-oscillating modulator. This modulation scheme has been analyzed and shows to have a higher bandwidth and error correction than standard Pulse Width Modulation (PWM). A practical implementation in CMOS 0.25um technology has been done to validate our theoretical and simulation results, based on a modified PWM amplifier. Our amplifier demonstrated a Total Harmonic Distortion plus Noise (THD+N) as low as 0.007%, current consumption is 3.88mA at 3.6V (stereo) and the efficiency reaches 88% into 8Ohms. The integrated circuit measures 1.6×1.6mm and is able to work at supply voltages from 2.3V to 5.5V.