High-efficiency filterless Class D amplifier with peak detector

This paper presents a fully integrated filterless Class D amplifier embodying a peak detector to improve the power efficiency at low power range. The peak detector monitors the switching frequency accordingly by sensing the amplitude of the input signal. The Class D amplifier is fabricated using 0.18μm CMOS technology with a total area of 1 mm². From our measurements, the proposed design has high power efficiency (>;86%) for a wide output power range (50 mW-700 mW). Our design maintains very good low total harmonic distortion (THD) (<;0.09%) over both entire modulation index range and the audio band of interest (100 Hz-6 kHz).