New High-Efficiency 2.5 V/0.45 W RWDM Class-D Audio Amplifier for Portable Consumer Electronics

A single-chip of Class-D audio amplifier with high-power efficiency is presented. It includes a rectangular wave delta modulator (RWDM) and bridge-tied load output gate-drivers. The RWDM has a multiple inputs floating-gate hysteresis comparator and a feedback integrator formed by the external L–R low-pass filter. This monolithic Class-D audio amplifier with a maximum power efficiency of 92% has a flat frequency response with +- 0.3 dB up to 20 kHz, and is capable of delivering up to 0.45 W of continuous average power into an 8-(omega) load at less than 0.5% total harmonic distortion plus noise from a 2.5-V power supply in the high fidelity range (20 Hz–20 kHz).