Pulse width modulation for class D audio power amplifier in CMOS 0.18um Process with 85% of efficiency

In this paper a high efficiency Pulse Width Modulation PWM Complementary Metal Oxide Semiconductor CMOS audio power amplifier is proposed. The original idea is based on the difference close-loop feedback technique and the difference pre-amp. Thus, we conceive a rail to rail comparator with a constant gm. This rail-to-rail PWM comparator with hysteresis architecture has been embedded in the audio power amplifier. The simulation results based on the Taiwan Semiconductor Manufacturing Company TSMC 0.18μm CMOS process show that the power efficiency is 85%, the Power Supply Rejection Ratio PSRR is -70 dB, the power supply voltage range is 1.8-3.3V, the Total Harmonic Distortion plus Noise THD+N in 1 kHz input frequency is 0.2%, the quiescent current is 2.7 mA. With the good performance, the audio power amplifier can be applied to various kinds of small and medium power audio amplification system such as DVD, LCD-TV, MP4 and wireless phones.