Integrated low-voltage filter-less class-D Audio power amplifier with PWM DC/DC buck converter

Consumers desire that new generation of devices will be developed with smaller physical size and lower cost than existing devices. This paper presents the design of an integrated class D audio power amplifier with step-down (Buck) DC to DC converter. The high efficiency pulse-width modulation (PWM) buck converter is used to supply 1.5 V for the class D amplifier. The operating voltage range can be from 3V to 5V which is used for mobile devices. The class D amplifier uses the three level pulse width modulation (PWM) to eliminate the external output low-pass filter. The circuit is designed with TSMC 0.35um 2P4M 3.3V/5V mixed-signal CMOS process. The best total power efficiency of this integrated circuit achieves 84%, and the total harmonic distortion (THD) is less than 0.26% at 10 KHz with 8Ω load.