40nm CMOS DC-DC PWM boost converter for high power audio in mobile application

On-chip boost DC-DC converter used for high power audio ICs for mobile application is presented in this paper. For special systematic requirement, a combination of fixed-frequency pulse-width modulation (PWM) and hysteretic PWM control scheme is used. This converter is designed with a 40nm CMOS process and experimental results show that, the converter can operate with supply voltage from 2.7 to 4.2 V, which is suitable for single-cell lithium-ion rechargeable battery supply application, and boost voltage up to 4.9 V for delivering 1 W_rms audio power output. The output ripple voltage is about 45 mV with 20 μF off-chip capacitors and 2.2 μH off-chip inductor. The power efficiency is over 82% for lW_rms audio application while over 75% for load currents up to 900mA, and maximum to 88% for 200mA load current.