Dynamic Sawtooth Compensation (DSC) Technique with Self-tuning Mode Selection (SMS) for Current-Mode Buck-Boost Converter

Abstract

the current-mode Buck-Boost (BB) converter with the proposed dynamic sawtooth compensation (DSC) technique is able to improve transient response and system stability. To prevent the system switches between buck and boost operations once input and output are nearly equivalent, self-tuning mode selection (SMS) is proposed to decrease output ripple and redundant power consumption by eliminating the mode misjudgment. The duty cycle is decided by the output of error amplifier and sawtooth signal, which can be adequately adjusted to ensure small output ripple and thus to improve efficiency. Besides, the DSC and SMS technique can reduce the inductor current level and the numbers of switching to decrease switching and conduction losses for high efficiency. The converter with the switching frequency of IMHz was fabricated in IP3M 0.25-mu m CMOS process. The input voltage is in the range of 2.7V to 4.8V for battery-powered devices. The efficiency is higher than 88% when load ranges from 100mA to 400mA.