Dual-path frequency compensation for current-mode buck converters

Abstract

This paper proposes a dual-path frequency compensation (DPFC) for implementing on-chip error amplifier (EA). The DPFC uses two operation amplifiers to simultaneously charge and discharge a compensation capacitor. As a result, the equivalent capacitance is significantly multiplied with small additional power and silicon area. Since the slew rate of the EA is increased owing to the small compensation capacitance, the transient response of the buck converter is also enhanced dramatically. A laboratory converter with the DPFC is implemented with 0.35-μm CMOS process. Simulation results demonstrate the converter stability and transient response. The transient recovery time is less than 4 μs for load current changing from 500 mA to 50 mA. With the DPFC, the compensation capacitor is shrunk significantly and no compensation resistor is needed.