A High Efficiency Fast Transient Zero Output Ripple Buck Converter Using Split Pwm Controller With Inductor Mismatch Compensation

This paper proposes a zero output ripple buck converter for low noise applications. Unlike the conventional zero ripple converter which requires perfectly matched inductors, the proposed converter uses a novel inductor mismatch compensation technique to achieve perfect ripple cancellation. In order to prevent the loop instability due to inversion of PWM signal in the ripple cancellation path, a split PWM controller is used. Implemented in 180nm CMOS process, the proposed converter achieves simulated output ripple of less than 300 mu V for the entire range of duty cycle (0 to 100%) with peak efficiency of 93.5% for the load current of 0.1-1A at 2.5MHz switching frequency. An undershoot/overshoot of 86mV/56mV with settling time of less than 3.5 mu S was achieved when a load step of 0.5A/50ns is applied at the output.