An Efficiency-Enhanced DCM Buck Regulator With Improved Switching Timing of Power Transistors

This brief presents circuit techniques to improve the power efficiencies of a discontinuous-conduction mode (DCM) buck regulator for portable applications. A switched-capacitor-comparator-based adaptive dead-time control is developed to provide fast and accurate sensing and comparison for optimizing the switching timing of power transistors and thus simultaneously minimizing the power losses caused by the reverse inductor current, body-diode conduction, and shoot-through current. A new ringing suppression circuit is also proposed not to affect the dead-time of power transistors during switching instants for additional power savings. Implemented in a 0.35-mu m standard CMOS process, the proposed DCM buck regulator has only approximate to 20-ns sensing delay and achieves > 84% power efficiency for load currents of > 5 mA when the input voltage is 1.8 V.