Quasi-resonant converters for high-frequency voltage regulator applications

This paper introduces the quasi-resonant and active-clamped concepts into the high-frequency voltage regulator (VR) design. These new converters can realize constant switching frequency modulation, zero-voltage switching (ZVS), small turn-off currents, small circulating currents in the active-clamp circuit, no body-diode reverse-recovery loss, and no body-diode deadtime conduction loss. The operation principle is explained with the help of simulation and state-plane analysis. A prototype is developed for a 12 V-to-1.3 V/12.5 A DC-DC VR operating at 1 MHz switching frequency. The experimental results illustrate the advantages of the proposed topology for high-frequency, high-efficiency and high-power-density applications.