Quasi Square Wave Zero Voltage Switching Gate Drive

This paper presents techniques to enable non-isolated boost converters to achieve high power efficiencies under high-switching-frequency and high-voltage conditions. A quasi-square-wave zero-voltage switching (QSW-ZVS) boost converter topology is proposed to achieve high-frequency soft switching without any coupled inductors in the power stage and thus minimize the switching power loss of the converter. An on-chip dynamic dead-time controller is developed to provide near-optimum dead-time for power FETs during switching transitions under different output voltage and load current conditions in order to achieve ZVS with minimal body diode conduction loss ofpower FETs.

A synchronous gate driver is also proposed to provide fast propagation delays and output signal rise/fall time, enabling MHz operation of the converter. A hardware boost converter prototype is built with the synchronous gate driver circuitry implemented in a 0.5-μm high-voltage CMOS process. The proposed QSW-ZVS boost converter provides an output voltage of 150 V and delivers an output power of 130 W. The peak power efficiency of the proposed converter achieves 92.7% at the switching frequency of 1 MHz. Compared with state-of-the-art gate drivers, the worst-case propagation delay of the proposed synchronous gate driver is improved by at least 7.6 times. The operation frequency of the proposed non-isolated boost converter is also improved by at least 15 times compared with other state-of-the-art counterparts.