The mechanism of parasitic oscillation in a half bridge circuit including wide band-gap semiconductor devices

Abstract

This paper focuses on revealing the mechanism of parasitic oscillation observed when SiC MOSFETs (metal-oxide-semiconductor field-effect transistors) operate in halfbridge configuration. The relatively large parasitic feed-back capacitance (Cgd) of SiC MOSFETs, especially if the transistors have a low threshold voltage, enhances unintentional turn-on of the device, entailing parasitic oscillation in a half bridge circuit. The wide-band gap semiconductor power device should possess a structure of as low Cgd as possible in addition to a device-specific circuit design, if the general advantage of wide band-gap power devices is utilized to facilitate high-speed switching.