A novel gate drive circuit for high speed turn-on switching of ultra-low feedback capacitance SiC-VJFET

Abstract

A silicon carbide (SiC) vertical field effect transistor (VJFET) with ultra-low feedback capacitance C rss has been developed, which is called as screen grid VJFET (SG-VJFET). The SG-VJFET is a very promising power device because of the superior static characteristics such as normally off, low on-resistance, and high breakdown voltage, furthermore, issueless in terms of gate oxide reliability and long-term threshold voltage stability. The screen grid inserted between the gate and drain electrodes reduced the feedback capacitance Crss and improved the turn-off switching speed remarkably. On the other hand, the turn-on switching speed is considerably slower than the turn-off switching speed due to the influence of the forward pn diode parasitic between the gate and source of the switch. This drawback is inherited from normally-off SiC-JFETs with a similar device structure between the gate and the source. In recent years, several gate drive circuits have been reported to overcome this drawback for the normally-off SiC-VJFET, but there are limitations such as the need for complex logic circuits, switching frequency and possible duty cycle, additional cooling, and complexity of selecting electronic components. In this paper, we propose a novel gate drive circuit that can fully exploit the performance of the SG-VJFET. The proposed circuit consists of two standard gate driver ICs, a capacitor, and diodes, which can achieve fast turn-on switching without excessive power loss and can use with any duty cycle and high frequency.