Enhancement of Driving Capability of Gate Driver Using GaN HEMTs for High-Speed Hard Switching of SiC Power MOSFETs

Abstract

In this paper, we investigated a gate driver using a GaN HEMT push-pull configuration for the high-frequency hard switching of a SiC power MOSFET. Low on-resistance and low input capacitance of GaN HEMTs are suitable for a high-frequency gate driver from the logic level, and robustness of SiC MOSFET with high avalanche capability is suitable for a valve transistor in power converters. Our proposed gate driver consists of digital isolators, complementary Si MOSFETs, and GaN HEMTs. The GaN HEMT push-pull stage has a high driving capability owing to its superior switching characteristics, and complementary Si MOSFETs can enhance the control signal from the digital isolator. We investigated limiting factors of the switching frequency of the proposed gate driver by focusing on each circuit component and proposed an improved driving configuration for the gate driver. As a result, 20-MHz hard switching of a SiC MOSFET was achieved using the improved gate driver with GaN HEMTs.

Performance evaluation of GaN and Si based driver circuits for a SiC MOSFET power switch

“…On the other hand, Nagaoka et al [12] introduces for the first time the use of a driver output stage based on GaN HEMTs utilizing discrete custom devices. In addition to Nagaoka's work, Okuda et al [19] show the proof of concept of the GaN HEMT as part of a gate driver that targets a SiC MOSFET in a hard switching environment. Even though Okuda's work proposes the use of COTS devices, the PSW is used at low blocking voltage and drain current.…”