A Non-Isolated and Cost-Effective Hybrid Driving Solution for High Voltage GaN HEMTs

Wide Bandgap (WBG) power devices, and especially Gallium Nitride (GaN) High-Electron-Mobility Transistors (HEMTs), have recently demonstrated excellent performance in high-frequency, hard- and soft- switched topologies for various applications. This paper proposes a cost-effective and reliable "hybrid driving" approach to drive non-isolated GaN half- and full-bridge stages with high performance and low implementation costs. The proposed circuitry comprises an isolated high-side driver with >300 V/ns CMTI, a non-isolated low-side driver with common mode rejection capability, and a tunable bias supply circuit capable of negative bias. The overall solution prevents parasitic Miller self-turn-on present in bootstrapped bias supplies, and enables high dV/dt, shoot-through protection, and versatile layout with a cost-competitive bill of materials (BOM). The feasibility of the hybrid driving approach is demonstrated through successful tests on a half-bridge power stage using gate-injection transistor (GIT) GaN HEMTs, where a dV/dt of 246 V/ns was achieved and validated at 620kW and 2kW power switching at a frequency up to 2MHz.