Opportunities and design considerations of GaN HEMTs in ZVS applications

Gallium Nitride enhancement-mode high electron mobility transistors (GaN E-HEMTs) exhibit superior performance versus Si devices in both hard-switching and soft-switching converters. Due to the relatively higher switching-on loss compared with switching-off loss, zero voltage switching (ZVS) turn-on is still preferred to the application scope which efficiency is the primary design target. In this paper, the characteristics of GaN HEMTs under ZVS conditions is modeled. The packaging considerations on circuit parasitics and thermal management for soft switching applications is also discussed. An insulated metal substrate (IMS) based half-bridge power module consisting of two high-side and two low-side 650 V/60 A GaN HEMTs in parallel is designed and experimentally evaluated. A strong correlation is shown between simulations and experiments, verifying the power module design and GaN HEMTs' loss model.