Performances evaluation of ST’s new HEMT GaN vs SJ Si MOSFETs in resonant converters

This paper compares the performance of HEMT (high electron mobility transistor) GaN and SJ Si MOSFETs in a resonant LLC half bridge converter. The comparison begins with an analysis of the static and dynamic parameters, including Gate charge (Qg), input capacitance (Ciss), output capacitance (Coss), RDS(on) and threshold voltage (VTH), and conclude with an applicative analysis regarding device switch-off energy and system power efficiency using three different LLC tanks with three different resonance frequencies. The conduction during dead time, the impact of EOSS and ROSS on switching losses and gate driving aspects were also evaluated.