Cross Conduction of GaN HFETs in Half-Bridge Converters

Cross conduction in GaN HFETs is particularly critical due to the high dvDS/dt and small gate-source capacitances in conjunction with moderate drain-gate feed-back capacitances. Therefore, the switching speed is limited in current devices, which leads to increased losses. In this work, the turn-on peak current and increased turn-on losses due to cross conduction are investigated for two normally-off GaN HEFTs in a half-bridge topology. It is shown that a lower turn-off gate driver voltage level reduces cross conduction and can minimize the total device losses, despite of higher dead time conduction losses.