Analysis of GaN-HEMT Switching Current Overshoot in a Half-Bridge Circuit

Crosstalk is an issue in wide bandgap power elec-tronics circuit design due to fast switching. The outcomes such as instability and additional power looses have been well studied and analysed in literature. However, the bridge-leg shoot-through due to crosstalk, especially the switching current overshoot of GaN-HEMT has been little studied. Therefore, in this paper, the origin of the switching current overshoot of a GaN-HEMT half-bridge circuit due to both switching speed and circuit shoot-through are analysed. The influence of the parameters such as turn-ON gate resistance, turn-OFF gate resistance, device threshold voltage and circuit parasitic inductance on switching current overshoot are analysed and verified by simulation. Experimental measurement further confirms the simulation results of the influence of turn­ OFF gate resistance on switching current overshoot. It is shown that in order to mitigate the shoot-through issue and reduce the switching losses, an optimised $L_{\mathrm{S}}$ is needed rather than a small value.