Extraction of Dynamic Threshold Voltage and On-State Resistance of GaN Power HEMTs in Hard-Switching Operation

Abstract:
Analysing the electrical parameter degradation during device operation is crucial for proper circuit design and also to further improve the stability of GaN power devices. Consequently electrical instabilities need to be assessed, such as threshold voltage shift and variation in on-state resistance. Conventional curve tracers are inadequate for capturing dynamic instabilities in high-speed GaN power devices as those are not switched and the pulse widths are relatively long such as 500 mus. To overcome this limitation, this paper presents a modified pulse measurement circuit incorporating a tri-state gate driver and a clamp circuit to enable precise extraction of dynamic parameters of GaN HEMTs. As an example the dependence of threshold voltage Vth and dynamic on-state resistance Rds,on on off-state voltage level, temperature, voltage bias duration and switching frequency is investigated with a commercial 650V Schottky-type p-GaN gate GaN power HEMT under hard-switching conditions.