Measurement of GaN HEMTs’ Temperature Dependent On-State Resistance in Switching Operation

Inhalt:
GaN-HEMTs allow to achieve high switching frequency maintaining high converter efficiency. During switching operation, however, the on-state resistance of GaN devices rises not only depending on temperature, but temporarily also on voltage stress. Two types of commercial 650 V GaN devices have been evaluated and compared in this respect under conditions of hard switching: To guarantee a precise measurement of dynamic Rds,on, a modified double pulse test setup with clamp circuit is used. It has been found this way that the dynamic Rds,on demonstrates non-monotonic behaviour for off-state voltages ranging from 50 V to 400 V and reaches its maximum value at 200 V for both devices. In the low voltage range, a separation of the influence of voltage stress and temperature seems possible which allows to reasonably use the Rds,on as a temperature sensitive electrical parameter (TSEP) for specific GaN devices.