Measuring of Dynamic On-State Resistance of GaN-HEMTs in Half-Bridge Application under Hard and Soft Switching Operation

GaN-HEMTs convince with excellent properties and therefore attract a large amount of attention within the power electronics community. However, due to trapping effects, some devices show dynamic on-state resistance during switching operation. As the internal device structure is not visible for switch mode power supply designers, measuring the on-state resistance under the intended operating conditions is the only method to obtain this information. To characterize the dynamic on-state resistance, this paper uses a novel clamping circuitry to measure the dynamic resistance accurately. Implementing a high resolution digitizer card guarantees accurate results. This measurement setup allows for measuring the on-state resistance under hard and soft switching conditions with the parameters of the targeted application. In inverter applications, each switch operates under both hard and soft switching, thus the transition between these two operating modes is investigated in detail as well.