A New Method of Switching Loss Evaluation for GaN HEMTs in Half-Bridge Configuration

Gallium Nitride (GaN) devices have shown greater potential in high switching frequency operation due to its much lower switching loss compared to Silicon devices. However, the faster switching speed makes it more difficult for device dynamic characterization because it is more sensitive to the parasitic components in the circuit and it requires better testing equipment. Double Pulse Test (DPT) is commonly used to characterize device dynamic performance and proper device drain current probing method is a must for accurate switching loss measurement. However, for GaN devices designed to have loop inductance within sub-nH range, any coaxial shunt to measure drain current will insert enough parasitic inductance to influence switching performance and impact measurement results. In this paper, a novel and simple method is proposed to accurately evaluate switching loss without shunt resistor in series with GaN device in a half bridge configuration, which is a common building block in power electronics circuits. A 130 W GaN based buck converter prototype is built to verify the proposed method.