A Practical Test Platform for the Experimental Characterization of GaN Devices Switching Losses

The design of high-power-density converters utilizing Gallium Nitride (GaN) devices is often constrained by the limited accuracy of conventional datasheet-based loss models. This study introduces a comprehensive framework for the in-circuit characterization of high-voltage GaN transistors, establishing an experimentally validated and repeatable methodology for high-fidelity loss analysis. To implement and verify this approach, two dedicated synchronous buck converter test platforms were designed and constructed. This topology was deliberately chosen to allow the precise quantification and isolation of hard-switching losses through a calorimetric (power-balance) technique. Extensive experimental measurements were conducted on two representative 650 V GaN device architectures - an enhancement-mode HEMT and a cascode GaN FET - under a broad range of operating conditions. The results confirm that the proposed test platforms provide reliable empirical data that effectively captures the nonlinear and temperature-dependent loss characteristics of GaN devices, offering a robust alternative to traditional single-point datasheet evaluations.