An improved switching loss model for a 650V enhancement-mode GaN transistor

Abstract

This paper proposes an improved switching loss model for a 650V enhancement-mode gallium nitride (GaN) transistor. The interpolation fitting method is used to fit the strong nonlinear capacitance and transconductance, and it shows a better accuracy than the given function or polynomial fitting method. Meanwhile, because the input capacitance has a strong nonlinear relationship with gate-source voltage and a weak nonlinear relationship with drain-source voltage, this paper uses Qc-Vgs curve instead of the Ciss-Vds curve in the proposed model to improve the accuracy. The parasitic inductance is also considered in the model. Then the switching processes are analyzed in detail, and they are described as a fifth-order nonlinear differential equation. Finally, the accuracy of the model is validated by experiment. The error of the predicted switching loss is within 20% when the load current changes from 3.5A to 20A.