Equivalent Capacitance of Nonlinear Capacitance in GaN-FET for Improving Accuracy in Suppressing Conditions of Oscillatory False Triggering

While Gan-FET enables the miniaturization and increased efficiency of power modules, its low threshold voltage increases the likelihood of malfunctions. Additionally, the occurrence of oscillatory false triggering has been reported. This phenomenon is caused by oscillations in the gate-source voltage due to parasitic capacitors of GaN-FET and wiring inductors. These issues hinder the practical application of GaN-FETs. An existing method to suppress this involves adjusting the wiring inductance, a component of the parasitic oscillator, to match the parasitic capacitance, thereby avoiding oscillation conditions. However, this method does not sufficiently consider the nonlinear characteristics of the parasitic capacitance, which varies with voltage. This leads to discrepancies between the calculated and measured values of the wiring inductance required to suppress oscillatory false triggering. Therefore, the objective of this study is to propose a method for deriving the equivalent capacitance of nonlinear capacitance in oscillatory states to improve the suppression accuracy of oscillatory false triggering.