Modeling and Analysis of Bridge-Leg Crosstalk of GaN HEMT Considering Staged Effect of Common-Source Inductance

Wide band-gap (WBG) field-effect power devices such as gallium nitride (GaN) devices are being widely used for a better system-level performance as a result of their figures of merit compared to counterpart silicon devices. But they could also suffer from more severe bridge-leg crosstalk issue as a result of higher switching speed and special device features. To suppress the crosstalk phenomenon of GaN-based bridge-leg configurations, modeling and theoretical analysis of crosstalk voltage are necessary. However, the superposition of two noise excitations (di/dt and dv/dt) in time domain and the nonlinearities in capacitance-voltage (C-V) of GaN HEMTs bring difficulties to its modeling and analysis. In addition, as switching speed enhanced, the influence of parasitic inductance cannot be ignored. This paper proposes an analytical model of crosstalk voltage, considering staged effect of common-source inductance. By the physical behaviors of different switching stages, the two excitations are integrated into one-the current through common-source inductor in order to simplify the analysis and bridge direct relationship between two variables. Based on that, an investigation into the impact of circuit parameters on crosstalk voltage is conducted. Besides, the nonlinear characteristic of junction capacitances is taken into account in the model. The proposed model can be applied to guide GaN device selection and PCB design. The accuracy of model and the effectiveness of analysis results are verified.