Non-linear Input Capacitance Determination of WBG Power FETs using Gate Charge Measurements

This paper discusses the measurement of the input capacitances C gs and C gd of SiC and GaN power FETs in order to implement simulation models with an improved mapping of the drain-source voltage V ds and drain current id during the switching operation. Based on the gate charge characteristic measured at an inductive load condition using different drain current values and temperature settings, the gate current is allocated to the charging of the gate-drain capacitance C gd and the gate-source capacitance C gs . With this approach the capacitance characteristics C gs (v gs ) and C gd (V gd ) are determined in the full operating range of the gate-source voltage V gs and gate-drain voltage V gd.