Switched-Capacitor-Based Gate Driver with Real-time Gate-Source Leakage Current Detection and Indirect Bond Wire Liftoff Monitoring

An SiC MOSFET gate driver constructed to generate an adaptive negative voltage profile that mitigates off-state positive voltage pulses caused by the crosstalk in a bridge-leg configuration is presented. The tail of this off-state voltage profile approaches zero, enabling it to sustain higher negative crosstalk voltage pulses. The driver also performs real-time measurements of gate–source leakage current to monitor gate-oxide degradation in the SiC MOSFET. Variations in the negative voltage levels and gate–source leakage current are utilized to indirectly monitor bond wire liftoff. The adaptive negative voltage is produced using a switched-capacitor circuit with a digitally controlled voltage divider, while the gate–source leakage current is measured via a current mirror that replicates the leakage current onto a sensing resistor. This approach avoids the need for differential measurement and enhances measurement sensitivity. A bypass is included across the current mirror to reduce its impact on switching times. The proposed gate driver has been evaluated on a 1 kW inverter prototype under various intrinsic parameter variations to evaluate the feasibility of adaptive gate voltage driving and monitoring of gate–source leakage current and source inductance. In addition, a comparison of the switching performance between the proposed driver and a traditional gate driver is presented.

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