Switched-Capacitor-Based Gate Driver With Real-Time Gate–Source Leakage Current Detection and Indirect Bond Wire Liftoff Monitoring

A 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 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 1kW 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. Additionally, a comparison of the switching performance between the proposed driver and a traditional gate driver is presented.