Analysis and Suppression for Crosstalk in SiC MOSFET Turn-off Transient

Traditional Si devices are gradually replaced with SiC devices due to their fast switching speed, low on-resistance and high thermal conductivity. However, the faster switching speed, lower negative voltage threshold and lower gate threshold voltage of SiC MOSFET make the application is more sensitive to the crosstalk among the circuit, e.g. the upper and lower devices, which significantly limits the high speed and high reliability applications of SiC MOSFETs. In this paper, typical three kinds of sources (dv/dt, di/dt and oscillation in power loop) and two conductive paths (Miller capacitance and common source inductance) of the crosstalk are analyzed during turn-off transient. Their equivalent models are also established. Based on the analysis, a crosstalk suppression strategy with a gate-parallel high-frequency diode is adopted. Its operating characteristics and the influence on the crosstalk suppression effect are analyzed. The experimental verification was carried out in the switching application circuit, and the crosstalk is suppressed effectively.