Sub-Nanosecond Transient Analysis of SiC MOSFET Switching: "Sensor Gap TLP" as a Versatile Characterization Method with Very High Temporal Resolution

Abstract:
The Transmission Line Pulsing (TLP) based technique “sensor gap TLP” (sgTLP) is applied for transient characterization of SiC power MOSFET switching with nanosecond and sub-nanosecond temporal resolution. The sgTLP method overcomes the bandwidth limitation of a dedicated current sensor and thus is only limited by the passive components of the setup. The proposed sgTLP method is able to detect current rise times in the sub-ns range during pulses of 100 ns duration or more. The capability of sgTLP is shown by analyzing various transients during the switching of a SiC MOSFET. A detailed analysis of the gate charging process confirms that well-defined current pulses down to 1.2 ns duration have been realized using a combination of sgTLP and a TVS diode at the gate. The dependence of the turn-on switching time on the gate driving conditions is examined, resulting in even faster turn-on times than given in the specifications. Delay times down to 1.25 ns and current rise times down to 2.09 ns were demonstrated, which is considerably smaller than the respective values in the device data sheet.