Evaluation of the operation of depletion-mode SiC power JFET in DC-DC converter applications

This paper presents the system for the evaluation of operation of a depletion-mode silicon carbide (SiC) power junction field-effect transistor (JFET). The main part of the system is a dc-dc step-down converter which represents realistic operating conditions for the switching devices in a synchronous buck configuration. In order to test the importance of the dead-time value on the operation and efficiency of the synchronous buck converter, a precise two-channel time-delay pulse signal generator is developed and its operation is described. The ability to precisely regulate control signal parameters of the high-side FET and low-side FET (switching voltage and current, operating frequency, duty cycle, dead-times, etc.) is needed in order to fully characterise SiC power switches. The functionality of the complete system is verified by measurements performed under various operating conditions.