Design of High Temperature SiC LJFET-Based Logic Inverter and Integrated Gate Driver

I Power integrated circuit based on SiC lateral JFET promises to operate at temperatures beyond 300 degrees C. In this paper, design constraints in selecting the LJFET threshold voltage, the load resistance and the DC power supply voltage to obtain proper gate driver circuit functionality in the temperature range of 25 degrees C similar to 300 degrees C are investigated through extensive experimentation. The study shows that an appropriate load resistance needs to be chosen for a given LJFET for the trade-off between good output voltage swing and a good output current driving capability. It is also shown that increasing the power supply voltage usually increases both the voltage swing and output current capability, with the cost of increased power consumption. Measurements at various temperatures up to 300 degrees C reveal that the output voltage swing decreases significantly at higher temperatures. The design window for LJFET threshold voltage is found to be OV similar to 2.0V at 25 degrees C but narrows down to 0.5V similar to 1.2V at 300 degrees C. Such a threshold voltage window is considered to be achievable in a large scale IC facility. Finally, a 4-stage gate driver circuit capable of operation at both 25 degrees C and 300 degrees C is reported. This work aims at providing a foundation for the fabrication process and device design of a possible full-scale power IC on SiC.