High-Temperature SiC CMOS Comparator and Op-Amp for Protection Circuits in Voltage Regulators and Switch-Mode Converters

This paper describes a high temperature voltage comparator and an operational amplifier (op-amp) in a 1.2-mu m silicon carbide (SiC) CMOS process. These circuits are used as building blocks for designing a high-temperature SiC low-side over current protection circuit. The over current protection circuit is used in the protection circuitry of a SiC FET gate driver in power converter applications. The op-amp and the comparator have been tested at 400 degrees C and 550 degrees C temperature, respectively. The op-amp has an input common-mode range of 0-11.2 V, a dc gain of 60 dB, a unity gain bandwidth of 2.3 MHz, and a phase margin of 48 degrees at 400 degrees C. The comparator has a rise time and a fall time of 38 and 24 ns, respectively, at 550 degrees C. The over current protection circuit, implemented with these analog building blocks, is designed to sense a voltage across a sense resistor up to 0.5 V.