A SiC CMOS Digitally Controlled PWM Generator for High-Temperature Applications

This paper describes a silicon carbide pulse width modulation (PWM) signal generator in the 1.2 μm HiT-SiC CMOS process developed by Raytheon Systems Ltd. The design features a 6-b binary input, which allows for setting a system's duty cycle. The results presented in this paper utilize a field programmable gate array board in the test setup to dynamically set the duty cycle by controlling each bit. A control current is also available to give the user added flexibility for tuning the duty cycle. Experimental results show the duty cycle range of the PWM generator to be between 4.7% and 95.2% at 400°C. Sustained operation of the circuit is demonstrated over a period of 50 h at 300°C. Finally, the PWM generator is evaluated in the operation of a boost converter.