A Fully Monolithic 6H-SiC JFET-Based Transimpedance Amplifier for High-Temperature Capacitive Sensing

This paper introduces a high-temperature fully monolithic high gain-bandwidth 6H-SiC transimpedance amplifier for capacitive sensor interfacing. The amplifier achieves a gain of 235 kΩ and a bandwidth of 0.61 MHz at room temperature. Results from the proof-of-concept measurements performed with variable capacitors demonstrate the functionality of differential capacitive sensing across a wide temperature range, up to 450°C. The amplifier also exhibits a stable gain with respect to power supply variations. At elevated temperatures, the amplifier exhibits increasing gain with decreasing bandwidth, as expected. At 450°C, the gain and bandwidth are 774 kΩ and 0.17 MHz, respectively. This is the first report that demonstrates the capacitive sensing capability of a SiC transimpedance amplifier, and represents a critical step toward the goal of integrating a sensing element with its interface circuit in a single monolithic device for operation at extreme temperatures.