Silicon Carbide Fully Differential Amplifier Characterized Up to 500 °C

This paper presents a monolithic fully differential amplifier implemented in a low-voltage 4H-silicon carbide bipolar junction transistor technology. The circuit has been designed, considering the variation of device parameters over a large temperature range. A base-current compensation technique has been applied to overcome the low input resistance of the amplifier. The bare chip of the amplifier has been measured from 27 °C to 500 °C using a hot-chuck probe station. Its open-loop gain is 58 dB at 27 °C, and monotonically decreases to 37 dB at 500 °C. Its closed-loop gain reduction is ~5 dB over the investigated temperature range. The gain-bandwidth product drops from 2.8 MHz at 27 °C to 1.3 MHz at 500 °C with 470 pF off-chip compensation capacitors. A low total-harmonic-distortion of -58.4 dB at 27 °C and -46.9 dB at 500 °C is achieved due to the fully differential implementation. A low input offset voltage of 0.5 mV at 27 °C and 6.9 mV at 500 °C is achieved without calibration. The relative high linearity and the low offset demonstrate the potential of this technology to be further investigated for the front-end sensor circuits in high-temperature applications.