High frequency characteristic of a monolithic 500 degrees C OpAmp-RC integrator in SiC bipolar IC technology

摘要

This paper presents a comprehensive investigation of the frequency response of a monolithic OpAmp-RC integrator implemented in a 4H-SiC bipolar IC technology. The circuits and devices have been measured and characterized from 27 to 500 degrees C. The devices have been modelled to identify that the substrate capacitance is a dominant factor affecting the OpAmp's high-frequency response. Large Miller compensation capacitors of more than 540 pF are required to ensure stability of the internal OpAmp. The measured unit-gain-bandwidth product of the OpAmp is similar to 1.1 MHz at 27 degrees C, and decreases to similar to 0.5 MHz at 500 degrees C mainly due to the reduction of the transistor's current gain. On the other hand, it is not necessary to compensate the integrator in a relatively wide bandwidth similar to 0.7 MHz over the investigated temperature range. At higher frequencies, the integrator's frequency response has been identified to be significantly affected by that of the OpAmp and load impedance. This work demonstrates the potential of this technology for high temperature applications requiring bandwidths of several megahertz. (C) 2017 Elsevier Ltd. All rights reserved.