Gallium-Arsenide Operational Amplifier without High-Temperature Integrated Resistors

The existing design and technological solutions of integrated resistors do not ensure their satisfactory operation at temperatures above 200°C. It is shown that it is highly desirable to avoid the use of these passive elements when synthesizing high-temperature operational amplifier (OpAmp) circuits on wide-gap semiconductors (GaAs, etc.). A resistive-free differential cascade and an OpAmp based on it have been developed, which can be realized within the framework of the gallium-arsenide technological process on nJFET field-effect and p-n-p bipolar transistors, mastered by a number of microelectronic firms. The considered OpAmp is designed without using current mirrors on n-p-n bipolar or pJFET. The results of mathematical analysis and computer modeling showed that the proposed OpAmp circuit has a lower level of the systemic part of the zero-bias voltage (up to 260 $\mu$V) and provides an open-circuit voltage gain of more than 70 dB. This is sufficient for many, including high-temperature applications of OpAmp.