A 200°C general purpose rail-to-rail complementary input class-AB operational amplifier for high temperature applications

This paper covers the design and testing of an operational amplifier (opamp) used in a high temperature signal conditioning unit for integration with temperature and strain gauge sensors. The opamp was designed and fabricated in a 1 µm CMOS Silicon-on-Insulator (SOI) process and has been characterized up to 300°C. The measurement results at 200°C are showing a DC open-loop gain of 100dB, an offset voltage of 1mV, an input bias current of ±15pA, a common mode input range (CMIR) of [0–5]V and a unity gain frequency of 3.2MHz. The opamp has a size of 687µm × 218µm and draws a current of 550µA from a 5V supply. The opamp was used to design an instrumentation amplifier (IA) with a gain of 225 at 200°C.