A 300/spl deg/C dynamic-feedback instrumentation amplifier

Accurate instrumentation amplifiers with a long-term stability of only a few ppm per year are required for applications such as satellites and downhole oil wells, where accessibility is difficult or maintenance or re-calibration are unacceptable. Pressure measurements in downhole oil wells require extreme precision while the operating temperatures may exceed 250/spl deg/C. Conventional accurate and long-term-stable amplifiers rely on accurate and stable feedback components. In practice, the inaccuracy is limited to about 10/sup -3/. Moreover, calibration or trimming cannot guarantee good long-term amplifier stability. This instrumentation amplifier for such applications uses dynamic feedback.