THERMAL FEEDBACK DRIVES SENSOR BRIDGE SIMULTANEOUSLY WITH CONSTANT SUPPLY VOLTAGE AND CURRENT

Sensor bridges are frequently used in a large variety of measuring applications and for conversion of nonelectrical quantities into electrical ones. The use of bridges is a well-established technique, and the more common problems that may arise in their realization are related to drift. One often tries to eliminate drift by application of compensation circuitry or trimming techniques. In this paper an approach is presented which aims at prevention of drift using a basic biasing circuitry for sensor bridges. The principle we discuss provides a simultaneous constant supply current and voltage for the sensing bridge under all operational conditions. This is obtained by means of thermal feedback on a silicon substrate using two integrated bridges. © 1990 IEEE