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Abstract

A system and method for calibrating a transducer having a bridge-type network. The calibration includes a source of constant current and a calibration circuit including the source connected across one of the resistive-type transducer elements of the bridge. Switching means are provided in the calibration circuit so that the current can be selectively supplied to or withheld from the resistive-type transducer element across which the calibration circuit means is connected for producing a calibration signal. The calibration signal is substantially independent of the transducer output regardless of whether or not the signal is temperature compensated and whether it is switched mechanically, electromechanically, or electrically. An internal calibration resistor in the current source is used to make the current inversally proportional to the bridge arm resistance. The calibration resistor tracks the resistive-type transducer elements of the bridge over temprature. The calibration resistor is chosen to have almost any convenient value and it need not be trimmed. The change in output voltage produced by switching in the calibration current is independent of temperature provided the calibration resistor accurately tracks the bridge resistors. Furthermore, the output voltage is substantially constant even when the bridge is significantly unbalanced.

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First Claim