Importance

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Abstract

The present compensating circuit operates to reduce the span shift error due to ambient temperature changes of a span resistance compensated, bridge array circuit arrangement for a semiconductor transducer employing piezoresistive sensors. The span resistance method alone cannot reduce the span shift error to less than one percent (1%) for full scale. The present compensating circuit applies a constant voltage source, derived from the voltage source applied to the transducer, to a non-inverting input to an operational amplifier. The circuit also applies an ambient temperature dependent voltage, derived from the ambient temperature dependent bridge resistance of the bridge array circuit, to an inverting input of the operational amplifier. Both inputs to the operational amplifier are fed back through a different resistance loop to control the output voltage in response to the non-linearity of the ambient temperature dependent bridge resistance. The present circuit produces a compensation voltage which counteracts the downward span shift influence of the bridge resistance, resulting in a span shift error of less than five tenths of a percent (0.5%) for full scale.

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First Claim