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AssigneeKulite Semiconductor Products, Inc.
InventorsAnthony D. Kurtz, Wolf S. Landmann
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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.
In a pressure transducer apparatus containing one or more piezoresistive elements formed by an integrated circuit technique arranged in a bridge array on a force responsive member having a span resistance element connected between a source of biasing potential and a terminal of said bridge array and means for providing an additional voltage as a function of temperature from a separate source and output terminals for providing a transducer output voltage, said bridge array having an ambient temperature dependent bridge resistance operative to influence a non-linear response in said transducer output voltage, in combination therewith the improvement comprising:
An ambient temperature compensating apparatus for a transducer of the type employing a conventional Wheatstone bridge array having first and second input terminals for applying a source of biasing potential therebetween and first and second output terminals for obtaining a transducer output voltage therebetween and a span resistance connected between said Wheatstone bridge array and a source of biasing potential, said Wheatstone bridge array having an ambient temperature dependent bridge resistance operative to influence an undesirable non-linear response in said transducer output voltage, said ambient temperature compensating apparatus operative to counteract said ambient temperature dependent bridge resistance, comprising:
A method for improving the span shift response of a transducer employing the span resistor method of compensating for an ambient temperature dependent bridge array circuit arrangement, comprising the steps of:
Dependencies are inferred from the claim text.