US 4,715,003 AGranted

Method for temperature compensation and measuring circuit therefor

AssigneeKeller AG fur Druckmesstechnik

InventorsHans W. Keller, Michael Von Ritter

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Abstract

A measurement circuit for carrying out a method of compensation, in particular for a piezoresistive pressure transducer with a measurement bridge (7) and a following output/differential amplifier (15) further comprises a current supply circuit (13). To enable an optimal temperature compensation for the measurement bridge (7) with maximum resolution of the pressure measurement signal, a digitalized compensation circuit with an analog/digital converter (21), a memory (23) and at least one digital/analog converter (25, 27) is connected ahead of the output/differential amplifier (15). The temperature dependent voltage difference/input signal at the measurement bridge (7) is digitalized via the following converter (21) and converted to compensation values stored in the memory (23). These values are converted into an analog compensation signal in a converter (25, 27). For analog measured value determination per se, only error compensation is carried out in digitalized fashion (FIG. 2).

Claims27

Dependent claims

A method for compensation of an analog, temperature dependent differential output signal of a pressure measuring circuit in a piezoresistive pressure transducer, said measuring circuit including a measurement bridge disposed on a pressure measurement cell, wherein an analog difference/output signal of said measurement bridge is provided to an output differential amplifier for generating said differential output signal, said method including the steps of:

(a) storing a plurality of fixed compensation values in a digital memory means;
(b) converting a temperature dependent analog voltage difference/input signal of said measurement bridge to a digital difference signal;
(c) providing said digital difference signal to said memory means and generating, as the output of said memory means and as a function of the magnitude of said digital difference signal, at least one digital compensation signal, each digital compensation signal corresponding to one of said stored compensation values;
(d) converting each digital compensation signal into a corresponding analog compensation signal;
and
(e) providing each analog compensation signal to said pressure measuring circuit for compensation of said differential output signal, thus to generate a temperature compensated pressure measurement signal.

3 more elements

In a pressure measuring circuit of a piezoresistive pressure transducer, said circuit including a measurement bridge and an output differential amplifier receiving an analog difference/output signal of said measurement bridge for generating an analog pressure measurement signal, and a current supply circuit;

a temperature compensation circuit, said temperature compensation circuit including:
a first differential amplifier receiving an analog voltage difference/input of said measurement bridge;
a first analog/digital converter for receiving the output of said first differential amplifier and converting said output to a digital difference signal;
a digital memory means, having a plurality of digitalized temperature dependent compensation values stored therein, for receiving the output of said first differential amplifier and generating a digital compensation signal comprised of at least one of said temperature dependent compensation values selected as a function of the output of said first differential amplifier;
and
a digital/analog conversion means for receiving said digital compensation signal and converting it to a corresponding analog compensation signal, and for providing said analog compensation signal to said pressure measuring circuit.

3 more elements

Dependencies are inferred from the claim text.