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A resistive sensor readout circuit with intrinsic insensitivity to circuit parameters and its evaluation
Vijayakumar Sreenath, Koniyath Semeerali,
Published in Institute of Electrical and Electronics Engineers Inc.
2017
Volume: 66
   
Issue: 7
Pages: 1719 - 1721
Abstract
A novel readout circuit for interfacing single element resistive sensors is presented in this paper. The proposed scheme is based on a new relaxation oscillator (RO). The RO, along with a timer counter provides a digital output proportional to the resistance of the sensor. The output characteristic of most of the existing readout circuits for resistive sensors suffers from gain, offset, and nonlinearity errors. The sources of errors include various nonideal circuit parameters and their drift. The output of the proposed readout circuit has a special feature that it is not a function of the circuit parameters such as: 1) offset voltages of the opamps and comparators; 2) bias currents of the opamps and comparators; 3) gain of various units employed; 4) ON-resistance of the switches; 5) value or mismatch in the magnitudes of the reference voltages employed; 6) delay of the switches and comparator; 7) leakage current of the switch; and 8) slew rate of the opamp. Such a scheme will be useful for high accuracy measurements, even when the parameters 1)-8) may vary or drift, due to variation in the measurement environment. A prototype of the proposed readout scheme has been developed in the laboratory and the performance has been evaluated under various conditions. The output was found to be linear with a worst-case nonlinearity of 0.05%. Test results from a prototype developed show that the proposed scheme possesses all the features, described above, as expected. © 2017 IEEE.
About the journal
JournalData powered by TypesetIEEE Transactions on Instrumentation and Measurement
PublisherData powered by TypesetInstitute of Electrical and Electronics Engineers Inc.
ISSN00189456
Open AccessNo
Concepts (17)
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    Comparator circuits
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    Comparators (optical)
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    Electric network parameters
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    Operational amplifiers
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    Parameter estimation
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    Readout systems
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    Semiconductor junctions
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    Timing circuits
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    CIRCUIT PARAMETER
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    HIGH-ACCURACY MEASUREMENTS
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    INTRINSIC INSENSITIVITY
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    NON-LINEARITY ERRORS
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    Output characteristics
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    READ-OUT CIRCUIT
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    Reference voltages
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    RESISTIVE SENSOR
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    Delay circuits