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Author: search.filters.author.Katman, RatchanooSubject: search.filters.subject.Readout circuit

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    Simple and low-cost readout circuit for differential resistive sensors
    (2018-09-01)
    Katman, Ratchanoo
    ;
    Rerkratn, Apinai
    ;
    Kaewpoonsuk, Anucha
    In this paper, a simple and low-cost readout circuit for differential resistive sensors is presented. The realization method is based on the relaxation oscillation technique, which utilizes the operational amplifiers (op-amps) with a single supply voltage. The oscillating output Duty-Cycle is proportional to the difference of two sensing resistances. In comparison with the traditional voltage divider circuit or the Wheatstone bridge circuit or the previously reported readout circuit based on CCIIs, the proposed circuit can be interfaced with microcontroller without using an analog-to-digital converter. Theoretical predictions are supported by the PSPICE simulation results and the experimental data. In applying a slide potentiometer with changes of slider positions of ±15 mm, it is found that the maximum error of the proposed circuit is approximately-2.90% of full-scale. Copyright © 2018 Praise Worthy Prize S.r.l.-All rights reserved.
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    Readout circuit for conductivity measurement with parasitic resistance compensation
    (2018-08-01)
    Katman, Ratchanoo
    ;
    Petchmaneelumka, Wandee
    ;
    Rerkratn, Apinai
    ;
    Kaewpoonsuk, Anucha
    This paper presents a simple method based on commercially available current feedback operational amplifiers (CFOAs) to realize the readout circuit for measuring the solution conductivity including the parasitic resistance in the electrode sensor. The enhanced readout circuit for conductivity measurement in electrolyte solution, compared with the conventional readout circuit using the op-amp inverting amplifier, offers a technique for the parasitic resistance compensation to improve the linearity of the measurement results. The proposed readout circuit provides the digital output which is directly proportional to the conductivity of electrolyte solution. The experimental verification and the measured results of the method are included in this paper.
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    Simple DC-excited resistance-to-period converter using CFOAS
    (2018-05-01)
    Kaewpoonsuk, Anucha
    ;
    Katman, Ratchanoo
    ;
    Rerkratn, Apinai
    This paper presents a new method to implement a resistance-to-period converter for DC-excited resistive sensor. The proposed technique makes use of the characteristic of a controllable unity-gain inverting/non-inverting amplifier formed by current feedback operational amplifiers (CFOAs). Experimental results that verify the performance of the proposed circuit are also included.