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Cited by 3Sensor Technology and Measurement SystemsAnalog and Mixed-Signal Circuit DesignAdvanced Sensor Technologies Research

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A Multiplexable Op-Amp Interface for Accurate Readout of Remote Resistive Sensors

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Kuankid, Sanya, Jittakort, Jirapong, Aurasopon, Apinan·2026·Sensors
DOI 10.3390/s26020461PMC PMC12846225
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Abstract

This paper presents a compact and accurate readout circuit for remote two-wire resistive sensors, based on an inverting operational amplifier with a fixed bias voltage, diode steering, and unidirectional square-wave excitation generated by a microcontroller. The proposed method determines the sensor resistance by directly sampling two steady-state voltage plateaus at the op-amp output during alternating excitation phases. This approach enables fast, lead-wire-insensitive measurements without the need for analog filtering or precise PWM duty-cycle control. The architecture supports sensor array multiplexing via analog switches, allowing scalable, low-power implementation. Experimental results demonstrate a maximum relative error of 0.23% across a wide resistance range (0.5–3.5 kΩ), confirming the method’s suitability for low-cost, embedded, and remote sensing applications.

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Figure 1 Proposed readout architecture for multiplexed resistive sensors. (a) Circuit configuration employing an inverting op-amp, diode steering, and unidirectional square-wave excitation. Each sensor is selectively inserted into the feedback path via analog switch, enabling accurate two-wire measurement. The op-amp output alternates between two voltage plateaus, Vo⁺ and Vo⁻, depending on the conduction phase. (b) Microcontroller implementation, where the digital output generates the excitation signal vexc, the ADC samples the op-amp output vo during both excitation phases, and the select lines address individual sensors. The sensor resistance Rx is computed digitally from the sampled plateau voltages.
Figure 1 Proposed readout architecture for multiplexed resistive sensors. (a) Circuit configuration employing an inverting op-amp, diode steering, and unidirectional square-wave excitation. Each sensor is selectively inserted into the feedback path via analog switch, enabling accurate two-wire measurement. The op-amp output alternates between two voltage plateaus, Vo⁺ and Vo⁻, depending on the conduction phase. (b) Microcontroller implementation, where the digital output generates the excitation signal vexc, the ADC samples the op-amp output vo during both excitation phases, and the select lines address individual sensors. The sensor resistance Rx is computed digitally from the sampled plateau voltages.CC BY · PubMed Central
Figure 2 Measured op-amp output waveform vo, illustrating voltage plateaus Vo⁺ and Vo⁻ during each excitation phase and multiplexed scanning across sensors R1, RM, etc.
Figure 2 Measured op-amp output waveform vo, illustrating voltage plateaus Vo⁺ and Vo⁻ during each excitation phase and multiplexed scanning across sensors R1, RM, etc.CC BY · PubMed Central
Figure 3 Experimental setup showing the Arduino Mega2560, OP07 op-amp, CD4051B multiplexer, ±5 V power supplies, and oscilloscope used to capture vexc and vo waveforms during sensor scanning.
Figure 3 Experimental setup showing the Arduino Mega2560, OP07 op-amp, CD4051B multiplexer, ±5 V power supplies, and oscilloscope used to capture vexc and vo waveforms during sensor scanning.CC BY · PubMed Central
Figure 4 Oscilloscope waveforms of the excitation signal vexc (yellow trace) and the op-amp output waveform vo (blue trace) during sequential scanning of two resistive sensors. (a) Rx = 0.49 kΩ and 1.469 kΩ; (b) Rx = 2.18 and 3.47 kΩ.
Figure 4 Oscilloscope waveforms of the excitation signal vexc (yellow trace) and the op-amp output waveform vo (blue trace) during sequential scanning of two resistive sensors. (a) Rx = 0.49 kΩ and 1.469 kΩ; (b) Rx = 2.18 and 3.47 kΩ.CC BY · PubMed Central
Figure 5 Measured resistance versus actual resistance for various test resistors. Tests were conducted with RWM = RWN = 100 Ω. The blue squares represent measured values with best-fit linearity, while purple triangles indicate relative error ∆Rx/Rx. The maximum error was observed to be 0.23%.
Figure 5 Measured resistance versus actual resistance for various test resistors. Tests were conducted with RWM = RWN = 100 Ω. The blue squares represent measured values with best-fit linearity, while purple triangles indicate relative error ∆Rx/Rx. The maximum error was observed to be 0.23%.CC BY · PubMed Central
Figure 6 Measured resistance as a function of wire resistance (20–100 Ω) for four different sensor values. All measured values remained within 0.23% of the true resistance across the full range of parasitic wire conditions.
Figure 6 Measured resistance as a function of wire resistance (20–100 Ω) for four different sensor values. All measured values remained within 0.23% of the true resistance across the full range of parasitic wire conditions.CC BY · PubMed Central

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References 15 · Cited by 3

Research works printed but not linked: 17

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Metadata

Authors
Kuankid, S., Jittakort, J., & Aurasopon, A.
Affiliations
  • Nakhon Pathom Rajabhat University (TH)
  • Rajamangala University of Technology (TH)
  • Mahasarakham University (TH)
Corresponding author
Aurasopon, Apinan
ORCID
Venue
Sensors
Publisher
MDPI AG
Published
2026-01-10
Volume
26
Issue
2
Pages
461
ISSN
1424-8220 (ISSN-L)
DOI
10.3390/s26020461
PMC
PMC12846225
OpenAlex
W7122763239
Cited by
3
References
15
Citations by year
2026: 3
FWCI
11.29
Type
journal article
Language
en
Open access
Licence
Locations
  • Sensors (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • PubMed Central (publishedVersion, cc-by)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
Funders
Mahasarakham University
Topics
  • Physical Sciences › Physics and Astronomy › Instrumentation › Sensor Technology and Measurement Systems
  • Physical Sciences › Engineering › Electrical and Electronic Engineering › Analog and Mixed-Signal Circuit Design
  • Physical Sciences › Physics and Astronomy › Instrumentation › Advanced Sensor Technologies Research
Keywords
analog switches, low-power readout, embedded sensing

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CoChat. (2026). Citation check: A Multiplexable Op-Amp Interface for Accurate Readout of Remote Resistive Sensors. https://app.cochat.ai/papers/10.3390/s26020461
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Kuankid, S., Jittakort, J., & Aurasopon, A. (2026). A Multiplexable Op-Amp Interface for Accurate Readout of Remote Resistive Sensors. Sensors. https://doi.org/10.3390/s26020461