Enhanced Dual-Slope-Based Digitizer for 4-Wire Connected Resistive Sensors

This paper introduces a novel dual-slope-based digitizer circuit tailored for 4-wire connected resistive sensors. Utilizing cost-effective components, this circuit offers a simple yet robust method for accurate sensor readings. Experimental tests demonstrate the circuit's capability to measure sensor resistance within the range of 60 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Omega$</tex> to 390 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Omega$</tex>, corresponding to a temperature span of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$-100^{\circ}\mathrm{C}$</tex> to <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$850^{\circ}\mathrm{C}$</tex> using an RTD-Pt100 sensor. The circuit exhibits a maximum nonlinearity error of 0.06 % and a maximum measurement error of 0.6 <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Omega$</tex>, showcasing its high precision. One key advantage of this digitizer is its single measurement cycle requirement, streamlining the measurement process. Additionally, the circuit incorporates constant current excitation to mitigate self-heating effects and minimize its reliance on digital ports, enhancing its speed and reliability in sensor measurements. Moreover, its single-supply operation ensures efficiency, with an average power consumption of approximately 20 mW. These findings underscore the circuit's potential as a cost-effective and efficient solution for a variety of sensing applications.