Two Proposals of a Simple Analog Conditioning Circuit for Remote Resistive Sensors with a Three-Wire Connection

Area of Science:

• Electrical Engineering
• Sensor Technology
• Instrumentation

Background:

• Three-wire resistive sensors are widely used but susceptible to errors from parasitic wire resistance.
• Accurate measurement requires compensation techniques for these wire resistances.

Purpose of the Study:

• To propose and experimentally validate two novel front-end circuits for three-wire resistive sensors.
• To achieve compensation for wire resistance and improve measurement linearity.

Main Methods:

• Development of two circuit implementations: one using twin diodes, the other a switch.
• Utilizing square-wave input excitation for alternating current polarity.
• Employing a low-pass filter to extract the average output signal proportional to sensor resistance.

Main Results:

• Both circuit implementations demonstrate effective wire-resistance compensation.
• The switch-based circuit shows excellent linearity with a non-linearity error below 0.01% full-scale span.
• Performance is largely insensitive to wire resistance variations and mismatches.

Conclusions:

• The proposed front-end circuits offer a robust solution for accurate resistive sensor measurements.
• These circuits significantly reduce errors caused by parasitic wire resistances.
• The technology is particularly suitable for applications like Pt100 thermal sensing.