Fast Calibration Methods for Resistive Sensor Readout Based on Direct Interface Circuits

Area of Science:

• Electrical Engineering
• Sensor Technology
• Digital Electronics

Background:

• Direct interface circuits measure resistance via capacitor discharge time.
• Existing methods can be slow, especially for high resistance values, due to calibration steps.
• Time, temperature, and aging can affect measurement accuracy.

Purpose of the Study:

• To develop a faster resistance-to-digital conversion method.
• To reduce conversion time without significantly increasing measurement uncertainty.
• To improve the efficiency of sensor interface circuits.

Main Methods:

• A modified capacitor discharge process is proposed.
• Part of the discharge is performed using a calibration resistor instead of solely the sensor.
• Two variants of the method were tested for evaluation time and measurement uncertainty.
• Experiments were conducted using a field-programmable gate array (FPGA).

Main Results:

• Achieved reductions in resistance conversion time by up to 55%.
• Demonstrated that measurement uncertainty can be kept negligible with appropriate parameter selection.
• The modified method offers a significant speed improvement over traditional direct interface circuits.

Conclusions:

• The proposed modified resistance measurement technique substantially accelerates conversion speed.
• Negligible increases in measurement uncertainty are achievable, maintaining accuracy.
• This method provides a more efficient solution for integrating sensors into digital systems.