An Efficient Digitizer for Self-Heating Compensation in Resistive Sensor
Ashish Dineshkumar Joshi, Shiraz Sohail, Gopal Singh, Nandigama Praveen Kumar, Tarikul Islam · 2023
Self-heating (S-H) error is found in all resistive sensors (RX) when interfaced with an electronic circuit for the output signal. This work presents an efficient digitizer circuit for interfacing the resistive sensor to compensate the S-H error. The digitizer utilizes a dual-slope integrator and a comparator to generate a time sequence output signal, which can be directly fed to the digital pin of a microcontroller for signal processing. To minimize the self-heating error, the input current through RXis kept small in the micro-ampere range. However, a T-network is connected to the integrating capacitor to boost the incoming current in the feedback path and helps in achieving high accuracy, sensitivity, and resolution. This is a novel feature that has not been reported before. The digitizer is simulated for measuring RXin a wide range of 3.63 kΩ to 488.2 kΩ, with corresponding power dissipation of 0.275 mW to 2.03 μW respectively. The current through RXranges from 275.2 μA -2.04 μA, and the measurement time varies from 4.78 ms to 389.3 ms. If this range of current is fed to a conventional digitizer for integrating the feedback capacitor, the circuit requires a longer measurement time (103.4 ms to 13.76 s). However, with the current boosting approach employed (ranging from 21.07-49.41 times) in this digitizer, the measurement time is reduced. It is to be noted that the conventional digitizer with a measurement time of 4.78 ms to 389.3 ms would require 5800 μA – 101.19 μA to pass through RXwhich would dissipate 122.11 mW – 4998.88 μW . Thus, this scheme decreases power dissipation by 444 – 2462.4 times which represents a significant improvement. The proposed digitizer produces accurate results with an average error of ± 0.28 %.