Design Analysis and Experimental Validation of Relaxation Oscillator-Based Circuit for R-C Sensors
Abstract
Relaxation oscillator-based circuits are widely used for interfacing various resistive and capacitive sensors. The electrical equivalent of most resistive and capacitive sensors is represented using a parallel combination of resistor and capacitor. The relaxation oscillator-based circuits are not suitable for parallel R-C sensors. In this paper, we propose a modified circuit for parallel R-C sensors. The proposed relaxation oscillator-based circuit is based on a dual-slope and charge transfer technique to measure the resistance and capacitance of parallel R-C sensors separately. In addition, the paper provides a detailed analysis and design considerations for the oscillator design by taking into account the various sources of non-idealities. A method to reduce the error by using single-cycle averaging is also introduced. To verify the analyzed design criteria, the circuit is tested with multiple operational amplifiers with different non-idealities. Experimental results verify the performance of the proposed circuit. The circuit is tested for a range from 10 pF to 42 pF and 100 k to 1 M for parallel R-C sensors with an error of less than 1.5\%. The circuit is tested with a fabricated water-level sensor. The result confirms the efficacy of the proposed circuit.
Keywords
Cite
@article{arxiv.2307.07822,
title = {Design Analysis and Experimental Validation of Relaxation Oscillator-Based Circuit for R-C Sensors},
author = {Mohamad Idris Wani and Sadan Saquib Khan and Benish Jan and Meraj Ahmad and Maryam Shojaei Baghini and Laxmeesha Somappa and Shahid Malik},
journal= {arXiv preprint arXiv:2307.07822},
year = {2023}
}