A Simple Electronic Digitizer for Parallel RC Transducers

This letter proposes a straightforward digital interface circuit for the estimation of resistance and capacitance of parallel
RC
grounded impedance sensors. The circuit is designed to account for various nonidealities, such as stray capacitances, parasitic resistances, microcontroller threshold voltages, and switch resistances. It employs a ratiometricity-based operation to provide output indications. One of the key advantages of this circuit is its low component count, leading to reduced power consumption. The methodology and error analysis of the interface circuit are outlined in the letter. Experimental studies were conducted to verify the circuit performance, demonstrating a maximum nonlinearity of 0.3% and a relative error of 1.75% for the ranges of 10 kΩ–1 MΩ and 100 pF–4.1 nF, respectively. Furthermore, this letter compares the proposed circuit's performance with existing research works, highlighting its simplicity and efficiency as a linear digital interface for parallel
RC
impedance sensors.