A Self-Calibration Circuit for the Resistance Measurement of Parallel R-C sensor

A simple, relaxation oscillator based digital interface circuit for resistance measurement is proposed in this article. The proposed circuit has the merits of (i) independent from capacitor drifts (ii) independent from parasitic capacitance effect (iii) low complexity and non-requirement of a control unit (iv) less effect due to the circuit non-idealities. The methodology and the theoretical evaluation of the proposed circuit are discussed in this article and later, it is verified using simulation studies. These studies state that the proposed scheme gives better linearity (0.04 % nonlinearity) and the effect of error sources is less for a wide range of sensor resistances.