Design Validation and Performance Investigation of Signal Conditioning Circuit for Capacitive Sensor

The paper presents the implementation details of an oscillator based signal conditioning circuit for capacitive sensor. The transfer function model of the circuit has been developed. The model of the signal conditioning circuit is validated by calibrating the circuit using precession capacitors. The performance of the circuit is investigated using capacitive RH sensor at standard humidity levels. The standard humidity levels are generated using saturated binary salt solutions prepared as per OIML R121. The measurement uncertainty, accuracy and sensitivity of the system are presented in the paper.