A Versatile Interface Circuit for Capacitive and Resistive Sensors

his paper presents a circuit design technique for realization of a versatile interface circuit for capacitive and resistive sensors. The proposed method is based on the use of operation of relaxation oscillator. Time periods generated from two relaxation oscillators are employed for the reference signal and another sensing signal from sensor. The output signal obtained in the form of time period is proportional to the sensing value from sensor. The proposed approach provides the attraction in terms of simple configuration and low cost. The proposed circuit performances confirmed by the experimental results using commercial devices are agreed with the expected values.