A high-precision detection circuit for capacitive sensor

For the capacitance signal of capacitive sensor output is tiny, a capacitive sensor detection circuit is designed to solve the problem of hard measuring. Its sensitivity is 1V/pF. The design of noise suppression circuit is added, making the output DC voltage signal more stable. The detection circuit includes a sine wave generator circuit, a differential amplifier circuit, a band-pass filter circuit, a peak detector circuit and a low-pass filter circuit. The frequency of sine wave excitation signal is 20 kHz, peak to peak 20 V. Experimental results show that the measurement accuracy of the detection circuit is high, and the output is stable. It can meet the requirements of capacitive sensor.