A signal detection circuit of capacitance sensor for small displacement is given.The circuit is composed of phase-sensitive circuit

phase shift circuit and low-pass filter.The small displacement less than 0.15 mm can be measured and the displacement direction can be detected exactly.The circuit is simple

convenient and low cost.The circuit is used to process the signal output from the conversion bridge of the differential capacitance small displacement sensor.Experimental results show that the detection circuit has good stability and anti-jamming.The linearity is 0.492 %.The sensitivity is 0.629 1 V/mm.