Conditioning circuit for capacitive position sensor with nano-scale precision based on AC excitation principle

This paper designs a conditioning circuit for a bipolar capacitive sensor with nano-scale position measurement precision based on the principle of AC excitation. The circuit consists five parts including sinusoidal excitation circuit, C-V conversion circuit, peak value detection circuit, adder and amplifier circuit. Based on the simulation and analysis of circuit, a set of performance tests on the developed circuit board and corresponding data process was performed to show that the ripple RMS of the circuit board is less than 0.76mv and its nonlinear error is below 0.47%.