Abstract: In order to improve the measurement accuracy of the signal detection circuit of differential capacitive sensors, this paper proposes a method that combines Delta-Sigma modulation technology with differential capacitive sensors to create a new type of signal detection system. This signal detection method places differential capacitive sensors, preamplifiers, and phase sensitive detection circuits within a Delta-Sigma feedback loop, forming a large feedback loop. By deriving the system transfer function of the detection circuit, we analyzed the technical advantages of using Delta-Sigma modulation technology in this detection method a circuit board and tested it. The research results indicate that the digital output of the signal detection method proposed in this article has a high correlation with the magnitude and direction of the deviation of the center plate from the equilibrium position, which has a good promoting effect on further improving the measurement accuracy of the differential capacitive sensor detection circuit.

Key words: Differential capacitive sensor, Delta-Sigma Modulation Technology, Phase sensitive detection, Analog to digital convert