Research on high-resolution capacitance detection circuit based on T-type network

Abstract

Abstract The capacitance detection circuit is a key component of the servo circuit of the quartz flexible accelerometer, which needs to ensure high-precision capacitance detection. The small capacitance change of the quartz flexible accelerometer pendulum will be affected by the noise of each device in the servo loop. To solve this problem, we design a single carrier modulation and demodulation capacitance detection circuit based on a T-type network from the capacitance detection model of a quartz flexible accelerometer. We established a circuit noise model, quantitatively analyzed the noise of the entire capacitance detection circuit from the theoretical level, and obtained the equivalent capacitance noise of the circuit. The rationality and effectiveness of the high-precision capacitance detection circuit are verified by theoretical calculation. We also verify the accuracy of the theoretical calculation through simulation and obtain the signal-to-noise ratio of the circuit. Finally, we prove that the scheme is a high-precision capacitance detection scheme.