Study on driving noise of quartz flexible accelerometer torquer

Abstract

The distributed capacitance inside the quartz flexible accelerometer (QFA) coupled the high frequency voltage excitation signal in the differential capacitance detection circuit to the torquer coil, and superimposes the torquer driving current to form the driving noise. In this study, the values of the distributed capacitance inside the QFA were simulated. According to the formation mechanism of the QFA driving noise, the equivalent circuit model of the driving noise is established, and the driving noise characteristics of the detection circuit with single excitation and double excitation source are analysed. The theoretical and experimental results show that the electric field coupled driving noise transmission system is a first-order system with high-pass characteristics. The driving noise of the single excitation detection circuit is larger than that of the dual excitation detection circuit, and the dual excitation detection circuit can reduce the driving noise by 39.77% when the QFA shell is grounded. The equivalent acceleration of the electric field coupled driving noise is between tens of μg to hundreds of mg, which is one of the important noise sources that affect the measurement accuracy of the QFA. A measure was proposed to suppress the high-frequency driving noise by adding a low-pass filter after the sampling output of the driving current, which can reduce the driving noise to 1.85 μg and effectively reduce the influence of the driving noise on the measurement accuracy of the QFA.