The internal electric field coupling noise of a quartz flexible accelerometer (QFA) restricts the improvement of the measurement accuracy of the accelerometer. In this paper, the internal electric field coupling mechanism of a QFA is studied, an electric field coupling detection noise model of the accelerometer is established, the distributed capacitance among the components of the QFA is simulated, the structure of the detection noise transfer system of different carrier modulation differential capacitance detection circuits is analyzed, and the influence of each transfer chain on the detection noise is discussed. The simulation results of electric field coupling detection noise show that the average value of detection noise can reach 41.7 μg, which is close to the effective resolution of the QFA, 50 μg. This confirms that electric field coupling detection noise is a non-negligible factor affecting the measurement accuracy of the accelerometer. A method of adding a high-pass filter to the front of the phase-shifting circuit is presented to suppress the noise of electric field coupling detection. This method attenuates the average value of the detected noise by about 78 dB, and reduces the average value of the detected noise to less than 0.1 μg, which provides a new approach and direction for effectively breaking through the performance of the QFA.

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.