Optimizing detection interface and adopting force feedback control scheme can improve the signal-to-noise ratio(SNR)and the performance of MEMS accelerometer by changing the circuit parameters without affecting the sensitive structure of the MEMS sensor.Based on an array differential capacitance sensitive structure,the capacitance detection interface circuit is constructed and the output signal spectrum is analyzed on the basis of the equivalent capacitance model.It is proved that the single carrier capacitance detection has better output SNR.The STM32H743VIT6 processor is used for digital demodulation of the amplitude-modulated signals.It is applied to the movable pad as a feedback voltage,after the demodulation value is adjusted by PI control algo-rithm,and the digital closed-loop control of the accelerometer is realized.Experimental results has dem-onstrated that the velocity random walk(VRW)of the closed-loop accelerometer is 57 μg/Hz1/2,which is equivalent to that of the open-loop state.However,the bias stability of the accelerometer is im-prove from 184 μg in the open-loop state to 58 μg,which verifies the effect of the single-carrier modulated capacitance detection interface circuit and the force feedback control technology on im-proving the static performance of the accelerometer.
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