Frequency Locking Circuit of Resonant Accelerometer Based on Digital Phase-Frequency Detection Method

Abstract

The invention discloses a resonant accelerometer frequency locking circuit based on a digital phase frequency detection method. The locking circuit comprises two sets of signal sensitive electrodes and two sets of torque feedback electrodes of a microfabircated resonant micro accelerometer and two sets of constant amplitude frequency stabilization control circuits, wherein each set of constant amplitude frequency stabilization control circuit comprises a detection interface circuit, a demodulation filter circuit, an AD sampling circuit, a comparator circuit, an FPGA control algorithm, a DA conversion circuit and a driving interface circuit, the signal sensitive electrodes of the microfabircated resonant micro accelerometer are connected with the detection interface circuits, and the torque feedback electrodes of the microfabircated resonant micro accelerometer are connected with the driving interface circuits. The locking circuit is advantaged in that the signal amplitude and the phase information are separately acquired, high precision amplitude sampling can be realized through a low rate high precision AD, high-speed comparators are further utilized to convert signals to reserve the phase information of the signals, so a high conversion rate and quantitative precision coordination are realized, and integral precision of a measurement and control circuit is improved.

Description

technical field [0001] The invention relates to micro-electromechanical system (MEMS) and micro-inertial device measurement technology, in particular to a resonant accelerometer frequency locking circuit device based on a digital phase-frequency detection method. Background technique [0002] MEMS accelerometer refers to a type of accelerometer that uses microelectromechanical system (MEMS) technology and works according to the Gothic effect principle. According to different sensitive signals, MEMS accelerometers can be divided into capacitive micro-accelerometers, resonant micro-accelerometers, piezoresistive micro-accelerometers, piezoelectric micro-accelerometers and tunnel current micro-accelerometers. The resonant micro-accelerometer directly converts the measured acceleration into the frequency change of the resonator, and has the advantages of high sensitivity, wide dynamic range, and direct digital output, making it the development direction of a new generation of hi...

AI Technical Summary

Problems solved by technology

Many kinds of digital control methods have been reported in the prior art. Most of the control methods need to use high-precision and fast-speed AD conversion chips to sample the signal to completely retain the amplitude and phase information of the signal. However, the sampling rate of the AD conversion chip and the quantization accuracy are mutually restricted, thus limiting the accuracy of the entire measurement and control circuit

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