Low g value capacitive MEMS accelerometer and modal localization measurement circuit thereof

Abstract

The invention discloses a low g value capacitive MEMS accelerometer and a modal localization measurement circuit thereof. A capacitive MEMS acceleration sensor comprises a silicon-based mass block, a spring, capacitor plates, X, Y, and Z direction limit blocks, and capacitor plate electrodes. Four differential capacitors are formed by the capacitor plates and mass blocks. Through a first lead wire hole, a second lead wire hole and the capacitor plate electrodes, a differential capacitance signal is introduced into a modal localization circuit. A capacitance measurement system comprises an ASIC modal localization circuit, a reference voltage source, and a multi-phase clock source. The output current and capacitance of the ASIC modal localization circuit are approximately in a linear relationship. When a frequency analysis and data acquisition / retention module carries out sampling to obtain a modal frequency of the modal localization circuit, a response current signal is inputted into a DSP to carry out cache calculation via low pass filtering. A novel differential capacitance MEMS acceleration sensor and a modal localization measurement circuit which detects weak capacitive change are designed, and the high precision weak acceleration change is realized.

Description

[0001] 【Technical field】 [0002] The invention relates to the technical field of acceleration sensors, in particular to an ultra-low g-value MEMS capacitive acceleration sensor and a capacitance measurement method. [0003] 【Background technique】 [0004] Acceleration sensing technology is widely used in earthquake monitoring, coal mining and aerospace fields. Traditional moving coil acceleration sensors have gradually been unable to meet the needs of production and life due to their large size, high energy consumption, and insufficient accuracy. Micro-electromechanical system (MEMS) acceleration sensors The sensor has the characteristics of small size, high precision, high integration and good stability, and has the tendency to replace the traditional acceleration sensor and become the mainstream. [0005] According to the principle, MEMS acceleration sensors can include capacitive, piezoresistive, resonant, and tunnel current types, among which the capacitive acceleration se...

AI Technical Summary

Problems solved by technology

Due to the limitation of its MEMS capacitive accelerometer structure, the output capacitance change is limited, which is obviously insufficient for the gravity field detection of ultra-low g value

In general, the traditional capacitive accelerometer structure and capacitive reading technology are difficult to meet the needs of microgravity measurement

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