A weak capacitive detection circuit of MEMS device

Abstract

The invention is a weak capacitive detection circuit of MEMS device, mainly used for the weak capacitance variation detection in capacitive MEMS device. It consists of two groups of C / V converters, subtracter, integrator and peak detector. The two groups of C / V converters, based on differential circuit theory, convert the weak capacitor under test and compensation capacitor in MEMS device to the sinusoidal voltage respectively by using the same high-frequency sinusoidal excitation source; the subtracter conducts subtraction for two sinusoidal voltage inputted and the calculated sinusoidal signal peak is in proportion to the variation of the weak capacitor under test; the integrator conducts the signal filtering and amplification for the sinusoidal input; the peak detector directly detects the peak value of the sinusoidal signal, namely the DC signal proportional to the variation of the weak capacitor under test. The invention uses the compensation capacitor to offset the body capacitor of the weak capacitor under test, and realizes the classified differential detection for the single capacitor under test; it uses the peak detection method to directly obtain the DC signal proportional to the variation of the weak capacitor under test through the sinusoidal signal detection.

Description

technical field [0001] The invention belongs to the field of weak signal detection in MEMS devices, which is an important part of MEMS devices and plays a vital role in improving the performance of devices. Background technique [0002] MEMS devices have the characteristics of small size, long life, low energy consumption, easy integration and low cost, so they have been widely used in industry, information, aerospace, defense and other fields. [0003] According to different detection methods, MEMS devices can be divided into piezoresistive, piezoelectric, capacitive, thermocouple, optical fiber, electromagnetic, etc. Among them, piezoresistive, piezoelectric and capacitive are the current mainstream directions , and capacitive MEMS devices have been the most widely used due to their outstanding advantages such as large measurement range, high sensitivity, fast dynamic response, and good stability, and have become the research focus of major companies and scientific researc...

AI Technical Summary

Problems solved by technology

[0008] The technology of the present invention solves the problem: Aiming at the shortcomings of the traditional detection method, a new MEMS device weak capacitance detection circuit is proposed to solve the problem that the traditional weak capacitance detection method requires a pair of identical capacitors to be tested to achieve differential detection. The principle and structure of the sinusoidal signal demodulation part are complicated, which reduces the possible errors

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