Circuit for detecting dynamic weak capacitance of MEMS device

Abstract

The invention discloses a circuit for detecting dynamic weak capacitance of a micro electro mechanical system (MEMS) device, which is mainly applied to change detection of dynamic weak capacitance in a capacitive MEMS device. The circuit comprises a driving signal generation circuit, a capacitance to voltage (C / V) converting unit, a primary sampling and holding unit, a secondary sampling and holding unit and a signal processing unit. The driving signal generation circuit performs self-oscillation to generate a sine wave signal with fixed amplitude and frequency, and provides a detection pumping signal for the C / V converting unit; the C / V converting unit converts the weak capacitance variation into voltage, and a sine wave signal which can be processed by the subsequent stage of a samplingand holding circuit is output by an instrument amplifier; and the primary sampling and holding unit detects a positive peak point of the input sine wave, and when the positive peak point is detected,the output signal keeps the voltage of the positive peak point and half sine wave cycle is kept unchanged, the latter half cycle changes along with the input signal, and the output signal is used as a signal to be detected of the secondary sampling and holding unit.

Description

technical field [0001] The invention relates to a dynamic weak capacitance detection circuit of MEMS devices, which belongs to the field of weak signal detection in MEMS devices. Background technique [0002] MEMS devices have been widely used in the fields of industry, information, aerospace, and national defense because of their small size, long life, low energy consumption, easy integration, and low cost. [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 widely used because of 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 research institutions at home and abroad. [000...

AI Technical Summary

Problems solved by technology

[0009] The technology of the present invention solves the problem: Aiming at the shortcomings of traditional detection methods, a new type of dynamic weak capacitance detection circuit for MEMS devices is proposed, which provides a solution for low-cost and portable testing of the performance of resonant capacitive MEMS devices, and solves the problem of traditional measurement The instrument cannot test high-frequency dynamic capacitance with high precision and the structure of static capacitance measurement is complicated.

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