A self-calibration variable area capacitance detection method

Abstract

The invention discloses a self-aligning area-changing capacitive detection method. The method involves a capacitance / voltage conversion module, a motion range signal extracting module, and a motion phase signal detection module. According to the method, a detecting capacitance is of a variable-area structure composed of a rectangular electrode and a triangular electrode; the non-linear relationship between the detection capacitance and the motion displacement is utilized; a voltage detection signal obtained by converting the periodically time-varying detection capacitance includes 1 times frequency harmonic wave component and 2 times frequency harmonic wave component; a motion range signal and a motion phase signal can be represented through the correlation between the two harmonic wave components, and thus the influence of gain and phase delay on capacitance detection in a signal processing circuit can be removed, and as a result, the self-alignment function is realized. The method is simple in principle, convenient to realize, and can be applied to various capacitive displacement detection resonator structures like a micromechanical gyroscope.

Description

technical field [0001] The invention relates to capacitance detection, in particular to a self-calibrating variable-area capacitance detection method. Background technique [0002] Because of its simple structure, small temperature sensitivity, and good repeatability, capacitance detection is often used in the motion displacement detection of micro-mechanical devices. A time-varying capacitor is generated, and then converted into a conveniently processed voltage detection signal by the capacitor interface circuit. In this way, the voltage detection signal contains useful information of motion displacement. [0003] In the conventional capacitance detection method, the voltage detection signal is not only proportional to the time-varying capacitance, but also proportional to the initial capacitance, the voltage between the capacitor plates, and the gain of the processing circuit, and the sensitivity of these system parameters to the fluctuation of the ambient temperature limi...

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Problems solved by technology

However, the capacitive detection method of sideband ratio has the following two problems: first, the ratio of the motion amplitude signal to the two harmonic components is nonlinear, and the formula needs to be revised to obtain an accurate motion amplitude signal; second, the method It cannot eliminate the influence of the phase delay of the processing circuit on the moving phase signal, and it will also limit the system accuracy in phase-sensitive applications such as phase-locked loops

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