On-chip online self-detection system for digital closed-loop accelerometer and method

Abstract

The invention discloses an on-chip online self-detection system for a digital closed-loop accelerometer and a method. The online self-detection system comprises an MEMS sensitive structure, a charge amplifier, a loop compensator, a Sigma-Delta modulator, a digital self-detection excitation source, a digital operation unit and a digital signal processing module, wherein the MEMS sensitive structureis formed by a top electrode, an intermediate mass block and a bottom electrode; the MEMS sensitive structure, the charge amplifier, the loop compensator and the Sigma-Delta modulator form a closed-loop negative feedback servo system; and the closed-loop negative feedback servo system, the digital self-detection excitation source, the digital operation unit and the digital signal processing module form a digital closed-loop self-detection circuit. According to the system and the method, the MEMS sensitive structure is excited by adopting electrostatic force, so that self-detection of harmonicdistortion of the accelerometer can be realized, the dependence on complex instrument equipment in a traditional detection mode is avoided, and on-line measurement can be realized.

Description

technical field [0001] The invention belongs to the technical field of sensor interface application-specific integrated circuits, and relates to a MEMS accelerometer on-chip real-time online self-detection system and method. Background technique [0002] In MEMS accelerometers, the capacitive sensitive structure is the most widely used sensitive structure type in practical applications. This is not only due to its better stability and process adaptability, but also an important reason why its parallel plate structure is easier to realize closed-loop electrostatic servo through electrostatic force. The closed-loop electrostatic force servo technology not only effectively improves the bandwidth, linearity, dynamic range and other important indicators of the accelerometer, but also alleviates the contradictory compromises encountered in the design of sensitive structures, enabling the adoption of low-damping vacuum packaging structures. This significantly reduces the mechanica...

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Problems solved by technology

[0004] In order to solve the problem that MEMS device parameters are easy to drift, easy to fail, and the traditional detection scheme is limited by complex instruments and equipment, it is difficult to complete real-time online measurement. Based on the Sigma-Delta digital closed-loop accelerometer detection scheme, the present invention proposes a digital closed-loop acceleration On-chip online self-test system and method, so as to realize real-time monitoring of its working status and online measurement of loop harmonic distortion

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