A digital closed-loop accelerometer chip on-line self-test system and method

Abstract

The invention discloses an online self-detection system and method on a digital closed-loop accelerometer chip. The online self-detection system includes a MEMS sensitive structure, a charge amplifier, a loop compensator, a Sigma-Delta modulator, a digital self-detection excitation source, a digital An arithmetic unit and a digital signal processing module, wherein: the MEMS sensitive structure is composed of an upper electrode, an intermediate mass, and a lower electrode; the MEMS sensitive structure, a charge amplifier, a loop compensator, and a Sigma-Delta modulator form a closed-loop negative feedback Servo system: the closed-loop negative feedback servo system, digital self-test excitation source, digital operation unit, and digital signal processing module constitute a digital closed-loop self-test circuit. The invention adopts the electric electrostatic force to excite the MEMS sensitive structure, can realize the self-detection of the harmonic distortion of the accelerometer, avoids the dependence on complex instruments and equipment in the traditional detection method, and can realize online measurement.

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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