3-order continuous low-pass feedback type sigma-delta closed-loop control circuit of micro mechanical accelerometer

Abstract

The invention discloses a 3-order continuous low-pass feedback type sigma-delta modulator closed-loop control circuit of a micro mechanical accelerometer, belonging to the field of acceleration signal measurement. The circuit is sequentially composed of a charge amplifier 5, a high-pass filter 6, a diode 7, a low-pass filter 8, a fully-differential amplifier 9, a phase compensation circuit 10, an integrator 11, a comparer 12, a D flip flop 13 and an analog switch 14. The closed-loop control circuit has the beneficial effects that one integrator is added in a forward path, so that the noise shaping ability of the micro mechanical accelerometer system is improved, the signal to noise ratio is increased, and the dead zone characteristic is reduced; and meanwhile, local feedback parameters are regulated, so that system parameters can be more precisely regulated.

Description

technical field [0001] The invention relates to a third-order continuous low-pass feedback sigma-delta (ΣΔΜ) closed-loop control circuit for a micromechanical accelerometer, belonging to the field of acceleration signal measurement and processing. Background technique [0002] Micromachined accelerometer is a typical inertial sensor and one of the earliest micro-electromechanical systems (MEMS) devices. Compared with traditional accelerometers, micromachined accelerometers have small size, light weight, low power consumption, and low cost It has the advantages of low cost and good reliability, so it has been widely used in military and civilian fields. The working principle of the micromachined accelerometer is: when the external acceleration signal is loaded on the micromachined accelerometer, the central mass of the accelerometer will produce a displacement proportional to the magnitude of the acceleration signal in the direction of the acceleration signal, resulting in a ...

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Problems solved by technology

[0004] Since the micromachined accelerometer is a mechanical structure, its origin gain is relatively low compared to the electrical second-order link, which limits the improvement of the signal-to-noise ratio of the micromachined accelerometer system; at the same time, the second-order low of the micromachined accelerometer The dead zone characteristic of the pass ΣΔΜ digital closed-loop control circuit is also relatively obvious, resulting in the inability to detect small signals, thus limiting the application range of the low-pass ΣΔΜ digital closed-loop control circuit of the micromechanical accelerometer

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