A Capacitive Inertial Sensor Digital Servo Circuit

Abstract

The present invention provides a capacitance-type inertial sensor digital servo circuit. The capacitance-type inertial sensor digital servo circuit comprises a capacitance-type sensor, a reading-out amplification circuit, an analog-digital converter (ADC), a digital loop filter, a multi-digit quantizer and a pulse-width modulation generator. The capacitance-type sensor, the reading-out amplification circuit, the analog-digital converter (ADC), the digital loop filter, the multi-digit quantizer and the pulse-width modulation generator are connected in order and form a loop. Through adoption of the digital loop filter, the capacitance-type inertial sensor digital servo circuit is high in flexibility and accuracy; through adoption of the multi-digit quantizer, the capacitance-type inertial sensor digital servo circuit realizes multi-digit quantification and has small quantification noise, high linearity and high duty ratio; and moreover, through adoption of the pulse-width modulation generator, the capacitance-type inertial sensor digital servo circuit generates differential force feedback control signals to realize multi-digit force feedback control so as to greatly reduce the nonlinearity introduced by a common analog-digital converter (DAC) and improve the inhibition capability for common-mode noise.

Description

technical field [0001] The invention belongs to the technical field of sensor control, in particular to a capacitive inertial sensor digital servo circuit. Background technique [0002] Capacitive inertial sensors generally include inertial sensors such as acceleration sensors and gyroscopes. These inertial sensors measure the acceleration of the carrier relative to the ground and other parameters in real time to determine the position of the carrier and the parameters of the earth's gravity field, and the measured changes translates into a change in capacitance. [0003] The following is an example of a MEMS (Micro Electro Mechanical System) capacitive inertial sensor. [0004] With the increasing maturity of MEMS (Micro Electro Mechanical System) technology, MEMS capacitive inertial sensors are widely used due to their small size, high sensitivity, stable DC characteristics, small drift, low power consumption, and small temperature coefficient. However, MEMS The capaciti...

AI Technical Summary

Problems solved by technology

However, due to the complexity and particularity of the MEMS manufacturing process, the accuracy of the parameters of the MEMS capacitive inertial sensor itself is poor and the dispersion is large, which often leads to the mismatch of the originally matched loop filter, and the light one leads to digital closed-loop servo The performance of the circuit is degraded, and in serious cases, the digital closed-loop servo circuit is unstable and cannot work normally; the loop filter realized by the analog circuit is due to the error of integrated circuit processing and the existence of parasitic effects, resulting in poor parameter accuracy of the loop filter , it is difficult to accurately control

[0008] Since the single quantizer 1-bit feedback sigma-delta modulator uses a comparator and a 1-bit force feedback control signal generator to generate force feedback control signals, this digital closed-loop servo circuit has relatively large quantization noise, poor linearity, and stability. Poor, the actual maximum detection volume accounts for a small proportion of the entire system design range, etc.

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