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Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope

Traditional MEMS gyroscope readout eliminates quadrature error and relies on the phase relationship between the drive displacement and the Coriolis position to accomplish a coherent demodulation. This scheme shows some risk, especially for a mode-matching gyro. If only a slight resonant frequency de...

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Autores principales: Chen, Hua, Zhong, Yanqing
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7472230/
https://www.ncbi.nlm.nih.gov/pubmed/32823993
http://dx.doi.org/10.3390/s20164564
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author Chen, Hua
Zhong, Yanqing
author_facet Chen, Hua
Zhong, Yanqing
author_sort Chen, Hua
collection PubMed
description Traditional MEMS gyroscope readout eliminates quadrature error and relies on the phase relationship between the drive displacement and the Coriolis position to accomplish a coherent demodulation. This scheme shows some risk, especially for a mode-matching gyro. If only a slight resonant frequency deviation between the drive and sense mode occurs, a dramatic change in the phase relationship follows, which leads to a wrong demodulation. To solve this, this paper proposes a new readout based on the quadrature error and an auxiliary phase-locked loop (PLL). By tuning the phase shifter in the sense-mode circuit, letting the quadrature error and the carrier of the mixer be in 90° phase alignment, the Coriolis was simultaneously in phase with the carrier. Hence, the demodulation was accomplished. The carrier comes from the PLL output of the drive-mode circuit due to its low jitter and independence of the work mode of the gyro. Moreover, an auxiliary PLL is used to filter the quadrature error to enhance the phase alignment accuracy. Through an elaborate design, a printed circuit board was used to verify the proposed idea. The experimental results show the readout circuit functioned well. The scale factor of the gyro was 6.8 mV/°/s, and the bias instability was 204°/h.
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spelling pubmed-74722302020-09-04 Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope Chen, Hua Zhong, Yanqing Sensors (Basel) Article Traditional MEMS gyroscope readout eliminates quadrature error and relies on the phase relationship between the drive displacement and the Coriolis position to accomplish a coherent demodulation. This scheme shows some risk, especially for a mode-matching gyro. If only a slight resonant frequency deviation between the drive and sense mode occurs, a dramatic change in the phase relationship follows, which leads to a wrong demodulation. To solve this, this paper proposes a new readout based on the quadrature error and an auxiliary phase-locked loop (PLL). By tuning the phase shifter in the sense-mode circuit, letting the quadrature error and the carrier of the mixer be in 90° phase alignment, the Coriolis was simultaneously in phase with the carrier. Hence, the demodulation was accomplished. The carrier comes from the PLL output of the drive-mode circuit due to its low jitter and independence of the work mode of the gyro. Moreover, an auxiliary PLL is used to filter the quadrature error to enhance the phase alignment accuracy. Through an elaborate design, a printed circuit board was used to verify the proposed idea. The experimental results show the readout circuit functioned well. The scale factor of the gyro was 6.8 mV/°/s, and the bias instability was 204°/h. MDPI 2020-08-14 /pmc/articles/PMC7472230/ /pubmed/32823993 http://dx.doi.org/10.3390/s20164564 Text en © 2020 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Chen, Hua
Zhong, Yanqing
Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope
title Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope
title_full Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope
title_fullStr Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope
title_full_unstemmed Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope
title_short Design of Readout Circuit with Quadrature Error and Auxiliary PLL for MEMS Vibratory Gyroscope
title_sort design of readout circuit with quadrature error and auxiliary pll for mems vibratory gyroscope
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7472230/
https://www.ncbi.nlm.nih.gov/pubmed/32823993
http://dx.doi.org/10.3390/s20164564
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