A [Formula Omitted] Interface for MEMS Accelerometers Using Electrostatic Spring Constant Modulation for Cancellation of Bondwire Capacitance Drift

This paper presents a closed-loop accelerometer interface based on a force-feedback [Formula Omitted] loop. The interface reduces the offset, and its drift, arising from asymmetry in the parasitic capacitances of the bondwires connecting the CMOS interface IC and the MEMS sensor element. This is ach...

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Bibliographic Details
Published in:IEEE journal of solid-state circuits 2013-01, Vol.48 (1), p.265
Main Authors: Lajevardi, Pedram, Petkov, Vladimir P, Murmann, Boris
Format: Article
Language:English
Subjects:
Microelectromechanical systems
Online Access:Get full text
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Summary:This paper presents a closed-loop accelerometer interface based on a force-feedback [Formula Omitted] loop. The interface reduces the offset, and its drift, arising from asymmetry in the parasitic capacitances of the bondwires connecting the CMOS interface IC and the MEMS sensor element. This is achieved by modulating the spring constant of the sensor electrostatically and continuously measuring and nulling the offset via an offset cancellation loop. In a bondwire deformation experiment, we show that the offset cancellation loop reduces an induced offset of 350 mg by 54 dB down to 0.7 mg. The interface was fabricated in a 0.18-[Formula Omitted] CMOS technology. The active circuit area is 1.35 [Formula Omitted] and the interface consumes 3.1 mW from a 3-V supply, while achieving a noise floor of 220 [Formula Omitted] over a 1-kHz bandwidth. When the offset cancellation loop is turned on, the bandwidth available for the signal is 200[Formula Omitted]Hz.
ISSN:0018-9200
1558-173X
DOI:10.1109/JSSC.2012.2218721