A Monolithic CMOS-MEMS 3-Axis Accelerometer With a Low-Noise, Low-Power Dual-Chopper Amplifier

TitleA Monolithic CMOS-MEMS 3-Axis Accelerometer With a Low-Noise, Low-Power Dual-Chopper Amplifier
Publication TypeJournal Article
Year of Publication2008
AuthorsQu, H., D. Fang, and H. Xie
JournalIEEE Sensors Journal
Volume8
Issue9
Pagination1511 - 1518
Date Published09/2008
ISSN1530-437X
KeywordsAccelerometer, CMOS-MEMS, single-crystal silicon, three-axis accelerometer, z-axis accelerometer.
Abstract

This paper reports a monolithically integrated CMOS-MEMS three-axis capacitive accelerometer with a single proof mass. An improved DRIE post-CMOS MEMS process has been developed, which provides robust single-crystal silicon (SCS) structures in all three axes and greatly reduces undercut of comb fingers. The sensing electrodes are also composed of the thick SCS layer, resulting in high resolution and large sensing capacitance. Due to the high wiring flexibility provided by the fabrication process, fully differential capacitive sensing and common-centroid configurations are realized in all three axes. A low-noise, low- power dual-chopper amplifier is designed for each axis, which consumes only 1 mW power. With 44.5 dB on-chip amplification, the measured sensitivities of x-, y-, and z-axis accelerometers are 520 mV/g, 460 mV/g, and 320 mV/g, respectively, which can be tuned by simply changing the amplitude of the modulation signal. Accordingly, the overall noise floors of the x-, y-, and z-axis are 12 mug/radicHz , 14 mug/radicHz, and 110 mug/radicHz, respectively, when tested at around 200 Hz.

URLhttp://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=4582341
DOI10.1109/JSEN.2008.923582
Short TitleIEEE Sensors J.