Title :
An in-plane high-sensitivity, low-noise micro-g silicon accelerometer with CMOS readout circuitry
Author :
Chae, Junseok ; Kulah, Haluk ; Najafi, Khalil
Author_Institution :
Dept. of Electr. Eng. & Comput. Sci., Univ. of Michigan, Ann Arbor, MI, USA
Abstract :
A high-sensitivity, low-noise in-plane (lateral) capacitive silicon microaccelerometer utilizing a combined surface and bulk micromachining technology is reported. The accelerometer utilizes a 0.5-mm-thick, 2.4×1.0 mm2 proof-mass and high aspect-ratio vertical polysilicon sensing electrodes fabricated using a trench refill process. The electrodes are separated from the proof-mass by a 1.1-μm sensing gap formed using a sacrificial oxide layer. The measured device sensitivity is 5.6 pF/g. A CMOS readout circuit utilizing a switched-capacitor front-end Σ-Δ modulator operating at 1 MHz with chopper stabilization and correlated double sampling technique, can resolve a capacitance of 10 aF over a dynamic range of 120 dB in a 1 Hz BW. The measured input referred noise floor of the accelerometer-CMOS interface circuit is 1.6μg/√Hz in atmosphere.
Keywords :
CMOS integrated circuits; accelerometers; electrodes; micromachining; noise; Σ-Δ modulator; 0.5 mm; 1 Hz; 1 MHz; 10 aF; CMOS circuit; accelerometer-CMOS interface circuit; chopper stabilization; device sensitivity; double sampling technique; inertial sensors; micro-g silicon accelerometer; micromachining technology; polysilicon sensing electrodes; proof-mass; referred noise floor; sacrificial oxide layer; sensing gap; silicon microaccelerometer; switched-capacitor front-end; trench refill process; Accelerometers; CMOS technology; Capacitance; Choppers; Dynamic range; Electrodes; Micromachining; Sampling methods; Silicon; Switching circuits; Inertial sensors; micro-g; micromachined accelerometer; sigma-delta; switched-capacitor;
Journal_Title :
Microelectromechanical Systems, Journal of
DOI :
10.1109/JMEMS.2004.832653
