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Proceedings Paper

Airbag accelerometer with a simple switched-capacitor readout ASIC
Author(s): Masahiro Tsugai; Yoshiaki Hirata; Koji Tanimoto; Teruo Usami; Toru Araki; Hiroshi Otani
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Paper Abstract

A bulk micromachined capacitive accelerometer for airbag applications based on (110) silicon anisotropic KOH etching is presented. The sensor is a two-chip accelerometer that consists of a glass-silicon-glass stacked sense element and an interface ASIC containing an impedance converter for capacitance detection, an EPROM and DACs for digital trimming, and a self-test feature for diagnosis. A simple switched-capacitor readout circuit with DC offset error cancellation scheme is proposed as the impedance converter. The dependence of narrow gap etching, surface roughness, and uniformity of the groove depth on the KOH concentration are also investigated for the fabrication of the device, and it is shown that the etch rate of the plane intrinsically controls the depth of the narrow gap with a KOH concentration of over 30 wt. percent, and smooth surface and uniformity of groove depth are obtained at 40 wt. percent KOH. The nonlinearity of the output is about 1.5 percent FS. The temperature coefficient of sensitivity and the off-axis sensitivity are 150 ppm/degree C and 2 percent respectively. The dimensions of the sensor are 10.3 X 10.3 X 3 mm.

Paper Details

Date Published: 5 September 1997
PDF: 8 pages
Proc. SPIE 3224, Micromachined Devices and Components III, (5 September 1997); doi: 10.1117/12.284542
Show Author Affiliations
Masahiro Tsugai, Mitsubishi Electric Corp. (Japan)
Yoshiaki Hirata, Mitsubishi Electric Corp. (Japan)
Koji Tanimoto, Mitsubishi Electric Corp. (Japan)
Teruo Usami, Mitsubishi Electric Corp. (Japan)
Toru Araki, Mitsubishi Electric Corp. (Japan)
Hiroshi Otani, Mitsubishi Electric Corp. (Japan)


Published in SPIE Proceedings Vol. 3224:
Micromachined Devices and Components III
Kevin H. Chau; Patrick J. French, Editor(s)

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