Airbag accelerometer with a simple switched-capacitor readout ASIC

Masahiro Tsugai; Yoshiaki Hirata; Koji Tanimoto; Teruo Usami; Toru Araki; Hiroshi Otani

doi:10.1117/12.284542

5 September 1997 Airbag accelerometer with a simple switched-capacitor readout ASIC

Masahiro Tsugai, Yoshiaki Hirata, Koji Tanimoto, Teruo Usami, Toru Araki, Hiroshi Otani

Proceedings Volume 3224, Micromachined Devices and Components III; (1997) https://doi.org/10.1117/12.284542
Event: Micromachining and Microfabrication, 1997, Austin, TX, United States

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.

Citation Download Citation

Masahiro Tsugai, Yoshiaki Hirata, Koji Tanimoto, Teruo Usami, Toru Araki, and Hiroshi Otani "Airbag accelerometer with a simple switched-capacitor readout ASIC", Proc. SPIE 3224, Micromachined Devices and Components III, (5 September 1997); https://doi.org/10.1117/12.284542

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