Design Issues For Differential Z-Axis Accelerometers

Abstract: 

Accelerometers which are sensitive to inputs perpendicular to the substrate (2-Axis) are the key to monolithic three axis acceleration sensing. The inherent asymmetry of the capacitive interface of the Z-Axis sensing element fabricated in surface micromachining technology with a single structural layer results in a large offset and drift.

Two complementary techniques for minimizing this offset are proposed and analyzed. The first relies on a fixed value micromachined reference capacitor for optimal matching and a half-bridge configuration to minimize the resulting offset. The second approach uses an electronic signal to cancel the systematic mismatch between the sense and reference capacitors.

Both techniques are implemented in an experimental three axis acceleration sensor fabricated in a surface micromachining technology with a single structural polysilicon layer [I].

Author: 
Bernhard E. Boser
Publication date: 
September 20, 1996
Publication type: 
Master's Thesis
Citation: 
Ortiz, M. A. (1996). Design Issues for Differential Z-axis Accelerometers. United States: University of California, Berkeley.

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