CAPACITIVE SILICON ACCELEROMETER WITH HIGHLY SYMMETRICAL DESIGN

The design and performance of a capacitive micromechanical accelerometer, as well as an electronic circuit for the conditioning of the output signal are described. The sensing element consists of a differential capacitance which is formed by a seismic silicon mass and two counter electrodes situated on anodically bonded glass plates. The mass is symmetrically suspended on at least eight cantilever beams located on both sides of the silicon wafer. For a ±5 g device a typical sensitivity of 1 pF/g with a zero capacitance of 10 pF and a detection limit below 1 mg was achieved. For signal conditioning a switched capacitor CMOS-ASIC was developed, yielding an analogue voltage output signal. © 1990.