Accelerometer with a combined self-test and ground electrode

摘要

A micro-machined accelerometer includes a moveable metal plate, mounted upon a semiconductor substrate. The moveable metal plate includes an aperture which contains a pedestal and at least one torsion bar for connecting the pedestal to the moveable metal plate. Measurement electrodes formed on the semiconductor substrate combine with the metal plate to form measurement capacitors. A combined self-test/common electrode provides a dual function of a common electrode during operation of the accelerometer and a testing electrode during a self-test procedure.