Drive Electrodes

Drive electrodes are critical microelectromechanical system (MEMS) components within vibratory gyroscopes, typically fabricated on silicon substrates. They consist of patterned conductive structures (often comb-finger or parallel-plate designs) that, when an alternating voltage is applied, create time-varying electrostatic fields. These fields exert forces on a suspended proof mass, driving it into a precisely controlled resonant oscillation along a primary axis. This oscillation establishes the reference motion necessary for Coriolis force detection when the gyroscope rotates. The electrodes' geometry, spacing, and material properties are engineered to maximize force efficiency, minimize parasitic capacitance, and ensure stable, low-noise operation across specified temperature and voltage ranges.

Drive electrodes operate on the principle of electrostatic actuation. An AC voltage (often at the proof mass's mechanical resonant frequency) is applied between stationary drive electrodes and movable fingers or plates attached to the proof mass. The resulting electrostatic attraction/repulsion forces the proof mass into oscillatory motion. This driven oscillation is maintained at a constant amplitude via closed-loop control circuits that adjust the drive voltage based on motion sensing (e.g., through sense electrodes), ensuring stable reference vibration for Coriolis effect measurement.