Amplitude motion stabilization in drive resonators limited by an automatic feather contact mechanism

The work presents a technique for motion amplitude control in MEMS resonators based on a first mechanical contact of two anti-phase driven frames, and then on a consecutive self-adaptation of the frames motion amplitude, that at every cycle skim over one another. This feather contact (FC) technique is demonstrated on a test structure which includes an anti-phase drive mode, with a tuning fork coupling spring whose internal sidewalls are spaced by 3.2 μm. The structure includes also a capacitive pick-off for a decoupled sense mode, thus forming a preliminary demonstrator of an FC gyroscope. Results show an almost complete immunity of the motion amplitude to variation in the resonator equivalent resistance (Req), superior to any amplitude gain control circuit (AGC). The structure sensitivity to angular rates in the FC operation regime is consequently highly stable.