Mutual Closed-Loop Compensation of Hardening and Softening Nonlinearities in MEMS Capacitive Resonators

The research discloses a new closed-loop principle to hold a MEMS-based capacitive resonator in perfect linear operation. The concept, based on a negative feedback, leverages on the frequency-amplitude relationship to extract a signal from the oscillation loop which carries the information about the nonlinearity, and nulls it by dynamically acting on tuning electrodes in operation. The fabricated resonator is coupled to mixed-signal electronics and demonstrates linear operation well beyond the critical displacement with a 5-fold lower phase noise.