Active electronic cancellation of nonlinearity in a High-Q longitudinal-mode silicon resonator by current biasing

In this paper, we report the manipulation of nonlinear behavior in a bulk-mode micromechanical resonator for the first time. N-doped single-crystal-silicon (SCS) resonators of the same dimensions but different crystal orientations (<;100> and <;110>) were electrically characterized using capacitive drive and piezoresistive sense. Notably, reversed nonlinear behavior (from spring softening to hardening) was observed in the <;100> devices as a result of increasing the bias dc current. We have found that the energy storage capability of the resonator has been enlarged by over 10 times at the transition from spring softening to hardening. This newfound capability to electronically "cancel nonlinearity" could be conveniently applied to improve the phase noise (PN) performance of MEMS oscillators.