| AVS 63rd International Symposium & Exhibition | |
| MEMS and NEMS | Wednesday Sessions |
| Session MN-WeM |
| Session: | Multiscale Phenomena & Emerging Technologies in Micro- and Nano-Systems |
| Presenter: | David Czaplewski, Argonne National Laboratory |
| Authors: | D.A. Czaplewski, Argonne National Laboratory C. Chen, Argonne National Laboratory D. Lopez, Argonne National Laboratory P.M. Polunin, Michigan State University O. Shoshani, Michigan State University S.W. Shaw, Michigan State University M.I. Dykman, Michigan State University |
| Correspondent: | Click to Email |
MEMS and NEMS oscillators have been proposed as frequency generators to replace quartz as timing components in applications that require low power and a small footprint. The accuracy of a time measurement using a frequency generator is related to the fluctuations in both the generator amplitude and frequency. In many oscillators, the relative magnitude of frequency fluctuations is suppressed by increasing the vibration amplitude and choosing an operating point before the onset of non-linear response. Operating in a nonlinear region is generally avoided, primarily due to an additional contribution to the frequency fluctuations arising from the conversion of amplitude fluctuations into frequency fluctuations. However, we demonstrate a non-linear frequency generator that suppresses frequency fluctuations through means of an internal resonance. An internal resonance is accompanied by a pronounced transfer of energy between two coupled modes of a resonant structure [1,2]. For our frequency generator, the primary mode of operation is an in-plane flexural mode, which is actively controlled, and the second mode is a torsional mode with an eigenfrequency about three times larger than the flexural mode, which is passively coupled to the flexural mode. We present a theoretical model of the modal coupling and show, from our model and experimental observations, that the frequency fluctuations are reduced by several orders of magnitude due to a broad range of near-zero dispersion, i.e., near independence of the vibration frequency on the amplitude imposed by the presence of internal resonance. Within this near-zero dispersion region, a subset of operating conditions is found where frequency fluctuations are reduced even further due to a zero-dispersion point created by relationships of the parameters of the coupled equations. We present data on the stability of the frequency as a function of time (Allan deviation) and the spectrum of the frequency fluctuations (phase noise versus offset frequency) at different operating points of the generator. We also discuss the prospect of further increasing the frequency stability of MEMS/NEMS oscillators by reducing the noise floor of the system and approaching the thermomechanical noise limit of such systems.
[1] A. H. Nayfeh and D. T. Mook, Nonlinear oscillations (John Wiley & Sons, 2008).
[2] D. Antonio, D. H. Zanette, and D. Lopez, Nature communications 3 806 (2012).