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Abstract
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| When electronic feedback is used around resonant microcantilevers, their native resonance frequency f0 and that of the feedback loop fFB=f0±¿f will differ in general because the 0º or 360º phase condition aimed in the loop gain uses to have some small phase offset ¿¿. This feedback-induced frequency shift ¿f, that is static in constant-gain loops, becomes a frequency noise when the loop gain changes randomly as in oscillating loops by the action of noise on the Automatic Level Control (ALC) of the loop. The phase offset ¿¿ allows the ALC to modulate randomly the output frequency around its fFB value while it modulates in the same manner the feedback factor of the loop to keep constant the output amplitude. This phenomenon is thus an added source of phase noise in resonator-based oscillators, especially when the signals within the loop are noisy as those giving the instantaneous displacement of small microdevices like resonant MEMS (Micro- Electro-Mechanical Systems). | |
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International
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No |
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Congress
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XXIV Conference on Design of Circuits and Integrated Systems |
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960 |
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Place
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Zaragoza |
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Reviewers
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Si |
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ISBN/ISSN
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978-84-690-4144-4 |
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Start Date
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18/11/2009 |
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End Date
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20/11/2009 |
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From page
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231 |
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To page
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236 |
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Proc. of the DCIS'09 |