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7 May 2012 Piezoelectric nonlinear nanomechanical temperature and acceleration insensitive clocks
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This work presents the development of high frequency mechanical oscillators based on non-linear laterally vibrating aluminum nitride (AlN) piezoelectric resonators. Our efforts are focused on harnessing non-linear dynamics in resonant mechanical devices to devise frequency sources operating around 1 GHz and capable of outperforming state-of-the-art oscillators in terms of phase noise and size. To this extent, we have identified the thermal and mechanical origin of non-linearities in micro and nanomechanical AlN resonators and developed a theory that describes the optimal operating point for non-linear oscillators. Based on these considerations, we have devised 1 GHz oscillators that exhibit phase noise of < -90 dBc/Hz at 1 kHz offset and < -160 dBc/Hz at 10 MHz offset. In order to attain thermally stable oscillators showing few ppm shifts from - 40 to + 85 °C, we have implemented an embedded ovenization technique that consumes only few mW of power. By means of simple microfabrication techniques, we have included a serpentine heater in the body of the resonator and exploited it to heat it and monitor its temperature without degrading its electromechanical performance. The ovenized devices have resulted in high frequency stability with just few ppm of shift over the temperature range of interest. Finally, few of these oscillators were tested according to military standards for acceleration sensitivity and exhibited a frequency sensitivity lower than 30 ppb/G. These ultra stable oscillators with low jitter and phase noise will ultimately benefit military as well as commercial communication systems.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
A. Tazzoli, G. Piazza, M. Rinaldi, J. Segovia, C. Cassella, B. Otis, J. Shi, K. Turner, C. Burgner, K. McNaul, D. Bail, and V. Felmetsger "Piezoelectric nonlinear nanomechanical temperature and acceleration insensitive clocks", Proc. SPIE 8373, Micro- and Nanotechnology Sensors, Systems, and Applications IV, 83730A (7 May 2012);

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