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, et al.
"Piezoelectric nonlinear nanomechanical temperature and acceleration insensitive clocks", Proc. SPIE 8373, Micro- and Nanotechnology Sensors, Systems, and Applications IV, 83730A (May 1, 2012); doi:10.1117/12.920845; http://dx.doi.org/10.1117/12.920845