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We report on a 32-MHz quartz TCXO fully integrated with commercial CMOS electronics and vacuum packaged at wafer level using a low-temperature MEMS-after quartz process. The novel quartz resonator design provides for stress isolation from the CMOS substrate thereby yielding classical AT-cut f/T profiles and low hysteresis which can be compensated to < ± 0.2 ppm over temperature using on-chip third-order...
The miniaturization of resonators for timing applications brings with it new challenges in terms of device optimization. As the device size is reduced, design intolerances lead to more significant differences between modeled and fabricated devices leading to poor performance. In this paper we present a methodology for improving resonator designs. A 32MHz AT-cut quartz thick VHF shear mode resonator...
On-chip integration of quartz resonators with Si devices opens new opportunities for microsystem miniaturization and enhanced performance. In addition to integrating with electronics, the integration of piezoelectric quartz resonators with other sensors of different material composition is also possible. In this paper, we demonstrate that a VHF SC-cut quartz resonator can be integrated within a high-aspect-ratio...
UHF quartz MEMS oscillators operating at 813 MHz, 920 MHz and 1.048 GHz carrier frequencies utilizing a push-pull topology based on MOSIS SiGe 7WL technology have been demonstrated. The 1048 MHz resonator has an unloaded Q of 6,920 and a motional resistance of 31.7 ohms, as measured in a vacuum. This yields an fxQ product of 7.25×1012, close to the expected limit for quartz devices of 1×1013. Device...
Compact oscillators at UHF frequencies and below are challenging for IC designers because of the large size of the passive components, particularly the inductors. An integrated SiGe push-pull sustaining circuit fabricated in the IBM 7WL process eliminates the need for inductors. Combining this circuit with and an external quartz resonator allowed the development of 708 MHz and 744 MHz fundamental...
Processes for fabricating full wafers of UHF quartz MEMS oscillators bonded to Si have been developed at HRL over the past several years. These devices have shown state-of-the-art noise and stability along with extremely small vacuum packaged die size of less than 3 mm. An interesting by-product of the high frequency, small size, and wafer-scale fabrication of these devices is that several novel dynamics-based...
A 1 GHz AT-cut quartz thickness shear mode resonator is modeled for the first time with thermally induced bonding stresses and their effect on the device frequency-temperature (f-T) characteristic. Without the details of the bonding configuration, modeling indicates the f-T characteristic slightly rotates as a function of the change in stiffness of a simplified absorbing mount. However, if details...
A quartz resonator operating at 995 MHz in the fundamental mode has been characterized in a closed loop oscillating system under different drive levels to determine its nonlinear behavior and optimum phase noise performance. The best phase noise achieved was −106dBc/Hz at a 1 kHz offset frequency. The same quartz technology was used to build VCXOs in both the Colpitts and Pierce configurations at...
Characterization of a quartz resonator operating at 553 MHz in a closed loop oscillating system has been performed under various drive levels to characterize its nonlinear behavior. The voltage and current were measured across the resonator using differential active probes and used to calculate the magnitude of the admittance under drive. Our results show that nonlinear resonator operation widens...
The feasibility of a parametric amplification method for improving the Q of UHF quartz oscillators is considered. A fundamental thickness shear resonator operating at about 500 MHz was studied for estimating the magnitude of fractional change in stiffness, Δk/k that could be obtained at resonance and off-resonance. The Δk/k is employed in a parametric pumping of the thickness shear mode of vibration...
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