2010 IEEE International Frequency Control Symposium

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MEMS resonators have been discussed as replacements for quartz crystals in electronics timing applications for more than 40 years. The emergence of high-quality, low-cost packaging for MEMS resonators has enabled the first demonstrations of long-term stability and opened the door for commercial applications. View full abstract»

This paper reports on the first demonstration of single-ended-to-differential and differential-to-differential (S2D and D2D) channel-select filters based on single-layer (SL) and dual-layer-stacked (DLS) AlN contour-mode MEMS resonators. The key filter performances in terms of insertion loss (as low as 1.4 dB), operating frequency (250-1280 MHz), and out-of-band rejection (up to 60 dB) constitute ... View full abstract»

This paper reports fine frequency selection techniques for aluminum nitride (AlN) Lamb wave mode resonators (LWR) to control the relative frequency of resonators in an array to 0.1%. The technique that works the best is by adjusting the so-called AlN “overhang” dimension, OH, measured from the center of the outermost electrode to the edge of AlN plate independently of the interdigita... View full abstract»

Thermal compensation for aluminum nitride (AlN) Lamb wave resonators operating at high temperature is experimentally demonstrated in this study. By adding a compensating layer of silicon dioxide (SiO2), the turnover temperature can be designed for high temperature operation by varying the normalized AlN thickness (hAlN/λ) and the normalized SiO2 thickness (hSiO2 View full abstract»

This paper reports internal dielectric transduction of the 41st radial bulk-mode of a ring resonator at 2.79 GHz with a quality factor exceeding 11,500 in air. The transducer electrodes are integrated within the vibrating structure in a dense serpentine pattern, with the dielectric-filled gaps strategically placed on the nodal lines to excite the 41st order bulk radial mode. ... View full abstract»

Miniature AT-strip quartz crystal resonators are capable of providing excellent frequency stability with good immunity to environmental influences. In particular, the fractional frequency change under acceleration is typically about 2 × 10-9 g-1. While more than good enough for most applications, for those that require low phase noise under vibration this may not be ad... View full abstract»

Combination of FEM for thermal analysis and Harmonic Balance oscillation analysis can achieve the highly frequency/temperature stable OCXO such as a few parts per billion frequency/temperature performance for the wide temperature range by simple single oven. This design method basically has been applied to the new OCXO for the LTE(Long Term Evolution)base-station of the next generation of the mobi... View full abstract»

Traditional oscillators used in timing modules of CDMA and WiMAX base stations are large and expensive. Applying cheaper and smaller oscillators in timing modules is an interesting research challenge. An adaptive control algorithm is presented to enhance these cheap but more inaccurate oscillators to meet the requirements of base stations during holdover mode. An oscillator frequency stability mod... View full abstract»

The high frequency oscillator circuit is relatively more susceptive to Electro-Magnetic Interference (EMI) in Embedded Systems (ES). The effect of EMI can be both deterministic and random in nature that shows up as jitter in the time domain and translates into the phase noise in the frequency domain. If the impact of EMI is too large, the performance of the entire system would be affected in terms... View full abstract»

This paper presents the performances of an integrated oscillator working at 3.3V power supply for XO applications, extended to OCXO by digital selections. It is realized in a standard 0.35μm SiGe BiCMOS technology from austriamicrosystems AG®. Some experimental characterizations have been performed at 40 MHz and give good agreement with simulations. This die is then used t... View full abstract»

This paper describes analytical and experimental study of a zero-temperature-coefficient square Lamé-mode quartz resonator supported at four nodal points. Comparison of vibration mode shapes of the resonators with and without four supporting beams in the modal analysis using finite element analysis indicated that several contour modes vibrating at large amplitude in the corners with freque... View full abstract»

We describe the frequency shifts for trapped fermions, as in a optical lattice clock. We discuss the behavior of the shift and show that it is not proportional to the difference of partial densities, in contrast to previously observed clock shifts. We provide a simple counter-example and also show that large interactions may effectively cancel the frequency shifts due to collisions. View full abstract»

We developed a theoretical method within the framework of relativistic many-body theory to accurately treat correlation corrections in atoms with few valence electrons. Preliminary results for systems of interest to atomic clock development are reported. We also calculated the blackbody radiation shift of the ground-state hyperfine microwave transition in 87Rb using the relativistic all... View full abstract»

We report our recent progress made with the NRC 88Sr+ single-ion optical frequency standard. The long-term operation of the standard was improved by actively stabilizing the cooling, repump and clearout laser sources, and by using a femtosecond fiber laser frequency comb to link the probe laser frequency to the microwave time standards. With the femtosecond fiber comb, we hav... View full abstract»

A recent acoustic MEMS transducer, a mass sensor based on FBAR (film bulk acoustic resonator), is shown to detect addition of a single DNA base. As the FBAR sensor can detect minute amount of DNA (and/or RNA) markers without the need for optical imaging, it will enable us to develop an “easy to use” and reliable system to detect the presence of pathogen's nucleic acids in non-invasiv... View full abstract»

Sensing platforms (5mm*5mm) containing 5 piezoelectric membranes have been fabricated by standard micromachining techniques starting with a Silicon-On-Insulator wafer. Each membrane (circular, with radius varying from 360 microns to 440 microns) could be individually actuated through a PZT 1-micron thick film and sensed either via the same piezoelectric patch or via two terminal piezoresistances (... View full abstract»