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s DESCRIPTION Fujitsu resonators C4 series (G type) feature originally developed single crystals with a high electromechanical coefficient (LiNbO3 lithium niobate), the result is ultra compact packaging. C4 series (G type) with built-in capacitors for exclusive use in microcomputer clocks, and this series is chip type device for surface-mount.
We study the electrically forced thickness-shear and thickness-twist vibrations of stepped thickness piezoelectric plate mesa resonators made of polarized ceramics or 6-mm class crystals. A theoretical analysis based on the theory of piezoelec-tricity is performed, and an analytical solution is obtained using the trigonometric series. The electrical admittance, resonant frequencies, and mode shapes are calculated, and strong energy trapping of the modes is observed. Their dependence on the geometric parameters of the resonator is also examined.
2003
Certain materials produce electric charges on their surfaces as a consequence of applying mechanical stress. The induced charges are proportional to the mechanical stress. This is called the direct piezoelectric effect and was discovered in quartz by Piere and Jacques Curie in 1880. Materials showing this phenomenon also conversely have a geometric strain proportional to an applied electric field. This is the converse piezoelectric effect. The root of the word "piezo" means "pressure"; hence the original meaning of the word piezoelectricity implied "pressure electricity."
Microsystem Technologies, 2011
Over the past few years, microelectromechanical system (MEMS) based on-chip resonators have shown significant potential for sensing and high frequency signal processing applications. This is due to their excellent features like small size, large frequency-quality factor product, low power consumption, low cost batch fabrication, and integrability with CMOS IC technology. Radio frequency communication circuits like reference oscillators, filters, and mixers based on such MEMS resonators can be utilized for meeting the increasing count of RF components likely to be demanded by the next-generation multi-band/multi-mode wireless devices. MEMS resonators can provide a feasible alternative to the present-day well-established quartz crystal technology that is riddled with major drawbacks like relatively large size, high cost, and low compatibility with IC chips. This article presents a survey of the developments in this field of resonant MEMS structures with detailed enumeration on the various micromechanical resonator types, modes of vibration, equivalent mechanical and electrical models, materials and technologies used for fabrication, and the application of the resonators for implementing oscillators and filters. These are followed by a discussion on the challenges for RF MEMS technology in comparison to quartz crystal technology; like high precision, stability, reliability, need for hermetic packaging etc. which remain to be addressed for enabling the inclusion of micromechanical resonators into tomorrow's highly integrated communication systems.
Resonance, 2014
The presence or absence of piezoelectricity has a direct relationship with the point group of the crystal structure. In this article, starting from a general background, a brief account of the phenomena associated with anomalous piezoelectric response in advanced piezoelectric materials is presented. Some of the landmark discoveries that shaped the field, both in terms of new materials as well as the scientific understanding of the mechanisms are highlighted. Towards the end, there is a brief discussion of the viewpoints with regard to factors such as domain wall motion, low symmetry monoclinic phase, phase transition, polarization rotation theory and adaptive phase theory which contribute to the piezoelectric response in advanced piezoelectrics.
Journal of the Acoustical Society of America, 2005
Properties of transducers and substrates for bulk acoustic wave resonators and sensors are described. These resonators utilize one-dimensional thickness vibrations of structures consisting of a low-loss substrate crystal surmounted by a thin active piezoelectric film that drives the composite in resonant modes to achieve gigahertz frequencies. The structures considered include oblique orientations of the substrate, leading to generation of coupled elastic modes in the composite. A modified Christoffel-Bechmann ͑CB͒ formalism is presented to calculate acoustic wave speeds and displacements in the piezoelectric film transducer and the substrate. The CB method also yields the piezoelectric coupling coefficients of arbitrarily oriented piezofilms, for electric fields impressed either along the thickness or laterally. The calculations apply generally to transducer and substrate crystals of any symmetry class. The piezoelectric portion is then made specific for films of class 6 mm ͑wurtzite structure͒ with arbitrary orientation on the substrate, and the substrate calculations are specified for class 3m materials, but apply also to any substrate with 3m or 32 symmetry. Zinc oxide and sapphire are used in an example of the acoustic resonator structure.
Journal of The European Ceramic Society, 1999
The standard characterisation of piezoelectric materials requires speci®c boundary conditions. However the piezoelectric devices require quite dierent shaped materials and contour conditions from those that standard imposes. For these reasons, device characterisation usually requires models of equivalent electric circuits for non-electric properties as mechanical losses or coupling factors. Using a piezoelectric resonator model, similar to that used in the standard, we can make a more accurate characterisation of piezoelectric devices. #
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