11E-4 Application of a Vibrating Membrane Model to Bulk-Acoustic-Wave Resonators
ABSTRACT For a three-dimensional description of rectangular BAW resonators, a simple vibrating membrane model is revisited. Displacement profiles from this model are compared to measured profiles. Furthermore, a method for extraction of dispersion characteristics from electrical measurements is proposed and verified against interferometry measurements.
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ABSTRACT: 25 nm p Hz, and it is capable of directly measuring SAW's with frequencies ranging from 0.5 MHz up to 1 GHz. The fast scheme used for locating the optimum operation point of the interferometer facilitates high measuring speeds, up to 50,000 pointsh. The measured field image has a lateral resolution of better than 1 mm. The fully optical noninvasive scanning system can be applied to SAW device development and research, providing information on acoustic wave distribution that cannot be obtained by merely electrical measurements. 2000 Optical Society of America OCIS codes: 240.6690, 120.3180, 110.7170, 120.1880, 120.7280, 350.4010. The demand for high-frequency low-loss surface acous- tic wave (SAW) filters for wireless telecommunications has led to extensive research focusing on novel SAW de- signs. Detailed information is needed on the propaga- tion properties of SAW's within interdigital transducer and ref lector structures in novel miniaturized applica- tions featuring micrometer-scale structures and opera- tion frequencies in the 1-GHz range. Achieving low losses poses stringent demands for component design. An important factor is how well waveguides and resonators confine energy. Theoreti- cal models, 1 along with S-parameter measurements performed on test structures 2 and device prototypes, are the standard methods for analyzing these issues and improving SAW designs. However, evaluating acoustic activity in resonators, waveguides, and ref lectors with the above-described methods is tedious, indirect, and costly. Direct two- dimensional probing of SAW fields is needed. In ef- ficient probing aimed at assisting device development, the measuring setup must possess high sensitivity and permit measurements at frequencies reaching 1 GHz, at which the wavelength can be less than 4 mm. Linear response and an extensive dynamic range are also required from the probing system. The possibil- ity of scanning areas of arbitrary size and zooming in on details with high lateral resolution at will is crucial for analyzing any operating SAW device. Finally, fast scanning speed, allowing a large number of scanning points, is needed, along with the capability of measur- ing packaged devices at a given frequency without com- plex frequency- or amplitude-modulation schemes. Detection systems that were recently presented for probing SAW's 3-8 fulfilled some of the above criteria but often lacked the versatility required to measure two-dimensional profiles on high-frequency SAW de- vices effectively. Instead, most published results were obtained from test structures and with limited num- bers of data points. In particular, a scanning acoustic force microscope that was recently proposed for high- resolution probing of SAW's suffers from limitations if noninvasive probing of large areas is to be performed or a linear response is required. 3,4 To date, the most-advanced measuring setups suit- able for noninvasive probing of SAW devices have been based on the optical knife-edge technique. 5,8 By de- veloping a fast-scanning Michelson interferometer, we have been able to measure, for what is believed to be the first time, large two-dimensional scans from low-loss SAW devices operating at 1 GHz. These mea- surements revealed a new acoustic loss mechanism inOptics Letters. 01/2000; 25(9):613-615.
Article: Acoustic Fields and Waves in SolidsPhysics Today 01/1974; 27(10). · 6.76 Impact Factor
Conference Proceeding: Design and Characterisation of High-Q Solidly-Mounted Bulk Acoustic Wave Filters[show abstract] [hide abstract]
ABSTRACT: In this paper bulk-acoustic-wave (BAW) resonators with high Q-factor Q<sub>a</sub> at anti-resonance are demonstrated based on a redesigned reflector stack and a lateral design with a guard ring at the border of the resonator. Experimentally a clear maximum of Q<sub>a</sub> together with optimal suppression of spurious modes in the inductive region is observed for a guard ring width of about 7 mum. It is demonstrated that by measuring resonators of different size and aspect ratio, bulk and edge loss mechanisms can be differentiated. Furthermore, the most relevant part of the dispersion curve for the main acoustic mode can be extracted. The observed trends are confirmed by a recently developed finite element model.Electronic Components and Technology Conference, 2007. ECTC '07. Proceedings. 57th; 01/2007