SPUDT cells including two fingers are only known thus far for so-called NSPUDT directions. In that case, usual solid-finger cells are used. The purpose of the present paper is to find SPUDT cell types consisting of two fingers only for pure mode directions. Two-finger (TF) cells for pure mode directions on substrates like 128°YX LiNbO(3) and YZ LiNbO(3) were found by means of an optimization procedure. The forward direction of a TF-cell SPUDT on 128°YX LiNbO(3) was determined experimentally. The properties of the new cells are compared with those of conventional SPUDT cells. The reflectivity of TF cells on 128°YX LiNbO(3) turns out to be two to three times larger than that of distributed acoustic reflection transducer (DART) and Hanma-Hunsinger cells at the same metal layer thickness.
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http://dx.doi.org/10.1109/TUFFC.2011.1849 | DOI Listing |
SPUDT cells including two fingers are only known thus far for so-called NSPUDT directions. In that case, usual solid-finger cells are used. The purpose of the present paper is to find SPUDT cell types consisting of two fingers only for pure mode directions.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
April 2010
Usually, directivity is obtained in single-phase unidirectional transducers (SPUDTs) by cascading reflective cells and transduction cells in the same acoustic track. An alternate approach was presented which described a SPUDT using two tracks. The first track had only sources but the second track had sources and reflectors.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
July 2004
Leibniz Institute for Solid State and Materials Research Dresden, D-01171 Dresden, Germany.
The present paper describes single-phase unidirectional transducers (SPUDT) cells with all fingers wider than lambda/8 while maintaining the unidirectional effect. The first solution is related to a SPUDT consisting of lambda/4 and lambda/2 wide fingers arranged in two tracks. Each track has no significant unidirectional effect.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
December 2002
It is very important to extract all four coupling-of-modes (COM) parameters of the electrode cells for the simulation and optimal design of a low loss surface acoustic wave (SAW) filter. A new approach for fast and full extraction of the COM parameters for multielectrode-type grating is proposed. The field distribution of the wave under the periodic shorted grating is calculated by periodic Green's function method.
View Article and Find Full Text PDFIEEE Trans Ultrason Ferroelectr Freq Control
December 2002
Electrode width controlled (EWC) single-phase, unidirectional transducers (SPUDT) is widely used for low loss surface acoustic wave (SAW) filters. The insertion loss and fractional bandwidth of the filters are strongly related to the reflectivity of EWC cells. In order to achieve wide band and low loss simultaneously, it is necessary to obtain higher reflectivity.
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