| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave element without causing dispersion in frequencies and increase in a propagation loss, with ease of manufacture and an enhanced frequency temperature characteristic, and to provide a transmission filter and a reception filter provided with the surface acoustic wave element, and a duplexer having the filters. SOLUTION: The piezoelectric substrate 10 of a joined substrate 100 is composed of lithium tantalate (LT), a support substrate 20 is composed of sapphire, and the substrates above are configured so that a substrate thickness ratio T/t is smaller than 1/3, wherein T is the substrate thickness of the substrate 10 and t is the substrate thickness of the substrate 20 thereby being capable of stably improving the frequency temperature characteristic. Further, when the SAW element 110 above is used for the duplexer or the like, the SAW element 110 is configured such that the thickness T of the piezoelectric substrate 10 is greater than ten times of a wavelengthλof a SAW. Thus, it is possible to suppress spurious response being a cause for the disturbance of the characteristic of an adjacent pass band. COPYRIGHT: (C)2004,JPO&NCIPI
|
