title: Resonator filters using shear horizontal-type leaky surface acoustic wave consisting of heavy-metal electrode and quartz substrate.
abstract: The authors have succeeded in exciting a new type of leaky surface acoustic wave (LSAW) having only a shear horizontal (SH) component that has a large electromechanical coupling factor, a large reflection coefficient, and excellent temperature stability, by combining interdigital transducers (IDTs) and reflectors made of heavy-metal films such as gold (Au), tantalum (Ta), and tungsten (W) on the ST-cut 90 degrees X propagation (direction perpendicular to the X-axis) quartz substrate. This LSAW does not have a propagation decay. The square of the electromechanical coupling factor is 2.1-2.7 times larger than, the reflection coefficient is 30 times larger than, and the temperature characteristic is the same as those of a Rayleigh wave on an ST-cut X propagation quartz substrate. The authors applied this SH LSAW to resonators and resonator filters. As a result, we succeeded in developing the low loss and very small-sized resonators and resonator filters (1/5-1/4 of conventional device sizes) with IDTs with a small number of finger pairs and very small reflectors, for the first time.
authors.affiliation: Murata Mfg. Co., Ltd. Nagaokakyo-shi, Kyoto 617-8555, Japan. kadota@murata.co.jp
authors.forename: Michio
authors.initials: M
authors.lastname: Kadota
authors.forename: Toshimaro
authors.initials: T
authors.lastname: Yoneda
authors.forename: Koji
authors.initials: K
authors.lastname: Fujimoto
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nakao
authors.forename: Eiichi
authors.initials: E
authors.lastname: Takata