Kadota Michio, Yoneda Toshimaro, Fujimoto Koji, Nakao Takeshi, Takata Eiichi
Murata Mfg. Co., Ltd. Nagaokakyo-shi, Kyoto 617-8555, Japan.
IEEE Trans Ultrason Ferroelectr Freq Control. 2004 Feb;51(2):202-10.
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.
作者通过在ST切割90度X传播（垂直于X轴的方向）石英基板上，将叉指换能器（IDT）与由金（Au）、钽（Ta）和钨（W）等重金属薄膜制成的反射器相结合，成功激发了一种新型漏表面声波（LSAW），该LSAW仅具有水平切变（SH）分量，具有大的机电耦合系数、大的反射系数和优异的温度稳定性。这种LSAW没有传播衰减。其机电耦合系数的平方比ST切割X传播石英基板上瑞利波的大2.1 - 2.7倍，反射系数大30倍，温度特性相同。作者将这种SH LSAW应用于谐振器和谐振器滤波器。结果，首次成功开发出具有少量指对的IDT和非常小的反射器的低损耗、超小型谐振器和谐振器滤波器（尺寸为传统器件的1/5 - 1/4）。
