| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave(SAW) device capable of being miniaturized by delaying transmission speed and having a high electric/ mechanical connection coefficient (K2) characteristic and low temperature characteristic by specifying the relation between the pitch of an electrode and the thickness of a piezoelectric substrate. SOLUTION: This SAW device 5 has a glass substrate 1, a piezoelectric substrate 2 and electrodes 3. The piezoelectric substrate 2 is formed on the glass substrate 1 and consists of LT. The electrodes 3 having arrangement corresponding to the device are formed on the piezoelectric substrate 2. When the thickness of the piezoelectric substrate 2 is H, the pitch of the electrodes 3 isλand K is 2π/λ, KH is regulated to 0.5-1.5. Since the glass substrate 1 has a material whose sound velocity is slower than the LT substrate 2, the sound velocity of SAW can be delayed. Thus, the electrode pitchλcan be reduced. Since electric field distribution differs by the thickness H of the LT substrate 2 and the electrode pitchλ, the SAW can effectively be excited and K2 is improved.
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