| 摘要 |
PROBLEM TO BE SOLVED: To reduce the amount of frequency variation after long-term aging in a SAW (Surface Acoustic Wave) device using a crystal substrate. SOLUTION: A transversal surface acoustic wave filter employs a rotation Y cut X propagation crystal substrate as a piezoelectric substrate, and comprises two pieces of IDT electrodes formed with a pair of comb type electrodes having an electrode finger fit into each other on the piezoelectric substrate and arranged at a predetermined spacing in a propagation direction of a surface acoustic wave. A silicon dioxide (SiO<SB>2</SB>) insulating film of thickness of not less than 200Åand not more than 300Åis provided on and around a propagation path of the surface acoustic wave. COPYRIGHT: (C)2005,JPO&NCIPI
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