| 摘要 |
PROBLEM TO BE SOLVED: To achieve miniaturization simultaneously with a sufficient insertion loss and a sufficient attenuation rate for a vertical dual-mode SAW (Surface Acoustic Wave) filter comprising a first and a second IDTs (interdigital transducer) along the propagation direction of SAWs on a piezoelectric substrate and reflectors at the both sides. SOLUTION: Logarithms Nidt1 and Nidt2 of an interdigital electrode constituting a first and a second IDTS 3 and 4 and a logarithm Nr of a reflector electrode constituting each of reflectors 5 and 6 are selected so that the total logarithm N for them may be set to 0.11≤Nr/N≤0.20. Furthermore, when each end side 12a of a piezoelectric substrate 12 intersecting with the SAW propagation direction is made to incline at an angle of four degrees or more in relation to a direction perpendicular to the SAW propagation direction, impact of SAW reflected from the end face is suppressed. COPYRIGHT: (C)2008,JPO&INPIT
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