| 摘要 |
PROBLEM TO BE SOLVED: To obtain a longitudinally coupled resonator surface acoustic wave (SAW) filter, not only achieving a wider band but also significantly reducing the insertion loss in the pass band. SOLUTION: A longitudinally coupled resonator type surface acoustic wave filter includes at least three IDTs 13-15, each having a plurality of electrode fingers along the propagation direction of the surface acoustic wave provided on a piezoelectric substrate 2. In at least one of the IDTs 13-15, the electrode finger period of a narrow pitch section that is part of other adjacent IDT ends in the propagation direction of the surface acoustic wave is smaller than the electrode finger period of the remaining sections of the IDTs, and 0-th order mode, second-order mode, and inter-IDTs resonance modes are used. COPYRIGHT: (C)2006,JPO&NCIPI
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