| 摘要 |
PROBLEM TO BE SOLVED: To obtain a longitudinally coupled resonator surface acoustic wave (SAW) filter capable of not only achieving, a wider band but also significantly reducing the insertion loss in the passband. SOLUTION: The longitudinally coupled resonator SAW filter 1 is provided with at least three IDTs (interdigital transducers) 13-15, each having electrode fingers in the propagation direction of an SAW on a piezoelectric substrate 2. In at least one of the IDTs 13-15, the electric finger period of a first portion, which is one part from the end portion of another IDT adjacent in the propagation direction of the SAW, is set different from the electrode finger period of a second portion which is the remaining part of the IDT. COPYRIGHT: (C)2003,JPO
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