| 摘要 |
PROBLEM TO BE SOLVED: To provide a surface acoustic wave resonator and the like having excellent characteristics capable of reducing the deterioration of insertion loss while widely holding passband width and capable of improving the flatness of a passband. SOLUTION: A plurality of IDT electrodes 2 to 7 are arranged on a piezoelectric substrate 1, two adjacent IDT electrodes 3, 4 out of the IDT electrodes 2 to 7 are respectively constituted of first parts L2, L3 each of which is a part from the end of the opposite side and has an electrode finger pitch different from that of the remaining part and second parts L1, L4 each of which is the remaining part and has a fixed electrode finger pitch. The average value of the electrode finger pitches of the first parts L2, L4 is shorter than the electrode finger pitch of the second parts L1, L4, the electrode finger pitches of the first parts L2, L3 are made shorter toward the boundary of the two adjacent IDT electrodes 3, 4, and when it is defined that the minimum value of the electrode finger pitches of the first parts L2, L3 is P1 and the minimum value of the electrode finger pitches of the second parts L1, L4 is P2, P1/P2 > 0.9 is formed. COPYRIGHT: (C)2007,JPO&INPIT
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