| 摘要 |
PROBLEM TO BE SOLVED: To improve the attenuation gradient on the low-frequency side of a pass band by connecting multiple surface acoustic wave resonators in a ladder style and setting the IDT electrode cycle of surface acoustic wave resonators of parallel arms except the outermost side larger than that of the outermost parallel arms. SOLUTION: On a piezoelectric substrate 1, surface acoustic wave(SAW) resonators 2 to 6 are arranged. The connection parts of the bus bars of SAW resonators 2 and 3, and 5 and 6 are regarded as bonding pads for input and output. Other bus bars of the SAW resonators 2, 4, and 6 are regarded as a electrode pad 8 for grounding. The connection parts of the bus bars of the SAW resonators 3 and 4 and the other bus bar of the SAW resonator 5 are connected by a signal lead electrode 7. The IDT electrode cycleλof the outermost-side SAW resonators 2 and 6 of the ladder type SAW filter which is thus constituted and the IDT electrode cycleλ1 of other SAW resonators 4 are so set that 1<λ2/λ1<1.017.
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