| 摘要 |
PROBLEM TO BE SOLVED: To secure a wide attenuating area without sacrificing the insertion loss of a pass band in a surface acoustic wave(SAW) filter. SOLUTION: Plural serial arm SAW resonators 211-214 and parallel arm SAW resonators 221-224 are connected in a multistage ladder shape in order to secure an attenuating quantity in the attenuating area. The electrodes of the serial arm SAW resonators 211-214, among the resonators are respectively different in specific gravity. Therefore, sound speed is different in the respective SAW resonators 211-214 and the frequency of an attenuating pole generated by each resonator is different so that the band of the attenuating area constituted by the whole SAW filter is widened.
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