| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter device having an excellent attenuation property where there is no unnecessary jumping at a higher-frequency side than a passband. SOLUTION: The filter device includes: a laminate 1 in which dielectric layers 1a are laminated; ground electrodes 2a, 2a disposed while facing each other with the laminate 1 therebetween; a plurality of resonator electrodes 3a-3c, each having a short-circuiting terminal and an open terminal, laterally aligned so as to couple electromagnetic fields within the laminate 1; an input coupling electrode 4 and an output coupling electrode 5, which face each other along with the first-stage and final-stage resonator electrode 3a and 3c to couple electromagnetic fields, having an input point and an output point of electrical signals at open terminal sides of the first-stage and the final-stage resonator electrodes 3a and 3c; and an auxiliary coupling electrode 6 which is electrically connected to at least one of the input coupling electrode 4 and the output coupling electrode 5 and couples electromagnetic fields while facing an electrode connected to a ground potential. Unnecessary jumping that occurs at a high-frequency side of attenuation property is canceled by an attenuation pole shifted to a desired frequency by the auxiliary coupling electrode 6. COPYRIGHT: (C)2009,JPO&INPIT
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