| 摘要 |
PROBLEM TO BE SOLVED: To provide a filter device which is small-sized, facilitates the adjustment of a passband bandwidth and has sharp attenuation characteristics on both sides of a passband. SOLUTION: Disclosed is a filter device including: first and second ground electrodes 2a and 2b disposed to face each other across a laminate of dielectric layers; a plurality of resonator electrodes 3; a plurality of short-capacitance electrodes 4 opposed to the second ground electrode 2b; a coupling capacitance electrode 5 which is disposed oppositely to the second ground electrode 2b with respect to the short-capacitance electrodes 4 and of which terminal portions face adjacent two short-capacitance electrodes 4; an auxiliary capacitance electrode 6 which is located oppositely to the short-capacitance electrodes 4 with respect to the coupling capacitance electrode 5 and faces the terminal portions of the coupling capacitance electrode 5 and of which one terminal is connected to an open terminal of the resonator electrodes 3 by a first through-conductor 7 and another terminal is connected to a terminal portion of the short-capacitance electrodes 4 by a second through-conductor 8; and an external terminal connected to an initial stage and a final stage of the auxiliary capacitance electrode. The filter device facilitates the adjustment of a passband bandwidth and has sharp attenuation characteristics on both sides of a passband. COPYRIGHT: (C)2011,JPO&INPIT
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