| 摘要 |
<P>PROBLEM TO BE SOLVED: To ensure a constant amount of attenuation at a specific frequency. <P>SOLUTION: A filter includes: a plurality of series resonators S1-S4 and a plurality of parallel resonators P1-P4 connected in a ladder; and a first inductor L1 connected in parallel with at least one series resonator S1 of the plurality of series resonators. A part P3a of the plurality of parallel resonators has a resonance frequency frp3 and an antiresonance frequency fap3 outside a passband formed by the plurality of series resonators and the plurality of parallel resonators which are on a higher frequency side of a first attenuation pole 10 formed by the first inductor and at least one series resonator. At least one of the part of the plurality of parallel resonators has a resonance frequency frp31 of sub resonance on a lower frequency side of the resonance frequency. <P>COPYRIGHT: (C)2013,JPO&INPIT |
