Band attenuation filter, extractor, and communication device

Abstract

To provide a band attenuation filter capable of adjusting the width of a pass band.SOLUTION: The BE filter 7 includes a plurality of series arms 21 and one or more parallel arms 23. The plurality of series arms 21 are connected in series to each other. The one or more parallel arms 23 respectively connect one or more nodes 15 between the plurality of serial arms 21 and the reference potential part 13. The plurality of series arms 21 include a series arm 19A including the inductor 21A and a series arm 19B including the inductor 21B. The inductor 19A and the inductor 19B are inductively coupled. The series resonators 19A connected in series to the inductors 19B and 17X may be located between the inductors LA and LA. Additionally / alternatively, the series arm 21A and the series arm 21B may be connected in series to each other without the other series arm 21 interposed therebetween, and the inductor 19A and the inductor 19B may be cumulatively coupled to each other.SELECTED DRAWING: Figure 1

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