Filter circuit and communication device
To achieve a filter circuit that is configured to have a good frequency rejection characteristic and suppress an increase in size due to mounting, in a more preferred aspect. A filter circuit includes a first signal line that is arranged to extend longitudinally, and a second signal line that is arranged to extend in parallel with the first signal line, in which the second signal line has one end that is electrically connected to the first signal line, and the other end that is open, in a longitudinal direction, and a length in the longitudinal direction that is determined according to a frequency of a signal to be blocked of signals transmitted through the first signal line.
1. A filter circuit, comprising:
a first signal line that is arranged to extend longitudinally; and
a plurality of second signal lines that are arranged to extend in parallel with the first signal line,
wherein each of the second signal lines has:
one end that is electrically connected to the first signal line, and another end that is open, in a longitudinal direction, and
a length in the longitudinal direction that is determined according to a frequency of a signal to be blocked of signals transmitted through the first signal line,
wherein at least one of the plurality of second signal lines and another of the plurality of second signal lines are arranged so that the first signal line is positioned therebetween and each of the one of the plurality second signal lines, the another of the plurality of second signal lines, and the first signal line are arranged in different layers in a substrate having a laminated structure.
2. The filter circuit according to claim 1 , wherein the some of the plurality of second signal lines each have end portions in a direction in which the second signal line extends in parallel with the first signal line, and of the end portions, an end portion is electrically connected to the first signal line and located on the opposite side to an end portion where each of the other second signal lines is electrically connected to the first signal line.
3. The filter circuit according to claim 1 , wherein, of the plurality of the second signal lines, some of the second signal lines are arranged at positions different from positions where other second signal lines are arranged, in positions in a longitudinal direction of the first signal line.
4. The filter circuit according to claim 1 , wherein the plurality of second signal lines are arranged on a substrate on which the first signal line is arranged.
5. The filter circuit according to claim 1 , wherein the first signal line and the second signal lines that are arranged in a plurality of respective different layers are electrically connected through a via arranged so as to penetrate the plurality of layers.
6. The filter circuit according to claim 1 , wherein, of the plurality of the second signal lines, lengths of some of the second signal lines in a longitudinal direction are each determined according to a first frequency, and lengths of other second signal lines in a longitudinal direction are each determined according to a second frequency.
7. The filter circuit according to claim 1 , wherein, in a first region including a portion where at least one of the second signal lines is electrically connected of a region in a longitudinal direction, the first signal line is formed to have a line width smaller than a line width in a second region different from the first region.
8. The filter circuit according to claim 7 , wherein at least one of a width of the first region and a line width of the first signal line in the first region is determined according to an electrical characteristic of the at least one of the second signal lines.
9. A communication device comprising:
a transceiver that controls a radio signal to be transmitted or received via an antenna; and
a filter circuit that is arranged so as to be interposed between the antenna and the communication unit,
wherein the filter circuit includes
a first signal line that is arranged so as to extend longitudinally, and
a plurality of second signal lines that are arranged to extend in parallel with the first signal line,
wherein each of the second signal lines has
one end that is electrically connected to the first signal line, and another end that is open, in a longitudinal direction, and
a length in the longitudinal direction that is determined according to a frequency of a signal to be blocked, of signals transmitted through the first signal line,
wherein at least one of the plurality of second signal lines and another of the plurality of second signal lines are arranged so that the first signal line is positioned therebetween and each of the one of the plurality second signal lines, the another of the plurality of second signal lines, and the first signal line are arranged in different layers in a substrate having a laminated structure, and
the first signal line has one end that is electrically connected to the antenna, and another end that is electrically connected to the transceiver, in a longitudinal direction.