Filter chip and filter device
View Patent ↗A filter chip includes multiple series-arm resonators arranged in series arms of a ladder arrangement, and multiple parallel-arm resonators arranged in parallel arms of the ladder arrangement. A common line is connected to first electrodes of at least two parallel-arm resonators among the multiple parallel-arm resonators. Second electrodes of said at least two parallel-arm resonators are connected to associated series-arm resonators among the multiple series-arm resonators.
1. A filter chip comprising:
multiple series-arm resonators arranged in series arms of a ladder arrangement;
multiple parallel-arm resonators arranged in parallel arms of the ladder arrangement; and
a common line connected to first electrodes of at least two parallel-arm resonators among the multiple parallel-arm resonators, second electrodes of said at least two parallel-arm resonators being connected to associated series-arm resonators among the multiple series-arm resonators, wherein:
the multiple series-arm resonators are arranged in line from an input electrode of the filter chip to an output electrode thereof;
the multiple parallel-arm resonators are aligned with the multiple series-arm resonators; and
the second electrodes of the multiple parallel-arm resonators are integrally formed with electrodes of any of the multiple series-arm resonators.
2. The filter chip as claimed in claim 1 , wherein first electrodes of all the multiple parallel-arm resonators are connected to the common line.
3. The filter chip as claimed in claim 1 , wherein the common line has a ring shape.
4. The filer chip as claimed in claim 1 , wherein the common line is arranged so as to surround the multiple series-arm resonators and the multiple parallel-arm resonators.
5. The filter chip as claimed in claim 1 , wherein the common line is a conductive thin-film.
6. The filter chip as claimed in claim 1 , wherein:
the common line is a conductive thin-film; and
a conductive layer is provided on the common line.
7. The filter chip as claimed in claim 1 , wherein the common line is made of a material identical to that of the first electrodes of the multiple parallel-arm resonators, and is integrally formed with the first electrodes of the multiple parallel-arm resonators.
8. The filter chip as claimed in claim 1 , wherein the common line has extensions that extend from a body of the common line toward the first electrodes of the multiple parallel-arm resonators.
9. The filter chip as claimed in claim 1 , wherein the common line has extensions that extend from a body of the common line and reach the first electrodes of the multiple parallel-arm resonators.
10. The filter chip as claimed in claim 1 , wherein the multiple series-arm resonators and the multiple parallel-arm resonators form a band-pass filter.
11. The filter chip as claimed in claim 1 , wherein the common line has a ring shape that surrounds all the multiple series-arm resonators, all the multiple parallel-arm resonators, and an input electrode of the filter chip and an output electrode of the filter chip.
12. The filter chip as claimed in claim 1 , wherein the multiple series-arm resonators and the multiple parallel arm resonators are piezoelectric thin-film resonators.
13. The filter chip as claimed in claim 1 , wherein the common line is formed by a thin film that also forms the first electrodes of the multiple parallel-arm resonators.
14. The filter chip as claimed in claim 1 , wherein:
the filter chip comprises a substrate, and a laminate formed on the substrate;
the laminate comprises a layer that forms the first electrodes of the multiple parallel-arm resonators and another layer that forms the second electrodes thereof; and
the common line is formed by said layer.
15. The filter chip as claimed in claim 1 , wherein the second electrodes of the multiple parallel-arm resonators are closer to a substrate of the filter chip than the first electrodes thereof.
16. The filter chip as claimed in claim 1 , wherein:
the multiple series-arm resonators and the multiple parallel-arm resonators are formed on a substrate; and
the substrate has cavities via which electrodes of the multiple series-arm resonators and either the first or second electrodes of the multiple parallel-arm resonators are exposed via the cavities from a backside of the substrate.
17. The filter chip as claimed in claim 1 , wherein the multiple series-arm resonators and the multiple parallel-arm resonators are respectively surface acoustic wave resonators.
18. A filter chip comprising:
multiple series-arm resonators arranged in series arms of a ladder arrangement;
multiple parallel-arm resonators arranged in parallel arms of the ladder arrangement; and
a common line connected to first electrodes of at least two parallel-arm resonators among the multiple parallel-arm resonators, second electrodes of said at least two parallel-arm resonators being connected to associated series-arm resonators among the multiple series-arm resonators,
wherein the second electrodes of the multiple parallel-arm resonators are farther from a substrate of the filter chip than the first electrodes thereof.
19. A filter device comprising:
a package; and
a filter chip accommodated in the package, the filter chip comprising:
multiple series-arm resonators arranged in series arms of a ladder arrangement;
multiple parallel-arm resonators arranged in parallel arms of the ladder arrangement; and
a common line connected to first electrodes of at least two parallel-arm resonators among the multiple parallel-arm resonators, second electrodes of said at least two parallel-arm resonators being connected to associated series-arm resonators among the multiple series-arm resonators,
wherein the common line is connected to pads provided on the package by connecting members;
the multiple series-arm resonators are arranged in line from an input electrode of the filter chip to an output electrode thereof;
the multiple parallel-arm resonators are aligned with the multiple series-arm resonators; and
the second electrodes of the multiple parallel-arm resonators are integrally formed with electrodes of any of the multiple series-arm resonators.
20. The filter device as claimed in claim 19 , wherein the connecting members are bumps interposed between the common line and the pads.
21. The filter device as claimed in claim 19 , wherein:
the connecting members are bumps interposed between the common line and the pads; and
the filter chip is accommodated in the package in face-down mounting.
22. The filter device as claimed in claim 19 , further comprising a cap attached to the package, so that the filter chip is hermetically sealed.
23. A filter chip comprising:
multiple series-arm resonators arranged in series arms of a ladder arrangement;
multiple parallel-arm resonators arranged in parallel arms of the ladder arrangement; and
a common line connected to first electrodes of at least two parallel-arm resonators among the multiple parallel-arm resonators, second electrodes of said at least two parallel-arm resonators being connected to associated series-arm resonators among the multiple series-arm resonators,
the common line having a ring shape provided so as to surround the multiple series-arm resonators and the multiple parallel-arm resonators,
wherein the common line has a linear portion to which the first electrodes of all the multiple parallel-arm resonators are connected.
24. A filter chip comprising:
multiple series-arm resonators arranged in series arms of a ladder arrangement;
multiple parallel-arm resonators arranged in parallel arms of the ladder arrangement; and
a common line connected to first electrodes of at least two parallel-arm resonators among the multiple parallel-arm resonators, second electrodes of said at least two parallel-arm resonators being connected to associated series-arm resonators among the multiple series-arm resonators,
wherein the common line has a closed loop having a linear portion to which the first electrodes of all the multiple parallel-arm resonators are connected.