Surface acoustic wave branching filter

Details Surface acoustic wave branching filter Surface acoustic wave branching filter

2003-05-14

2004-11-23

Callahan, Timothy P. (Department: 2816)

Wave transmission lines and networks

Coupling networks

Electromechanical filter

C310S31300R

Reexamination Certificate

active

06822537

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to surface acoustic wave branching filters for use as branching filters that are connected to, for example, antenna portions of wireless communication apparatuses. More specifically, the present invention relates to a surface acoustic wave branching filter having a structure in which first and second surface acoustic wave filter chips having different center frequencies are joined via bumps provided on the surface acoustic wave filter chips, to a wiring pattern provided on a packaging member.
2. Description of the Related Art
In recent years in order to achieve further miniaturization, various branching filters using surface acoustic wave filters have been under development for use in compact wireless communications apparatuses, such as portable telephones.
In this type of surface acoustic wave filter branching filter, first and second surface acoustic wave filters having different center frequencies are mounted in a package. There is a strong demand for more secured isolation between the first and second surface acoustic wave filters.
One example of structures for improving the isolation is disclosed in Japanese Unexamined Patent Application Publication No. 5-167389 (Patent Document 1). Thus, as shown in
FIG. 19
, in a surface acoustic wave branching filter
201
described in Patent Document 1, first and second surface acoustic wave filter chips
203
and
204
are mounted in a packaging member
202
. The packaging member
202
has signal input/output terminals C
1
, C
2
, D
1
, and D
2
. The first surface acoustic wave filter chip
203
has signal input/output terminals A
1
and A
2
, and the second surface acoustic wave filter chip
204
has signal input/output terminals B
1
and B
2
. The signal input/output terminals A
1
, A
2
, B
1
, B
2
, C
1
, C
2
, D
1
, and D
2
are arranged such that a signal line connecting the signal input/output terminals A
1
, A
2
, and C
2
and a signal line connecting the signal input/output terminals B
1
, B
2
, and D
2
are arranged along two straight lines (X, Y) that cross each other at substantially right angles. With such an arrangement of the signal input/output terminals, inductive coupling is suppressed between the plurality of signal lines and the isolation is improved.
Meanwhile, Japanese Unexamined Patent Application Publication No. 8-18393 (Patent Document 2) teaches a branching-filter package shown in FIG.
20
. In this case, first and second surface acoustic wave filter chips
212
and
213
are accommodated in a branching-filter package
211
having a multilayer structure. Striplines
214
and
215
are embedded in the branching-filter package
211
to constitute phase matching circuits. The characteristic impedances of the striplines
214
and
215
are greater than the characteristic impedance of an external circuit that is connected to the branching-filter package. In addition, at least two ground terminals are provided in the package for one surface acoustic wave filter chip, thereby improving the attenuation.
In a surface acoustic wave branching filter disclosed in Japanese Unexamined Patent Application Publication No. 2003-51731 (Patent Document 3), surface acoustic wave chips that constitute first and second surface acoustic wave filters are accommodated in a package. In this case, the first and second surface acoustic wave filters are electrically connected to terminal electrodes arranged in the package using bonding wires. In this surface acoustic wave branching filter, a bonding wire that is connected to a signal terminal and a bonding wire that is connected to a ground terminal cross each other in the first surface acoustic wave filter, thereby improving the isolation and attenuation.
In the configuration described in Patent Document 1, the signal lines of the first and second surface acoustic wave filter chips are arranged in a manner described above to suppress mutual inductive coupling therebetween. However, with this arrangement, although the mutual inductance can be suppressed to some extent, the suppression is still not enough. Thus, with the surface acoustic wave branching filter
201
, the isolation between the first and second surface acoustic wave filter chips is not sufficient.
Additionally, when a mounting displacement between the first and second surface acoustic wave filter chips occurs, there is a problem in that the attenuation and isolation characteristics deteriorate to a great extent.
Meanwhile, for the configuration described in Patent Document 2, when it is applied to a flip-chip-bonding system packaging structure having low inductance components, the attenuation cannot be sufficiently improved because of its low inductance components.
The surface acoustic wave branching filter described in Patent Document 3 achieves cancellation of current due to mutual inductance, by crossing the bonding wires. This structure, however, makes it difficult to achieve miniaturization of a surface acoustic wave branching filter because of the use of bonding wires.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide a surface acoustic wave branching filter that has first and second surface acoustic wave filter chips mounted with bumps in a packaging member by a flip-chip bonding system, that allows miniaturization, that further improves isolation between the surface acoustic wave filter chips, that achieves a favorable attenuation characteristic, and that has small characteristic variations due to mounting displacement of the surface acoustic wave filter chips.
According to a first preferred embodiment of the present invention, a surface acoustic wave branching filter includes a first surface acoustic wave filter chip having a relatively low center frequency and a second surface acoustic wave filter chip having a relatively high center frequency which are joined using a plurality of bumps provided on the first and second surface acoustic wave filter chips to wiring patterns disposed on a chip-mounting surface of a packaging member. The surface acoustic wave branching filter includes a first surface acoustic wave filter chip that includes a plurality of SAW resonators and that has a plurality of bumps on the lower surface, a second surface acoustic wave filter chip that includes a plurality of SAW resonators and that has a plurality of bumps on the lower surface, and a packaging member to which the first and second surface acoustic wave filter chips are joined using the plurality of bumps. The chip mounting surface of the packaging member has, at least, a signal wiring pattern that is connected to an output end of the second surface acoustic wave filter chip and a ground wiring pattern that is connected to a ground potential of a SAW resonator that is in closest proximity to the output end of the second surface acoustic wave filter chip. The chip mounting surface has a signal via hole electrode and a ground via hole electrode which are connected to the signal wiring pattern and the ground wiring pattern, respectively, and which penetrate at least one portion of the packaging member. The signal wiring pattern is configured to have a pattern portion that is in closer proximity to the ground wiring pattern than to the bump, joined to the signal wiring pattern, of the second surface acoustic wave filter chip.
In the first preferred embodiment of the present invention, the signal wiring pattern is bent so as to be in close proximity to the ground wiring pattern. Thereby, the signal wiring pattern has a pattern portion that is in close proximity to the ground electrode pattern.
In the first preferred embodiment of the present invention, the signal wiring pattern has first, second, and third wiring pattern portions. The first wiring pattern portion extends substantially parallel to an edge of the ground wiring pattern at a portion in close proximity to the ground wiring pattern. The second and third wiring pattern portions are bent from two opposite ends of the

Affiliated with

Also associated with

Rating

Surface acoustic wave branching filter does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Surface acoustic wave branching filter, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Surface acoustic wave branching filter will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3349232