Wave transmission lines and networks – Coupling networks – Frequency domain filters utilizing only lumped parameters
Reexamination Certificate
2001-08-30
2003-07-01
Bettendorf, Justin P. (Department: 2817)
Wave transmission lines and networks
Coupling networks
Frequency domain filters utilizing only lumped parameters
C333S177000, C333S204000
Reexamination Certificate
active
06587020
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to multilayer LC composite components. More particularly, the present invention relates to multilayer LC composite components used in mobile communication apparatuses such as mobile phones.
2. Description of the Related Art
As a conventional multilayer LC composite component of this kind, there is known a multilayer LC filter having a structure as shown in FIG.
12
. In a multilayer LC composite component
1
, inductor patterns
8
and
9
and resonant capacitor patterns
10
and
11
are provided on a ceramic sheet
5
, a ground pattern
12
is disposed on a ceramic sheet
3
, a ground pattern
13
is disposed on a ceramic sheet
4
, a ground pattern
14
is disposed on a ceramic sheet
6
, and a ground pattern
15
is disposed on a ceramic sheet
7
.
The ceramic sheets
2
to
7
are stacked to be integrally burned so as to constitute a multilayer body
17
as shown in FIG.
13
. The multilayer body
17
includes an input terminal
18
, an output terminal
19
, and ground terminals G
1
and G
2
. The input terminal
18
is connected to an extended portion
8
a
of the inductor pattern
8
. The output terminal
19
is connected to an extended portion
9
a
of the inductor pattern
9
. The ground terminal G
1
is connected to the grounded portions of the inductor patterns
8
and
9
and one end of each of the ground patterns
12
to
15
. The ground terminal G
2
is connected to the resonant capacitor patterns
10
and
11
and the remaining ends of the ground patterns
12
to
15
.
In the above-described LC filter
1
, an LC resonator Q
1
is defined by an inductor L
1
composed of the inductor pattern
8
, a resonant capacitor C
1
that is defined by arranging the resonant capacitor pattern
10
opposite to the open-circuited end of the inductor pattern
8
, and a capacitor C
3
that is defined by arranging the inductor pattern
8
opposite to the ground patterns
12
to
15
. Similarly, an LC resonator Q
2
is defined by an inductor L
2
composed of the inductor pattern
9
, a resonant capacitor C
2
that is defined by arranging the resonant capacitor pattern
11
opposite to the open-circuited end of the inductor pattern
9
, and a capacitor C
4
that is defined by arranging the inductor pattern
9
opposite to the ground patterns
12
to
15
. In addition, in a direction in which the ceramic sheets
2
to
7
are stacked, a pair of the ground patterns
12
and
13
are arranged adjacent to each other above the LC resonators Q
1
and Q
2
, and a pair of the ground patterns
14
and
15
are arranged adjacent to each other below the LC resonators Q
1
and Q
2
.
In the multilayer LC filter, preferably, the widths of the extended portions of the ground patterns are broadened to reduce the inductances of the extended portions. On the other hand, such an arrangement causes separations to occur between the ground patterns and the ceramic sheets. This results from loosen bonds between the ground patterns and the ceramic sheets due to deteriorated contacts between them. Thus, usually, similar to the extended portions
12
a
to
15
a
of the ground patterns
12
to
15
shown in
FIG. 12
, the widths of the extended portions are narrowed and the extended portions are arranged to have a plurality of separate portions.
However, as shown in
FIG. 14
, the extended portions
12
a
and
13
a
of the ground patterns
12
are arranged in the same positions in plan view, and so are the extended portions
14
a
and
15
a
of the ground patterns
14
and
15
. As a result, magnetic fields generated at the extended portions
12
a
and
13
a
converge on the same portions, and the same phenomenon happens to the extended portions
14
a
and
15
a.
Thus, in the conventional multilayer LC filter
1
, the extended portions of the ground patterns
12
to
15
result in having significantly large inductances. Additionally, openings
16
are formed between the extended portions
12
a
and
12
a
and also formed between the extended portions
13
a
and
13
a.
However, this arrangement causes a problem in which electromagnetic waves generated inside the LC filter
1
leak to the outside through the openings
16
.
Furthermore, when the positions of the extended portions
12
a
to
15
a
deviate due to variations occurring in the manufacturing process, the areas of the openings
16
of the ground patterns
12
to
15
change in plan view. Then, the capacitances of the capacitors C
3
and C
4
composed of the inductor patterns
8
and
9
and the ground patterns
12
to
15
are changed. This causes variations in the filter characteristics of the filter
1
.
SUMMARY OF THE INVENTION
In order to overcome the problems described above, preferred embodiments of the present invention provide a multilayer LC composite component that minimizes the inductances of ground patterns to prevent electromagnetic waves from leaking outside the component.
According to a preferred embodiment of the present invention, a multilayer LC composite component includes a plurality of insulation layers stacked to define a multilayer body, an inductor and a capacitor arranged in the multilayer body to define LC resonators, at least two ground patterns arranged on two different insulation layers that are adjacent to each other, and the ground patterns arranged above or below the LC resonator in the direction in which the insulation layers are stacked, the two ground patterns electrically connected to an external ground electrode via extended portions respectively, the external ground electrode disposed on the multilayered body, wherein the extended portions of the ground patterns are arranged in different positions in plan view.
In addition, the LC composite component may further include a via-hole connected in the direction in which the insulation layers are stacked to define the inductor, and a capacitor pattern arranged to define the capacitor, in which one end of each inductor is electrically connected to the capacitor pattern of the capacitor defining the LC resonator and the other end of the inductor is electrically connected to the ground pattern.
With the above-described unique and novel arrangement, since the extended portions that are disposed on the different insulation layers are arranged in different positions in plan view, magnetic fields generated at the extended portions do not converge on the same portions. As a result, this arrangement minimizes the inductances of the extended portions.
Furthermore, the extended portions of the plurality of ground patterns may be arranged in a state in which no clearance is left between the extended portions in plan view. This arrangement prevents electromagnetic waves that are generated inside the component from leaking outside.
Other features, elements, characteristics, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention with reference to the attached drawings.
REFERENCES:
patent: 5392019 (1995-02-01), Ohkubo
patent: 5822174 (1998-10-01), Yamate et al.
patent: 2303495 (1997-02-01), None
patent: 4-11022 (1992-09-01), None
Williams, Electronic Filter Design Handbook, 1981, McGraw-Hill, New York, NY, pp. 5-19.
Bettendorf Justin P.
Keating & Bennett LLP
Murata Manufacturing Co. Ltd.
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