LC-included electronic component

Details LC-included electronic component LC-included electronic component

2001-04-17

2003-06-24

Ham, Seungsook (Department: 2817)

Wave transmission lines and networks

Coupling networks

Frequency domain filters utilizing only lumped parameters

C333S185000

Reexamination Certificate

active

06583686

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to LC-included electronic components, and in particular, to an LC-included electronic component for use in a high frequency band.
2. Description of the Related Art
A conventional laminated LC filter is shown in
FIGS. 10 and 11
. As shown in
FIG. 10
, a laminated LC filter
1
includes ceramic sheets
2
to
8
each having a plurality of inductor via holes
10
a
to
10
d
,
11
a
to
11
d
, and
12
a
to
12
d
, resonant capacitor patterns
13
to
15
, coupling capacitor patterns
19
to
26
, input/output lead patterns
30
and
31
, and shield patterns
28
and
29
.
The laminated unit
34
shown in
FIG. 11
is obtained by stacking the ceramic sheets
2
to
8
in the Z direction, covering the top and bottom surfaces of the sheets with protecting ceramic sheets, and monolithically burning the ceramic sheets. An input terminal P
1
, an output terminal P
2
, and ground terminals G
1
and G
2
are provided on the laminated unit
34
. The input/output lead pattern
30
is connected to the input terminal P
1
, and the input/output lead pattern
31
is connected to the output terminal P
2
. Ends of the shield patterns
28
and
29
are connected to the ground terminal G
1
and the other ends of the shield patterns
28
and
29
are connected to the ground terminal G
2
.
In the above-described LC filter
1
, the inductor via holes
10
a
to
10
d
,
11
a
to
10
d
, and
12
a
to
12
d
, which are arranged in the X direction in
FIG. 10
, are successively connected to one another in a direction in which the ceramic sheets are stacked, defining columnar inductors L
1
, L
2
, and L
3
. The resonant capacitor patterns
13
,
14
, and
15
are opposed to the shield pattern
29
, with the ceramic sheets
6
and
7
provided therebetween, defining resonant capacitors C
1
, C
2
, and C
3
, respectively. Accordingly, the columnar inductor L
1
and the capacitor C
1
define an LC resonator Q
1
, the columnar inductor L
2
and the capacitor C
2
define an LC resonator Q
2
, and the columnar inductor L
3
and the capacitor C
3
define an LC resonator Q
3
.
In general, filter characteristics of an LC filter are subject to resonator Q. The Q of the resonator is primarily determined by the Q of an inductor. The Q of the inductor is subject to a loss (resistance) of the inductor. Accordingly, to increase Q of the LC resonators Q
1
to Q
3
which define the LC filter
1
, the section areas on the X-Y plane of the columnar inductors L
1
to L
3
formed by successively connecting the via holes must be increased. However, since the conventional columnar inductors L
1
to L
3
have circular section shapes, the increased section areas narrow the intervals of the columnar inductors L
1
to L
3
, which are adjacent, and generate excessively strong inductive coupling. Therefore, to obtain the desired inductive coupling, the intervals of the columnar inductors L
1
to L
3
must be substantially widened, which results in a substantially increased product size.
In When the via holes
10
a
to
12
d
having section areas are provided on the ceramic sheets
2
to
5
to increase Q, cracks often occur in the laminated unit
34
when it is burned, due to the difference in thermal contraction between conductive material of the via holes
10
a
to
12
d
and insulating material of the ceramic sheets
2
to
5
. Thus, the section areas of the via holes
10
a
to
12
d
cannot be sufficiently increased.
SUMMARY OF THE INVENTION
To overcome the above-described problems with the prior art, preferred embodiments of the present invention provide a small-sized LC-included electronic component having an increased Q of a resonator and having outstanding reliability.
An LC-included component according to a preferred embodiment of the present invention includes an LC resonator having at least one inductor and at least one capacitor. The at least one inductor and the at least one capacitor are provided in a laminated unit defined by stacked insulating layers. The inductor is defined by via holes successively connected in a stack direction in which the insulating layers are stacked. In the section shape of each of the via holes on an X-Y plane perpendicular to the stack direction, a dimension in the X direction differs from a dimension in the Y direction.
By differentiating the X dimension and Y dimension of each via hole, a desired balanced inductive coupling and resonator Q are achieved, even when the section area of each via hole is increased.
In addition, by arranging the Y-direction ends of the section shape of each via hole defining the inductor to have a relatively large width, current concentration at each longitudinal end of each via hole due to the edge effect of high frequency current is reduced.


REFERENCES:
patent: 5834992 (1998-11-01), Kato et al.
patent: 5945892 (1999-08-01), Kato et al.
patent: 6124779 (2000-09-01), Yamamoto
patent: 1 079 520 (2001-02-01), None
patent: 08288142 (1996-11-01), None
patent: 9-035936 (1997-02-01), None
patent: 9-205018 (1997-08-01), None
patent: 09219315 (1997-08-01), None
patent: 2000165171 (2000-06-01), None

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