Laminated LC component with rotationally symmetric capacitor...

Details Laminated LC component with rotationally symmetric capacitor... Laminated LC component with rotationally symmetric capacitor...

1999-04-19

2002-11-05

Bettendorf, Justin P. (Department: 2817)

Wave transmission lines and networks

Coupling networks

Frequency domain filters utilizing only lumped parameters

C333S184000, C361S321200

Reexamination Certificate

active

06476690

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a laminated LC component, and more particularly, to a laminated LC component for use as a noise filter or the like in a high-frequency electronic circuit.
2. Description of the Related Art
FIGS. 5 and 6
illustrate an example of a conventional laminated LC component of the above-described type. The laminated LC component
1
includes insulating sheets
2
having respective coil conductors
21
-
28
provided on the surface of the respective insulating sheets
2
, insulating sheets
2
having respective capacitor electrodes
31
and
32
disposed on the surface of the respective insulating sheets
2
, and a cover sheet
2
. These sheets
2
have a rectangular shape.
The coil conductors
21
-
24
are electrically connected in series through via-holes
33
a-
33
c
formed in the insulating sheets
2
so that the connected coil conductors define a helical coil L
11
. Similarly, the coil conductors
25
-
28
are electrically connected in series through via-holes
33
j-
33
l
formed in insulating sheets
2
so that the connected coil conductors define a helical coil L
12
. The capacitor electrodes
31
and
32
face each other with the insulating sheet
2
disposed therebetween such that a capacitor C
11
is formed thereby. The plurality of capacitor electrodes
31
are electrically connected to one another through via-holes
33
e-
33
h
formed in insulating sheets
2
.
An end of the coil L
11
(more specifically, an end of the coil conductor
24
) is electrically connected through a via-hole
33
d
to the capacitor electrode
31
which functions as one electrode of the capacitor C
11
. Similarly, an end of the coil L
12
(more specifically, an end of the coil conductor
25
) is electrically connected through a via-hole
33
i
to the capacitor electrode
31
which functions as an electrode of the capacitor C
11
. Both ends
32
a
and
32
b
of the capacitor electrode
32
are exposed at the front side and rear side, respectively, of the insulating sheet
2
.
The insulating sheets
2
are stacked on one another and fired into the form of a single unitary laminated block
15
as shown in FIG.
6
. External input/output electrodes
11
and
12
are formed on the left and right ends, respectively, of the laminated block
15
, and external ground electrodes
13
a
and
13
b
are formed on the front and rear side surfaces
15
c
and
15
d,
respectively. An end of the coil L
11
(more specifically, an end of the coil conductor
21
) is electrically connected to the external input/output electrode
11
and an end of the coil L
12
(more specifically, an end of the coil conductor
28
) is electrically connected to the external input/output electrode
12
. The ends
32
a
and
32
b
of the capacitor electrodes
32
are electrically connected to the external ground electrodes
13
a
and
13
b,
respectively.
FIG. 7
is an equivalent electric circuit diagram of the laminated LC component
1
obtained in the above-described manner.
In the conventional laminated LC component
1
, external ground electrodes
13
a
and
13
b
are provided only on the front and rear side surfaces
15
c
and
15
d.
As a result, the mounting surface of the laminated type LC component
1
is limited to either the upper side surface
15
a
or the lower side surface
15
b
of the laminated block
15
. That is, the LC component
1
has directivity in terms of mounting orientation.
One possible technique to solve the above problem associated with the mounting directivity is to form an external ground electrode into the form of a band circumferentially extending over the four side surfaces of the laminated block
15
. However, when the external ground electrode is simply formed along the entire circumference over the side surfaces
15
a-
15
d,
the ends
32
a
and
32
b
of the capacitor ground electrode
32
of the capacitor C
11
formed in the laminated block
15
are exposed only at the side surfaces
15
c
and
15
d
of the laminated block
15
and thus, the length of the conductor path between the external ground electrode to the capacitor electrode
32
varies depending on which of the side surfaces
15
a-
15
d
is used as the mounting surface. Therefore, the high-frequency characteristics of the LC component
1
vary depending on the mounting surface that is used. That is, the LC component
1
has directivity in terms of the component characteristics.
Furthermore, because the laminated block
15
has a rectangular shape in lateral cross section, the external ground electrode formed along the entire circumference over the side surfaces
15
a-
15
d
has different shapes between the side surfaces
15
a,
15
b
and the side surfaces
15
c,
15
d.
Therefore, when the external ground electrode is produced, two different sets of jigs or tools are required. This results in a reduction in productivity efficiency.
SUMMARY OF THE INVENTION
To overcome the problems described above, preferred embodiments of the present invention provide a laminated LC component having no directivity in terms of mounting and component characteristics.
According to one preferred embodiment of the present invention, a laminated LC component includes a laminated block having a substantially square shape in lateral cross section and a plurality of insulating layers, a plurality of coil conductors, and a plurality of capacitor electrodes, a coil formed by electrically connecting the plurality of coil conductors, the coil having an axis that is substantially parallel to a stacking direction of the laminated block and also substantially parallel to the mounting surface of the laminated block; a capacitor defined by the plurality of capacitor electrodes, the capacitor being electrically connected to the coil, an external input/output electrode disposed on an end of the laminated block, and an external ground electrode having a band shape and extending along a circumference over four side surfaces of the laminated block, wherein the ends of the capacitor electrode, at the ground side, of the capacitor are exposed at the four respective side surfaces of the laminated block and the ends of the capacitor electrode are electrically connected, at the four side surfaces, to the external ground electrode, and wherein any of the four side surfaces is arranged to be usable as a mounting surface.
In the laminated type LC component constructed in the above-described manner, because the external ground electrode has a band shape extending along the circumference of the laminated block over the four side surfaces, there is no directivity in terms of mounting. Furthermore, because the ends of the capacitor ground electrode of the capacitor are electrically connected, at the four respective side surfaces, to the external ground electrode, the length of the conductor path from a ground pattern on a circuit board to the capacitor ground electrode via the external ground electrode becomes substantially equal whichever of the four side surfaces is used as the mounting surface. Therefore, the LC component has substantially equal high-frequency characteristics regardless of which of the four side surfaces of the laminated block is used as the mounting surface. That is, the LC component has no directivity in terms of the component characteristics.


REFERENCES:
patent: 5357227 (1994-10-01), Tonegawa et al.
patent: 5392019 (1995-02-01), Ohkubo
patent: 6147573 (2000-11-01), Kumagai et al.

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