Information
-
Patent Grant
-
6414567
-
Patent Number
6,414,567
-
Date Filed
Monday, December 11, 200024 years ago
-
Date Issued
Tuesday, July 2, 200222 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Pascal; Robert
- Takaoka; Dean
Agents
-
CPC
-
US Classifications
Field of Search
US
- 333 134
- 333 126
- 333 204
- 333 219
- 333 185
- 333 132
-
International Classifications
-
Abstract
A duplexer having a laminated structure includes a first three-stage band-pass filter having parallel LC resonators, and a second three-stage band-pass filter having parallel LC resonators. The first and second three-stage band-pass filters are coupled through impedance matching patterns. An inductor of each of the resonators is defined by via-holes formed on insulator sheets which are connected in sequence in the laminating direction of the sheets.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a duplexer for use in communication systems such as microwave communication systems, and more particularly, to a duplexer having a laminated structure.
2. Description of the Related Art
A conventional laminated type duplexer is shown in
FIGS. 4 and 5
. Referring first to
FIG. 4
, a laminated duplexer
1
includes a laminated structure defined by ceramic sheets
2
to
9
. Inductor patterns
12
to
17
are provided on a surface of the ceramic sheet
6
. Frequency-adjusting capacitor patterns
18
to
23
are provided on a surface of the ceramic sheet
7
. Coupling-adjusting capacitor patterns
24
to
27
are provided on a surface of the ceramic sheet
5
. Shield patterns
28
a
and
29
a
are provided on a surface of the ceramic sheet
3
, and shield patterns
28
b
and
29
b
are provided on a surface of the ceramic sheet
9
.
The duplexer
1
includes a three-stage band-pass filter BPF
1
having LC resonators Q
1
to Q
3
at the left as viewed in
FIG. 4
, and a three-stage band-pass filter BPF
2
having LC resonators Q
4
to Q
6
at the right as viewed in FIG.
4
. The inductor patterns
12
to
17
define inductors L
1
to L
6
of the LC resonators Q
1
to Q
6
, respectively. The frequency-adjusting capacitor patterns
18
to
23
and the ends of the inductor patterns
12
to
17
which face the frequency-adjusting capacitor patterns
18
to
23
define capacitors Cl to C
6
of the LC resonators Q
1
to Q
6
, respectively.
The LC resonators Q
1
to Q
3
of the band-pass filter BPF
1
are electrically connected to coupling capacitors Cs
1
and Cs
2
(not shown in FIGS.
4
and
5
). The coupling and adjusting capacitors Cs
1
and Cs
2
are defined by the inductor patterns
12
to
14
and coupling-adjusting capacitor patterns
24
and
25
, which face these inductor patterns
12
to
14
. The shield patterns
28
a
and
28
b
are arranged such that the patterns
12
to
14
,
18
to
20
,
24
and
25
are positioned therebetween.
Likewise, the LC resonators Q
4
to Q
6
of the band-pass filter BPF
2
are electrically connected to coupling capacitors Cs
3
and Cs
4
(not shown). The coupling capacitors Cs
3
and Cs
4
are defined by the inductor patterns
15
to
17
and coupling-adjusting capacitor patterns
26
and
27
, which face the inductor patterns
15
to
17
. The shield patterns
29
a
and
29
b
are arranged such that the patterns
15
to
17
,
21
to
23
,
26
and
27
are positioned therebetween.
The ceramic sheets
2
to
9
are laminated, and are integrally fired to define a laminate
35
shown in FIG.
5
. The laminate
35
is provided with a transmitter terminal electrode Tx, a receiver terminal electrode Rx, an antenna terminal electrode ANT, and grounding terminal electrodes G
1
to G
4
. The inductor pattern
12
of the LC resonator Q
1
is connected to the transmitter terminal electrode Tx, and the inductor pattern
17
of the LC resonator Q
6
is connected to the receiver terminal electrode Rx. The inductor patterns
14
and
15
of the LC resonators Q
3
and Q
4
are connected to the antenna terminal electrode ANT. The grounding terminal electrode G
1
is connected to one end of each of the inductor patterns
12
to
14
, and the grounding terminal electrode G
2
is connected to one end of each of the frequency-adjusting capacitor patterns
18
to
20
in the LC resonators Q
1
to Q
3
. The grounding terminal electrodes G
1
and G
2
are also connected with the shield patterns
28
a
and
28
b
. The grounding terminal electrode G
3
is connected to one end of each of the inductor patterns
15
to
17
, and the grounding terminal electrode G
4
is connected to one end of each of the frequency-adjusting capacitor patterns
21
to
23
of the LC resonators Q
4
to Q
6
. The grounding terminal electrodes G
3
and G
4
are also connected with the shield patterns
29
a
and
29
b.
In general, duplexers have characteristics that depend upon the Q factor of inductors of LC resonators. The Q factor of an inductor is expressed by Q=2πf
0
L/R, where L represents the inductance of the inductor, R represents the resistance of the inductor, and f
0
represents the resonant frequency. From the equation, it is clear that the resistance R should be reduced to increase the Q factor of the inductor. The resistance R is inversely proportional to the cross-sectional area S of an inductor pattern that is used to define the inductor. To increase the Q factor of the inductor, therefore, the cross-sectional area S of the inductor patterns
12
to
17
must be increased.
However, increasing the thickness of the inductor patterns
12
to
17
to increase the cross-section S of the inductor patterns
12
to
17
produces undesirable results. Specifically, an internal strain of the laminate
35
is increased causing delamination when the ceramic sheets
2
to
9
are integrally fired. Furthermore, if pattern widths of the inductor patterns
12
to
17
are increased to increase the cross-section S of the inductor patterns
12
to
17
, the LC resonators Q
1
to Q
6
is greatly increased.
The axial directions of the inductors L
1
to L
6
of the LC resonators Q
1
to Q
6
are perpendicular to the stacking direction of the ceramic sheets
2
to
9
. When an electric current flows through the inductors L
1
to L
6
, a magnetic flux φ is generated so as to surround the inductors L
1
to L
6
on planes perpendicular to the axial directions of the inductors L
1
to L
6
. However, since the inductors L
1
to L
6
and the patterns
18
to
23
,
24
to
27
,
28
a
,
28
b
,
29
a
and
29
b
are arranged in parallel, the magnetic flux φpasses through the patterns
18
to
23
,
24
to
27
,
28
a
,
28
b
,
29
a
and
29
b
, so that eddy currents are generated in the patterns
18
to
23
,
24
to
27
,
28
a
,
28
b
,
29
a
and
29
b
. This produces inductors L
1
to L
6
that have very low Q factors.
SUMMARY OF THE INVENTION
To overcome the above-described problems, preferred embodiments of the present invention provide a laminated-type duplexer which is compact and which has inductors with very high Q factors.
To this end, preferred embodiments of the present invention include a laminated type duplexer having insulator layers which are laminated to define a laminate including a plurality of filters embedded therein, each of the filters having an inductor and a capacitor, wherein each inductor includes a via hole or via-holes connected in sequence in the stacking direction of the insulator layers, and at least two adjacent filters of the plurality of filters are electrically connected to each other through a matching inductor pattern.
Since the inductor is defined by the via-holes connected in sequence, increasing the cross-section of each via-hole or increasing the number of via-holes results in increased cross-sectional area of the inductor. This improves the Q factor of the inductor without increasing the thickness or width of inductor patterns in conventional technique.
When an electric current flows through the inductor, magnetic flux is generated to surround the inductor on a plane that is substantially perpendicular to the axial direction of the inductor. However, since the inductor is substantially perpendicular to a capacitor pattern and a shield pattern, the generated magnetic flux does not pass through such patterns, so that no eddy current occurs in such patterns. This results in an inductor having a very high Q factor and reduced eddy current loss.
Other features, elements, characteristics and advantages of present invention will become apparent from the following detailed description of preferred embodiments thereof with reference to the attached drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1
is an exploded perspective view showing a laminated type duplexer according to a preferred embodiment of the present invention;
FIG. 2
is a perspective view of the external appearance of the laminated type duplexer shown in
FIG. 1
;
FIG. 3
is an equivalent circuit diagram of the laminated type duplexer shown in
FIG. 2
;
FIG. 4
is an exploded perspective view showing a conventional laminated type duplexer; and
FIG. 5
is a perspective view of the external appearance of the laminated type duplexer shown in FIG.
4
.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
A laminated type duplexer according to a preferred embodiment of the present invention is described with reference to the accompanying drawings.
FIG. 1
shows a laminated type duplexer
41
.
FIG. 2
in perspective view of the external appearance of the duplexer
41
.
FIG. 3
is an equivalent circuit diagram of the duplexer
41
. The duplexer
41
preferably includes a three-stage band-pass filter BPF
1
having parallel LC resonators Q
1
to Q
3
, and a three-stage band-pass filter BPF
2
having parallel LC resonators Q
4
to Q
6
, the band-pass filters BPF
1
and BPF
2
being connected through inductor patterns
84
and
85
arranged to achieve impedance matching.
Referring first to
FIG. 1
, the laminated type duplexer
41
is defined by insulator sheets
42
to
49
having frequency-adjusting capacitor patterns
50
to
55
, inductor via-holes
61
a
to
61
e
,
62
a
to
62
e
,
63
a
to
63
e
,
64
a
to
64
e
,
65
a
to
65
e
, and
66
a
to
66
e
, capacitor patterns
70
to
75
, coupling-adjusting capacitor patterns
76
to
79
, the inductor patterns
84
and
85
, and shield patterns
90
a
,
90
b
,
91
a
and
91
b.
The insulator sheets
42
to
49
are produced preferably by kneading dielectric powder and magnetic powder with a binder to form sheets. The inductor via-holes
61
a
to
61
e
,
62
a
to
62
e
,
63
a
to
63
e
,
64
a
to
64
e
,
65
a
to
65
e
, and
66
a
to
66
e
are formed by filling conductive paste of Ag, Pd, Cu, Au, Ag Pd, etc. in openings that have been provided in the insulator sheets
43
to
47
. The frequency-adjusting capacitor patterns
50
to
55
, etc. are made of Ag, Pd, Cu, Au, Ag-Pd, etc., and are formed by, for example, printing.
The inductor via-holes
61
a
to
61
e
,
62
a
to
62
e
,
63
a
to
63
e
of the band-pass filter BPF
1
are provided in substantially the left-hand region of the insulator sheets
43
to
47
. The inductor via-holes
61
a
to
61
e
are connected in sequence in the laminating direction of the sheets
43
to
47
to define a columnar inductor L
1
. Similarly, the inductor via-holes
62
a
to
62
e
, and
63
a
to
63
e
are connected in sequence in the laminating direction of the sheets
43
to
47
to define columnar inductors L
2
and L
3
, respectively. The inductors L
1
to L
3
have axes that extend substantially parallel to the stacking direction of the sheets
43
to
47
.
When the length of the columnar inductors L
1
to L
3
defined by the inductor via-holes
61
a
to
61
e
,
62
a
to
62
e
, and
63
a
to
63
e
is approximately λ/4, where λ is the wavelength corresponding to a desired resonant frequency, the LC resonators Q
1
to Q
3
function as λ/4 resonators. Of course, the length of the inductors L
1
to L
3
is not limited to about λ/4 and other lengths may be used.
The inductor via-hole
61
c
is connected to a lead pattern
81
, and the lead pattern
81
is exposed at the left edge of the sheet
45
. The inductor via-hole
63
c
is connected to the inductor pattern
84
. The inductor pattern
84
defines an inductor Ls
1
used for impedance matching. The inductor via-holes
61
d
,
62
d
and
63
d
are connected to the capacitor patterns
70
,
71
and
72
, respectively, provided on the left-hand region of the insulator sheet
46
.
The frequency-adjusting capacitor patterns
50
,
51
and
52
are provided on substantially the left-hand region of the insulator sheet
48
as viewed in the Figures to extend from the front edge to the rear edge of the sheet
48
. The frequency-adjusting capacitor patterns
50
,
51
and
52
face the shield pattern
90
b
through the sheet
48
to define capacitors C
1
, C
2
and C
3
, respectively. One end of the inductor L
1
, that is, the via-hole
61
e
, is directly connected to the frequency-adjusting capacitor pattern
50
; one end of the inductor L
2
, that is, the via-hole
62
e
, is directly connected to the frequency-adjusting capacitor pattern
51
; one end of the inductor L
3
, that is, the via-hole
63
e
, is directly connected to the frequency-adjusting capacitor pattern
52
.
The other end of the inductor L
1
, that is, the via-hole
61
a
, is directly connected to the shield pattern
90
a
on the insulator sheet
43
. Also, the other end of the inductor L
2
, that is, the via-hole
62
a
, is directly connected to the shield pattern
90
a
, and the other end of the inductor L
3
, that is, the via-hole
63
a
, is directly connected to the shield pattern
90
a.
The coupling-adjusting capacitor patterns
76
provided on the left-hand region of the insulator sheet
47
faces the capacitor patterns
50
and
51
across the sheet
47
, and faces the capacitor patterns
70
and
71
across the sheet
46
, defining a coupling capacitor Cs
1
. The coupling-adjusting capacitor pattern
77
faces the capacitor patterns
51
and
52
through the sheet
47
, and also faces the capacitor patterns
71
and
72
through the sheet
46
, defining a coupling capacitor Cs
2
.
The inductor L
1
defined by the inductor via-holes
61
a
to
61
e
and the capacitor C
1
formed by the frequency-adjusting capacitor pattern
50
and the shield pattern
90
b
then form a parallel LC resonant circuit, thus providing the first-stage LC resonator Q
1
of the band-pass filter BPF
1
. The inductor L
2
defined by the inductor via-holes
62
a
to
62
e
and the capacitor C
2
defined by the frequency-adjusting capacitor pattern
51
and the shield pattern
90
b
form a parallel LC resonant circuit, thus providing the second-stage LC resonator Q
2
of the band-pass filter BPF
1
. The inductor L
3
defined by the inductor via-holes
63
a
to
63
e
and the capacitor C
3
defined by the frequency-adjusting capacitor pattern
52
and the shield pattern
90
b
form a parallel LC resonant circuit, thus providing the third-stage LC resonator Q
3
of the band-pass filter BPF
1
. The LC resonators Q
1
to Q
3
are electrically coupled via the coupling capacitors Cs
1
and Cs
2
, whereby the three-stage band-pass filter BPF
1
is provided.
The inductor via-holes
64
a
to
64
e
,
65
a
to
65
e
, and
66
a
to
66
e
of the band-pass filter BPF
2
are formed in substantially the right-hand region of the insulator sheets
43
to
47
. The inductor via-holes
64
a
to
64
e
are connected in sequence in the laminating direction of the sheets
43
to
47
to form a columnar inductor L
4
. Similarly, the inductor via-holes
65
a
to
65
e
and
66
a
to
66
e
are connected in sequence in the laminating direction of the sheets
43
to
47
to form columnar inductors L
5
and LG, respectively. The inductors L
4
to L
6
have axes that extend substantially parallel to the laminating direction of the sheets
43
to
47
.
When the length of the columnar inductors L
4
to L
6
defined by the inductor via-holes
64
a
to
64
e
,
65
a
to
65
e
, and
66
a
to
66
e
is approximately λ/4, where λ is the wavelength corresponding to a desired resonant frequency, the LC resonators Q
4
to Q
6
function as λ/4 resonators. Of course, the length of the inductors L
4
to L
6
is not limited to approximately λ/4.
The inductor via-hole
64
c
is connected to the inductor pattern
85
. The inductor pattern
85
defines an impedance matching inductor Ls
2
. The inductor pattern
85
, as well as the inductor pattern
84
, is connected to a lead pattern
83
. The lead pattern
83
is exposed at an approximately central portion at the rear of the sheet
45
. The inductor via-hole
66
c
is connected to a lead pattern
82
, and the lead pattern
82
is exposed at the right edge of the sheet
45
. The inductor via-holes
64
d
,
65
d
and
66
d
are connected to the capacitor patterns
73
,
74
and
75
, respectively, provided on the right-hand region of the insulator sheet
46
as viewed in the Figures.
The frequency-adjusting capacitor patterns
53
,
54
and
55
are provided on substantially the right-hand region of the insulator sheet
48
to extend from the front to the rear of the sheet
48
. The frequency-adjusting capacitor patterns
53
,
54
and
55
face the shield pattern
91
b
across the sheet
48
to define capacitors C
4
, C
5
and C
6
, respectively. The via-hole
64
e
, that is, an end of the inductor L
4
, is directly connected to the frequency-adjusting capacitor pattern
53
. The via-hole
65
e
, that is, an end of the inductor L
5
, is directly connected to the frequency-adjusting capacitor pattern
54
. The via-hole
66
e
, that is, an end of the inductor L
6
, is directly connected to the frequency-adjusting capacitor pattern
55
.
The other end of the inductor L
4
, that is, the via-hole
64
a
, is directly connected to the shield pattern
91
a
on the insulator sheet
43
. The other end of the inductor L
5
, that is, the via-hole
65
a
, is directly connected to the shield pattern
91
a
, and the other end of the inductor L
6
, that is, the via-hole
66
a
, is directly connected to the shield pattern
91
a.
The coupling-adjusting capacitor pattern
78
provided on the right-hand region of the insulator sheet
47
faces the capacitor patterns
53
and
54
through the sheet
46
, and also faces the capacitor patterns
73
and
74
through the sheet
47
, defining a coupling capacitor Cs
3
. The coupling-adjusting capacitor pattern
79
faces the capacitor patterns
54
and
55
through the sheet
46
, and also faces the capacitor patterns
74
and
75
through the sheet
47
, defining a coupling capacitor Cs
4
.
The inductor L
4
defined by the inductor via-holes
64
a
to
64
e
, together with the capacitor C
4
defined by the frequency-adjusting capacitor pattern
53
and the shield pattern
91
b
, defines a parallel LC resonant circuit, thus providing the first-stage LC resonator Q
4
of the band-pass filter BPF
2
. The inductor L
5
defined by the inductor via-holes
65
a
to
65
e
, together with the capacitor C
5
defined by the frequency-adjusting capacitor pattern
54
and the shield pattern
91
b
, defines a parallel LC resonant circuit, thus providing the second-stage LC resonator Q
5
of the band-pass filter BPF
2
. The inductor L
6
defined by the inductor via-holes
66
a
to
66
e
, together with the capacitor C
6
defined by the frequency-adjusting capacitor pattern
55
and the shield pattern
91
b
, defines a parallel LC resonant circuit, thus providing the third-stage LC resonator Q
6
of the band-pass filter BPF
2
. The LC resonators Q
4
to Q
6
are electrically coupled via the coupling capacitors Cs
3
and Cs
4
, whereby the three-stage band-pass filter BPF
2
is provided.
The thus constructed sheets
42
to
49
are laminated in a manner shown in
FIG. 1
, and are then integrally fired to define a laminate
100
shown in FIG.
2
. The laminate
100
has a transmitter terminal electrode Tx and a receiver terminal electrode Rx provided on the left and right ends thereof, respectively. An antenna terminal electrode ANT and grounding terminal electrodes G
1
and G
3
are provided on the rear surface of the laminate
100
, and grounding terminal electrodes G
2
and G
4
are provided on the front surface thereof.
The lead patterns
81
,
82
and
83
are connected to the transmitter terminal electrode Tx, the receiver terminal electrode Rx, and the antenna terminal electrode ANT, respectively. An end of the shield pattern
90
a
and the associated end of the shield pattern
90
b
are connected to the grounding terminal electrode G
1
. The other end of the shield pattern
90
a
and the associated end of the shield pattern
90
b
are connected to the grounding terminal electrode G
2
. Likewise, an end of the shield pattern
91
a
and the associated end of the shield pattern
91
b
are connected to the grounding terminal electrode G
3
. The other end of the shield pattern
91
a
and the associated end of the shield pattern
91
b
are connected to the grounding electrode terminal G
4
.
FIG. 3
shows an electrical circuit equivalent to the laminated type duplexer
41
having the construction described heretofore.
The resonators Q
1
to Q
3
are electrically coupled to each other via the coupling capacitors Cs
1
and Cs
2
, whereby the three-stage band-pass filter BPF
1
is provided. The resonators Q
4
to Q
6
are electrically coupled to each other via the coupling capacitors Cs
3
and Cs
4
, whereby the three-stage band-pass filter BPF
2
is provided. One end of the band-pass filter BPF
1
(resonator Q
1
) is connected to the transmitter terminal electrode Tx, and the other end thereof (resonator Q
3
) is connected to the antenna terminal electrode ANT through the impedance matching inductor Ls
1
. One end of the band-pass filter BPF
2
(resonator Q
6
) is connected to the receiver terminal electrode Rx, and the other end thereof (resonator Q
4
) is connected to the antenna terminal electrode ANT through the impedance matching inductor Ls
2
.
In operation, a transmission signal is input from a transmitter circuit system (not shown) into the transmitter terminal electrode Tx, while a reception signal is input from the antenna terminal electrode ANT. In turn, the laminated type duplexer
41
outputs the transmission signal from the antenna terminal electrode ANT through the band-pass filter BPF
1
. The duplexer
41
also outputs the reception signal from the receiver terminal electrode Rx to a receiver circuit system (not shown) though the band-pass filter BPF
2
.
The transmission frequency of the band-pass filter BPF
1
depends upon the respective resonant frequencies of the resonator Q
1
defined by the inductor L
1
and the capacitor C
1
, the resonator Q
2
defined by the inductor L
2
and the capacitor C
2
, and the resonator Q
3
defined by the inductor L
3
and the capacitor C
3
. The transmission frequency of the band-pass filter BPF
1
is adjusted by, for example, changing the areas of the capacitor patterns
50
,
51
, and
52
of the capacitors C
1
, C
2
, and C
3
to change the electrostatic capacitance of the capacitors C
1
, C
2
, and C
3
.
The transmission frequency of the band-pass filter BPF
2
depends upon the respective resonant frequencies of the resonator Q
4
defined by the inductor L
4
and the capacitor C
4
, the resonator Q
5
defined by the inductor L
5
and the capacitor C
5
, and the resonator Q
6
defined by the inductor L
6
and the capacitor C
6
. The transmission frequency of the band-pass filter BPF
2
is adjusted by, for example, changing the areas of the capacitor patterns
53
,
54
, and
55
of the capacitors C
4
, C
5
, and C
6
.
In the laminated type duplexer
41
of various preferred embodiments of the present invention, improvements in the Q factors of the columnar inductors L
1
to L
6
are achieved when the cross-sectional areas of these inductors are increased to reduce resistances. This is achieved by using an increased number of via-holes
61
a
to
61
e
,
62
a
to
62
e
,
63
a
to
63
e
,
64
a
to
64
e
,
65
a
to
65
e
, and
66
a
to
66
e
connected in sequence, or otherwise increasing the cross-sectional areas of the individual via-holes. Accordingly, it is not necessary to increase the thickness or width of inductor patterns as is conventionally done, to overcome problems with delamination during the firing or with large components.
Furthermore, since the inductors L
1
to L
6
are substantially perpendicular to the patterns
50
to
55
,
70
to
75
, and
90
a
to
91
b
, any magnetic flux φ generated by electric currents flowing through the inductors L
1
to L
6
does not pass through these patterns, so that no eddy current occurs in these patterns. As a result, the inductors L
1
to L
6
having very high Q factors are obtained and eddy current loss is greatly reduced.
The laminated type duplexer according to the present invention is not limited on the illustrated preferred embodiments, and a variety of modifications may be made without departing from the spirit and scope of the invention. For example, it is not necessary for the inductor via-holes to be linear, and meandering or spiral via-holes may be used instead. The shield patterns may also be provided only in the upper or lower portion of the laminate. A duplexer having one of the impedance matching inductors Ls
1
and Ls
2
is also possible.
The duplexer in accordance with the present invention is not limited to a duplexer having a combination of band-pass filters, and may include a branching filter such as a duplexer or triplexer including low-pass filters, high-pass filters and trap circuits, and a combination of these different kinds of circuits. Furthermore, it is not essential that all of the inductors of resonators in filters be defined by via-holes, and a duplexer in which only selected inductors are formed by via-holes falls within the scope of the present invention.
In the illustrated preferred embodiments, the insulator sheets each having the conductor patterns and via-holes provided thereon are laminated and then integrally fired. This, however, is only illustrative and the insulator sheets may be fired in advance of the firing. The resonators and the other components may be produced by a process as will be described below. That is, an insulator layer is formed of a paste of insulating materials by using a technique such as printing. Then, a paste of conductive materials is applied to a surface of the insulator layer to define conductor patterns or via-holes. The paste of insulating materials is applied thereto and overlaid thereon to define an insulator layer. Sequential layering operations in this manner make it possible to provide a duplexer having a laminated structure.
While the invention has been particularly shown and described with reference to preferred embodiments, it will be understood by those skilled in the art that the foregoing and other changes in form and details can be made without departing from the spirit and scope of the invention.
Claims
- 1. A laminated type duplexer comprising:a plurality of insulator layers stacked on each other to define a laminate; a plurality of filters embedded in the laminate, each of said filters having an inductor and a capacitor, each of said filters having a parallel LC resonant circuit and being disposed such that the inductors are adjacent to and substantially parallel with one another; wherein each of the inductors is defined by via-holes connected in sequence in the direction of stacking of the insulator layers, and a matching inductor pattern is arranged such that at least two adjacent filters of said plurality of filters are electrically connected to each other through the matching inductor pattern, wherein each of the inductors extends in an axial direction that is substantially perpendicular to a plane in which the matching inductor pattern is disposed.
- 2. A laminated type duplexer according to claim 1, wherein the impedance matching pattern includes an inductor pattern.
- 3. A laminated type duplexer according to claim 1, wherein said insulator sheets include frequency-adjusting capacitor patterns, shield patterns, inductor via-holes, capacitor patterns, and coupling-adjusting capacitor patterns.
- 4. A laminated type duplexer according to claim 1, wherein said insulator sheets are made of dielectric material and magnetic powder.
- 5. A laminated type duplexer according to claim 1, wherein said insulator sheets include via-holes filled with conductive paste.
- 6. A laminated type duplexer according to claim 1, further including frequency-adjusting capacitor patterns.
- 7. A laminated type duplexer according to claim 1, wherein the inductor via-holes are connected in sequence in the laminating direction to define a columnar inductor.
- 8. A laminated type duplexer according to claim 1, wherein the inductors are defined by the frequency-adjusting capacitor pattern and the shield pattern defining a parallel LC resonant circuit.
- 9. A laminated type duplexer according to claim 1, wherein the inductors have axes that extend substantially parallel to the stacking direction of the sheets.
- 10. A laminated type duplexer according to claim 1, wherein the length of the inductors defined by the inductor via-holes is approximately λ/4, where λ is the wavelength corresponding to a desired resonant frequency.
- 11. A laminated type duplexer according to claim 1, wherein the laminate includes a transmitter terminal electrode and a receiver terminal electrode provided thereon.
- 12. A laminated type duplexer according to claim 1, wherein at least one of the inductors and least one of the capacitors and a shield plate define a parallel LC resonant circuit that is a first stage resonator of a band pass filter.
- 13. A laminated type duplexer according to claim 1, wherein at least one of the inductors and least one of the capacitors and a shield plate define a parallel LC resonant circuit that is a second stage resonator of a band pass filter.
- 14. A laminated type duplexer according to claim 1, wherein at least one of the inductors and least one of the capacitors and a shield plate define a parallel LC resonant circuit that is a third stage resonator of a band pass filter.
- 15. A laminated type duplexer according to claim 1, wherein the laminate includes an antenna terminal electrode and grounding terminal electrodes provided thereon.
- 16. A laminated type duplexer according to claim 1, wherein the plurality of filters are arranged to define a three-stage band-pass filter BPF1.
- 17. A laminated type duplexer according to claim 1, further comprising a duplexer including a first three-stage band-pass filter having parallel LC resonators, and a second three-stage band-pass filter having parallel LC resonators, wherein the first and second band-pass filters are connected through inductor patterns.
- 18. A laminated type duplexer according to claim 17, wherein the LC resonators are constructed to define λ/4 resonators, where λ is the wavelength corresponding to a desired resonant frequency.
- 19. A laminated type duplexer according to claim 1, wherein a plurality of the inductors and capacitors and a plurality of shield plates are arranged to define LC resonators.
- 20. A laminated type duplexer according to claim 19, wherein the LC resonators are electrically coupled to define a three-stage band-pass filter.
Priority Claims (1)
| Number |
Date |
Country |
Kind |
| 11-350771 |
Dec 1999 |
JP |
|
US Referenced Citations (3)
| Number |
Name |
Date |
Kind |
|
5029043 |
Kitahara et al. |
Jul 1991 |
A |
|
5719539 |
Ishizaki et al. |
Feb 1998 |
A |
|
6011959 |
Reeser et al. |
Jan 2000 |
A |
Foreign Referenced Citations (2)
| Number |
Date |
Country |
| 2303495 |
Feb 1997 |
GB |
| 6-85506 |
Mar 1994 |
JP |
