JPH06112735A - Shared device - Google Patents

Abstract

PURPOSE:To provide a shared device which has a structure suited to the miniaturization and excels in the stability and the reliability. CONSTITUTION:The triplet filters 500 and 600 and a branching circuit are provided in a single body. The inductance of the branching circuit consists of a transmission line 70 set on a dielectric layer 14, and the electrostatic capacity is generated at an overlapping part of the capacity coupling electrodes 50 and 60 and the line 70. Then the inductance of the branching circuit is connected in parallel to both filters 500 and 600, and the electrostatic capacity is connected in series to both filters 500 and 600 respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer, and more particularly to a duplexer having a function of separating one transmission signal from a reception signal by sharing one antenna between a transmission side and a reception side.

[0002]

2. Description of the Related Art A duplexer, for example, an antenna duplexer having a function of sharing one antenna between a transmitting side and a receiving side and separating a transmission signal and a reception signal is mainly used. Since two filters with different frequencies are connected in parallel, even at the center frequency of one of these two filters, the other filter seen from the antenna that is the input / output terminal shared by these filters It is necessary to make the impedance infinite so as not to interfere with the pass characteristic of the filter.

For this purpose, it is common practice to insert a branching circuit into the connecting part of two filters. Figure 10
Are transmission lines 411 and 4 having predetermined electric lengths, respectively.
12 shows a case where the demultiplexing circuit 400 is configured by inserting 12 between the antenna 700 and the filter 500 and the filter 600, respectively. In this structure, since the transmission lines 411 and 412 need to have a predetermined electric length, it is necessary to route these transmission lines 411 and 412 to a predetermined length, and these transmission lines 411 and 412 are arranged in the dielectric substrate. When forming 411 and 412, there is a problem that a large area is required and the duplexer cannot be downsized.

Therefore, instead of the transmission line, a lumped constant element such as a capacitor or a coil is used to form a demultiplexing circuit. FIG. 11 shows a coil 42 as an example.
1 and 422 are inserted in series between the filters 500 and 600 and the antenna 700, respectively, and the capacitor 423 is inserted in parallel with the filters 500 and 600. In order to configure such a demultiplexing circuit, conventionally, individual components in which leads are actually wound are used as the coils 421 and 422, and individual components such as a chip capacitance are used as the capacitance 423. Therefore, there is a problem that the number of parts increases and the duplexer cannot be downsized. Further, there is a problem that the reactance of the coil changes due to the vibration, and the stability and reliability are low.

Therefore, an object of the present invention is to provide a duplexer having a structure suitable for miniaturization.

Another object of the present invention is to provide a duplexer which is excellent in stability and reliability because parts such as a coil are unnecessary for constructing a branching circuit.

[0007]

According to the present invention, a first filter and a second filter having different center frequencies;
Even at the center frequency of one of the first and second filters, the first and second filters seen from the input / output terminals shared by the first and second filters
A duplexer in which the impedance of the other of the filters is set to infinity, and at least one of the first and second filters has a resonant element integrated in a dielectric substrate. Provided in a dielectric plate, at least a part of the demultiplexing circuit is provided in the dielectric substrate, and the first filter, the second filter and the demultiplexing circuit are provided in the dielectric substrate. It is possible to obtain a duplexer which is characterized by being integrally formed in the.

Preferably, the demultiplexing circuit has a capacitance connected in series with each of the first and second filters and an inductance connected in parallel with each of the first and second filters. It

More preferably, the tip of the inductance is short-circuited to the ground and is constituted by a transmission line having an electrical length of 90 degrees or less.

More preferably, the transmission line that constitutes the inductance of the branching circuit is a microstrip line.

[0011]

In the present invention, the first filter and the second filter having different center frequencies and the first and second filters are provided.
Even at the center frequency of any one of the first and second filters, the impedance of the other of the first and second filters seen from the input / output terminal shared by the first and second filters is infinite. In the duplexer having the branching circuit configured as described above, at least one of the first and second filters is a triplate type filter in which a resonant element is integrally provided in a dielectric substrate, At least a part of the demultiplexing circuit is provided in the dielectric substrate, and the first filter, the second filter and the demultiplexing circuit are integrally formed on the dielectric substrate. Since it can be downsized, the number of parts is reduced, and parts such as coils are unnecessary, a duplexer excellent in stability and reliability can be obtained.

Here, the reason why the filter to be used is a triplate type filter is that when connecting a partially built-in demultiplexing circuit and the filter, the connection is made by using electrodes built in the substrate. It is desirable that
This is because a laminated triplate filter is preferable because it allows a multilayer structure with a built-in conductor and facilitates formation of electrodes for connecting the branching circuit and the filter.

The reason why at least one is the triplate type is that when the specifications required for the remaining one filter are low, a lumped constant type LC filter (bandpass, lowpass, etc.) is used. Is possible.

Preferably, a triplate filter is used for both the first and second filters.

Further, in the duplexer of the present invention, the demultiplexing circuit is composed of the capacitors connected in series to the first and second filters and the inductances connected in parallel to the first and second filters. Thus, the demultiplexing circuit can be easily formed on the dielectric substrate. That is, when forming an inductance using a conductor formed in or on a dielectric substrate, one end of the conductor needs to be short-circuited or open.
One end of the filter can be easily short-circuited or opened by connecting the filter in parallel. The capacitors connected in series to the first and second filters can be easily formed by using the electrodes built in the dielectric substrate.

The inductance can be compactly formed on the dielectric substrate by constructing the inductance by a transmission line whose tip is short-circuited to ground and whose electric length is 90 degrees or less. Since the impedance of the transmission line short-circuited at the tip changes to jZtan θ, any impedance value can be supported.

Further, the characteristic impedance of the transmission line can be increased by using the microstrip line as the transmission line which constitutes the inductance of the branching circuit. The transmission line that constitutes the inductance of the branching circuit replaces the coil, which is a lumped element,
When the characteristic impedance of this transmission line becomes higher, the change in reactance with respect to the frequency becomes closer to that in the case of the coil, so that the demultiplexing circuit can have a wider band.

[0018]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic development view of a first embodiment of a duplexer of the present invention, and FIG. 2 is a perspective view of this embodiment.

On the lower surface of the dielectric layer 11, the earth electrode 1 will be formed later.
10 is provided, but a through hole 91 for connecting the ground electrode 110 to the tip of the transmission line 70 described later is formed in the dielectric layer 11.

Inner layer ground electrodes 81, which are overlapped with the dielectric layers 14 and 13 on the open end sides of the resonance elements 21 and 22 described later, with the dielectric layers 14 and 13 interposed therebetween, and the ground electrode 110, which will be described later, and the resonance elements 23 and 24 described later, , 25 are overlapped on the open end sides with the dielectric layers 14 and 13 interposed therebetween, and the end portions of the inner layer ground electrode 83 connected to the ground electrode 110 described later are connected to the dielectric layer 1
Form on 2. Further, a through hole 92 for connecting the ground electrode 110 and the tip portion of the transmission line 70 described later is also formed in the dielectric layer 12.

On the dielectric layer 13, one end 51 thereof overlaps a part of a transmission line 70 described later with the dielectric layer 14 sandwiched therebetween, and the other end 52 partly overlaps a part of a resonance element 23 described later with the dielectric layer 14. A capacitive coupling electrode 50 and an input / output electrode 42 which overlap with a part of a resonance element 25 which will be described later are formed. Furthermore, the ground electrode 110 and the transmission line 70 described later
A through hole 93 for connecting to the tip end of is also formed in the dielectric layer 13.

Resonant elements 21 to 25, each of which is connected to a ground electrode 110 to be described later and which constitutes a quarter-wavelength stripline resonator, are formed on the dielectric layer 14, and one end thereof will be described later. Electrodes 31 to 35, which are connected to the ground electrode 110 and are separated from the open ends of the resonant elements 21 to 25 for a predetermined period and respectively oppose the open ends of the resonant elements 21 to 25, are formed on the dielectric layer 14. Then, the comb-line type filter 500 is configured by utilizing the distributed coupling of the resonant elements 21 and 22, and the resonant elements 23 and 2
The comb line type filter 600 is configured by utilizing the distributed coupling of 4 and 25.

Further, the resonance element 22 and the resonance element 2 are further provided.
A transmission line 70 for forming an inductance is formed on the dielectric layer 14 between the wirings 3 and 3. A through hole 94 for connecting to the ground electrode 110 is provided at the tip of the transmission line 70, and the tip of the transmission line 70 is provided on the lower surface of the dielectric layer 11 via the through holes 94, 93, 92 and 91. Is short-circuited to the ground electrode 110 provided in the. Since the through hole 94 is provided at a position where the electrical length of the transmission line 70 is a predetermined length of 90 degrees or less,
The transmission line 70 constitutes an inductance. The reason why the conductor width of the front end 71 of the transmission line 70 is narrowed is to make the characteristic impedance of the transmission line 70 as high as possible to widen the band of the demultiplexing circuit, and the rear end 72 of the transmission line 70. The conductor width is widened because it is necessary to widen the external lead portion to some extent in order to facilitate mounting.

On the dielectric layer 15, one end 61 thereof overlaps a part of the transmission line 70 with the dielectric layer 15 interposed therebetween, and the other end 62 thereof overlaps a part of the resonance element 22 with the dielectric layer 15 interposed therebetween. The input / output electrode 41 is formed so as to overlap with the capacitive coupling electrode 60 and a part of the resonant element 21.

Opening of the inner layer ground electrode 82 and the resonant elements 23, 24, 25 which overlap the open ends of the resonant elements 21, 22 with the dielectric layers 15, 16 sandwiched therebetween and whose ends are connected to the ground electrode 110 described later. An inner-layer ground electrode 84 is formed on the dielectric layer 16 so as to overlap the end layers with the dielectric layers 15 and 16 sandwiched therebetween and the end portion of which is connected to a ground electrode 110 described later.

The earth electrode 11 is provided on the surface of the dielectric layer 16.
The dielectric layer 17 in which 0 is formed is laminated to form the dielectric layer 11
To 17 are integrally configured and then fired to form the laminated body 100.
To form.

As shown in FIG. 2, the ground electrode 110 is provided on the upper and lower surfaces of the laminate 100 and on the side surfaces except the input / output terminal portion 131, the input / output terminal portion 132 and the antenna terminal portion 133.
To form. Further, in the input / output terminal portion 131 on the side surface of the laminated body 100, the input / output terminal 121 insulated from the ground electrode 110 and connected to the input / output electrode 41 is formed. In the input / output terminal portion 132, the input / output electrode 42 is insulated from the ground electrode 110.
An input / output terminal 122 connected to is formed. Further, in the antenna terminal portion 133, the antenna terminal 123 insulated from the ground electrode 110 and connected to the rear end portion 72 of the transmission line 70 is formed.

An equivalent circuit of the duplexer configured as above is shown in FIG. The resonance elements 21 and 22 form a bandpass filter 500, and the resonance elements 23 and 2
The bandpass filter 600 is composed of 4 and 25. Capacitance 211, 221, 231, 241, 25
1 and inductances 212, 222, 232, 24
Reference numerals 2 and 252 denote capacitance and inductance when the resonant elements 21, 22, 23, 24, and 25 are equivalently converted. Capacitance 213, 223, 233, 24
Reference numerals 3, 253 denote resonant elements 21, 22, 23, 2 respectively.
4 and 25 and the electrodes 31, 32, 33, 34, and 35, which are electrostatic capacitances. Due to the presence of these electrostatic capacitances, the resonance element 21 and the resonance element 22 are coupled by the inductance 311. The resonance element 23 and the resonance element 2
4 is coupled with the inductance 312, and the resonance element 24
And the resonance element 25 are coupled by an inductance 313.

Further, in this embodiment, the resonance element 2
Inner layer ground electrodes 81, 8 facing the open end sides of 1, 22
2 and inner layer ground electrodes 83 and 84 facing the open ends of the resonance elements 23, 24 and 25. The open-end side portions of the resonance elements 21 and 22 facing the inner-layer ground electrodes 81 and 82 are closer to the ground, and electrostatic charges are present between the open-end side of the resonance element 21 and the inner-layer ground electrodes 81 and 82. Capacitors 214 and 215 are formed respectively, and the resonance element 2
Capacitances 224 and 225 are formed between the open end side of 2 and the inner layer ground electrodes 81 and 82, respectively. Similarly, the open end side portions of the resonance elements 23, 24, 25 facing the inner layer ground electrodes 83, 84 become closer to the ground, and the open end side of the resonance element 23 and the inner layer ground electrodes 83, 84. Capacitances 234 and 235 are formed between them, and the open end side of the resonant element 24 and the inner layer ground electrode 8 are formed.
Capacitances 244 and 245 are formed between the electrodes 3 and 84, respectively, and capacitances 254 and 255 are formed between the open end side of the resonant element 25 and the inner-layer ground electrodes 83 and 84, respectively. . These capacitances 214, 2
15, 224, 225, 234, 235, 244, 24
5, 254, 255 are also resonant elements 21, 22, 23, 2
It is added to the electrostatic capacitances 211, 221, 231, 241, and 251 of the parallel resonant circuit when the equivalent conversion of 4 and 25 is performed. Therefore, if the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and the lengths of the resonance elements 21, 22, 23, 24, 25 are also shorter.

Furthermore, the inner layer ground electrodes 81, 82 are also provided.
The open-end side portions of the resonance elements 21 and 22 facing each other and the open-end side portions of the resonance elements 23, 24 and 25 facing the inner-layer ground electrodes 83 and 84 are closer to the ground, and Of the resonance elements 21, 22 facing the inner-layer ground electrodes 81, 82 and the resonance elements 23, 24, 25 facing the inner-layer ground electrodes 83, 84 are opened. The coupling between the resonant elements in the end portion becomes weak. Therefore, the resonance elements are coupled to each other mainly at the portions which do not overlap the inner layer ground electrodes 81 and 82 or the inner layer ground electrodes 83 and 84. This means that the coupling electric length of the resonant element is substantially shortened. When the coupling electric length is shortened in this manner, the reactance of the distributed constant element that couples the resonant elements is also reduced, the resonant elements are strongly inductively coupled, and the characteristics of the filters 500 and 600 are broadened.

A capacitance 301 is a capacitance formed between the input / output electrode 41 and the resonance element 21, and the capacitance 3
Reference numeral 02 is an electrostatic capacitance formed between the capacitive coupling electrode 60 and the resonance element 22, and electrostatic capacitance 303 is a capacitive coupling electrode 5
0 is the capacitance formed between the resonance element 23,
The capacitance 304 is a capacitance formed between the input / output electrode 42 and the resonance element 25.

The capacitance 401 is a capacitance formed between the capacitance coupling electrode 60 and the transmission line 70, and the capacitance 402 is a capacitance formed between the capacitance coupling electrode 50 and the transmission line 70. It is the electric capacity. The inductance 403 is an inductance formed by the transmission line 70. The inductance 403 is connected in parallel with the filters 500 and 600, and the capacitance 401 is the antenna 700 and the filter 5.
00 is connected in series, and the electrostatic capacitance 402 is connected in series between the antenna 700 and the filter 600, and these inductance 403 and electrostatic capacitances 401, 402 are connected.
The demultiplexing circuit 400 is configured by.

As described above, in this embodiment, since the filters 500 and 600 and the demultiplexing circuit 400 are integrally formed in one laminated body 100, the duplexer can be downsized and the number of parts can be reduced. In addition, since parts such as coils are unnecessary, a duplexer with excellent stability and reliability can be obtained.

In the present embodiment, the demultiplexing circuit 4
Inductance 403 that constitutes
Since it is connected in parallel with 0 and 600, the tip of the transmission line 70 forming the inductance 403 can be easily short-circuited to the ground. The transmission line 70 becomes the inductance 403 by short-circuiting the tip of the transmission line 70 to the ground and setting its electrical length to 90 degrees or less. Note that the impedance of the transmission line thus short-circuited at the tip is jZt
Since it changes with an θ, it can correspond to any impedance value. Further, the electrostatic capacitance 401 connected in series to the filter 500 can be easily formed by the capacitive coupling electrode 60, the dielectric layer 15 and the transmission line 70 provided on the dielectric layer 15, and is connected to the filter 600 in series. The electrostatic capacitance 402 can be easily formed by the capacitive coupling electrode 50, the dielectric layer 14 and the transmission line 70 provided on the dielectric layer 13.

Next, a method of manufacturing the duplexer of the first embodiment will be described.

The duplexer of this embodiment is composed of the resonance elements 21 to 25,
The electrodes 31 to 35, the input / output electrodes 41 and 42, the capacitive coupling electrodes 50 and 60, the transmission line 70, and the inner layer ground electrodes 81 to 81.
Since 84 is completely embedded in the dielectric, the resonance element 2
1 to 25, the electrodes 31 to 35, the input / output electrodes 41 and 42, the capacitive coupling electrodes 50 and 60, the transmission line 70, and the inner layer ground electrodes 81 to 84 are preferably low loss and low specific resistance. It is preferable to use an Ag-based or Cu-based conductor of resistance.

As the dielectric to be used, a ceramic dielectric which is highly reliable and has a large permittivity εγ and which can be miniaturized is preferable.

As a manufacturing method, a conductor paste is applied to a ceramic powder compact to form an electrode pattern, the compacts are laminated and fired to densify, and a conductor is laminated therein. It is desirable to integrate the ceramic dielectric with the ceramic dielectric.

When Ag-based or Cu-based conductors are used, the melting points of these conductors are low and it is difficult to co-fire with ordinary dielectric materials. Therefore, their melting points (1100 ° C. or less) are used. It is necessary to use a dielectric material that can be fired at lower temperatures. Also, due to the nature of the device as a microwave filter, the temperature characteristic (temperature coefficient) of the resonance frequency of the formed parallel resonance circuit is ± 50 ppm / ° C.
The following dielectric materials are preferred. Examples of such a dielectric material include glass-based materials such as a mixture of cordierite-based glass powder, TiO ₂ powder and Nd ₂ Ti ₂ O ₇ powder, and BaO—TiO ₂ —Re ₂ O.
_3- Bi ₂ O ₃ -based composition (Re: rare earth component) with some glass-forming components or glass powder added, barium oxide-titanium oxide-neodymium oxide-based dielectric ceramic composition powder with some glass powder added There is something I did.

As an example, MgO: 18 wt% -Al _{2
O 3: 37wt% -SiO 2:} 37wt% -B 2 O 3:
5 wt% -TiO _2: and 73 wt% of glass powder 3 wt% a composition, and 17 wt% of a commercially available TiO ₂ powder, N
10 wt% of the d ₂ Ti ₂ O ₇ powder was thoroughly mixed to obtain a mixed powder. The Nd ₂ Ti ₂ O ₇ powder is Nd ₂ O.
₃ powder and TiO ₂ powder were calcined at 1200 ° C. and then pulverized to be used. Next, an acrylic organic binder, a plasticizer, toluene and an alcohol solvent were added to this mixed powder, and the mixture was thoroughly mixed with alumina cobblestone to form a slurry. Then, using this slurry, a green tape having a thickness of 0.2 mm to 0.5 mm was prepared by a doctor blade method.

Next, in the case of the first embodiment, holes for through holes are formed at predetermined positions and then filled with silver paste. Then, the conductor patterns shown in FIG. 1 are printed by using the silver paste as the conductor paste, and then the green tapes necessary for adjusting the thickness of the green tape on which these conductor patterns are printed are overlapped to form the conductor pattern shown in FIG.
After stacking and stacking so as to have the structure of (1), firing was performed at 900 ° C. to prepare a laminated body 100.

As shown in FIG. 2, the ground electrode 110 made of a silver electrode is printed on the upper surface and the lower surface of the laminated body 100 having the above-described structure and on the side surfaces except the input / output terminal portions 131 and 132 and the antenna terminal portion 133, Further, a silver electrode that is insulated from the ground electrode 110 and is connected to the input / output electrodes 41 and 42 and the transmission line 70 separately is connected to the input / output terminal portion
The I / O terminals 121 and 122 and the antenna terminal 123 were printed in the Nos. 1 and 132 and the antenna terminal portion 133, and the printed electrodes were baked at 850 ° C.

Next, a second embodiment of the duplexer of the present invention will be described. FIG. 4 is a schematic development view of this embodiment, and FIG. 5 is a perspective view of this embodiment.

In the first embodiment, the branching circuit 400
The transmission line 70 constituting the inductance 403 of the above is a strip line formed inside the laminated body 100. However, in the present embodiment, the inductance 4 of the demultiplexing circuit 400 is
The transmission line 70 that constitutes 03 is a microstrip line formed on the dielectric layer 17, that is, on the laminated body 100. As described above, by using the microstrip line as the transmission line 70 that constitutes the inductance 403 of the demultiplexing circuit 400, the characteristic impedance of the transmission line 70 can be increased. The transmission line 70 forming the inductance 403 of the branching circuit 400 replaces the coil which is a lumped constant element, but when the characteristic impedance of this transmission line 70 becomes high, the change in the reactance with respect to the frequency becomes closer to that of the coil. Therefore, the demultiplexing circuit 400 can have a wider band.

In this embodiment, the inductance is the microstrip line on the surface, but in practice, a thin insulating layer may be formed on the conductor of the microstrip line as a protective layer.

In the present embodiment, further, the demultiplexing circuit 4
The capacitance 401 of 00 is set to the one end 61 of the capacitive coupling electrode 60.
And the capacitive coupling electrode 73 on the dielectric layer 14 are overlapped with each other, and the capacitance 402 of the demultiplexing circuit 400 is formed by the one end 51 of the capacitive coupling electrode 50 and the capacitive coupling electrode 7 on the dielectric layer 14.
3 is different from the first embodiment in that it is formed at the overlapping portion with 3 and that the tip of the transmission line 70 is directly connected to the ground electrode provided on the dielectric layer 17, but other configurations are the same. This is similar to the first embodiment. The rear end portion 72 of the transmission line 70 and the capacitive coupling electrode 73 are connected by the antenna terminal 123 provided in the antenna terminal portion 133.
The materials used and the manufacturing method are also the same as in the first embodiment.

Next, a third embodiment of the duplexer of the present invention will be described. FIG. 6 is a schematic development view of this embodiment, and FIG. 7 is a perspective view of this embodiment.

In the second embodiment, the ground electrode 110 provided on the lower surface of the dielectric layer 11 is removed only in the lower part 141 of the transmission line 70, and other structures are the second embodiment. Similar to the example, the materials used and the manufacturing method are also the same as those in the first embodiment. In this embodiment, since the ground electrode 110 is not provided in the lower part 141 of the transmission line 70, the characteristic impedance of the transmission line 70 can be made higher than that of the second embodiment, and the branching circuit 40 can be used.
The band of 0 can be made wider. Note that the filter 5
The portions of the ground electrode 110 corresponding to 00 and 600 are provided in the same manner as in the first and second embodiments, so that the characteristics of the filters 500 and 600 are hardly affected.

Next, a fourth embodiment of the duplexer of the present invention will be described. 8 is a schematic development view of this embodiment, FIG. 2 is a perspective view of this embodiment, and FIG. 9 is an equivalent circuit diagram of this embodiment.

In the first to third embodiments, the demultiplexing circuit 400 is composed of the two capacitances 401 and 402 and the one inductance 403, but in the present embodiment, the demultiplexing circuit 400 is composed of four capacitances. Capacitance 431-43
4 and two inductances 435 and 436. By configuring the demultiplexing circuit 400 in this manner, the demultiplexing circuit 400 can be easily designed and its characteristics can be broadened.

In order to realize such a demultiplexing circuit 400, in this embodiment, a capacitive coupling electrode 77 is provided on the dielectric layer 11 and an inner layer ground electrode 8 is provided on the dielectric layer 12.
1, 83, a transmission line 76 is provided, a ground electrode 800 is provided on the dielectric layer 14 instead of the transmission line 70, and a transmission line 74 is provided on the dielectric layer 16 in addition to the internal ground electrodes 82, 84. Unlike the first embodiment, a dielectric layer 18 is provided between the dielectric layer 16 and the dielectric layer 17, and a capacitive coupling electrode 75 is provided on the dielectric layer 18, but another configuration is used. Is the same as in the first embodiment, and the materials and manufacturing methods used are also the same.

In the present embodiment, the electrostatic capacitance 431 of the demultiplexing circuit 400 is formed at the overlapping portion of the one end 61 of the capacitive coupling electrode 60 and the rear end 742 of the transmission line 74 on the dielectric layer 16. The capacitance 432 is connected to the rear end portion 74 of the transmission line 74.
2 and the front end portion 75 of the capacitive coupling electrode 75 on the dielectric layer 18
2 and the transmission line 74 forms an inductance 435. The front end portion 741 of the transmission line 74 is connected to the ground electrode 110 provided on the front side surface of the stacked body 100, and the rear end portion of the capacitive coupling electrode 75 is provided on the rear side surface of the stacked body 100.
Connected with.

Further, the electrostatic capacitance 434 of the demultiplexing circuit 400 is formed at the overlapping portion of the one end 51 of the capacitive coupling electrode 50 on the dielectric layer 13 and the rear end 762 of the transmission line 76 on the dielectric layer 12. Then, the capacitance 434 is applied to the rear end portion 7 of the transmission line 76.
62 and the front end portion 7 of the capacitive coupling electrode 77 on the dielectric layer 11.
It is formed in the overlapping portion with 72, and the inductance 436 is formed by the transmission line 76. The front end 761 of the transmission line 76 is connected to the ground electrode 110 provided on the lower surface of the laminated body 100 by the through hole 92 provided in the dielectric layer 12 and the through hole 91 provided in the dielectric layer 11. . In this way, the transmission line 76
Is not connected to the ground electrode 110 provided on the front side surface of the laminated body 100, but is connected to the ground electrode 110 provided on the lower surface of the laminated body 100 by the through hole 92 and the through hole 91. This is to obtain an inductance 436 having a value different from the inductance 435 of 74. In addition, the capacitive coupling electrode 7
The rear end portion 771 of 7 is connected to the antenna terminal 123 provided on the rear side surface of the stacked body 100.

Further, in this embodiment, the dielectric layer 14
The ground electrode 800 provided on the transmission line 74, 7
It functions as a shield that prevents distributed coupling between the six. The front end portion of the ground electrode 800 is connected to the ground electrode 110 provided on the front side surface of the laminated body 100, and the rear end portions 801 and 8 are provided.
Reference numeral 02 denotes a ground electrode 1 provided on the rear side surface of the laminated body 100.
Connected with 10. The rear end of the ground electrode 800 is separated into two parts 801 and 802, and the rear end 8
No electrodes are provided between 01 and 802 in order to prevent the ground electrode 800 from short-circuiting with the antenna terminal 123 provided on the rear side surface of the laminate 100.

In each of the above embodiments, bandpass filters are shown as the filters 500 and 600, but in the present invention, not only bandpass filters, but also band rejection filters, lowpass filters, highpass filters, etc. Filters 500 and 6 respectively
00 can be used.

[0057]

According to the present invention, the first and second filters having different center frequencies and the center frequency of either one of the first and second filters can be used for the first and second filters. A duplexer in which the impedance of the other of the first and second filters viewed from the input / output terminal shared by the two filters is set to infinity, At least one of the second filters is a triplate type filter in which a resonance element is integrally provided in a dielectric substrate, and at least a part of the demultiplexing circuit is provided in the dielectric substrate. The filter, the second filter, and the demultiplexing circuit are integrally formed on the dielectric substrate, so that the duplexer can be downsized, the number of parts can be reduced, and the coil Since it becomes unnecessary parts, excellent in stability and reliability duplexer can be obtained.

In this case, the demultiplexing circuit is connected to the first and second filters in series with the capacitance and the first capacitance, respectively.
Also, the demultiplexing circuit can be easily formed on the dielectric substrate by configuring the demultiplexing circuit with the second filter and the inductance connected in parallel to the second filter.

The inductance can be compactly formed on the dielectric substrate by constructing the inductance by a transmission line whose tip is short-circuited to ground and whose electric length is 90 degrees or less.

Further, by using a microstrip line for the transmission line forming the inductance of the demultiplexing circuit, the characteristic impedance of the transmission line can be increased, and as a result, the demultiplexing circuit can have a wider band.

[Brief description of drawings]

FIG. 1 is a schematic development view of a duplexer according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the duplexer according to the first embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the duplexer according to the first embodiment of the present invention.

FIG. 4 is a schematic development view of a duplexer according to a second embodiment of the present invention.

FIG. 5 is a perspective view of a duplexer according to a second embodiment of the present invention.

FIG. 6 is a schematic development view of a duplexer according to a third embodiment of the present invention.

FIG. 7 is a perspective view of a duplexer according to a third embodiment of the present invention.

FIG. 8 is a schematic development view of a duplexer according to a fourth embodiment of the present invention.

FIG. 9 is a perspective view of a duplexer according to a fourth embodiment of the present invention.

FIG. 10 is a diagram for explaining a conventional duplexer.

FIG. 11 is a diagram for explaining a conventional duplexer.

[Explanation of symbols]

 11-17 ... Dielectric layers 21-25 ... Resonance elements 31-35 ... Electrodes 41, 42 ... Input / output electrodes 50, 60, 73 ... Capacitive coupling electrodes 70, 74, 76 ... Transmission lines 81-84 ... Inner layer ground electrode 91 To 94 ... through hole 100 ... laminated body 110 ... earth electrode 400 ... demultiplexing circuit 500, 600 ... filter

Claims (4)

[Claims] 1. A first filter and a second filter having different center frequencies, and the center frequency of one of the first and second filters is shared by the first and second filters. A duplexer circuit in which the impedance of the other filter of the first and second filters viewed from the input / output terminal is set to infinity. At least one resonance element is a triplate filter integrally provided in a dielectric substrate, at least a part of the branching circuit is provided in the dielectric substrate, the first filter, the first filter, A duplexer in which the second filter and the demultiplexing circuit are integrally formed on the dielectric substrate. 2. The duplexer according to claim 1, wherein the demultiplexing circuit is connected in series with the first and second filters and in parallel with the first and second filters. A duplexer characterized by having an inductance. 3. The duplexer according to claim 2, wherein the end of the inductance is short-circuited to the ground and the transmission line has an electrical length of 90 degrees or less. 4. The duplexer according to claim 2 or 3,
A duplexer characterized in that the transmission line forming the inductance of the branching circuit is a microstrip line.