JPH1131905A - Duplexer, duplexer using the same, and mobile communication device for dual frequency band - Google Patents

Abstract

(57) Abstract: A duplexer used for mobile communication such as a mobile phone, which can split two bands with a simple configuration and does not affect each other's bands. The purpose is to realize. SOLUTION: One-polar π-type three-stage low-pass filter 115
By connecting an inductor 105 as a first matching circuit between the common terminal 113 and the common terminal 113, and connecting a capacitor 106A as a second matching circuit between the one-polarized bandpass filter 116 and the common terminal 113, A duplexer that does not affect the frequency band and attenuates harmonic components sufficiently can be easily realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a duplexer mainly used for mobile communication such as a portable telephone, a duplexer using the same, and a mobile communication device for a two-frequency band.

[0002]

2. Description of the Related Art Generally, this type of duplexer is shown in FIGS.
The configuration shown in FIG. That is, in the conventional duplexer, as shown in FIG. 10, the circuit shown in FIG. 9 is composed of a low-pass filter and a high-pass filter formed in a low dielectric constant ceramic.

[0003] In FIG. 10, a conductor layer 24 as a shield electrode is formed on a low dielectric constant layer 16i, and a low dielectric constant layer 16h is laminated thereon. On this low dielectric layer 16h, inductor electrodes 23a and 23b are formed, and a low dielectric layer 16g is laminated.
The capacitor electrode 22 is formed on the low dielectric constant layer 16g, and the low dielectric constant layer 16f is laminated. The capacitor electrode 21 is formed on the low dielectric constant layer 16f, and the low dielectric constant layer 16e is laminated. A conductor layer 2 as a shield electrode is formed on the low dielectric layer 16e.
0 is formed, and the low dielectric constant layer 16d is laminated. The capacitor electrode 19 is formed on the low dielectric layer 16d.
a and 19b are formed, and the low dielectric constant layer 16c is formed.
Are laminated. The inductor electrode 18 is formed on the low dielectric constant layer 16c, and the low dielectric constant layer 16b is laminated. The inductor electrode 17 is formed on the low dielectric constant layer 16b, and the low dielectric constant layer 16a is laminated. Note that a via hole 25 for obtaining conduction between the inductor electrodes 17 and 18 is formed in the low dielectric constant layer 16b.

FIG. 11 is a perspective view of a conventional duplexer. The conductor layers 20 and 24 are connected to end electrodes 26b, 26d, 26f, and 26g on the dielectric side surfaces, and are connected to the end electrodes 26b, 26d, 26f, and 26g.
Is grounded to form a shield electrode.

[0005] As shown in FIG. 9, a first terminal 907 is formed by connecting an end face electrode 26 a and an inductor electrode 17 on a dielectric side surface, and the inductor electrode 17 is connected to the inductor electrode 1 via a via hole 25.
8, the first inductor 902 is formed. Further, the end face electrode 26a is also connected to the capacitor electrode 19a on the dielectric side face, and
0 forms the first capacitor 901. Further, a common terminal 908 is formed by connecting the inductor electrode 18, the capacitor electrode 21, and the end face electrode 26c on the dielectric side surface. Furthermore, the end face electrode 26c
Is also connected to the capacitor electrode 19 b on the dielectric side surface, and the second capacitor 903 is connected to the conductor layer 20.
To form Thus, the low-pass filter 910 is configured.

Next, a third capacitor 905 is formed between the capacitor electrode 21 connected to the end face electrode 26c and the opposite capacitor electrode 22. The end surface electrode 26c is also connected to the inductor electrode 23b on the dielectric side surface, and is connected to the end surface electrode 26g at the other end, thereby forming the second inductor 904. Similarly, on the dielectric side surface, the capacitor electrode 22 is connected to the inductor electrode 23a, and the other end is connected to the end face electrode 26f to form the third inductor 906. Further, on the dielectric side surface, the capacitor electrode 2
3 is also connected to the end face electrode 26e, and the second terminal 9
09 is formed. Thus, the high-pass filter 911 is configured.

The low-pass filter 910 is set to increase the attenuation at the pass band frequency of the high-pass filter 911, and the high-pass filter 911 is set to increase the attenuation at the pass band frequency of the low-pass filter 910. By doing so, both isolations were obtained.

[0008]

However, in recent years,
As the number of users of mobile communication increases rapidly, attempts are being made to use systems of two frequency bands with one communication device in order to secure a communication channel. In this case, a device having a function of demultiplexing two bands is required.However, a conventional demultiplexer includes a low-pass filter and a high-pass filter formed in ceramics having a low dielectric constant. Therefore, in order to realize such a system, there have been problems that harmonic components cannot be removed due to restrictions on the configuration, and the shape becomes large due to restrictions on the design.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has as its object to realize a small-sized device capable of separating two bands and removing a harmonic component.

[0010]

According to the present invention, there is provided a low-pass filter comprising a low-permittivity layer and a high-permittivity layer formed integrally with each other. In this example, an inductor as a matching circuit is formed on a low dielectric layer, and a band-pass filter and a capacitor as a matching circuit for the band-pass filter are formed on a high dielectric layer.

According to this configuration, a signal input to the common terminal is split into two bands, and a small device capable of removing harmonic components can be realized.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention has a first terminal, a second terminal, and a common terminal, and a first terminal connected between the first terminal and the common terminal. And a second low-pass filter having a frequency band higher than the first band connected between the common terminal and the second terminal.
And a first matching circuit connected between the low-pass filter and the common terminal, and a second matching circuit between the common terminal and the band-pass filter. A duplexer, wherein a signal input from a common terminal is split into a first band and a second band, and a band-pass filter is provided in the first band. And the signal flowing between the first terminal and the common terminal is
And the effect of the low-pass filter in the second band can be reduced, and the signal flowing between the second terminal and the common terminal can be prevented from flowing into the first terminal. .

According to a second aspect of the present invention, there is provided the duplexer according to the first aspect, wherein the first matching circuit is an inductor connected in series. One matching circuit can be easily configured.

According to a third aspect of the present invention, there is provided the duplexer according to the first aspect, wherein the second matching circuit is a capacitor connected in series. The second matching circuit can be easily configured.

According to a fourth aspect of the present invention, in the duplexer according to any one of the first to third aspects, the low-pass filter is a low-pass filter of a π-type circuit. In addition, this configuration has an effect that a low-pass filter capable of easily achieving impedance matching and sufficiently removing harmonic components can be configured.

The invention according to claim 5 of the present invention is the duplexer according to any one of claims 1 to 3, wherein the low-pass filter has at least one attenuation pole. The configuration has an effect that harmonic components can be sufficiently removed.

The invention according to claim 6 of the present invention is the duplexer according to claim 5, wherein one of the attenuation poles is a low-pass filter existing in the second band. ,
This configuration has an effect that the isolation in the second band between the first terminal and the common terminal can be increased.

According to a seventh aspect of the present invention, the duplexer according to any one of claims 1 to 3, wherein the band-pass filter is a band-pass filter having at least one attenuation pole. This configuration has the effect of realizing a filter having good attenuation characteristics.

The invention according to claim 8 of the present invention is the duplexer according to claim 7, wherein one of the attenuation poles is a band-pass filter existing in the first band.
This configuration has an effect that the isolation in the first band between the common terminal and the second terminal can be increased.

According to a ninth aspect of the present invention, at least two layers of a high dielectric constant layer and a low dielectric constant layer are laminated, and the high dielectric constant layer includes a band-pass filter and a second matching circuit. 2. A low-pass filter and a first matching circuit are formed on the low dielectric constant layer.
The duplexer described above has an effect that a small-sized duplexer can be realized because the low-pass filter and the band-pass filter can be configured small.

According to a tenth aspect of the present invention, in the high dielectric layer, a resonator electrode and a capacitor electrode for forming a band-pass filter and a capacitor electrode for forming a second matching circuit are provided. And the low dielectric constant layer has
An inductor electrode and a capacitor electrode for forming a low-pass filter, and an inductor electrode for forming a first matching circuit; and a band at an interface between the high dielectric layer and the high dielectric layer. 2. The duplexer according to claim 1, wherein a common shield electrode is provided for the pass filter and the low-pass filter, whereby the high dielectric layer ceramic is diffused into the low dielectric layer ceramic. Is reduced, so that simultaneous batch firing of the dielectric can be performed, and the production cost can be reduced.

According to an eleventh aspect of the present invention, in the high dielectric layer, a resonator electrode, a capacitor electrode, and a shield electrode for forming a band-pass filter and a second matching circuit are formed. A low dielectric constant layer, an inductor electrode for forming a low-pass filter, a capacitor electrode and a shield electrode, and an inductor electrode for forming a first matching circuit. 2. The duplexer according to claim 1, wherein the duplexer has an effect that the dielectric can be easily fired and the low-pass filter and the band-pass filter can be manufactured stably. .

In a twelfth aspect of the present invention, the high dielectric constant layer is a Bi ₂ O ₃ —CaO—Nb ₂ O ₅ based dielectric ceramic, and the low dielectric constant layer is a SiO ₂ —BaO—La ₂ O ₃ system to consist of glass and forsterite powder from claim 9, wherein 11 is a duplexer according to any one of,
This configuration has an effect that the composite multilayer ceramic component can be integrally realized by simultaneous simultaneous firing.

The invention according to claim 13 of the present invention provides a highly attractive device.
The electric power layer is BaO-Nd_TwoO_Five-TiO _TwoBased dielectric ceramic
And SiO_Two-BaO-La_TwoO_ThreeMade of base glass, low
Dielectric layer is SiO_Two-BaO-La_TwoO_ThreeGlass and glass
10. The method according to claim 9, which is composed of lusterite powder.
11. The duplexer according to claim 11, wherein
Composite multi-layer ceramic parts
It has the effect that it can be realized.

According to a fourteenth aspect of the present invention, the two splitters according to any one of the first to thirteenth aspects are combined with the SPD.
A duplexer comprising a T switch, wherein one output terminal of an SPDT switch is connected to a common terminal of the duplexer, and a common terminal of another duplexer is connected to the other output terminal. , Time Division Multiple Access (TD) that can be used in two bands
This has an effect that a duplexer compatible with the MA method can be easily configured.

According to a fifteenth aspect of the present invention, there is provided a duplexer according to any one of the first to thirteenth aspects, wherein the duplexer operates in the first band and the duplexer operates in the second band. And an antenna terminal operating in a first band is connected to a first terminal of the duplexer, and an antenna terminal operating in a second band is connected to a second terminal of the duplexer. This has the effect that a duplexer compatible with a system other than the TDMA system that can be used in two bands can be easily configured.

According to a sixteenth aspect of the present invention, there is provided a two-frequency band mobile communication device using the duplexer according to any one of the first to thirteenth aspects in a high-frequency circuit. With this configuration, there is an effect that a high-frequency circuit of a mobile communication device terminal that can use two frequency bands can be simply configured.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG. (Embodiment 1) FIG. 1 is a circuit diagram showing a configuration of a duplexer according to Embodiment 1 of the present invention. In FIG. 1, the first
One end of the first capacitor 101, one end of the first inductor 102, and one end of the second capacitor 103 are connected to the terminal 112, and the other end of the first capacitor 101 is grounded. One end of a third capacitor 104 and one end of a second inductor 105 are connected to the other end of the first inductor 102 and the other end of the second capacitor 103, respectively.
04 is grounded. The other end of the second inductor 105 was connected to one end of the fourth capacitor 106A, connected to the common terminal 113, and connected in series. One end of the first quarter-wave resonator 107, one end of the fifth capacitor 108, and the third inductor 109 are connected to the other end of the fourth capacitor 106B.
To one end. The other end of the fifth capacitor 108 has a second quarter-wave resonator 110 and a sixth capacitor 11
1 and the other end of the third inductor 109 and the other end of the sixth capacitor 111 to connect the second terminal 11
Connect to 4.

Here, in order to make the description easy to understand, the fourth capacitors 106A, 106A,
The following description will be made by replacing 106B with one capacitor, that is, the fourth capacitor 106.

Regarding the duplexer constructed as described above,
The operation will be described below. The first capacitor 101, the first inductor 102, the second capacitor 103, and the third
The capacitor 104 constitutes a π-type three-stage one-pole low-pass filter 115, and is set so as to form a pass band in the first band and an attenuation pole in the second band. The fourth capacitor 106, the first quarter-wave resonator 107, the fifth capacitor 108, the third inductor 109, the second quarter-wave resonator 110, and the sixth capacitor 11
1 constitutes a two-stage one-pole bandpass filter 116,
Is set so as to form a pass band in the band and an attenuation pole in the first band.

In the circuit from the common terminal 113 to the second terminal 114, the fourth capacitor 10 connected in series
6 is 1 / (ω
C), the first quarter-wave resonator 107 is replaced by a parallel resonance circuit of a capacitor and an inductor, and one end is grounded, so that the impedances are expressed as ωC and 1 / (ωL), respectively. (L is the inductance of the inductor), so that the lower the frequency, the higher the impedance of the fourth capacitor 106 becomes.
波長 wavelength resonator 107 is in a low impedance state.

Therefore, in the first band, the band-pass filter 116 has a capacitive property and acts as a capacitor connected between the common terminal 113 and the ground. First
Of the second inductor 105 connected as a matching circuit of
In addition, between the first terminal 112 and the common terminal 113 is equivalently a π-type five-stage low-pass filter.

As a result, the signal of the first band input to the common terminal 113 is sufficiently attenuated on the second terminal 114 side, most is output on the first terminal 112 side, and the harmonic component is low. It is sufficiently attenuated by the band pass filter 115. Conversely, the signal of the first band input to the first terminal 112 does not flow to the second terminal 114 side, but the common terminal 11
3 is output.

Next, the operation between the common terminal and the second terminal 114 will be described. From the common terminal 113 to the first terminal 1
In the circuit on the 12th side, the impedance of the second inductor 105 connected in series is represented by L
Is expressed as ωL, and expressed as 1 / (ωC), the impedance of the third capacitor 104 connected to the ground (C is the capacitance of the capacitor). Therefore, the second inductor increases as the frequency increases. 105 is in a high impedance state, and the third capacitor 104 is in a low impedance state. Therefore, in the second band, the low-pass filter 115 exhibits inductive properties and acts as an inductor connected between the common terminal 113 and the ground.

Here, it is assumed that a capacitor is connected in series between the common terminal 113 and the band-pass filter 116, and an inductor is connected between the other end of the capacitor, the connection point of the band-pass filter 116 and the ground. This inductor can be equivalently represented as a negative capacitor connected to the ground, and can be substituted by shortening the resonator length of the first quarter-wave resonator 107. As for the capacitor, the band-pass filter 116 is used.
Since the input / output coupling is a capacitive coupling, it can be composed of one element as a combined capacitance.

As a result, the circuit of FIG. 1 adjusts the resonator length of the fourth capacitor 106 and the first quarter-wave resonator 107 to provide a series connection between the common terminal 113 and the band-pass filter 116. Can be set to include an inductor connected between the capacitor connected to the ground and the ground.

Therefore, in the second band, an inductor connected between the common terminal 113 and the second terminal 114 to the ground, a capacitor connected in series, and an inductor connected to the ground. Are equivalently configured. This circuit is a π-type high-pass filter type transfer circuit known as a matching circuit in a band lower than the pass band.

As a result, the signal of the second band input to the common terminal 113 is sufficiently attenuated at the first terminal 112 side, most of the signal is output to the second terminal 114 side, and the harmonic component is It is sufficiently attenuated by the pass filter 116. Conversely, the signal of the second band input to the second terminal 114 does not flow to the first terminal 112 side, and the common terminal 11
3 is output.

With the above configuration, this embodiment functions as a duplexer that divides an input signal into two bands.

Although there are other circuit types constituting a single-polarized bandpass filter, the details of the duplexer of the present invention are not affected by the circuit type of the bandpass filter.

Further, in a portable telephone terminal capable of using two frequency bands, the use of the duplexer of the present invention makes it possible to configure a high-frequency demultiplexing circuit of the terminal with a simple circuit, thereby reducing the size and weight of the terminal. it can.

(Embodiment 2) FIG. 2 is a schematic diagram showing a configuration of a duplexer according to Embodiment 2 of the present invention, and FIG. 3 is a perspective view of the duplexer. In FIG. 2, SiO ₂ -B
aO-La ₂ O ₃ system glass on the low dielectric constant layer 3 mainly composed, together with the conductor layer 13 as a shield electrode is _{formed, Bi 2 O 3 -CaO-Nb} 2 O 5 based dielectric ceramics or a high dielectric constant layer 2c are laminated consisting of BaO-Nd ₂ O ₅ -TiO ₂ based dielectric ceramic. Also,
Resonator electrodes 12a and 12a
with b is _{formed, Bi 2 O 3 -CaO-Nb} 2 O 5 based dielectric ceramics or BaO-Nd ₂ O ₅ -TiO ₂
A high dielectric constant layer 2b made of a dielectric ceramic is laminated. Further, on the high dielectric layer 2b, an input / output coupling capacitor electrode 9 and a load capacitor electrode 10 are provided.
A capacitor electrode 11 for forming a second matching circuit with a and 10b is arranged. On top of this, Bi ₂
O ₃ -CaO-Nb ₂ O ₅ based dielectric ceramics or B
high dielectric constant layer 2a made of aO-Nd ₂ O ₅ -TiO ₂ based dielectric ceramics are laminated, the conductor layer 8 as a shield electrode is formed on the upper surface of the high dielectric constant layer 2a.

Next, the high dielectric constant layer 2 provided with the conductor layer 8
SiO on a_Two-BaO-La_TwoO _ThreeBased glass
Is provided, and the low dielectric layer 1d
Electrodes 7a and 7b are formed on the upper surface of
With SiO_Two-BaO-La_TwoO_ThreeBased glass
Is provided, and the low dielectric constant layer 1c
A capacitor electrode 6 is formed on the upper surface of
O_Two-BaO-La_TwoO _ThreeLow dielectric based on glass
A low dielectric constant layer 1b.
An inductor for forming a first matching circuit with the inductor electrode 4.
A ductor electrode 5 is provided. On top of this, SiO_Two
-BaO-La_TwoO_ThreeLow dielectric constant layer based on glass
1a is provided.

The duplexer having the above-described structure is formed by batch firing and printing and laminating green sheets.

Next, the low dielectric constant layers 1a to 1c, which are features of the present invention,
The material of 1d and the high dielectric layers 2a to 2c will be described.

The low dielectric layers 1a to 1d and the high dielectric layer 2a
To 2c were prepared as described below. The green sheet of the low dielectric constant layer was prepared as follows. The glass used for the low dielectric layers 1a to 1d is SiO
₂ , H ₃ BO ₃ , Al (OH) ₃ , CaCO ₃ , BaCO ₃ , S
Raw materials such as rCO ₃ and La ₂ O ₃ were melted in a platinum or platinum rhodium crucible, cooled and pulverized to produce a glass powder. 500 g of the obtained glass powder was added to a solution in which 25 g of dibutyl phthalate and 50 g of polyvinyl butyral resin were dissolved in 200 g of methyl ethyl ketone, and mixed and pulverized with a ball mill for 24 hours. From the obtained slurry, a low dielectric constant layer green sheet having a thickness of 50 μm was prepared by a well-known doctor blade method.

Bi ₂ O ₃ —CaO—Nb ₂ O ₅ (hereinafter BC)
N) is used in the production of the high dielectric constant layer.
No. 225826, a dielectric constant of 58, 500 g of BCN-based dielectric powder, 200 g of methyl ethyl ketone, 10 g of dibutyl phthalate, and a polyvinyl butyral resin 25
g was dissolved in the solution and mixed with a ball mill for 24 hours. From the obtained slurry, a BCN high dielectric constant layer green sheet having a thickness of 50 μm was prepared by a doctor blade method.

Similarly, BaO—Nd ₂ O ₅ —TiO ₂ —
In producing a Bi ₂ O ₃ -based high dielectric constant layer, Japanese Patent Application No.
No. 108788, dielectric constant 60, BaO—Nd ₂ O ₅ −
TiO ₂ -Bi ₂ O ₃ based high dielectric powder 100 wt% with respect to SiO ₂ -BaO-La ₂ O ₃ based glass powder 20 wt%
In addition, it was blended so as to be 500 g in total. This powder (hereinafter referred to as BNTG) is treated with methyl ethyl ketone 20
0 g was added to a solution in which 10 g of dibutyl phthalate and 25 g of polyvinyl butyral resin were dissolved, and mixed with a ball mill for 24 hours. From the obtained slurry, a BNTG high dielectric constant layer green sheet having a thickness of 50 μm was prepared by a doctor blade method.

The high-dielectric-constant layer sheets produced by the above-described method are laminated and thermocompression-bonded at 60 ° C. to form a high-dielectric-constant layer 2a and a high-dielectric-constant layer 2c having a thickness of 600 μm, A 50 μm thick high dielectric constant layer 2b interposed between the input / output coupling capacitor electrode 9, the load capacitor electrodes 10a and 10b, and the second matching circuit capacitor electrode 11 was produced. Similarly, a low dielectric constant layer sheet was laminated and thermocompression bonded at 60 ° C. to produce low dielectric constant layers 1 a to 1 d and a low dielectric constant layer 3. Via holes 14a and 14b for obtaining conduction between conductor layers were formed in the low dielectric constant layer 1b, and filled with silver paste. A predetermined conductive pattern is printed on each of the green sheets of the low dielectric layers 1b to 3 by a screen printing method using a silver paste, and the inductor electrode 4, the matching circuit inductor electrode 5, the capacitor electrode 6, and the capacitor electrodes 7a and 7b are respectively printed. , Conductor layer 8, input / output coupling capacitor electrode 9, load capacitor electrodes 10a and 10
b, matching circuit capacitor electrode 11, resonator electrode 12a
And 12b, and the conductor layer 13 were formed. Next, the green sheets of the low dielectric constant layers 1a to 3 were sequentially positioned and laminated, and after thermocompression bonding at 80 ° C, the binder was removed at 400 ° C to 450 ° C, and then fired at 900 ° C to 950 ° C.

Next, in order to obtain an end surface electrode for connecting to a printed board on the side surface of the sintered body, a silver paste is printed and fired by a screen printing method, and the end surface electrode 15a shown in FIG.
~ 15e. Next, a nickel and solder plating layer was formed by barrel plating.

Regarding the duplexer configured as described above,
The operation will be described below. Although the duplexer of this configuration is represented by the equivalent circuit shown in FIG. 4, it is basically the same as the duplexer described in the first embodiment, and the same parts are denoted by the same reference numerals and detailed description. Is omitted.

The conductor layer 8 and the conductor layer 13 are connected to the end electrodes 15a and 15d on the dielectric side surfaces, and form a shield electrode by grounding the end electrodes 15a and 15d.

By connecting the end face electrode 15b and the inductor electrode 4 on the dielectric side surface, the first terminal 11
2 and the first inductor 102, and the end face electrode 15b is also connected to the capacitor electrode 7a. The capacitor electrode 7a forms the first capacitor 101 with the conductor layer 8, and the capacitor electrode 6 is arranged so as to face a part of the inductor electrode 4, thereby forming the second capacitor 103. Then, the inductor electrode 4 and the capacitor electrode 6 are connected by a via hole 14b. Further, the second inductor 105 is formed by connecting the matching circuit inductor electrode 5, the capacitor electrode 6, and the capacitor electrode 7b with the via hole 14a, and the capacitor electrode 7b is connected to the conductor layer 8 with the third electrode.
Are formed.

As described above, the low-pass filter 415
And by connecting the matching circuit inductor electrode 5 and the end face electrode 15e on the dielectric side surface,
The common terminal 113 is formed.

Next, the end face electrode 15e and the matching circuit capacitor electrode 11 are connected. The end face electrode 15e is the common terminal 11
3, and the fourth capacitor 106 is formed by disposing the matching circuit capacitor electrode 11 so as to face a part of the resonator electrode 12b. Also, the end face electrode 15c
And the input / output coupling capacitor electrode 9 are connected to form the second terminal 114, and the input / output coupling capacitor electrode 9 is disposed so as to face a part of the resonator electrode 12a. 111 are formed. One end of the resonator electrode 12b is connected to the grounded end face electrode 15a to form a first quarter-wave resonator 417, and similarly, the resonator electrode 12a is connected to the grounded end face electrode 15a. To form the second quarter-wave resonator 418. Load capacitor electrode 10b
Is disposed so as to face a part of the resonator electrode 12b, and one end thereof is connected to a grounded end face electrode 15c to form a first load capacitor 419. The load capacitor electrode 10a is connected to the resonator electrode 12a. And a second load capacitor 420 is formed by connecting one end of the second load capacitor 420 to the grounded end face electrode 15c.
The bandpass filter 416 is configured as described above.

The band-pass filter 416 formed in the high dielectric layers 2a to 2c has a first quarter-wave resonator 417
An attenuation pole is formed by electromagnetic field coupling between the first and second quarter-wave resonators 418, and a pass band is formed in the second band and an attenuation pole is formed in the first band. . In the second band, the low-pass filter 415 acts as an inductor connected between the common terminal 113 and the ground as in the first embodiment. At this time, by adjusting the resonator length of the first quarter-wave resonator 417 and the capacity of the first load capacitor 419, a π-type high-pass filter type transfer circuit is configured. By using such a structure in which two types of dielectric layers are simultaneously laminated, a duplexer can be configured with a small size and a low profile.

With the above configuration, this embodiment functions as a duplexer that divides an input signal into two bands.

In the present embodiment, an example in which the shield electrode is arranged at the interface between the low dielectric constant layer and the high dielectric constant layer has been described. However, as shown in FIG. It is also possible to form conductor layers 16a, 16b, 17a and 17b as shield electrodes. in this case,
Diffusion of the high dielectric constant layer ceramics into the low dielectric constant layer ceramics during firing is reduced, and simultaneous batch firing of dielectrics can be facilitated, so that variations in the characteristics of the band-pass filter can be suppressed and manufacturing costs can be reduced. Can be reduced.

In this embodiment, the input / output coupling of the band-pass filter is a capacitor coupling. However, this coupling may be performed by a tapping electrode 621 as shown in FIG.
In this case, there is an effect that impedance matching of a bandpass filter having a wide band and low insertion loss can be easily achieved.

Further, in a portable telephone terminal capable of using two frequency bands, by using the duplexer of the present invention, a high-frequency demultiplexing circuit of the terminal can be constituted by a simple circuit, and the terminal can be reduced in size and weight. it can.

(Embodiment 3) FIG. 7 is a diagram showing a configuration of a duplexer according to Embodiment 3 of the present invention. 7, a common terminal of the first duplexer 702 is connected to one output terminal of the SPDT switch 701, and a second terminal is connected to the other output terminal.
The common terminal of the duplexer 703 is connected. Thus, the input terminal of the SPDT switch 701 is the antenna terminal 704, the first terminal of the first duplexer 702 is the first transmission terminal 708, and the second terminal of the first duplexer 702 is the second terminal. , The first terminal of the second duplexer 703 is the first receiving terminal 711, and the second terminal of the second duplexer 703 is
Are used as the second receiving terminal 712.

For the duplexer configured as described above,
The operation will be described below. Since the duplexer of this configuration is the duplexer described in the first and second embodiments,
A detailed description of the operation is omitted.

In a portable telephone terminal adopting the TDMA system, transmission and reception do not occur at the same time. Therefore, the SPDT switch 70 that switches the path in time
1 can be used.

The transmission signal of the first band input to the first transmission terminal 708 does not flow into the second transmission terminal 709 by the first demultiplexer 702, and the common terminal 7 of the first demultiplexer.
07 and the first of the SPDT switches 701
Flows to the output terminal 705 of FIG. And SPDT switch 7
01 and is output from the antenna terminal 704 without flowing into the second output terminal 706. Similarly, the transmission signal of the second band input to the second transmission terminal 709 does not flow into the first transmission terminal 708 by the first demultiplexer 702, and the common terminal of the first demultiplexer 702 707,
Further, a first output terminal 705 of the SPDT switch 701
Flows to The signal is output from the antenna terminal 704 without flowing into the second output terminal 706 by the SPDT switch 701.

Next, the received signal of the first band input to the antenna terminal 704 is not flown into the first output terminal 705 by the SPDT switch 701 but is supplied to the second output terminal 7.
06, and further flows to the common terminal 710 of the second duplexer 703. Then, the second splitter 703 outputs the second
Of the first receiving terminal 71
1 is output. Similarly, the reception signal of the second band input to the antenna terminal 704 is output to the second output terminal 706 without flowing into the first output terminal 705 by the SPDT switch 701, and is output to the second splitter 703. Flows to the common terminal 710. Then, the first splitter 703
Does not flow into the receiving terminal 711 of the second receiving terminal 71
2 is output.

With the above-described configuration, the present embodiment operates as a TDMA-compatible duplexer usable in two frequency bands.

As an example, in the first band, a Japanese digital mobile phone (Personal Digital Cellular:
) And a Japanese simple portable phone (PHS) is used in the second band, the duplexer of the present invention is used in both PDC and PHS systems. be able to.

As an example, a first band uses a European mobile / mobile phone (Group Special Mobile: hereinafter referred to as GSM) and a second band uses a European Personal Communications Network (hereinafter referred to as GSM). , PCN), the duplexer of the present invention uses G
It can be used in both SM and PCN systems.

Although there are various types of SPDT switches, the details of the duplexer of the present invention are as follows.
It is not affected by the type of switch.

Further, in a portable telephone terminal that can use two frequency bands, by using the duplexer of the present invention, the duplexer circuit of the terminal can be configured with a simple circuit, and the terminal can be reduced in size and weight.

(Embodiment 4) FIG. 8 is a diagram showing a configuration of a duplexer according to Embodiment 4 of the present invention. In FIG. 8, a first duplexer 8 is connected to a first terminal 805 of a duplexer 801.
02 antenna terminal 807 to the second terminal 806
Antenna terminal 810 of the duplexer 803 is connected.
Thus, the common terminal of the duplexer 801 is the antenna terminal 804, the transmission terminal of the first duplexer 802 is the first transmission terminal 808, the reception terminal of the first duplexer 802 is the first reception terminal 809, A duplexer is configured in which the transmission terminal of the second duplexer 803 is a second transmission terminal 811, and the reception terminal of the second duplexer 803 is a second reception terminal 812.

With respect to the duplexer configured as described above,
The operation will be described below. Since the duplexer of this configuration is the duplexer described in the first and second embodiments,
A detailed description of the operation is omitted.

In a portable telephone terminal adopting a system other than the TDMA system, transmission and reception occur simultaneously, so that it is not possible to use an SPDT switch for temporally switching paths. Therefore, first, the first band and the second band are demultiplexed by the demultiplexer, and the transmission signal and the reception signal are separated in each band.

The transmission signal of the first band inputted to the first transmission terminal 808 does not flow into the first reception terminal 809 by the first duplexer 802 but is output to the antenna terminal 807 of the first duplexer. Then, it flows to the first terminal 805 of the duplexer 801. The signal is output from the antenna terminal 804 without flowing into the second terminal 806 side by the duplexer 801. The received signal of the first band input to the antenna terminal 804 is output to the first terminal 805 without flowing into the second terminal 806 by the demultiplexer 801, and is further output to the antenna terminal of the first duplexer 802. It flows to 807. Then, the signal is not output to the first transmission terminal 808 by the first duplexer 802 but is output to the first reception terminal 809.

Next, the transmission signal of the second band input to the second transmission terminal 811 is converted by the second duplexer 803 into the second transmission signal.
Does not flow into the receiving terminal 812 of the second duplexer, but is output to the antenna terminal 810 of the second duplexer.
To the terminal 806. Then, the first light is split by the duplexer 801.
Are output from the antenna terminal 804 without flowing into the terminal 805 side. The received signal of the second band input to the antenna terminal 804 is supplied to the first terminal 8 by the duplexer 801.
The signal is output to the second terminal 806 without flowing into the terminal 05, and further flows to the antenna terminal 810 of the second duplexer 803. Then, the second transmission terminal 8 is operated by the second duplexer 803.
11, and is output to the second reception terminal 812.

With the above-described configuration, this embodiment functions as a duplexer compatible with a system other than the TDMA system that can be used in two frequency bands.

As an example, in the first band, an analog mobile phone (Advanced Mobile Phone Service: hereinafter, AM)
PS), and in the second band, the US Personal Communications System (Personal Communications System:
Using the PCS, the duplexer of the present invention can be used in both AMPS and PCS systems.

Further, in a portable telephone terminal capable of using two frequency bands, by using the duplexer of the present invention, the duplexer circuit of the terminal can be constituted by a simple circuit, and the terminal can be reduced in size and weight.

[0079]

As described above, according to the present invention, a duplexer comprising a low-pass filter, a band-pass filter and a matching circuit can be constituted by a simple circuit, and the low-pass filter is a band-pass filter. And it is easy to set the band-pass filter so as not to affect the pass band of the low-pass filter.

Also, the low-permittivity layer and the high-permittivity layer are integrally formed, and the matching circuit of the low-pass filter and the low-pass filter is provided in the low-permittivity layer, and the band-pass filter and the band-pass filter By forming the matching circuit on the high dielectric constant layer, the size of the duplexer can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a duplexer according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a configuration of a duplexer according to a second embodiment of the present invention.

FIG. 3 is a perspective view of the duplexer.

FIG. 4 is a circuit diagram of the duplexer.

FIG. 5 is a schematic view showing another example of the configuration of the duplexer.

FIG. 6 is a circuit diagram showing another configuration example of the resonator electrode in the duplexer.

FIG. 7 is a circuit diagram showing a configuration of a duplexer according to Embodiment 3 of the present invention.

FIG. 8 is a circuit diagram showing a configuration of a duplexer according to a fourth embodiment of the present invention.

FIG. 9 is a circuit diagram showing a configuration of a conventional duplexer.

FIG. 10 is a schematic diagram showing a configuration of the duplexer.

FIG. 11 is a perspective view of the duplexer.

[Explanation of symbols]

 101 first capacitor 102 first inductor 103 second capacitor 104 third capacitor 105 second inductor 106 fourth capacitor 107 first quarter-wave resonator 108 fifth capacitor 109 third Inductor 110 Second quarter-wave resonator 111 Sixth capacitor 112 First terminal 113 Common terminal 114 Second terminal 115 Low-pass filter 116 Band-pass filter

────────────────────────────────────────────────── ─── Continued on the front page (51) Int.Cl. ⁶ Identification symbol FI H03H 7/01 H03H 7/46 A 7/46 H04B 1/50 H04B 1/50 C04B 35/46 D (72) Inventor Hidenori Katsumura Matsushita Electric Industrial Co., Ltd. (72) Inventor Ryuichi Saito, 1006 Kadoma Kadoma, Kadoma City, Osaka Prefecture 1006 Matsushita Electric Industrial Co., Ltd.

Claims (16)

[Claims] A low-pass filter having a first terminal, a second terminal, and a common terminal, wherein the low-pass filter is connected between the first terminal and the common terminal and has a first band as a pass band. Terminal and second
And a band-pass filter having a pass band of a second band, which is a frequency band higher than the first band, connected between the low-pass filter and the common terminal. And a second matching circuit connected between the common terminal and the band-pass filter. 2. The duplexer according to claim 1, wherein the first matching circuit is an inductor connected in series. 3. The duplexer according to claim 1, wherein the second matching circuit is a capacitor connected in series. 4. The duplexer according to claim 1, wherein the low-pass filter is a low-pass filter of a π-type circuit. 5. The duplexer according to claim 1, wherein the low-pass filter has at least one attenuation pole. 6. The method according to claim 5, wherein one of the attenuation poles is a low-pass filter present in the second band.
The duplexer described. 7. The duplexer according to claim 1, wherein the band-pass filter has at least one attenuation pole. 8. The filter of claim 7, wherein one of the attenuation poles is a bandpass filter present in the first band.
The duplexer described. 9. At least two of a high dielectric constant layer and a low dielectric constant layer
A band-pass filter and a second matching circuit are formed on the high dielectric layer, and a low-pass filter and a first matching circuit are formed on the low dielectric layer. The duplexer according to claim 1, wherein 10. The low dielectric constant layer includes a resonator electrode and a capacitor electrode for forming a band-pass filter, and a capacitor electrode for forming a second matching circuit. Are provided with an inductor electrode and a capacitor electrode for forming a low-pass filter, and an inductor electrode for forming a first matching circuit, and the high dielectric layer and the high dielectric layer The duplexer according to claim 1, wherein a shield electrode common to the band-pass filter and the low-pass filter is provided at an interface. 11. A high dielectric constant layer includes a resonator electrode, a capacitor electrode, and a shield electrode for forming a band-pass filter, and a capacitor electrode for forming a second matching circuit. 2. The dielectric layer further includes an inductor electrode, a capacitor electrode, and a shield electrode for forming a low-pass filter, and an inductor electrode for forming a first matching circuit. The duplexer described. 12. The high dielectric constant layer is made of Bi ₂ O ₃ —CaO—Nb.
₂ O ₅ dielectric ceramic, wherein the low dielectric constant layer is SiO ₂
Duplexer according to any one of claims 9 to 11, characterized in that it consists -BaO-La ₂ O ₃ based glass and forsterite powder. 13. The high dielectric constant layer is made of BaO—Nd ₂ O ₅ —Ti.
O ₂ -based dielectric ceramic and SiO ₂ -BaO-La ₂ O ₃ -based glass, wherein the low dielectric constant layer is SiO ₂ -BaO-La ₂
The duplexer according to any one of claims 9 to 11, comprising an O ₃ glass and a forsterite powder. 14. A duplexer according to claim 1, comprising two switches and a single-pole double-throw switch (hereinafter referred to as an SPDT switch).
A duplexer in which one output terminal of a switch is connected and a common terminal of another duplexer is connected to the other output terminal. 15. A duplexer comprising the duplexer according to claim 1, a duplexer operating in a first band, and a duplexer operating in a second band. A duplexer, wherein an antenna terminal operating in a first band is connected to a terminal, and an antenna terminal operating in a second band is connected to a second terminal of the duplexer. 16. A mobile communication device for a two-frequency band, wherein the duplexer according to claim 1 is used in a high-frequency circuit.