JP4678570B2 - Demultiplexer and high frequency composite parts using the same - Google Patents

Description

  The present invention relates to a duplexer used in a mobile communication device such as a cellular phone. Specifically, the duplexer is used in a high frequency circuit (front end unit) and demultiplexes high frequency signals of at least two communication systems having different frequencies. The present invention relates to a duplexer and a high-frequency composite component using the duplexer.

In recent years, as one form of mobile communication device, there is a multi-band mobile phone that can make a call using two or more communication systems with a single mobile phone. In this cellular phone, a demultiplexing circuit that demultiplexes a high-frequency signal having a frequency corresponding to each system is required.
As such a demultiplexing circuit, there is a demultiplexer configured by combining a plurality of filter circuits. Patent Document 1 proposes a multilayer duplexer having a multilayer structure in which a filter circuit is composed of an inductance element and a capacitance element, and each element is formed as an electrode pattern in the multilayer body. FIG. 6 shows an equivalent circuit diagram thereof.
In this laminated duplexer, a patterned electrode is formed inside a laminated body in which insulating layers made of a dielectric are laminated and integrated, and an inductance element and a capacitance element constituted by the patterned electrode are connected in series to form two notches. Circuit (series resonant circuit), a low-pass filter circuit (another inductance element) and a first series resonant circuit are arranged between the first port P1 and the second port P2, and the first port P1 and the third A high-pass filter circuit (another capacitance element) and a second series resonance circuit are arranged between the port P3.
The second series resonance circuit is configured to maximize the insertion loss at the frequency f1, and the first series resonance circuit is configured to maximize the insertion loss at a frequency f2 different from the frequency f1. Therefore, the microwave signal having the frequency f1 input to the first port P1 is not output to the third port P3, and the microwave signal having the frequency f2 input to the first port P1 is not input to the second port P2. Since it is not output, the microwave signal can be distributed.
JP 2001-119258 A

Currently, it can operate as a mobile communication device in communication systems of multiple frequency bands such as DCS1800 (transmission frequency 1710 to 1785 MHz, reception frequency 1805 to 1880 MHz) and GSM900 (transmission frequency 880 to 915 MHz, reception frequency 925 to 960 MHz). Dual-band mobile phone, DCS1800 and PCS1900 (transmission frequency 1850-1910 MHz, reception frequency 1930-1990 MHz) and triple-band mobile phone that can operate with GSM900, and GSM850 (transmission frequency 824-849 MHz, A quad-band mobile phone to which a system having a reception frequency of 869 to 894 MHz) has been proposed, and this is collectively called a multi-band mobile phone.
The use frequency bands of these communication systems are roughly classified into a communication system using a frequency band of 800 MHz to 1 GHz and a communication system using a relatively high frequency band of 1.5 GHz to 2.4 GHz.

With the recent increase in the number of multi-band cellular phones, it has become necessary for the demultiplexing circuit to demultiplex a plurality of low frequency band communication systems and a plurality of high frequency band communication systems. However, in the conventional branching circuit, it is difficult to secure an attenuation amount over a wide frequency band including the frequency bands of a plurality of communication systems. For this reason, a desired insertion loss cannot be obtained in the pass band. was there.
Therefore, in the present invention, an attenuation amount can be obtained over a wide band in a duplexer that is used in a multiband mobile phone that enables a call in two or more communication systems and demultiplexes a high-frequency signal corresponding to the communication system. An object of the present invention is to provide a small duplexer that can provide excellent insertion loss characteristics in the passband, and a high-frequency composite component using the same.

The present invention is a duplexer that demultiplexes a high-frequency signal of at least two communication systems having different frequencies, and is connected between a first port and a second port, and the first frequency band is defined as a passing frequency band. And a second filter connected between the first port and the third port and having a second frequency band as a pass frequency band, wherein the first filter includes a first port and a second filter. A first inductance element connected between the first inductance element, a first capacitance element connected in parallel with the first inductance element to form a parallel resonance circuit, and a second port side of the first inductance element and a ground And a first series resonant circuit having a second inductance element and a second capacitance element, wherein the second filter is connected between the first port and the third port. A capacitance element; a fourth capacitance element connected in series with the third capacitance element; and a connection point between the third capacitance element and the fourth capacitance element and a ground, and a third inductance element and a fifth capacitance element. A second series resonant circuit including a capacitance element, wherein the first to third inductance elements and the second to fifth capacitance elements are configured by electrode patterns formed in a laminate, and the first capacitance The element is formed of only stray capacitance generated between the electrode patterns constituting the first inductance element formed in different dielectric layers closer to each other in the stacking direction than between the other electrode patterns . 3 and the electrode pattern of the fourth capacitance element constitutes the first inductance element. Ting overlap in the stacking direction, and the electrode pattern of the first inductance element adjacent with the dielectric layer and the electrode pattern of the third capacitance element, a duplexer arranged at an interval of at least 75 [mu] m.

In the present invention , the first series resonant circuit has an attenuation pole in the second frequency band,
It said parallel resonant circuit, an attenuation pole possess a 2.5-3 times in the frequency band of the first frequency band,
The second series resonant circuit is preferably configured to have an attenuation pole in the first frequency band .

  In the present invention, a filter circuit or a switch circuit is further connected to the second port, and / or another filter circuit or another switch circuit is connected to the third port, and the filter circuit and the switch circuit are connected to the stacked layer. It is also preferable that the body is configured with a duplexer to form a high frequency composite part.

  Since the duplexer of the present invention is small in size and can obtain attenuation over a wide band, and an excellent insertion loss characteristic can be obtained in the pass band, it can be used in two or more communication systems, particularly three or more communication systems. This is useful for a multi-band mobile phone that enables calls.

  FIG. 1 is a diagram showing an equivalent circuit of a duplexer according to an embodiment of the present invention. The duplexer is connected between the first port P1 and the second port P2, and includes a first filter having a first frequency band f1 as a pass frequency band, and a first port P1 and a third port P3. And a second filter connected in between and having the second frequency band f2 as a pass frequency band. The first frequency band f1 is on the lower frequency side compared to the second frequency band f2, and is set to a frequency band that does not overlap each other. The first filter exhibits a large attenuation in the second frequency band (high frequency band) f2, and the second filter exhibits a large attenuation in the first frequency band (low frequency band) f1. .

  The first filter connected between the first port P1 and the second port P2 has a first inductance element L1 having one end connected to the first port P1, and a parallel resonance circuit connected in parallel with the first inductance element. A first capacitance element to be formed; and a first series resonance circuit that is disposed between the second port side of the first inductance element and the ground, and includes a second inductance element and a second capacitance element. The series resonant circuit has an attenuation pole in the second frequency band f2 and is configured to maximize the insertion loss. The parallel resonant circuit is configured to have an attenuation pole in a frequency band 2.5 to 3 times the first frequency band. With this configuration, a large attenuation is obtained over a wide band.

  The second filter connected between the first port P1 and the third port P3 includes a third capacitance element C3 connected between the first port P1 and the third port P3, and the third capacitance element C3. A fourth capacitance element C4 connected in series, and a connection point between the third capacitance element C3 and the fourth capacitance element C4 and the ground, and a third inductance element L3 and a fifth capacitance element C5. The second series resonant circuit has an attenuation pole in the first frequency band f1, and is configured to maximize the insertion loss. Compared to the conventional duplexer, the fourth capacitance element C4 is further added to obtain a large attenuation over a wide band in the low frequency band.

  With this configuration, the first frequency band f1 input to the first port P1 appears at the second port P2, but is not output to the third port P3, and is input to the first port P1. Although the second frequency band f1 appears at the third port P3 but is not output to the second port P2, the high frequency signal can be demultiplexed with low loss.

  In the duplexer of the present invention, the first to fifth inductance elements and the first to sixth capacitance elements are configured by electrode patterns formed in a laminate, and the first capacitance element is the first capacitance element. An electrode pattern constituting one inductance element is constituted by a stray capacitance formed so as to be substantially opposed to each other in the stacking direction via a dielectric layer. For this reason, since it is not necessary to add the electrode pattern which forms a 1st capacitance element further, a splitter is not enlarged.

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto.
FIG. 2 is an equivalent circuit of a front end portion of a multiband mobile phone including the duplexer of the present invention. Here, the front end unit corresponding to the first to third communication systems in which the filter circuits LPF1 and LPF2 and the switch circuits SW1 and SW2 are arranged in addition to the duplexer 1 will be described. In the description, the first communication system is GSM900 (transmission frequency 880 to 915 MHz, reception frequency 925 to 960 MHz), the second communication system is DCS1800 (transmission frequency 1710 to 1785 MHz, reception frequency 1805 to 1880 MHz), the third The communication system is PCS1900 (transmission frequency 1850 to 1910 MHz, reception frequency 1930 to 1990 MHz).

2, the first port P1 of the duplexer 1 is connected to the antenna ANT, and the second port P2 and the third port P3 of the duplexer 1 are connected to the switch. Circuits SW1 and SW2 are connected. The transmission circuits EGSMTX and DCS / PCSTX are connected to the switch circuits SW1 and SW2 through the filter circuits LPF1 and LPF2, and the reception circuits EGSMRX, DCSRX, and PCSRX are connected.
The duplexer 1 includes a plurality of filter circuits selected from a low-pass filter, a band-pass filter, and a notch filter so that transmission / reception signals of GSM900, DCS1800, and PCS1900 do not wrap around each other. In the present embodiment, the duplexer shown in FIG. 1 is used. In the figure, the portion indicated by the dotted line is a first capacitance element formed of stray capacitance.

Although the configuration of the duplexer has already been described, a description thereof will be omitted. However, an attenuation pole is formed in the second frequency band (1710 MHz to 1990 MHz) by the first series resonance circuit, and An attenuation pole is formed in a frequency band (2200 MHz to 2880 MHz) 2.5 to 3 times the frequency band of 1 (880 MHz to 960 MHz), and the resonance frequency of the first series resonance circuit is determined from the resonance frequency of the parallel resonance circuit. Is also set to low frequency. The second series resonant circuit is configured to have an attenuation pole in the first frequency band (880 MHz to 960 MHz).
With this configuration, the duplexer according to the present invention can obtain a large attenuation over a wide band, and an excellent insertion loss characteristic in the pass band. Therefore, the first duplexer input to the first port P1 can be obtained. The frequency band f1 appears at the second port P2 but is not output to the third port P3, and the second frequency band f1 input to the first port P1 appears at the third port P3. Since it is not output to the port P2, a high frequency signal can be demultiplexed. The demultiplexed high frequency signal is input to the switch circuits SW1 and SW2 arranged in the subsequent stage of the demultiplexing circuit.

The front end portion can be formed in a laminate formed by laminating an insulator and an electrode pattern. FIG. 3 is a perspective view of the laminate, and FIG. 4 is an exploded perspective view thereof. This laminated body is a composite high-frequency component that is constructed by using a sheet laminating method and incorporates circuit elements constituting a duplexer, filter circuit, and switch circuit as electrode patterns.
Although not shown here, the inductance element is configured in a multilayer substrate, and a switching element, a high-capacity capacitor that cannot be incorporated in the multilayer body, or an inductor is mounted on the multilayer body as a chip element. Yes.

The laminated body constituting this composite high-frequency component is made of an insulator, for example, a ceramic dielectric material that can be fired at a low temperature, and a green sheet having a thickness of 50 μm to 200 μm is manufactured, and Ag is mainly formed on each green sheet. It can be manufactured by forming a desired electrode pattern by printing a conductive paste, laminating and integrating a plurality of green sheets having the desired electrode pattern, and firing. The ceramic dielectric material that can be sintered at low temperature includes (a) Al ₂ O ₃ as a main component, and at least one of SiO ₂ , SrO, CaO, PbO, Na ₂ O, and K ₂ O as subcomponents. (B) Al ₂ O ₃ as a main component and MgO, SiO ₂ and GdO as at least one subcomponent, (c) Al ₂ O ₃ , SiO ₂ , SrO, Bi ₂ O ₃ , such as those containing TiO ₂ as a main component can be mentioned. A preferable dielectric constant is 5-15.

Hereinafter, the configuration of the duplexer in the laminate will be described in detail.
In the lowermost layer, an insulator layer 17 having a ground pattern electrode GND formed so as to cover almost the entire surface is disposed. In addition, an electrode pattern formed in the laminated body and an external terminal (not shown) appropriately connected through a via hole are formed on the back surface side of the insulator layer 17. An insulator layer 16 having electrode patterns C2 and C5 formed thereon is disposed on the insulator layer 17. An insulator layer 15 having a ground pattern electrode GND formed thereon is disposed thereon. The electrode patterns C2 and C5 and the electrode pattern GND form a capacitance element C2 of the first filter and a capacitance element C5 of the second filter.

  A pattern for forming the second inductance element L2 of the first filter between the ground pattern electrode GND formed on the insulator layer 15 and the ground pattern electrode GND formed on the insulator layer 10. Electrodes L2a to L2d and electrode patterns L3a to L3d forming the third inductance element L3 of the second filter are arranged.

  An electrode pattern C4a is formed in a region surrounded by the electrode pattern GND of the insulator layer 10. The electrode pattern C4a is electrically connected to the electrode layers C4c and C4d formed on the insulator layer 8 and the insulator layer 6 via via holes (indicated by black circles in the figure). An electrode pattern C4b is formed on the insulator layer 9, and the electrode pattern C4a, C4c forms a fourth capacitance element C4 of the second filter. An electrode pattern C1 is formed on the insulator layer 7, and a third capacitance element C3 of a second filter is formed between the electrode patterns C4c and C4d.

On the insulator layers 5 to 3, electrode patterns L1a to L1c constituting the inductance element L1 of the first filter are formed. In the present invention, the first capacitance element C1 connected in parallel to the inductance element L1 is formed by the electrode pattern constituting the inductance element L1. FIG. 5 is a partial plan view of extracted electrode patterns L1a to L1c for explaining a method of forming the first capacitance element C1.
The electrode patterns L1a to L1c are composed of electrode patterns of less than one turn, and the electrode patterns are stacked so as to overlap in the stacking direction, and form a coil that is connected by a via hole and circulates. In this embodiment, the electrode patterns are configured so that almost the entire surfaces overlap each other, and the thickness of the intervening insulating layer is set to 25 μm so that the electrode patterns are close to each other. With this configuration, the first capacitance element C1 of the first filter is configured by stray capacitance generated between the electrode patterns L1a to L1c. The pattern electrode that forms the inductance element L1 may be a meander line, a spiral line, or the like. However, according to the configuration of the present invention, the line length can be shortened, and the inductance element L1 can be formed in a small size.
The electrode pattern C4d formed on the insulator layer 6 and the electrode pattern L1a of the insulator layer 5 are spaced apart from each other so as not to form stray capacitance, and are arranged at an interval of approximately 75 μm. In addition, the electrode patterns constituting the duplexer of the present invention, including the electrode patterns L1a to L1c, are arranged in the horizontal direction so as not to overlap with the electrode patterns constituting the filters and switches in the laminated body. They are stacked in different areas. With such a configuration, interference with electrode patterns constituting other circuit elements is prevented, and unnecessary stray capacitance is prevented from being generated as much as possible. Each of the first series resonance circuit, the second series resonance circuit, and the parallel resonance circuit Deterioration of insertion loss due to fluctuation of the resonance frequency from a desired frequency is prevented.

The laminated body thus formed was fired at about 900 ° C., and chip components such as diodes, chip capacitors, and chip inductors were mounted on pattern electrodes (land electrodes) formed on the outer surface of the laminated body. A high frequency composite part was created.
Using this high-frequency composite part, the frequency characteristics of insertion loss were evaluated between GSMTX and the antenna and between DCS / PCSTX and the antenna. The insertion loss was 0.9 dB in the frequency band of GSM900, and an attenuation of 25 dB or more was obtained in the frequency band of 2 to 3 times. Further, the insertion loss was 0.9 dB even in the frequency band of GSM850 (transmission frequency 824 to 849 MHz, reception frequency 869 to 894 MHz), and an attenuation of 25 dB or more was obtained even in a frequency band 2 to 3 times that frequency band. Thus, a high-frequency composite component corresponding to the frequency band of GSM850 / GSM900 can also be obtained. On the other hand, the insertion loss is 1.1 dB in the frequency band of DCS1800 / PCS1900, and an attenuation of 25 dB or more is obtained even in a frequency band two to three times larger than that, and a large attenuation can be obtained over a wide band.

  According to the present invention, the duplexer is constituted by a laminated structure, and the capacitance element constituting the parallel resonance circuit is constituted by the stray capacitance generated between the electrode patterns forming the inductance element of the parallel resonance circuit. While suppressing the increase in pattern electrodes, it is possible to obtain a small duplexer with good demultiplexing characteristics and insertion loss characteristics and high-frequency composite parts using this, thereby reducing the size and performance of multiband mobile phones. It contributes.

It is an equivalent circuit of the duplexer which concerns on one Example of this invention. It is the equivalent circuit of the front end part of the multiband mobile phone comprised using the duplexer of this invention. It is a perspective view of the high frequency composite component which comprised the front end part of FIG. 2 in the laminated body. It is a disassembled perspective view which shows the internal structure of the laminated body of FIG. It is a fragmentary top view of the electrode pattern which comprises the splitter which concerns on one Example of this invention. This is an equivalent circuit of a conventional duplexer.

Explanation of symbols

1 duplexer 100 laminated body LPF1, LPF2 filter circuit SW1, SW2 switch circuit

Claims (3)

A demultiplexer for demultiplexing high-frequency signals of at least two communication systems having different frequencies,
A first filter connected between the first port and the second port and having a first frequency band as a pass frequency band, and connected between the first port and the third port, and having a second frequency band And a second filter as a pass frequency band,
The first filter includes a first inductance element connected between a first port and a second port, a first capacitance element connected in parallel with the first inductance element to form a parallel resonance circuit, and the first filter A first series resonance circuit that is disposed between the second port side of the inductance element and the ground and includes a second inductance element and a second capacitance element;
The second filter includes a third capacitance element connected between the first port and the third port, a fourth capacitance element connected in series with the third capacitance element, the third capacitance element, and a fourth capacitance. A second series resonant circuit disposed between a connection point of the capacitance element and the ground and having a third inductance element and a fifth capacitance element;
The first to third inductance elements and the second to fifth capacitance elements are constituted by electrode patterns formed in a laminate,
The first capacitance element is a floating formed by bringing the electrode patterns of less than one turn constituting the first inductance element formed in different dielectric layers closer to each other in the stacking direction than between the other electrode patterns. Formed only by capacity ,
The electrode patterns of the third inductance element and the fourth capacitance element overlap with the electrode pattern constituting the first inductance element in the stacking direction, and the electrode pattern of the first inductance element and the third capacitance adjacent to each other via a dielectric layer. A duplexer, wherein the electrode pattern of the element is disposed at an interval of at least 75 μm . The first series resonant circuit has an attenuation pole in a second frequency band,
The parallel resonant circuit has an attenuation pole in a frequency band 2.5 to 3 times the first frequency band,
The duplexer according to claim 1, wherein the second series resonant circuit has an attenuation pole in the first frequency band. A filter circuit or a switch circuit is connected to the second port and / or another filter circuit or another switch circuit is connected to the third port, and the filter circuit and the switch circuit are demultiplexed into the laminate. The high frequency composite component according to claim 1, wherein the high frequency composite component is configured together with a container.

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