JP2006129001A - Branching filter and radio communications device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a branching filter having superior isolation characteristics between a high-pass filter and a low-pass filter. <P>SOLUTION: The branching filter has a laminate formed by laminating a plurality of dielectric layers and is composed of a high pass filter consisting of a first inductor and a first capacitor, and a low-pass filter, consisting of a second inductor portion and a second capacitor portion. The first capacitor and the second capacitor are laminated with a shielding electrode in-between, and the first inductor and the second inductor are arranged at positions opposite to each other with this laminated part in-between. Moreover, a grounding electrode is arranged on a plane facing the shielding electrode with the capacitor in-between. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a duplexer that distributes or combines high-frequency signals in two different frequency regions in a radio communication device such as a mobile phone, and a radio communication device using the same.

  2. Description of the Related Art In recent years, a multiband mobile phone that enables a telephone call in two or more frequency bands with a single mobile terminal is known as a form of a wireless communication device of the mobile terminal. This portable terminal device needs a function of distributing or combining a high-frequency signal in a frequency band corresponding to each system, and a small and high-performance duplexer is required.

  As a means for constituting a small duplexer, L (inductor), C ((internal) formed on a wiring board formed by laminating a plurality of dielectric layers and a surface electrode formed on the surface are used. In general, in such a multiband mobile phone, for example, two frequency bands are used to form a duplexer by forming a capacitor) and forming a filter circuit by combining these filter circuits. In the case of using with one portable terminal, a method of realizing a duplexer by arranging and connecting a low-pass filter and a high-pass filter in a laminated body is used.

  In addition, for such a duplexer, there is an increasing demand for high isolation characteristics and thinning of the low-pass filter and the high-pass filter.

  In order to satisfy the above requirements, a duplexer having a configuration as shown in Patent Document 1 or Patent Document 2 has been proposed.

  A conventional duplexer disclosed in Patent Document 1 will be described with reference to FIGS. FIG. 7 is a cross-sectional view schematically showing the duplexer of Patent Document 1, and FIG. 8 is an exploded perspective view schematically showing the duplexer of FIG. The duplexer disclosed in Patent Document 1 is formed by stacking a high-pass filter unit 31, a low-pass filter unit 33, and a shield electrode 32 for electromagnetically shielding the high-pass filter unit 31 and the low-pass filter unit 33. It has the structure. According to such a structure, since the high-pass filter unit 31 and the low-pass filter unit 33 are shielded by the shield electrode 32, the interference between the two filters can be reduced, and the isolation characteristics can be improved. .

  However, the duplexer having a structure as shown in Patent Document 1 has a problem in that it is difficult to reduce the thickness because the number of stacked layers increases. In addition, it is necessary to provide a shield electrode between the high-pass filter portion and the low-pass filter portion, and there is a problem in that the location where both filters are provided is limited.

In order to solve such a problem, a duplexer having a structure shown in Patent Document 2 has been proposed. A conventional duplexer disclosed in Patent Document 2 will be described with reference to FIGS. 9 is a perspective view schematically showing the duplexer of Patent Document 2. FIG. 10 is a cross-sectional view schematically showing the duplexer in FIG. In the duplexer shown in Patent Document 2, a high-pass filter unit 42 and a low-pass filter unit 43 are provided side by side in a horizontal view when viewed from above, and a ground electrode 41 is disposed on the entire bottom surface. Capacitor portions 44 and 46 that form ground capacitances of the high-pass filter portion 42 and the low-pass filter portion 43 are disposed below the stripline electrode portions 45 and 47 that form inductors of the high-pass filter portion 42 and the low-pass filter portion 43. Yes. According to the structure of this patent document 2, since the shield electrode as shown in patent document 1 is not required, the freedom degree of arrangement | positioning of each filter improves compared with the structure of patent document 1, and also a thin demultiplexer is used. Can be realized.
JP-A-6-85506 Japanese Patent No. 3223848

  However, a stripline electrode in which a high-pass filter unit and a low-pass filter unit as shown in Patent Document 2 are arranged side by side in a top view, and a capacitor unit forming a grounding capacitor forms an inductor for the high-pass filter and the low-pass filter. In the structure arranged below the capacitor, the capacitor parts and inductor parts of both filters are arranged adjacent to each other at close positions, so that the capacitor parts and inductor parts interfere with each other to improve isolation characteristics. There was a problem of being an obstacle.

  The present invention has been devised in view of the above-mentioned problems, and its purpose is a duplexer that is excellent in the isolation characteristics of the high-pass filter portion and the low-pass filter portion, has a high degree of freedom in arranging each filter, and can be thinned. And providing a wireless communication device with good communication characteristics by reducing transmission / reception signal leakage.

  The duplexer of the present invention includes a high-pass filter including a first inductor portion and a first capacitor portion, a second inductor portion, a second inductor portion, and a second inductor portion. In the duplexer comprising a low-pass filter including a capacitor unit, the first and second capacitor units are arranged in parallel in the stacking direction of the dielectric layers with a shield electrode therebetween, and The first and second inductor portions are disposed on both sides of the juxtaposed region extending in a direction perpendicular to the direction, and at least one main surface of the multilayer body is interposed between the shield electrode and the shield electrode. A grounding electrode facing each other with one of the first and second capacitor portions interposed therebetween is deposited.

  The duplexer of the present invention is characterized in that the second capacitor portion is disposed between the ground electrode and the shield electrode.

  The wireless communication device of the present invention includes the above-described duplexer, an antenna commonly connected to each one end of the high-pass filter and the low-pass filter, and a switch circuit at each other end of the high-pass filter and the low-pass filter. And a transmission / reception circuit that is individually connected to each other.

  According to the duplexer of the present invention, since the capacitor portion of the high-pass filter and the capacitor portion of the low-pass filter are arranged with the shield electrode interposed therebetween, electromagnetic interference is reduced, and further, the inductor portion of the high-pass filter and the low-pass filter Therefore, the duplexer having excellent isolation characteristics between the high-pass filter and the low-pass filter can be obtained.

  According to the duplexer of the present invention, the ground electrode is disposed on one surface facing the shield electrode with the second capacitor portion interposed therebetween, so that the capacitor electrode between the high pass filter and the ground electrode, and the capacitor An extra stray capacitance generated between the electrode and the shield electrode can be suppressed, and a duplexer having better isolation characteristics can be obtained.

  According to the wireless communication device of the present invention, the antenna is commonly connected to one end of each of the high-pass filter and the low-pass filter of the above-described duplexer, and the other end of the high-pass filter and the low-pass filter is connected via a switch circuit. By including the transmission / reception circuits connected individually, the isolation characteristics between the low-frequency circuit block and the high-frequency circuit block are improved. It can be reduced, and better communication characteristics can be obtained.

  Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

  1 is a perspective view of a duplexer according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing an example of a high-pass filter constituting the duplexer of FIG. 1, and FIG. 3 is a diagram of the duplexer of FIG. It is a circuit diagram which shows an example of the low-pass filter to comprise.

  In FIG. 1, 10 to 12, 14 to 17 are capacitor electrodes, 13 is a shield electrode, 18 to 19 are inductor electrodes, 20 is an antenna terminal, 21 is an output terminal corresponding to the high-pass filter side output terminal 66 of FIG. Is an output terminal, 23 is a through conductor for electrically connecting the electrodes of each layer, and 24 is a ground electrode.

  2, 61 is an antenna terminal (input terminal) of the high-pass filter, 62 to 64 are capacitors constituting the high-pass filter, 65 is an inductor, and 66 is an output terminal of the high-pass filter. In FIG. A terminal (input terminal), 68 is an inductor constituting a low-pass filter, 69 to 70 are capacitors, and 71 is an output terminal of the low-pass filter.

  Here, the capacitor electrodes 10 to 12 in FIG. 1 form the capacitors 69 and 70 in FIG. 3, the capacitor electrode 14 forms the capacitor 64 in FIG. 2, and the capacitor electrodes 15 to 17 in the capacitors 62 and 63 in FIG. Forming. Further, the inductor electrode 18 in FIG. 1 forms the inductor 65 in FIG. 2, the inductor electrode 19 forms the inductor 68 in FIG. 3, the output terminal 21 corresponds to the high-pass filter side output terminal 66 in FIG. Reference numeral 22 corresponds to the low-pass filter side output terminal of FIG. The antenna terminal 20 in FIG. 1 is commonly connected to the antenna terminal 61 in FIG. 2 and the antenna terminal 67 in FIG.

  In the branching filter shown in these drawings, the antenna terminal 61 of the high-pass filter and the antenna terminal 67 of the low-pass filter are connected to a common antenna terminal, and a plurality of dielectric layers are stacked inside the stacked body. In addition, an electrode pattern for forming various inductors and various capacitors is provided.

  The duplexer includes a high-pass filter including a first inductor section 18 and first capacitor sections 14 to 17, a low-pass filter including a second inductor section 19 and second capacitor sections 10 to 12, a shield electrode. 13, and the first capacitor portions 14 to 17 and the second capacitor portions 10 to 12 are arranged side by side in the stacking direction of the dielectric layers with the shield electrode 13 interposed therebetween. Has been.

  In addition, on both sides of the juxtaposed region of the first capacitor portions 14 to 17 and the second capacitor portions 10 to 12, specifically, on both sides in the direction orthogonal to the above-described stacking direction of the dielectric layers. The first inductor portion 18 and the second inductor portion 19 are arranged at positions facing each other across the juxtaposed region, and at least one main surface of the multilayer body is opposed to the shield electrode 13. A ground electrode 24 facing the second capacitor portions 10 to 12 is sandwiched between them.

  The shield electrode 13 is electrically connected to the ground electrode by a through conductor or the like, and the antenna terminal 20 and the output terminals 21 and 22 are formed by electrodes (not shown) provided on the side surface of the laminate.

  In the high-pass filter, the first capacitor portion includes a capacitor 62 between the capacitor electrode 17 and the capacitor electrode 16, a capacitor 63 between the capacitor electrode 16 and the capacitor electrode 15, and a capacitor 64 between the capacitor electrode 14 and the shield electrode 13. And the first inductor portion is configured by connecting two meander-shaped inductor electrodes 18 disposed via a dielectric layer therebetween via a through conductor 23, and The output terminal 21 is drawn from the capacitor electrode 15 to the outside of the substrate.

  On the other hand, in the low-pass filter, the second capacitor portion is composed of a capacitor 69 between the capacitor electrode 10 and the capacitor electrode 12, and a capacitor 70 between the capacitor electrode 12 and the shield electrode 13 and between the capacitor electrode 10 and the ground electrode 24. The second inductor section is configured by connecting two meander-shaped inductor electrodes 19 arranged with a dielectric layer therebetween via a through conductor 23, and an output terminal 22 thereof is It is drawn out of the substrate from the capacitor electrode 12.

  In the duplexer of the present embodiment, for example, a high-frequency signal having a frequency of about 500 MHz to 10 GHz is used for wireless communication, and various materials used for known high-frequency wiring boards are used for the dielectric layer and conductor. Or in form.

  Examples of the dielectric layer include ceramic materials such as alumina ceramics and mullite ceramics, inorganic materials such as glass ceramics, tetrafluoroethylene resin (polytetrafluoroethylene; PTFE), and tetrafluoroethylene-ethylene copolymer resins. (Tetrafluoroethylene-ethylene copolymer resin; ETFE), fluoropolymer such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin; PFA), glass epoxy resin, polyimide Resin-based materials such as are used. The shape and dimensions (thickness, width, and length) of the dielectric layer made of these materials are set according to the frequency and application of the high-frequency signal used.

In addition, as a conductor, a conductor layer of a metal material for high-frequency signal transmission, such as a Cu layer, a Mo-Mn metallization layer with a Ni plating layer and an Au plating layer deposited thereon, and a W metallization layer with Ni that the plating layer and an Au plating layer was deposited, Cr-Cu alloy layer, Cr-Cu alloy layer Ni plating layer on and Au plating layer that is deposited, Ni-Cr alloy on the Ta ₂ N layer Layer and Au plated layer deposited, Pt layer and Au plated layer deposited on Ti layer, Pt layer and Au plated layer deposited on Ni-Cr alloy layer, etc. And is formed by a conventionally known thick film printing method or various thin film forming methods or plating methods. The thickness and width are also set according to the frequency and application of the transmitted high-frequency signal.

  According to the branching filter of the present embodiment as described above, the capacitor parts 14 to 17 of the high-pass filter and the capacitor parts 10 to 12 of the low-pass filter are arranged with the shield electrode 13 interposed therebetween, so that electromagnetic interference occurs. Further, since the inductor portion 18 of the high-pass filter and the inductor portion 19 of the low-pass filter are formed at a distance, mutual interference between the inductor portions is suppressed, and the isolation characteristics between the high-pass filter and the low-pass filter are excellent. A waver can be obtained.

  The high-pass filter capacitors 62 and 63 preferably have a small stray capacitance with the ground, and the ground electrode 24 is disposed on one surface facing the shield electrode 13 with the capacitor units 10 to 12 of the low-pass filter interposed therebetween. Compared with the case where the capacitor parts 14 to 17 of the high-pass filter are arranged at the same location, the excess stray capacitance generated between the capacitor electrode and the ground electrode of the high-pass filter and between the capacitor electrode and the shield electrode can be suppressed. Better characteristics can be obtained.

  Next, the case where the above-described duplexer is used in a wireless communication device will be described with reference to FIG.

  In FIG. 4, 80 is an antenna terminal, 81 is a high-pass filter of the above-described duplexer, 82 is a low-pass filter of the above-described duplexer, 83 is a duplexer, 84 is a transmission / reception selector switch on the high frequency side, and 85 is a low-frequency filter. A transmission / reception selector switch on the side, 86 is a low pass filter on the high frequency side, 87 is a low pass filter on the low frequency side, 88 is a reception terminal on the high frequency side, 89 is a transmission terminal on the high frequency side, 90 is a reception terminal on the low frequency side, and 91 is The transmission terminals on the low frequency side, and the transmission / reception terminals 88 and 91 are connected to a signal processing block in the communication device.

  In such a radio communication device, when receiving a high frequency, the received signal passes from the antenna terminal 80 through the high pass filter 81 of the duplexer 83 and is transmitted to the high frequency side block. Then, the transmission / reception changeover switch 84 on the high frequency side is switched to the reception terminal 88 side to be transmitted to the reception terminal. When transmitting a high-frequency signal, the transmission signal transmitted from the transmission terminal 89 passes through the low-pass filter 86, and the transmission / reception selector switch 84 on the high-frequency side is switched to the transmission terminal 89 side to pass through the duplexer 83 and the antenna terminal 80. A high-frequency transmission signal is emitted.

  At the time of low frequency reception, the received signal is transmitted from the antenna terminal 80 through the low pass filter 82 of the duplexer 83 to the low frequency block. Then, the transmission / reception change-over switch 85 on the low frequency side is switched to the reception terminal 90 side to be transmitted to the reception terminal. When transmitting a low-frequency signal, the transmission signal transmitted from the transmission terminal 91 passes through the low-pass filter 87, and the transmission / reception changeover switch 85 on the low-frequency side is switched to the transmission terminal 90 side, whereby the duplexer 83 and the antenna terminal 80. A low-frequency transmission signal is radiated through.

  According to such a wireless communication device of the present embodiment, the isolation characteristic between the circuit block on the low frequency side and the circuit block on the high frequency side is improved, so that leakage of transmission / reception signals between both circuit blocks is reduced. And better communication characteristics can be obtained.

  As an example, a duplexer was configured with a low-pass filter having a pass band of 0.9 GHz and a high-pass filter having a pass band of 1.8 GHz. In addition, both filters generate attenuation poles in the other pass band, and the isolation characteristics are improved in each pass band. Then, a computer simulation was performed to model the laminated structure shown in FIG. Similar high-pass filters and low-pass filters were modeled with the arrangement shown in FIGS. 9 and 10 as a structure of the prior art, and characteristic analysis was performed. The dielectric material had a dielectric constant of 7.7 and a tan δ of 0.0005. Conductivity of conductors such as conductor electrodes and through conductors was set to 20e6 (S / m). The frequency range to be analyzed was 0.1 GHz to 3 GHz.

  FIG. 5 and FIG. 6 show the simulation results under the above conditions. FIG. 5 is a graph showing transmission characteristics as simulation results, and FIG. 6 is an enlarged view of the vicinity of the passband. These graphs show the transmission characteristics of signals passing from the antenna terminal to each output terminal. The horizontal axis is frequency (GHz), and the vertical axis is I.V. L. (Insertion loss) (dB). 5 and 6, 70 is a curve showing the transmission characteristics of the high-pass filter in the duplexer having the structure of the present invention, 71 is a curve showing the transmission characteristics of the high-pass filter in the duplexer having the conventional structure, and 72 is the curve of the present invention. A curve showing the transmission characteristics of the low-pass filter in the branching filter having the above structure, and 73 is a curve showing the transmission characteristics of the low-pass filter in the branching filter having the conventional structure.

  As a comparison of the characteristics of the high-pass filter, when comparing 70 and 71 in the vicinity of the passband, the insertion loss of the characteristic 71 of the conventional structure is lower than the characteristic 70 of the structure of the present invention, and the characteristic of the filter is deteriorated. It is confirmed. Similarly, when comparing the characteristics of the low-pass filter with 72 and 73 in the vicinity of the passband, the insertion loss of the characteristic 73 of the conventional structure is lower than the characteristic 72 of the structure of the present invention, and the characteristics of the filter are deteriorated. That is confirmed. From this result, it was confirmed that the duplexer having the structure of the present invention is superior in isolation characteristics to the duplexer having the conventional structure.

  Note that the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

  For example, depending on the circuits constituting the high-pass filter and the low-pass filter, the number of capacitors and inductors to be constructed, the positions to be arranged, the connection locations, etc. can be changed. The electrode pattern forming the inductor may be a spiral shape.

It is a see-through | perspective perspective view which shows the structure of the duplexer concerning one Embodiment of this invention. FIG. 2 is a circuit diagram showing an example of a high-pass filter that constitutes the duplexer of FIG. 1. It is a circuit diagram which shows an example of the low pass filter which comprises the branching filter of FIG. It is a block diagram which shows the circuit structure of the radio | wireless communication apparatus concerning one Embodiment of this invention. It is a graph which shows the simulation result of the Example of this invention, and the conventional structure 2. FIG. It is a graph which shows the simulation result of the Example of this invention, and the conventional structure 2, and is the figure which expanded the passband. It is sectional drawing which shows the conventional duplexer schematically. FIG. 8 is an exploded perspective view schematically showing the duplexer of FIG. 7. It is a see-through perspective view schematically showing a conventional duplexer. FIG. 10 is a cross-sectional view schematically showing the duplexer of FIG. 9.

Explanation of symbols

10-12, 14-17: Capacitor electrode 13: Shield electrode 18, 19 ... Inductor electrode 20 ... Antenna terminal 21 ... Output terminal of high-pass filter 22 ... Output terminal of low-pass filter 23 ... Penetration conductor 24 ... Ground electrode

Claims (3)

A high-pass filter including a first inductor section and a first capacitor section, and a low-pass filter including a second inductor section and a second capacitor section inside a multilayer body formed by stacking a plurality of dielectric layers. In the duplexer that is arranged,
The first and second capacitor portions are juxtaposed in the laminating direction of the dielectric layer with a shield electrode therebetween, and the first and second capacitor portions are arranged on both sides of the juxtaposed region in a direction perpendicular to the laminating direction. 1 and a second inductor portion, and further, a ground electrode opposed to the shield electrode with one of the first and second capacitor portions interposed between at least one main surface of the multilayer body. A duplexer characterized by being attached. 2. The duplexer according to claim 1, wherein the second capacitor portion is disposed between the ground electrode and the shield electrode. 3. The duplexer according to claim 1; an antenna commonly connected to one end of each of the high-pass filter and low-pass filter of the duplexer; and a switch circuit at each other end of the high-pass filter and low-pass filter. A wireless communication device comprising a transmission / reception circuit that is individually connected via the wireless communication device.

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