JP4502937B2 - Multilayer stripline filter - Google Patents

Description

  The present invention relates to a laminated stripline filter used in, for example, wireless communication devices such as mobile phones and wireless LANs and other various communication devices.

  In recent years, filters used in mobile communication devices such as mobile phones have resonated distributed constant circuits from filters using dielectric coaxial resonators in response to demands for thinner and smaller mobile communication devices. It has progressed to the laminated stripline filter used in the vessel.

  In addition, with the diversification of frequencies used in mobile communication devices, there is an increasing demand for filters that can easily obtain various frequency characteristics.

  In response to these requirements, for example, a multilayer stripline filter having a structure as shown in Patent Document 1 has been proposed. A multilayer stripline filter having a structure disclosed in Patent Document 1 will be described with reference to FIGS.

  4 is an exploded perspective view of the multilayer stripline filter of Patent Document 1, FIG. 5 is a top perspective view, FIG. 6 is a cross-sectional view taken along line b-b ′ in FIG. 5, and FIG.

  In the multilayer stripline filter shown in Patent Document 1, the first open electrode 24 and the first short-circuit electrode 25 are formed between the sequentially laminated dielectric layers 10 to 12, and the first open electrode 24 is opened. The first resonator (resonant electrode) is formed by electrically connecting the end opposite to the end 26 and the end opposite to the short-circuit end 27 of the first short-circuit electrode 25. Further, a second open electrode 22 and a second short-circuit electrode 23 are formed between different layers, an end of the second open electrode 22 opposite to the open end 26, and the second short-circuit electrode 23. The second resonator (resonant electrode) is formed by electrically connecting the opposite end of the short-circuited end 27 to the first and second open electrodes 24 and 22 and the short-circuited electrodes 25 and 23. Of the first and second resonators so that at least a part of the first and second resonators face each other across the dielectric layer 11 And to include inwardly plan perspective, has a structure forming the ground electrode 20, 21 above and below the first and second resonator. The first and second resonators are provided with power supply ports 29 and 28, respectively.

The structure of Patent Document 1 can be replaced with an equivalent circuit diagram shown in FIG. An inductor component and a capacitance component formed between the first and second resonators and the ground electrodes 20 and 21 correspond to LB and CB, respectively, and a region WA where the first and second resonators overlap with each other when viewed from above. An inductance component and a capacitance component formed between both resonators in WB correspond to Lfr and Cfr, respectively. Lfr and Cfr are the parts that contribute to the generation of attenuation poles in the filter characteristics, and adjust the size of each open electrode and short circuit electrode, the width of the region where the resonator overlaps when viewed from above, the thickness of the dielectric, the dielectric constant, etc. Thus, a multilayer stripline filter that can obtain various filter characteristics has been realized.
JP-A-9-331201

  However, a multilayer stripline filter having a conventional structure as shown in Patent Document 1 is a portion where the first resonator and the second resonator face each other, that is, in a region where both resonators overlap when viewed from above. Since the inductance component and the capacitance component that contribute to the attenuation pole of the filter characteristics are formed by the coupling amount, the dielectric has a longitudinal direction (direction extending from the open end or short-circuited end of each electrode to the opposite end) When stacking misalignment occurs in the horizontal direction (direction perpendicular to the vertical direction), the coupling amount changes due to the change in the area of the opposing portion between the resonant electrodes, and the resulting inductance and capacitance components change. Resulting in. Therefore, there is a problem that the attenuation pole of the filter characteristic is shifted and it is difficult to obtain a desired filter characteristic.

  The present invention has been completed to solve the above-mentioned problems, and an object of the present invention is to provide a laminated stripline filter that has an extremely small influence on the filter characteristics even if a laminating deviation occurs in the horizontal direction or the vertical direction. is there.

  The laminated stripline filter of the present invention has a pair of ground electrodes disposed above and below a laminate formed by laminating a plurality of dielectric layers, and has one end connected to the ground electrode inside the laminate. An upper short-circuited electrode that is a short-circuited end, an upper resonant electrode that has one open end and the other open end is connected to the other end of the upper short-circuited electrode, and one end is connected to the ground electrode. The upper short-circuit electrode and the lower short-circuit are connected to the lower short-circuit electrode, which is a short-circuited end, and the lower resonance electrode including one open end and the other open-ended electrode connected to the other end of the lower short-circuit electrode. A laminated stripline filter in which an electrode, and the upper open electrode and the lower open electrode are respectively arranged so as to face each other through the dielectric layer, the upper short-circuit electrode The first and second upper short-circuit electrodes are arranged at intervals and each other end is connected to the upper open electrode, and the upper open electrode and the lower open electrode are orthogonal to each other in plan view It is characterized by that.

  According to the multilayer stripline filter of the present invention, the upper short-circuit electrode includes the first and second upper short-circuit electrodes arranged at intervals and having the other ends connected to the upper open electrode. Since the open electrode and the lower open electrode are orthogonal to each other when seen in a plan view, even if a stacking shift occurs in the vertical or horizontal direction between the dielectric layers, the upper and lower resonance electrodes face each other due to the stacking shift. It is possible to provide a laminated stripline filter that can suppress a change in width, a shift in coupling, and the like and that has very little influence on filter characteristics.

  That is, on the short-circuit electrode side, the sum of the width of the first upper short-circuit electrode and the lower short-circuit electrode facing each other and the width of the second upper short-circuit electrode and the lower short-circuit electrode facing each other (that is, the upper short-circuit electrode and the lower short-circuit electrode). For example, even when a laminating shift occurs in the lateral direction, the inner end portion of the second upper short-circuit electrode is reduced by the amount reduced at the inner end portion of the first upper short-circuit electrode. Will be offset by an increase in

  In addition, the short-circuit electrode side functions as an inductor, and mutual inductance is generated in a portion facing the dielectric layer between the upper and lower short-circuit electrodes. Since the variation of the area is slight with respect to the area of the original facing portion, this vertical stacking deviation does not greatly affect the mutual inductance. Therefore, the mutual inductance component is kept substantially constant even if the vertical and horizontal stacking shifts occur.

  In order to effectively obtain the mutual inductance generated between the upper and lower short-circuit electrodes, it is necessary to effectively generate the mutual inductance in the upper and lower short-circuit electrodes with the same or opposite direction of the flowing current. desirable. On the other hand, in the multilayer stripline filter of the present invention, the upper and lower short-circuit electrodes are parallel in the vertical direction, and the direction of the flowing current is the same. That is, in the structure of the present invention, on the short-circuit electrode side, each short-circuit electrode is arranged so that the upper and lower short-circuit electrodes can be effectively coupled, and the coupling shift due to the stacking shift is minimized.

  On the other hand, on the open electrode side, a part of the upper open electrode faces the lower open electrode and is arranged so as to be orthogonal to each other. Therefore, the opposed area between the upper and lower open electrodes is the width of each open electrode. Corresponds to a rectangular region with the length of one side. Therefore, even if horizontal and vertical stacking deviations occur in the dielectric layer, the length of each side of the facing region does not change, so the area of the facing portion of the open electrodes does not change and remains constant. Kept.

  Accordingly, the capacitance component generated by the upper and lower open electrodes facing each other is effectively prevented from changing from a desired value.

  From the above, it is possible to effectively prevent the total sum of the areas of the portions where the short-circuit electrode and the open electrode face each other across the dielectric layer from being changed, and to obtain the same electromagnetic coupling as a whole as a whole. be able to. Therefore, even if a stacking error occurs, the attenuation pole fluctuation can be made extremely small, and the influence on the filter characteristic fluctuation can be made extremely small.

  As an example of the laminated stripline filter of the present invention, an example is shown in which three dielectric layers are laminated, a pair of ground electrodes are arranged on the upper and lower surfaces, and an upper resonance electrode and a lower resonance electrode are arranged inside. Hereinafter, it demonstrates using drawing. FIG. 1 is a perspective view showing an example of an embodiment of a laminated stripline filter of the present invention, FIG. 2 is a top perspective view, and FIG. 3 is a cross-sectional view taken along line a-a ′ of FIG.

  1 to 3, reference numerals 30 to 32 denote dielectric layers, 33 and 34 denote ground electrodes, 35a and 35b denote first and second short-circuit electrodes forming an upper short-circuit electrode, 36 denotes a lower short-circuit electrode, and 37 denotes an upper part. An open electrode 38 is a lower open electrode. The first and second upper short-circuit electrodes 35a and 35b are spaced apart from each other by the width of the WA (the distance between the first upper short-circuit electrode 35a and the second upper short-circuit electrode 35b). The upper open electrode 37 and the lower open electrode 38 are arranged perpendicular to each other in plan view so that a part of the upper open electrode 37 and the lower open electrode 38 face each other.

  The upper short-circuit electrode (first and second upper short-circuit electrodes 35a and 35b) and the lower short-circuit electrode 36 are connected to the ground electrode at one end (in this embodiment, a portion located on the outer edge of the dielectric layer) Has been. One end of each of the upper and lower open electrodes 37 and 38 is an open end.

  The first and second upper short-circuit electrodes 35a and 35b (upper short-circuit electrodes) and the upper open electrode 37 are electrically connected at the other ends by a connection conductor 39, and the lower short-circuit electrode 36 and the lower open electrode 38 are connected. The other ends are electrically connected by the connection conductor 40.

  The connected end portions of the first and second upper short-circuit electrodes are electrically connected to the end portion on the opposite side to the open end of the upper open electrode 37 via the connection conductor 39, so that the upper resonance An electrode is formed. Further, the lower short-circuit electrode 36 is electrically connected at its end opposite to the short-circuit end to an end opposite to the open end of the lower open electrode 38 via the connection conductor 40. A resonant electrode is formed.

  The pair of resonant electrodes are arranged so that the respective short-circuit electrodes and the open electrodes are partially opposed to each other in plan view, and an inductance component and a capacitance component are generated by coupling at the opposed portions, respectively, thereby attenuating the filter characteristics. The pole is generated. The upper open electrode 37 is not linearly connected to the first and second upper short-circuit electrodes 35a and 35b, but is formed to be bent with the connection conductor 39 interposed therebetween, It is orthogonal to the lower open electrode 38 in perspective. Each short-circuit electrode 35a, 35b, 36 and each open electrode 37, 38 are formed in a pattern having a constant width over the entire length, for example, a rectangular pattern such as a rectangular shape, according to the generated filter characteristics.

  The ground electrodes 33 and 34 are formed above and below the laminate so as to include the respective short-circuit electrodes 35a, 35b and 36 and the respective open electrodes 37 and 38 on the inner side in a plan view. In this embodiment, a ground conductor is arranged on the side surface of the multilayer body (not shown). The ground conductor on the side surface is electrically connected to the short-circuited ends of the respective short-circuit electrodes 35a, 35b, 36, and serves to ground each short-circuit electrode 35a, 35b, 36 to form a short-circuit electrode. The ground conductor is connected to the ground electrodes 33 and 34 and grounded, for example.

  The short-circuit ends of the respective short-circuit electrodes 35a, 35b, and 36 are not necessarily grounded via the ground conductors on the side surfaces. The short-circuit ends are connected via via conductors that penetrate the dielectric layers 30 to 32 in the thickness direction. You may make it carry out by electrically connecting with the ground electrodes 33 and 34. FIG.

  An input port is set at the midpoint of the connection conductor 39, and an output port is set at the midpoint of the connection conductor 40 (not shown).

  In the multilayer stripline filter having such a structure, the attenuation pole of the filter characteristics is the width of the region where the first and second upper short-circuit electrodes 35a and 35b and the lower short-circuit electrode 36 are opposed to each other, that is, the width of WB and WC. It is determined by the area that is held, and the area where the upper open electrode 37 and the lower open electrode 38 face each other, that is, the size of S (the opposed area). Here, WB indicates an overlapping portion between the first upper short-circuit electrode 35a and the lower short-circuit electrode 36 when viewed through, and WC indicates an overlapping portion between the second upper short-circuit electrode 35b and the lower short-circuit electrode 36.

  According to the structure of the present invention, in FIG. 2 and FIG. 3, for example, the lower short-circuit electrode 36 is moved rightward in the lateral direction (the direction perpendicular to the mutually opposing sides of the first and second upper short-circuit electrodes 35a and 35b). If a 10 μm stacking error is caused, WB is reduced by 10 μm on the short-circuit electrode side, but WC is increased by 10 μm. Accordingly, the sum of the sizes of the opposing portions of the first and second short-circuit electrodes and the third short-circuit electrode 36 does not change even if a stacking error occurs.

  That is, the sides parallel to the mutually opposing sides of the first and second upper short-circuit electrodes 35a and 35b of the lower short-circuit electrode 36 (sides located on the left and right in FIG. 2) are first and first viewed through the plane, respectively. 2 upper short-circuit electrodes 35a and 35b. That is, the lower short-circuit electrode 36 overlaps only part of the first upper short-circuit electrode 35a and overlaps only part of the second upper short-circuit electrode 35b.

  Also, the short-circuit electrode side acts as an inductor, and mutual inductance occurs between the upper and lower short-circuit electrodes (parts facing each other across the dielectric layer). Therefore, the vertical stacking deviation does not significantly affect the mutual inductance.

  Therefore, the mutual inductance component is kept substantially constant even if the vertical and horizontal stacking shifts occur.

  In order to effectively obtain the mutual inductance generated between the upper and lower short-circuit electrodes, it is necessary to effectively generate the mutual inductance in the upper and lower short-circuit electrodes with the same or opposite direction of the flowing current. desirable. On the other hand, in the multilayer bandpass filter of the present invention, the upper and lower short-circuit electrodes are parallel in the vertical direction, and the direction of the flowing current is the same.

  That is, in the structure of the present invention, on the short-circuit electrode side, each short-circuit electrode is disposed so that the upper and lower short-circuit electrodes can be effectively coupled, and the coupling shift due to the stacking shift can be minimized. .

  In addition, since the upper and lower open electrodes 37 and 38 are arranged orthogonal to each other on the open end side, the shape of the opposing regions in the plan view of the both has the respective line widths corresponding to the respective pairs facing each other. The size (area) S of the opposing region does not change because the length of one side of the region is constant even if, for example, misalignment occurs in the lateral direction.

  Similarly, even when a stacking shift occurs in the vertical direction, since they are arranged orthogonally, the size S of the opposing regions does not change before and after the stacking shift.

  Therefore, the capacitance component generated when the upper and lower open electrodes 37 and 38 face each other is effectively prevented from changing from a desired value.

  In other words, the multilayer stripline filter of the present invention effectively connects the upper and lower short-circuit electrodes 35a, 35b, and 36 on the short-circuit electrode side, and secures a mutual inductance component while minimizing fluctuations caused by stacking deviations. In addition, the misalignment can be effectively absorbed on the open electrode side where the capacitance component fluctuates even with a slight misalignment.

  As a result, even when a stacking error occurs in the dielectric layer, the attenuation pole of the filter characteristic does not change, and a stable characteristic can be obtained.

  Note that the upper and lower open electrodes 37 and 38 are not limited to the illustrated example, and may be arranged so as to be orthogonal to each other when seen in a plan view. For example, the lower open electrode 38 is an extension line of the lower short-circuit electrode 36. The upper open electrode 37 is arranged so as to be parallel to the extension line of the upper short-circuit electrode (the first upper short-circuit electrode 35a and the second upper short-circuit electrode 35b). May be orthogonal.

  Further, in order to widely cope with the laminating deviation in the horizontal direction and the vertical direction, it is desirable to arrange the patterns so that the centers of the patterns face each other. It is to be noted that the upper and lower open electrodes 37 and 38 are best in a state where they intersect at a right angle in plan view, but the positional accuracy when forming each pattern (for example, when formed by a thick film printing method described later) A slight angle deviation caused by processing accuracy such as (printing accuracy) is allowed.

  In addition, each short-circuit electrode and open electrode can be formed between different layers. However, in consideration of design complexity and labor, it is desirable that the electrodes constituting each resonance electrode be located between the same layers. In addition, in consideration of parasitic components (such as stray capacitance) of the connection conductor, the shape of the connection conductor is desirably smaller.

  The multilayer stripline filter according to the present invention uses, for example, a high-frequency signal having a frequency of about 500 MHz to 10 GHz for wireless communication, and various dielectric layers and conductors used for known high-frequency wiring boards. The materials and forms can be used.

  As the dielectric layers 30 to 32, for example, ceramic materials such as alumina ceramics and mullite ceramics, inorganic materials such as glass ceramics, ethylene tetrafluoride resin (polytetrafluoroethylene; PTFE), ethylene tetrafluoride-ethylene Fluoropolymers and glass epoxies such as copolymer resins (tetrafluoroethylene-ethylene copolymer resin; ETFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resins (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin; PFA) Resin-based materials such as resin and polyimide are used. When importance is attached to the reliability of secondary mounting, a material having a high coefficient of thermal expansion is also used. The shapes and dimensions (thickness, width, and length) of the dielectric layers 30 to 32 made of these materials are set according to the frequency and application of the high-frequency signal used.

  If the dielectric layers 30 to 32 are made of alumina ceramics, for example, a raw material powder obtained by adding silica, calcia or the like to alumina powder is formed into a sheet shape together with an organic solvent and a binder, and then a ceramic green sheet It is manufactured by stacking a plurality of sheets and firing them.

  Moreover, if it is a resin-type material, the dielectric layers 30-32 which consist of a glass epoxy resin can be formed by making it harden | cure after impregnating a non-hardened epoxy resin to a glass base material, for example.

In addition, each electrode in the multilayer stripline filter of the present invention is obtained by depositing a Ni plating layer and an Au plating layer on a conductive layer of a metal material for high-frequency signal transmission, such as a Cu layer or a Mo-Mn metallization layer. , W plated metallized layer with Ni plated layer and Au plated layer, Cr—Cu alloy layer, Cr—Cu alloy layer coated with Ni plated layer and Au plated layer, Ta ₂ Ni-Cr alloy layer and Au plating layer deposited on N layer, Pt layer and Au plating layer deposited on Ti layer, or Pt layer and Au plating on Ni-Cr alloy layer It is formed by a thick film printing method, various thin film forming methods, a plating method, or the like using a layer to which a layer is applied. The thickness and width are also set according to the frequency and application of the transmitted high-frequency signal.

  For example, in the case of a W metallized layer, a metal paste prepared by kneading W powder with an organic solvent and a binder is printed in a predetermined pattern on a ceramic green sheet to be the dielectric layers 30 to 32 by a screen printing method or the like. Is formed.

  In the case of forming by plating, a well-known electrolytic plating method or electroless plating method can be appropriately selected and used.

  Further, the width WA of the blank portion, the width (area S) of the facing region, and the like can be appropriately set according to desired filter characteristics to be generated.

  As a ceramic substrate, particularly a substrate that handles high-frequency signals, Cu or the like of a high conductivity material is used as a conductor material, and a glass ceramic that is sintered at a temperature lower than the melting point of the high conductivity material is also used.

  FIG. 8 shows the results of analyzing transmission characteristics by modeling an electromagnetic field analysis simulator designed as an embodiment of the present invention with a pass band around 3.2 GHz and an attenuation pole around 2.8 GHz. The horizontal axis represents frequency (GHz) and the vertical axis represents insertion loss (dB).

  The dielectric constants of the dielectric layers 30 to 32 were set to 7.7. Then, modeling is performed again on the assumption that stacking misalignment has occurred in the lateral direction of plus 100 μm, minus 100 μm, and in the longitudinal direction of 100 μm, and the results of analysis are superimposed.

  In FIG. 8, A is an analysis result in a model having no stacking deviation, B is an analysis result in a model in which B is plus 100 μm in the horizontal direction, C is minus 100 μm in the horizontal direction, and D is 100 μm in the vertical direction. FIG. 9 shows the result of analyzing the characteristic change caused by the stacking deviation in the same manner by generating the filter characteristic with the conventional structure. In FIG. 9, A ′ is an analysis result in a model having no stacking deviation, and B ′ is an analysis result in a model having a stacking shift of 100 μm in the horizontal direction and C ′ is 100 μm in the vertical direction.

  As is apparent from the results of FIGS. 8 and 9, the attenuation pole fluctuates due to stacking deviation in the conventional structure, whereas the structure of the present invention is stable with almost no fluctuation of the attenuation pole due to stacking deviation. It turns out that it is a result.

  From this result, it was confirmed that the multilayer stripline filter having the structure of the present invention has an extremely small influence on the filter characteristics even when the stacking deviation occurs, compared with the multilayer stripline filter having the conventional structure.

  In addition, this invention is not limited to the example of the above embodiment, A various change and improvement may be added within the range which does not deviate from the summary of this invention. For example, the position of the input / output port can be set as appropriate. In addition, each upper electrode and lower electrode may be turned upside down.

It is a perspective perspective view which shows an example of embodiment about the lamination | stacking stripline filter of this invention. FIG. 2 is a top perspective view of the multilayer stripline filter of FIG. 1. FIG. 3 is a cross-sectional view taken along line a-a ′ of the multilayer stripline filter of FIG. 2. It is a perspective perspective view which shows the structure of the conventional multilayer stripline filter. FIG. 5 is a top perspective view of the multilayer stripline filter of FIG. 4. It is sectional drawing in the b-b 'line | wire of the lamination | stacking stripline filter of FIG. FIG. 5 is an equivalent circuit diagram of the multilayer stripline filter of FIG. 4. It is a graph which shows the simulation result of the Example of this invention. It is a graph which shows the simulation result in the conventional structure.

Explanation of symbols

30 to 32 ... dielectric layers 33 and 34 ... ground electrode 35a ... first upper short-circuit electrode 35b ... second upper short-circuit electrode 36 ... lower short-circuit electrode 37 ... upper open Electrode 38 ... lower open electrode

Claims (1)

A pair of ground electrodes are arranged above and below a laminate formed by laminating a plurality of dielectric layers, and inside the laminate,
An upper resonance electrode comprising an upper short-circuit electrode having one end connected to the ground electrode and being a short-circuited end, and an upper open electrode having one end being an open end and the other end connected to the other end of the upper short-circuit electrode; A lower resonance electrode comprising a lower short-circuit electrode having one end connected to the ground electrode and being a short-circuited end, and a lower open electrode having one end connected to the other end of the lower short-circuit electrode and one end being an open end;
A laminated stripline filter in which the upper short-circuit electrode, the lower short-circuit electrode, and the upper open-electrode and the lower open-electrode are respectively arranged so as to face each other through the dielectric layer. And
The upper short-circuit electrode includes first and second upper short-circuit electrodes that are arranged at intervals and each other end is connected to the upper open electrode,
The multilayer open strip filter, wherein the upper open electrode and the lower open electrode are orthogonal to each other when seen in a plan view.

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