JP4303664B2 - Filter device - Google Patents

Description

  The present invention relates to a filter device used in, for example, a wireless communication device such as a mobile phone and a wireless LAN, and other various communication devices.

  2. Description of the Related Art In recent years, filter devices used in mobile communication devices such as mobile phones have been distributed from a filter using a dielectric coaxial resonator to meet demands for thinning and miniaturization of mobile communication devices. Progress has been made in laminated stripline filters used in resonators.

  As such a conventional multilayer stripline filter, Patent Document 1 proposes a configuration having a perspective view shown in FIG. 5 and a perspective plan view shown in FIG. 5 and 6, reference numeral 71 denotes a first dielectric layer, 72 denotes a second dielectric layer laminated on the first dielectric layer 71, and 73 denotes a second dielectric layer 72. The laminated third dielectric layer, 81 is a first ground electrode disposed on the lower surface of the first dielectric layer 71, and 82 is a second ground disposed on the upper surface of the third dielectric layer 73. The electrodes 83 and 84 are a first one-end open rectangular resonance electrode and a first one-end short-circuited rectangular resonance electrode 85 and 86 disposed between the first dielectric layer 71 and the second dielectric layer 72, respectively. Are a second one-end open rectangular resonance electrode and a second one-end short-circuited rectangular resonance electrode arranged between the second dielectric layer 72 and the third dielectric layer 73.

  The first and second one-end open rectangular resonance electrodes 83 and 85 have substantially the same shape, are parallel in plan view, and part of the first one-end open rectangular resonance electrode 83 and the second one-end open. A part of the rectangular resonance electrode 85 is arranged to face each other so as to form a first coupling portion 87 having substantially the same width with the second dielectric layer 72 interposed therebetween.

  The first and second one-end short-circuited rectangular resonance electrodes 84 and 86 have substantially the same shape, are parallel to each other in plan view, and a part of the first one-end short-circuited rectangular resonance electrode 84 and the second A part of the one-end short-circuited rectangular resonance electrode 86 is arranged to face each other so as to form a second coupling portion 88 having the same width and overlapping with the second dielectric layer 72 interposed therebetween.

  Further, the end portion of the first one-end open rectangular resonance electrode 83 opposite to the open end 90 and the end portion of the first one-end short-circuit rectangular resonance electrode 84 opposite to the short-circuit end 91 are electrically connected. The end of the second one-end open rectangular resonant electrode 85 opposite to the open end 90 and the end of the second one-end short-circuited rectangular resonant electrode 86 opposite to the short-circuited end 91 are electrically connected. It became the composition to be. In FIG. 6, the first and second ground electrodes 81 and 82 are not shown.

The width W1 of the first and second one-end open rectangular resonance electrodes 83 and 85, the width W2 of the first and second one-end short-circuited rectangular resonance electrodes 84 and 86, the width W3 of the first coupling portion 87, In addition, by adjusting the width W4 of the second coupling portion 88, between the first and second one-end open rectangular resonance electrodes 83 and 85 and between the first and second one-end short-circuited rectangular resonance electrodes 84 and 86. When capacitive coupling is dominant as the formed coupling, a filter characteristic having one attenuation pole on the low band side with respect to the pass band is obtained. Conversely, when inductive coupling is dominant, the pass band is obtained. In contrast, a filter characteristic having one attenuation pole on the high frequency side has been realized.
JP-A-9-331201

  However, in such a conventional multilayer stripline filter, the lengths L11 and L12 of the first and second coupling portions 87 and 88 and the first coupling portion 87 in the first one-end open rectangular resonance electrode 83 are used. The length L13 of the portion excluding the first portion, the length L14 of the portion excluding the first coupling portion 87 in the second one-end open rectangular resonance electrode 85, and the second coupling in the first one-end short-circuited rectangular resonance electrode 84 The length L15 of the portion excluding the portion 88 and the length L16 of the portion excluding the second coupling portion 88 in the second one-end short-circuited rectangular resonance electrode 86 (each length is indicated by a one-dot chain line in FIG. However, unless the conditions of L11 = L13 = L14 and L12 = L15 = L16 are satisfied, there is a limitation that a desired filter characteristic cannot be obtained. Therefore, in the conventional multilayer stripline filter, the first and second one-end open rectangular resonance electrodes 83 and 85 and the first and second one-end short-circuited rectangular resonances are used in order to reduce the size of the multilayer stripline filter. If the shapes of the electrodes 84 and 86 are inadvertently changed from a rectangular shape, the conditions of L11 = L13 = L14 and L12 = L15 = L16 are broken, the filter characteristics change greatly, and the desired filter characteristics cannot be obtained. As a result, there has been a problem that the miniaturization of the multilayer stripline filter cannot be realized.

  The present invention has been completed in view of the above problems, and an object of the present invention is to provide a filter device that has a high degree of design freedom and can be easily miniaturized in a multilayer stripline filter.

The filter device of the present invention includes a first dielectric layer, a second dielectric layer laminated on the first dielectric layer, and a second dielectric layer laminated on the second dielectric layer. 3 dielectric layers, a first ground electrode disposed on the lower surface of the first dielectric layer, and a first open-ended resonant electrode disposed between the first and second dielectric layers And a first one-end short-circuited resonance electrode, a second one-end open-resonance electrode and a second one-end-short-circuited resonant electrode arranged between the second and third dielectric layers, and the third dielectric layer And a second ground electrode disposed on the upper surface of
The first and second one-end open resonance electrodes are arranged in parallel so that at least a part of each of them overlaps in plan view across the second dielectric layer,
The first and second one-end short-circuited resonant electrodes are arranged in parallel so that at least a part of each of them overlaps in plan view with the second dielectric layer interposed therebetween,
The first and second ground electrodes are arranged so as to cover the first and second one-end open resonance electrodes and the first and second one-end short-circuit resonance electrodes in a plan view,
The first and second open-ended resonant electrodes are branched into a plurality of lines toward the open end, and the length from the end opposite to the open end is the same at those branch portions. Form the open end as
The first and second single-ended short-circuit resonant electrodes are branched into a plurality of lines toward the short-circuited end, and the length from the end opposite to the short-circuited end is the same at those branch portions. Form a short-circuited end so that
An end of the first one-end open resonance electrode opposite to the open end and an end opposite to the short-circuit end of the first one-end short-circuit resonance electrode are electrically connected to form a first resonator. Forming,
An end of the second one-end open resonant electrode opposite to the open end and an end of the second single-ended short-circuited resonant electrode opposite to the short-circuited end are electrically connected to form a second resonator. Forming,
The first and second input / output terminals are electrically connected to the first and second resonators, respectively.

  In the filter device according to the present invention, preferably, each ground electrode or each short-circuited resonance electrode of each one-end short-circuited resonance electrode and each ground electrode are formed inside the dielectric layer and a side surface. It is electrically connected by the side conductor formed in this.

  In the filter device (first filter device) of the present invention, the first and second one-end open resonance electrodes branch into a plurality of lines toward the open end, or the first and second one-end short-circuit resonance electrodes Is branched into a plurality of lines toward the open end, and more specifically, the resonance electrode arranged in parallel so that at least a part of each of them overlaps in plan view with the dielectric layer in between, the open end or the short-circuit end Branching into an electrode part that overlaps in plan view and an electrode part that does not overlap in plan view, and preferably branches into a plurality of lines so that the ratio of the width and length of the branched line is 1 to 3 or more. Therefore, the branched line can be easily bent into an approximately L shape.

  The sum of the self-impedance of the multiple lines after branching is almost equal to the self-impedance of the line before branching, and the sum of the mutual impedances of the multiple lines after branching is the mutual impedance of the line before branching. The open end is easy so that the length from the end opposite to the open end of the single-ended open resonant electrode to the open ends of each of the multiple lines is substantially the same. Or the short-circuited end can be easily formed so that the length from the end opposite to the short-circuited end of the single-ended short-circuited resonant electrode to the open ends of each of the plurality of lines is substantially the same. Almost equivalent filter characteristics can be obtained. As a result, it is possible to provide a filter device that has a high degree of design freedom and can be easily reduced in size while ensuring desired filter characteristics.

  In the filter device (second filter device) of the present invention, preferably, each ground electrode, or the short-circuited end of each one-sided short-circuited resonant electrode and each grounded electrode are formed on the through conductor formed inside the dielectric layer and on the side surface. Therefore, the degree of freedom in designing a filter device for forming each electrode inside a plurality of stacked dielectric layers is improved, and a small and high-performance filter device is provided. Can be provided.

  The filter device of the present invention will be described in detail below. 1 is a see-through perspective view showing an example of an embodiment of the present invention, FIG. 2 is a see-through plan view of the filter device of FIG. 1 (viewed from the stacking direction), and FIG. 2 is a cross-sectional view taken along the line aa ′ in FIG. 2, FIG. 3B is a cross-sectional view taken along the line bb ′ in FIG. 2, and FIG. 3C is a cross-sectional view taken along the line cc ′ in FIG.

  1 to 3, reference numeral 21 denotes a first dielectric layer, 22 denotes a second dielectric layer laminated on the first dielectric layer 21, and 23 denotes a second dielectric layer 22. The laminated third dielectric layer, 15 is a first ground electrode disposed on the lower surface of the first dielectric layer 21, and 16 is a second ground disposed on the upper surface of the third dielectric layer. Electrodes 31 and 32 are a first one-end open resonance electrode and a first one-end short-circuit resonance electrode disposed between the first and second dielectric layers 21 and 22, respectively, and 41 and 42 are a second and a third, respectively. The second one-end open resonance electrode and the second one-end short-circuit resonance electrode disposed between the dielectric layers 22 and 23, 50 are the open ends of the first and second one-end open resonance electrodes 31, 41, 51 Are short-circuited ends of the first and second short-circuited resonant electrodes 32 and 42, respectively.

  As shown in FIGS. 1 to 3, the first and second one-end open resonance electrodes 31 and 41 are parallel so that at least a part of each of them overlaps in plan view with the second dielectric layer 22 in between. The first and second one-end short-circuited resonant electrodes 32 and 42 are arranged in parallel so that at least a part of each of the first and second one-sided short-circuited resonant electrodes 32 and 42 overlap each other in plan view. The first and second ground electrodes 15 and 16 are arranged so as to cover the first and second one-end open resonance electrodes 31 and 41 and the first and second one-end short-circuit resonance electrodes 32 and 42 in a plan view. ing.

  The first one-end open resonant electrode 31 branches into a plurality of lines 31a, 31b, 31c toward the open end 50, and the length from the end opposite to the open end at those branch portions. And the second one-end open resonance electrode 41 branches into a plurality of lines 41a, 41b, 41c toward the open end 50, and the open ends at those branch portions. The open end is formed so that the length from the opposite end is the same, and the first single-ended short-circuit resonant electrode 32 is branched into a plurality of lines 32a, 32b, and 32c toward the short-circuited end 51. In addition, the short-circuited ends are formed so that the lengths from the ends opposite to the short-circuited ends are the same at the branch portions, and the second single-ended short-circuit resonant electrode 42 has a plurality of lines toward the short-circuited end 51. 42a, 42b, 42c Together are a length from the opposite end and the short-circuited end at their branches form a short-circuited end to be the same.

  Then, an end of the first one-end open resonance electrode 31 opposite to the open end 50 and an end of the first one-end short-circuit resonance electrode 32 opposite to the short-circuit end 51 are electrically connected to each other. The end of the second one-end open resonance electrode 41 opposite to the open end 50 and the end of the second one-end short-circuit resonant electrode 42 opposite to the short-circuit end 51 are electrically connected. To form a second resonator 12.

  Further, the first and second input / output terminals 61 and 62 are electrically connected to the first and second resonators 11 and 12, respectively, and are electrically connected to an external circuit via a transmission line. The high frequency signal is input / output.

  The filter device of the present invention having such a configuration is provided between the first and second ground electrodes 15 and 16 or between the first and second ground electrodes 15 and 16 and the first and second one-end short-circuited resonant electrodes 32, By using a ground connection conductor that electrically connects the short-circuit ends 51 of the 42 in the stacking direction and a through conductor (not shown) formed inside the dielectric layer as the connection conductor, a three-dimensional structure is obtained. Wiring design is possible, and the degree of freedom in designing a filter device for forming each electrode in a plurality of stacked dielectric layers is improved, so that the filter device is small and has a high performance.

  In constructing the filter device of the present invention, the first to third dielectric layers 21 to 23, the first and second ground electrodes 15 and 16, the first and second one-end open resonance electrodes 31 and 41, the first Various materials and configurations used for known high-frequency wiring boards can be applied to the first and second single-ended short-circuit resonant electrodes 32 and 42.

  As the first to third dielectric layers 21 to 23, for example, ceramic materials such as alumina ceramics and mullite ceramics, inorganic materials such as glass ceramics, or ethylene tetrafluoride resin (polytetrafluoroethylene; PTFE), four Fluoroethylene-ethylene copolymer resin (tetrafluoroethylene-ethylene copolymer resin; ETFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer resin; PFA), etc. Resin-based materials such as fluororesin, glass epoxy resin, and polyimide are used. The shapes and dimensions (thickness, width, length) of the first to third dielectric layers 21 to 23 made of these materials are set according to the frequency used, the application, and the like.

The first and second ground electrodes 15 and 16, the first and second one-end open resonance electrodes 31, 41, the first and second one-end short-circuit resonance electrodes 32 and 42, and the through conductor are conventionally used for high-frequency signal transmission. It consists of a conductor layer of a metal material used in Specifically, for example, a Cu layer, a Mo-Mn metallization layer with a Ni plating layer and an Au plating layer deposited thereon, or a W metallization layer with a Ni plating layer and an Au plating layer deposited thereon , Cr-Cu alloy layer, that a Ni plating layer and an Au plating layer is deposited on the Cr-Cu alloy layer, which the Ni-Cr alloy layer and an Au plating layer on the Ta ₂ N layer was deposited, Thick film printing method or various thin films using a Pt layer and Au plating layer deposited on a Ti layer or a Pt layer and Au plating layer deposited on a Ni-Cr alloy layer It is formed by a forming method or a plating method. The thickness and width are also set according to the frequency and application of the high-frequency signal transmitted.

  In forming the first to third dielectric layers 21 to 23, for example, when the dielectric layer is made of glass ceramics, first, a glass ceramic green sheet to be a dielectric layer is prepared and subjected to predetermined punching processing. After forming a through hole to be a through conductor, a conductive paste such as Cu is filled into the through hole by a screen printing method, and a predetermined transmission line pattern and other conductor layer patterns are printed and applied. Next, baking is performed at 850 to 1000 ° C., and finally Ni plating and Au plating are performed on the conductor layer exposed on the outer surface.

  FIG. 4 shows filter characteristics obtained when capacitive coupling is dominant in the filter device of the present invention having the configuration shown in FIGS. 1 to 3 and the conventional multilayer stripline filter shown in FIGS. Is.

  In FIG. 4, the horizontal axis represents frequency (unit: GHz), the vertical axis represents insertion loss (unit: dB), and fr represents the attenuation pole. The filter characteristic shown in FIG. 4 has a characteristic that one attenuation pole fr is formed on the low band side of the pass band BW. The filter device of the present invention having the configuration shown in FIGS. 1 to 3 and the conventional multilayer stripline filter shown in FIGS. 5 and 6 can both achieve the filter characteristics shown in FIG.

  In the case of the filter device of the present invention having the configuration shown in FIGS. 1 to 3, the resonance electrodes arranged in parallel so that at least a part of each of the dielectric layers overlap in plan view with the dielectric layer interposed therebetween are connected to the open end or the short-circuit end. It is further branched to a plurality of lines so that the ratio of the width and the length of the branched line is 1: 3 or more. The branched line is bent into an approximately L shape (a shape in which the angle of the bent portion is a right angle). Thereby, the dimension L in the length direction of the resonant electrode can be substantially reduced to about half of the dimension L of the conventional filter device and about 65% of the conventional area in a plan view. A filter device can be provided.

  In the filter device of the present invention, preferably, the first and second ground electrodes 15 and 16 are electrically connected in the stacking direction and the first to fourth one-end short-circuited resonance electrodes 41 in the above configuration. The connection conductors that electrically connect the short-circuit ends 51 to 44 in the stacking direction are through conductors formed inside the dielectric layer or side conductors formed on the side surfaces. As a result, the degree of freedom in designing a filter device for forming each electrode in a plurality of stacked dielectric layers is improved, and a small and high-performance filter device is obtained.

  In addition, this invention is not limited to the above embodiment, A various change and improvement can be added in the range which does not deviate from the summary of this invention.

It is a see-through | perspective perspective view which shows an example of embodiment of the filter apparatus of this invention. It is a see-through plan view showing an example of an embodiment of a filter device of the present invention. It is sectional drawing of the filter apparatus of this invention of FIG. 2, (a) is sectional drawing in the aa 'line, (b) is sectional drawing in the bb' line, (c) is in cc 'line. It is sectional drawing. It is a diagram which shows the example of the insertion loss in the filter apparatus of this invention, and the conventional filter apparatus. It is a see-through | perspective perspective view which shows the example of the conventional filter apparatus. It is sectional drawing which shows the example of the conventional filter apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 ... 1st resonator 12 ... 2nd resonator 21 ... 1st dielectric material layer 22 ... 2nd dielectric material layer 23 ... 3rd dielectric material layer 15 First ground electrode 16 ... Second ground electrode 31 ... First one-end open resonance electrode 32 ... First one-end short-circuit resonance electrode 41 ... Second one-end open resonance electrode 42 ... Second one-end shorted resonance electrode 50 ... Open end 51 ... Short-circuited end 61 ... First input / output terminal 62 ... Second input / output terminal

Claims (2)

A first dielectric layer; a second dielectric layer stacked on the first dielectric layer; a third dielectric layer stacked on the second dielectric layer; A first ground electrode disposed on a lower surface of the first dielectric layer; a first one-end open resonance electrode disposed between the first and second dielectric layers; and a first one-end short-circuit resonance An electrode, a second one-end open resonance electrode disposed between the second and third dielectric layers, a second one-end short-circuit resonance electrode, and a second one disposed on an upper surface of the third dielectric layer. Consisting of two ground electrodes,
The first and second one-end open resonance electrodes are arranged in parallel so that at least a part of each of them overlaps in plan view across the second dielectric layer,
The first and second one-end short-circuited resonant electrodes are arranged in parallel so that at least a part of each of them overlaps in plan view with the second dielectric layer interposed therebetween,
The first and second ground electrodes are arranged so as to cover the first and second one-end open resonance electrodes and the first and second one-end short-circuit resonance electrodes in a plan view,
The first and second one-end open resonant electrodes are branched into an electrode portion that overlaps in plan view and an electrode portion that does not overlap in the plan view toward the open end, and overlaps in plan view from the end opposite to the open end. Each of the open ends is formed such that the length to the open end of the electrode portion and the length from the end opposite to the open end to the open end of the electrode portion that does not overlap in plan view are substantially the same,
The first and second one-end short-circuited resonant electrodes branch into an electrode portion that overlaps in a plan view and an electrode portion that does not overlap in a plan view toward the short-circuit end, and overlap in a plan view from an end opposite to the short-circuit end The short-circuit ends are formed so that the length to the short-circuit end of the electrode portion and the length from the opposite end portion of the short-circuit end to the short-circuit end of the electrode portion that does not overlap in plan view are substantially the same,
An end of the first one-end open resonance electrode opposite to the open end and an end opposite to the short-circuit end of the first one-end short-circuit resonance electrode are electrically connected to form a first resonator. Forming,
An end of the second one-end open resonant electrode opposite to the open end and an end of the second single-ended short-circuited resonant electrode opposite to the short-circuited end are electrically connected to form a second resonator. Forming,
A filter device, wherein first and second input / output terminals are electrically connected to the first and second resonators, respectively. Each ground electrode or each short-circuited end of each one-end short-circuited resonant electrode and each ground electrode are electrically connected by a through conductor formed inside the dielectric layer and a side conductor formed on a side surface. The filter device according to claim 1, wherein:

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