JP4336319B2 - Multilayer stripline filter - Google Patents

Description

  The present invention relates to a multilayer stripline filter for a high-frequency circuit composed of a line conductor, which is 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.

  As an example of such a conventional multilayer stripline filter, Japanese Patent Application Laid-Open No. 9-331201 proposes a configuration shown in an exploded perspective view of FIG. 9 and a perspective plan view of FIG.

  9 and 10, reference numeral 30 denotes a dielectric in which first to third dielectric layers 30a to 30c are sequentially stacked, and reference numerals 31 and 32 denote between the first dielectric layer 30a and the second dielectric layer 30b. The first one-end open line conductor, the first one-end short-circuit line conductor, the end of the first one-end open-line conductor 31 opposite to the open end 37, and the first one-end short-circuit line conductor 32. The short-circuit end 38 and the opposite end are electrically connected. Reference numerals 33 and 34 denote second one-end open line conductors and second one-end short-circuit line conductors arranged between the second dielectric layer 30b and the third dielectric layer 30c. The end of 33 opposite to the open end 37 is electrically connected to the end of the second short-circuited line conductor 34 opposite to the short-circuited end 38. Reference numeral 35 denotes a pair of ground electrodes disposed on both upper and lower sides of the dielectric 30, and 36 denotes a connection conductor. In the dielectric 30, the first and second one-end open line conductors 31, 33 are arranged so that at least a part thereof is opposed to each other when viewed from the stacking direction, and are coupled electromagnetically, and the first The second one-end short-circuited line conductors 32 and 34 are disposed so that at least a part thereof is opposed to each other when viewed from the stacking direction, and are coupled electromagnetically. In FIG. 10, the pair of ground electrodes 35 and connection conductors 36 are not shown.

  The short-circuit ends 38 of the first and second one-end short-circuit line conductors 32 and 34 are electrically connected to the pair of ground electrodes 35 via the connection conductor 36, respectively.

  FIG. 11 is a circuit diagram showing the configuration of the conventional multilayer stripline filter. FIG. 12 shows filter characteristics realized by the conventional multilayer stripline filter.

  The width W1 of the first and second one-end open line conductors 31 and 33, the width W2 of the first and second one-end short-circuited line conductors 32 and 34, the first one-end open line conductor 31 and the second one-end open The width W3 where the line conductor 33 overlaps the dielectric layer 30b and the width W4 where the first one-end short-circuit line conductor 32 and the second one-end short-circuit line conductor 34 overlap each other across the dielectric layer 30b are adjusted. As a result, a capacitance is formed as an electromagnetic field coupling formed between the first one-end open line conductor 31 and the second one-end open line conductor 33 and between the first one-end short-circuit line conductor 32 and the second one-end short-circuit line conductor 34. When the sexual coupling becomes dominant, the filter characteristic (FIG. 12-a) having one attenuation pole on the low band side with respect to the pass band is reversed. On the contrary, when the inductive coupling becomes dominant, the pass band With one attenuation pole on the high-frequency side Data characteristics has been realized (FIG. 12-b).

  As another example of a conventional multilayer stripline filter, Japanese Patent Application Laid-Open No. 8-70201 proposes a configuration shown in FIG. FIG. 13 shows a configuration in which a conventional multilayer stripline filter is connected in two stages by adding a third one-end open line conductor 39 and a third one-end short-circuit line conductor 40 to FIG. 9. Accordingly, the amount of attenuation outside the passband is increased by increasing the number of connection stages of the multilayer stripline filter.

On the other hand, in recent years, various types of wireless communication devices such as mobile phones and wireless LANs have emerged, and in order to select a desired frequency signal for wireless communication from among mixed frequency signals for wireless communication, The demand for increasing the amount of attenuation outside the passband has become apparent for the filters used. In addition, with the trend of miniaturization of wireless communication devices, there is an increasing demand for miniaturization of filters used inside various communication devices.
JP-A-9-331201 Japanese Patent Laid-Open No. 8-70201

  However, in the conventional multilayer stripline filter proposed in Japanese Patent Laid-Open No. 9-331201, one attenuation pole is provided on the low band side or one attenuation pole is provided on the high band side with respect to the pass band. However, since it can only be formed, there is a problem that a sufficient amount of attenuation outside the passband cannot be secured.

  Also, the conventional method of increasing the attenuation outside the pass band by connecting two layers of multilayer stripline filters proposed in Japanese Patent Laid-Open No. 8-70201 has a configuration in which two filters are connected. However, the size of the laminated stripline filter in the planar direction is increased, and there is a problem that it is impossible to meet the demand for miniaturization.

  The present invention has been made to solve the above problems, and an object of the present invention is to provide a multilayer stripline filter having high attenuation and a small size.

Laminated stripline filter of the present invention includes a laminated body formed by laminating a plurality of dielectric layers, one end is Rutotomoni other end is a short-circuit end is an open end, said during an internal of the laminate first and second line conductors, first, arranged on both sides in the laminating direction of the dielectric layer to the second line conductor at least a part across the dielectric layer is disposed so as to face a pair of ground electrodes, one end Rutotomoni other end is a short-circuit end is an open end, positioned between the pair of ground electrodes, respectively, through the first coupling conductor and the second line conductor The third and fourth line conductors arranged in an electrically connected state and shifted in a direction perpendicular to the laminating direction, and the open ends of the first and third line conductors, Connections where the open ends of the second and fourth line conductors are different from each other. And it is characterized in that it is connected through the body.

  The multilayer strip line filter of the present invention is characterized in that the line widths of the first and second line conductors are different.

According to the multilayer stripline filter of the present invention, the open ends of the first and third line conductors, and the open ends of the second and fourth line conductors are connected to the first and third line conductors and the second and second line conductors. The open ends of the first and third line conductors are electrically connected to each other through connecting conductors that are different from the connecting conductors that electrically connect the fourth line conductors. In addition, the open ends of the second and fourth line conductors are electrically open ends. Therefore, the difference between the electrical length reaching the open end of the first line conductor and the electrical length reaching the open end of the third line conductor via the connecting conductor, which is caused by the electrical connection via the connecting conductor, The difference between the electrical length reaching the open end of the second line conductor and the electrical length reaching the open end of the fourth line conductor via the connecting conductor can be reduced. As a result, it is possible to suppress the anti-resonance phenomenon on the high frequency side of the pass band caused by the difference in the electrical length reaching these open ends. As a result, the amount of attenuation outside the pass band can be increased , and a high-attenuation and small-sized multilayer stripline filter can be provided.

  According to the multilayer stripline filter of the present invention, even if a stacking shift occurs in the process of stacking a plurality of dielectric layers by changing the line widths of the first and second line conductors, the stacking shift Thus, the change in the electromagnetic field coupling amount between the first and second line conductors can be further reduced, whereby the frequency fluctuation of the attenuation pole of the filter characteristic can be further reduced. In addition, by making the line widths of the first and second line conductors different, the capacitive additional component on the open end side due to the difference in the line widths of the first and second line conductors, and the short-circuit end side Inductive additional components can be offset, and fluctuations in the input / output impedance of the laminated stripline filter can be reduced. As a result, a higher performance laminated stripline filter can be provided.

  The laminated stripline filter of the present invention will be described below with reference to the drawings. In the following embodiment, a multilayer stripline filter corresponding to the frequency of a wireless LAN (frequency band 5 GHz), which is a system in which peripheral devices such as a personal computer and a printer are connected wirelessly, will be described.

  FIG. 1 is an exploded perspective view showing an example of an embodiment of a first laminated stripline filter of the present invention, and FIG. 2 is a perspective plan view of FIG. 1 viewed from the lamination direction.

  1 and 2, 10a is a first dielectric layer, 10b is a second dielectric layer, 10c is a third dielectric layer, 11 is a first line conductor, 12 is a second line conductor, Reference numeral 13 denotes a third line conductor, 14 denotes a fourth line conductor, 15 denotes a ground electrode, 16 denotes a connecting conductor, and 17 denotes a connecting conductor. The first to third dielectric layers 10 a to 10 c are sequentially stacked and included in the stacked body 10.

  The first to fourth line conductors 11 to 14 each have an open end 18 and a short-circuit end 19, and the first line conductor 11 is between the first dielectric layer 10 a and the second dielectric layer 10 b. And a third line conductor 13 are disposed, and a second line conductor 12 and a fourth line conductor 14 are disposed between the second dielectric layer 10b and the third dielectric layer 10c, The second line conductors 11 and 12 are electrically connected to the third and fourth line conductors 13 and 14 and the connecting conductor 16, respectively.

  Further, a pair of ground electrodes 15 are disposed below the first dielectric layer 10a and above the third dielectric layer 10c, and the first to fourth line conductors 11 to 14 are respectively provided. The short-circuit end 19 is electrically grounded to the ground electrode 15 through the connection conductor 17. In addition, the first line conductor 11 and the second line conductor 12 are disposed so that at least a part of the first line conductor 11 and the second line conductor 12 face each other with the second dielectric layer 10b interposed therebetween. In FIG. 2, the pair of ground electrodes 15 and connection conductors 17 are not shown.

  The laminated body 10 including the first to third dielectric layers 10a to 10c used in the first laminated stripline filter of the present invention includes, for example, ceramic materials such as alumina ceramics and mullite ceramics, inorganic materials such as glass ceramics, Or tetrafluoroethylene resin (polytetrafluoroethylene; PTFE), tetrafluoroethylene-ethylene copolymer resin (tetrafluoroethylene-ethylene copolymer resin; ETFE), tetrafluoroethylene-perfluoroalkoxyethylene copolymer resin ( A fluorocarbon resin such as tetrafluoroethylene-perfluteroalkyl vinyl ether copolymer resin (PFA) or a resin-based material such as glass epoxy resin or polyimide is used. The shape and dimensions (thickness, width, and length) of the laminated body 10 including the first to third dielectric layers 10a to 10c made of these materials are set according to the frequency and application to be used.

The first to fourth line conductors 11 to 14, the pair of ground electrodes 15, the connection conductor 16, and the connection conductor 17 used in the first multilayer stripline filter of the present invention are a conductor layer of a metal material for high-frequency signal transmission, for example, Cu layer ・ Mo-Mn metallization layer with Ni plating layer and Au plating layer deposited ・ W metallization layer with Ni plating layer and Au plating layer deposited ・ Cr-Cu alloy layer · Cr-Cu alloy layer on the Ni plating layer and a Pt layer and an Au plating layer to Ni-Cr alloy layer and an Au plating layer on those · Ta ₂ N layer was deposited on one · Ti layer was deposited A thick film printing method or various thin film forming methods, plating methods, etc. using a coating with an Au plating layer or a Ni-Cr alloy layer with a Pt layer and an Au plating layer By It is made. The thickness and width are also set according to the frequency and application of the high-frequency signal transmitted.

  The material and the forming method of the first laminated stripline filter of the present invention described above are the same for the second laminated stripline filter of the present invention described later.

  In the production of the laminated body 10 including the first to third dielectric layers 10a to 10c used in the first laminated stripline filter of the present invention, for example, each dielectric layer including the dielectric layers 10a to 10c is made of glass ceramics. First, a glass ceramic green sheet as a dielectric layer is prepared, a predetermined punching process is performed on the green sheet to form a through hole as a through conductor, and then a conductor such as Cu is formed by screen printing. The paste is filled in the through holes, and a predetermined pattern of each line conductor 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 each conductor layer.

  FIG. 3 is a circuit diagram of the first multilayer stripline filter of the present invention shown in FIGS. 1 and 2, and FIG. 4 can be realized by the first multilayer stripline filter of the present invention shown in FIGS. It is a filter characteristic figure.

  In the first multilayer stripline filter of the present invention, one end is a short-circuit end 19 and the other end is an open end 18 in the multilayer body 10 in which the first to third dielectric layers 10a to 10c are sequentially laminated. The first and second line conductors 11 and 12 are disposed so that at least a part of the first and second line conductors 11 and 12 are opposed to each other with the second dielectric layer 10b interposed therebetween. 11 and 12, a pair of ground electrodes 15 are arranged on both sides in the stacking direction of the laminate 10, and one end is a short-circuit end 19 and the other end is an open end 18 between the pair of ground electrodes 15. The third and fourth line conductors 13 and 14 are shifted in the direction perpendicular to the stacking direction in a state where they are electrically connected to the first and second line conductors 11 and 12 via the connecting conductor 16, respectively. As a result, the connection conductor 16 and the third line conductor are shown in FIG. 13 resonant circuit 1 formed by, and can constitute a resonance circuit 2 is formed the connecting conductor 16 in the fourth line conductor 14. As a result, in addition to the fact that one attenuation pole can be formed on the low band side or the high band side of the pass band with the first and second line conductors, the resonance circuit 1 and the resonance circuit 2 provide a high pass band. One new attenuation pole can be formed on the band side, and a filter characteristic having two attenuation poles shown in FIG. 4- (a) or FIG. 4- (b) can be realized. As a result, the amount of attenuation outside the passband can be further increased without increasing the number of stages of the laminated stripline filter, so that a highly attenuated and small laminated stripline filter can be provided.

  FIG. 5 is a graph showing frequency characteristics of the first multilayer stripline filter of the present invention shown in FIGS. 1 and 2. In FIG. 5, the horizontal axis represents the frequency (unit: GHz), the vertical axis represents the frequency characteristic of the multilayer stripline filter in signal attenuation (unit: dB), and the solid line characteristic curve represents the first multilayer strip of the present invention. The frequency characteristics of the line filter and the frequency characteristics of the broken line indicate the frequency characteristics of the conventional multilayer strip line filter. The thicknesses of the first to third dielectric layers 10a to 10c in the first multilayer stripline filter of the present invention and the conventional multilayer stripline filter are set to be the same.

  From the result of FIG. 5, according to the first multilayer stripline filter of the present invention, the resonance circuit 1 and the resonance circuit 2 shown in FIG. It can be seen that one new attenuation pole can be formed and a filter characteristic having two attenuation poles can be realized. As a result, the amount of attenuation outside the passband can be further increased without increasing the number of stages of the laminated stripline filter, so that a highly attenuated and small laminated stripline filter can be provided. For example, in the case of the example shown in FIG. 5, the first laminated stripline filter of the present invention is 30% smaller in size in the planar direction than the conventional laminated stripline filter.

  Note that the first to fourth line conductors 11 to 14 have line widths on the open end side and short-circuit end side of each line conductor, as shown in FIGS. Can be set arbitrarily.

  Next, an embodiment of the second laminated stripline filter of the present invention is shown in an exploded perspective view of FIG. 6 and a perspective plan view of FIG. 6 and 7, the same parts as those in FIGS. 1 and 2 are denoted by the same reference numerals.

  6 and FIG. 7 are connected to the open end 18 of the first line conductor 11 and the open end 18 of the third line conductor 13 by the connecting conductor 16 with respect to FIGS. The open end 18 of the line conductor 12 and the open end 18 of the fourth line conductor 14 are connected by a connecting conductor 16. With this configuration, the open ends 18 of the first and third line conductors 11 and 13 become an electrically common open end, and the open ends of the second and fourth line conductors 12 and 14. Since the ends 18 are electrically common open ends, the electrical length leading to the open end 18 of the first line conductor 11 and the connection conductor 16 caused by being electrically connected via the connection conductor 16 Then, the difference in electrical length to the open end 18 of the third line conductor 13, and the electrical length to the open end 18 of the second line conductor 12 and the connection conductor 16, and the fourth line conductor 14 The difference in electrical length reaching the open end 18 can be relaxed, and the anti-resonance phenomenon on the high frequency side of the pass band caused by the difference in electrical length reaching these open ends can be suppressed. As a result, the amount of attenuation outside the pass band can be further increased, and a more compact and compact multilayer stripline filter can be provided.

  FIG. 8 is a graph showing frequency characteristics of the second multilayer stripline filter of the present invention shown in FIGS. In FIG. 8, the horizontal axis represents the frequency (unit: GHz), the vertical axis represents the frequency characteristic of the multilayer stripline filter in signal attenuation (unit: dB), and the solid line characteristic curve represents the second multilayer strip of the present invention. The frequency characteristic of the line filter and the frequency characteristic of the broken line indicate the frequency characteristic of the first laminated strip line filter of the present invention. Note that the thicknesses of the first to third dielectric layers 10a to 10c in the first and second multilayer stripline filters of the present invention are set to be the same.

  From the result of FIG. 8, according to the second multilayer stripline filter of the present invention, the open end 18 of the first line conductor 11 and the open end 18 of the third line conductor 13 are connected by the connecting conductor 16. Since the open end 18 of the second line conductor 12 and the open end 18 of the fourth line conductor 14 are connected by the connecting conductor 16, the open ends 18 of the first and third line conductors 11 and 13 are connected to each other. Since the open ends 18 of the second and fourth line conductors 12 and 14 are electrically open ends, they are electrically connected via the connecting conductor 16. The difference between the electrical length reaching the open end 18 of the first line conductor 11 and the electrical length reaching the open end 18 of the third line conductor 13 via the connecting conductor 16, and the second line conductor 12 through the open end 18 and the connecting conductor 16. Thus, the difference in electrical length to the open end 18 of the fourth line conductor 14 can be reduced, and the anti-resonance on the high band side of the pass band caused by the difference in electrical length to these open ends The phenomenon can be suppressed. As a result, the amount of attenuation outside the pass band can be further increased, and a more compact and compact multilayer stripline filter can be provided.

  Furthermore, the laminated stripline filter of the present invention having such a configuration has a difference in lamination in the process of laminating a plurality of dielectric layers by making the line widths of the first and second line conductors 11 and 12 different. Even when it occurs, it is possible to further reduce the change in the amount of electromagnetic coupling between the first and second line conductors 11 and 12 due to the stacking deviation, thereby further reducing the frequency fluctuation of the attenuation pole of the filter characteristic. Can be reduced. In addition, by making the line widths 11 and 12 of the first and second line conductors different, the capacitive additional component on the open end side caused by the difference in the line widths of the first and second line conductors 11 and 12 And the inductive additional component on the short-circuit end side can be canceled, and fluctuations in the input / output impedance of the multilayer stripline filter can be reduced. As a result, a higher performance laminated stripline filter can be provided.

  The difference between the line widths of the first and second line conductors 11 and 12 is caused by the difference between the line widths of the first and second line conductors 11 and 12 and the capacitive additional component on the open end side and the short-circuited end. The difference in line width on the open end side and the difference in line width on the short-circuit end side may be arbitrarily set so as to cancel out the inductive additional component on the side.

  The laminated stripline filter of the present invention is not limited to the example of the above embodiment, and various modifications may be made without departing from the gist of the present invention. For example, in the example shown in FIG. 1, the multilayer stripline filter of the present invention includes the first line conductor 11 and the third line conductor 13 arranged on the same plane, and the second line conductor 12 and the second line conductor 12. The four line conductors 14 are arranged on the same plane. However, the present invention is not limited to this configuration, and each line conductor may be arranged on an arbitrary plane. To provide a more compact and high performance multilayer stripline filter by arranging in an arbitrary plane, further improving the design flexibility of the multilayer stripline filter formed inside a plurality of laminated dielectric layers. Can do.

  Further, the first to fourth line conductors 11 to 14 used for forming the laminated strip line filter are set to have the same length in each line conductor in the example of FIG. The length of the conductor may be set arbitrarily.

  In the example shown in FIG. 1, the laminated strip line filter of the present invention has a pair of ground electrodes 15 disposed below the first dielectric layer 10a and above the third dielectric layer 10c. Although the first to fourth line conductors 11 to 14 are arranged between the ground electrodes 15, the present invention is not limited to this configuration, and another ground is provided between the pair of ground electrodes 15. A plurality of electrodes may be inserted. By inserting a plurality of other ground electrodes between the pair of ground electrodes 15, the line widths of the first to fourth line conductors 11 to 14 can be further adjusted, and a plurality of laminated dielectric layers The degree of freedom of design of the laminated stripline filter formed inside is further improved, and a more compact and high performance laminated stripline filter can be provided.

  Further, the first to fourth line conductors 11 to 14 used for forming the laminated stripline filter are each formed of a single line conductor in the example of FIG. You may form with several conductors which can be regarded as a track | line.

  The system in which the laminated stripline filter is used may be GSM (Global System for Mobile Communications), DCS (Digital Cell System), Bluetooth, or the like.

  Further, in the example of FIG. 1, the laminated body 10 used for forming the laminated stripline filter shows a case where the laminated body includes three layers of the first to third dielectric layers 10 a to 10 c. The number of layers may be four or more.

It is a disassembled perspective view which shows an example of embodiment of the lamination | stacking stripline filter of this invention. 1 is a perspective plan view showing an example of an embodiment of a laminated stripline filter of the present invention. It is a circuit diagram of the lamination | stacking stripline filter of this invention. It is a diagram which shows the signal attenuation amount (unit: dB) in the lamination | stacking stripline filter of this invention. It is a diagram which shows the signal attenuation amount (unit: dB) in the multilayer stripline filter of this invention and the conventional multilayer stripline filter. It is a disassembled perspective view which shows other embodiment of the lamination | stacking stripline filter of this invention. It is a see-through | perspective top view which shows other embodiment of the lamination | stacking stripline filter of this invention. It is a diagram which shows the signal attenuation amount (unit: dB) in the lamination | stacking stripline filter of this invention. It is a disassembled perspective view which shows an example of embodiment of the conventional multilayer stripline filter. It is a perspective top view which shows an example of embodiment of the conventional multilayer stripline filter. It is a circuit diagram of the conventional multilayer stripline filter. It is a diagram which shows the signal attenuation amount (unit: dB) in the conventional multilayer stripline filter. It is a disassembled perspective view which shows other embodiment of the conventional multilayer stripline filter.

Explanation of symbols

10: laminates 10a to 10c: first to third dielectric layers 11: first line conductor 12: second line conductor 13: third line conductor 14: fourth line conductor 15: ground electrode 16 : Connection conductor 17: Connection conductor 18: Open end 19: Short-circuit end

Claims (3)

A laminated body formed by laminating a plurality of dielectric layers, one end Rutotomoni other end is a short-circuit end is an open end, at least a portion across the dielectric layer between an interior of the laminate First and second line conductors disposed so as to face each other, a pair of ground electrodes disposed on both sides of the dielectric layer in the stacking direction with respect to the first and second line conductors, and one end There Rutotomoni other end is a short-circuit end is an open end, positioned between the pair of ground electrodes, wherein each of the first, in a state being electrically connected via the second line conductor and the connecting conductor, and A third and fourth line conductors arranged to be shifted in a direction orthogonal to the lamination direction, and a laminated stripline filter comprising:
The open ends of the first and third line conductors and the open ends of the second and fourth line conductors are connected to each other via a connecting conductor different from the connecting conductor. Stripline filter. The multilayer stripline filter according to claim 1, wherein the first and second line conductors have different line widths . The multilayer stripline filter according to claim 1 or 2 , wherein a plurality of ground electrodes different from the pair of ground electrodes are inserted between the pair of ground electrodes .

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