JP2004180032A - Dielectric filter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small-sized dielectric filter which extends an adjustment range of an electromagnetic field coupling state by arranging a strip line and a coupling conductor between different dielectric layers and obtains filter characteristics of a wide pass band width and a large magnitude of the cutoff area attenuation of the filter. <P>SOLUTION: A dielectric filter 1 has ground electrodes deposited to both principal surfaces of a stacked body 2 constituted by stacking a plurality of dielectric layers, has a pair of strip lines 5 and 6 arranged between the dielectric layers, and further has the strip lines 5 and 6 and the ground electrodes connected by a pair of via-hole conductors 7 and 8 formed in the stacked body 2. Two or more dielectric layers exist in areas where the pair of via-hole conductors 7 and 8 are formed, and a coupling conductor 9 for electrically connecting the pair of via-hole conductors 7 and 8 is arranged between these dielectric layers. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a dielectric filter incorporated in various communication devices such as a mobile phone and a personal computer, and an electronic device.
[0002]
[Prior art]
Conventionally, dielectric filters have been used in communication devices such as mobile phones.
As such a conventional dielectric filter, for example, as shown in FIG. 4, a ground 102 is formed inside a laminated body 102 formed by laminating a plurality of dielectric layers 102a to 102f, specifically, between the dielectric layers 102a and 102b. The electrode 103a is formed by forming a ground electrode 103b between the dielectric layers 102e and 102f, and by connecting the two strip lines 105 and 106 and the coupling conductor 109 arranged substantially in parallel between the dielectric layers 102c and 102d. One having a structure in which a capacitive coupling pattern 110 is formed between the body layers 102b and 102c and connected from the strip lines 105 and 106 to the ground electrode 103 formed on the main surface of the stacked body via via hole conductors 107 and 108 It is known (for example, refer to Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Application No. 2001-393205
[Problems to be solved by the invention]
By the way, in the above-mentioned conventional dielectric filter, adjacent strip lines are connected to each other with a coupling conductor in order to form a filter characteristic having a large pass band width and a large stop band attenuation. The electromagnetic field coupling state is adjusted by changing the line length.
[0005]
However, in the conventional structure in which the coupling conductor is arranged in the same plane as the strip line, when setting the line length of the coupling conductor to a predetermined length, there is a limit in adjusting the connection position of the coupling conductor, and the pass band is limited. There is a disadvantage that it is difficult to obtain a filter characteristic having a large width and a large stopband attenuation.
[0006]
The present invention has been devised in view of the above drawbacks, and has as its object to provide a small-sized dielectric filter capable of obtaining a filter characteristic having a wide pass band width of the filter and a large amount of attenuation in a stop band. It is in.
[0007]
[Means for Solving the Problems]
The dielectric filter according to the present invention is configured such that a ground electrode is attached to both main surfaces of a laminate formed by laminating a plurality of dielectric layers, and a pair of strip lines is disposed between the dielectric layers. And the ground electrode are connected by a pair of via-hole conductors formed inside the multilayer body, wherein at least two or more dielectric layers are present in the formation region of the pair of via-hole conductors. And a coupling conductor for electrically connecting a pair of via-hole conductors is provided between the dielectric layers.
[0008]
Further, in the dielectric filter of the present invention, the pair of strip lines are arranged in parallel in the same plane, the via hole conductor is provided at one end of one strip line, and the other end of the other strip line is provided. And via-hole conductors are connected to the respective holes.
[0009]
Further, in the dielectric filter of the present invention, a capacitive coupling pattern for forming a predetermined capacitance between the pair of strip lines is provided between the dielectric layers located between the pair of strip lines and the ground electrode. It is characterized by being arranged.
[0010]
According to the dielectric filter of the present invention, since the coupling conductor for electrically connecting the pair of strip lines is arranged between the dielectric layers different from the strip lines, the magnetic field coupling between the strip lines can be minimized. The state can be further reduced.
[0011]
According to the dielectric filter of the present invention, a pair of strip lines are arranged in parallel in the same plane, a via hole conductor is provided at one end of one strip line, and a via hole conductor is provided at the other end of the other strip line. Are connected to each other, the pair of via-hole conductors are arranged diagonally, whereby the adjustment range of the line length of the coupling conductor in the same plane can be increased.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an exploded perspective view of a dielectric filter according to an embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram of the dielectric filter of FIG.
[0013]
In the dielectric filter 1 shown in these figures, a ground electrode 3 is applied to both main surfaces of a laminated body 2 formed by laminating a plurality of dielectric layers 2a to 2f, and an interdigital type is provided between the dielectric layers. Are provided, and the strip lines 5 and 6 are connected to the ground electrode 3 by a pair of via-hole conductors 7 and 8 formed inside the laminate 2. It has a structure in which a coupling conductor 9 that electrically connects the pair of via-hole conductors 7 and 8 is disposed between dielectric layers located in regions where the pair of via-hole conductors 7 and 8 are formed.
[0014]
The laminate 2 is formed by laminating, for example, six dielectric layers 2a to 2f, and each of the dielectric layers 2a to 2f is made of a dielectric ceramic material, a sintering aid, a low melting glass material, or the like. It is configured. As the dielectric ceramic material, for example, ceramic materials such as BaO—TiO ₂ , Ca—TiO ₂ , and MgO—TiO ₂ are used. When these ceramic materials are used, the dielectric constant is relatively high and the area is small. However, since a sufficient capacitance can be obtained, the strip line length can be shortened, and the overall structure can be reduced in size. As the sintering aid, for example, BiVO ₄ , CuO, Li ₂ O, B ₂ O _{3 and the} like are used. The thickness of each of the dielectric layers 2a to 2f is set to about 50 to 300 μm per layer.
[0015]
Note that, in addition to the strip lines 5, 6 and the coupling conductor 9, a capacitive coupling pattern 10, ground electrodes 3a, 3b, and the like are provided inside the laminate 2, and input / output terminals 4a, 4b are provided on side surfaces thereof. Is provided.
[0016]
The ground electrode 3 includes a ground electrode 3 provided on both main surfaces and side surfaces of the multilayer body 2, a ground electrode 3a provided on the surface of the dielectric layer 2b, and a ground provided on the surface of the dielectric layer 2f. And the electrode 3b.
[0017]
As the material of the ground electrode 3, for example, a conductive material mainly containing a metal such as Ag or Cu is preferably used. The surface of the ground electrode 3 exposed to the outside is provided for the purpose of preventing oxidation corrosion and the like. For example, an Au plating film, a Ni—Au plating film, or the like is appropriately deposited and formed.
[0018]
On the other hand, the strip lines 5 and 6 are interposed in the laminated body 2, specifically, in parallel with each other between the dielectric layer 2 c and the dielectric layer 2 d. , 6 are connected to the ground electrode 3 on the main surface of the multilayer body via via-hole conductors 7, 8 at one end thereof. More specifically, of the pair of strip lines 5, 6, one end of one strip line 5 is connected via a via-hole conductor 8, and the other end of the other strip line 6 is connected via a via-hole conductor 7. The ground electrode 3 is electrically connected.
[0019]
Such a stripline resonator forms a capacitive component and an inductive component between the striplines 5 and 6 and the ground electrode 3 facing the stripline resonator, and functions as a λ / 4 stripline resonator. Become.
[0020]
The strip lines 5 and 6, the via-hole conductors 7 and 8, the coupling conductor 9, and the capacitive coupling pattern 10 that constitute the above-described strip line resonator are formed of, for example, the same conductive material as the ground electrode 3.
[0021]
Next, a method for manufacturing the above-described dielectric filter 1 will be described.
First, a ground electrode 3a formed by using a conductive paste on a ceramic green sheet made of a dielectric material and a resin material, strip lines 5, 6 and via hole conductors 7, 8 formed, a coupling conductor 9, and a via hole conductor 7 and 8, the ground electrode 3b and the via hole conductors 7 and 8 are laminated in the order shown in FIG.
[0022]
Next, the above-described laminate of ceramic green sheets is fired at a high temperature, and the dielectric layer and the internal conductor are simultaneously fired to form a laminate 2. Finally, a ground electrode is provided on the side surface of the obtained laminate 2. By forming 3, a dielectric filter as a product is completed.
[0023]
In the dielectric filter of the present embodiment as described above, since the pair of strip lines 5 and 6 and the coupling conductor 9 are arranged between different dielectric layers, in addition to the magnetic field coupling state on the same plane, the dielectric layer And the degree of freedom of adjustment of the magnetic field coupling state can be increased.
[0024]
In the dielectric filter of the present embodiment, the strip lines 5 and 6 and the coupling conductor 9 are arranged such that the short-circuit ends of the strip lines 5 and 6 are connected to the coupling conductor 9 via the via holes 7 and 8. It is preferable that the magnetic field coupling between the strip lines 5 and 6 can be reduced by increasing the distance between the strip lines 5 and 6 and the dielectric layer where the coupling conductor 9 is disposed, so that the pass band width of the filter is wide. Thus, a filter characteristic having a large stop band attenuation can be obtained.
[0025]
Further, in the above-described dielectric filter of the present embodiment, a via-hole conductor 8 is provided at one end of one of the pair of strip lines 5 and 6 arranged in parallel on the same plane, and the other By connecting the via-hole conductors 7 to the other end of the pair 6, respectively, the pair of via-hole conductors 7 and 8 are arranged diagonally, thereby adjusting the line length of the coupling conductor 9 in the same plane. There is also the advantage that the range can be increased.
[0026]
Next, the operation and effect of the present invention will be described with reference to FIG. FIG. 3 is a comparison diagram showing the filter characteristics of the dielectric filter of the present invention and the conventional dielectric filter. A in the figure shows the filter characteristics of the conventional dielectric filter, and B and C show the filter characteristics of the dielectric filter of the present invention. B shows a case where the strip lines 5 and 6 and the coupling conductor 9 are arranged in different layers, and C shows a filter characteristic in a case where the strip lines 5 and 6 and the coupling conductor 9 are arranged in two different layers.
[0027]
As is clear from the drawing, the filter characteristic A of the conventional product has a narrow pass band width, whereas the filter characteristics B and C of the present invention have a wide pass band width and a large stop band attenuation. It turns out that it has a filter characteristic. This is because the magnetic field coupling between the strip lines 5 and 6 can be weakened by disposing the strip lines 5 and 6 and the coupling conductor 9 between different dielectric layers. In the characteristics of the conventional product A, the connection between the strip lines 5 and 6 and the coupling line 9 are filter characteristics when the short-circuited ends of the strip lines 5 and 6 are connected, and the connection with the coupling line 9 is stripped. By setting the lines 5 and 6 on the open end side, the attenuation pole on the lower side of the filter pass band moves further to the high frequency side, and the filter has a filter characteristic in which the pass band width of the filter becomes narrower.
[0028]
Note that the present invention is not limited to the above-described embodiment, and various changes, improvements, and the like can be made without departing from the gist of the present invention.
[0029]
For example, in the embodiment of the present invention, the coupling conductors 9 are arranged in an L-shaped linear shape, but may be arranged in a meandering shape.
[0030]
【The invention's effect】
According to the dielectric filter of the present invention, since the coupling conductor for electrically connecting the pair of strip lines is arranged between the dielectric layers different from the strip lines, the magnetic field coupling between the strip lines can be minimized. The state can be further reduced.
[0031]
According to the dielectric filter of the present invention, a pair of strip lines are arranged in parallel in the same plane, a via hole conductor is provided at one end of one strip line, and a via hole conductor is provided at the other end of the other strip line. Are connected to each other, the pair of via-hole conductors are arranged diagonally, whereby the adjustment range of the line length of the coupling conductor in the same plane can be increased.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a dielectric filter according to an embodiment of the present invention.
FIG. 2 is an equivalent circuit diagram of the dielectric filter of FIG.
FIG. 3 is a comparison diagram showing filter characteristics of a dielectric filter of the present invention and a conventional dielectric filter.
FIG. 4 is an exploded perspective view of a conventional dielectric filter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Dielectric filter 2 ... Laminated body 2a-2f ... Dielectric layer 3, 3a, 3b ... Ground electrode 4a, 4b ... Input / output terminal 5, 6 ... Strip line 7 .. 8 via-hole conductor 9 coupling conductor 10 capacitive coupling pattern

Claims (3)

A ground electrode is attached to both main surfaces of a laminate formed by laminating a plurality of dielectric layers, and a pair of strip lines is disposed between the dielectric layers, and the strip line and the ground electrode are laminated. A dielectric filter connected by a pair of via-hole conductors formed inside the
At least two or more dielectric layers are present in the formation region of the pair of via-hole conductors, and a coupling conductor for electrically connecting the pair of via-hole conductors is provided between these dielectric layers. Dielectric filter. The pair of strip lines are arranged in parallel on the same plane, and the via hole conductor is connected to one end of one strip line and the via hole conductor is connected to the other end of the other strip line, respectively. The dielectric filter according to claim 1, wherein A capacitive coupling pattern for forming a predetermined capacitance between the pair of strip lines is disposed between a dielectric layer located between the pair of strip lines and the ground electrode. 3. The dielectric filter according to claim 1 or 2.

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