JP3210615B2 - Multilayer filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer filter used in a high-frequency circuit of a mobile communication device such as a mobile phone,
That is, the present invention relates to a bandpass filter including a pair of substantially λ / 4 resonators in a dielectric.

[0002]

2. Description of the Related Art A laminated filter has a structure in which a pair of resonators are built in a dielectric body and shield electrodes are arranged on upper and lower surfaces. Conventionally, both resonators are electromagnetically coupled by arranging the resonance electrodes on the same laminated surface in the base. According to this structure, the width in the arrangement direction of the resonance electrodes is widened, so that miniaturization is difficult. It is.

On the other hand, when the resonance electrodes are arranged in the laminating direction and are built in a dielectric material, and when the thickness is reduced, the distance between the two resonance electrodes must be reduced, so that the capacitance component between the two resonance electrodes increases. However, steep frequency characteristics as a stripline type filter cannot be obtained.

[0004] In Japanese Patent Application Laid-Open No. 9-69701,
In order to reduce the area occupied by the resonance electrodes for the purpose of reducing the size of the multilayer filter, the resonance electrodes are formed in a rectangular spiral shape, and these resonance electrodes are provided on different layers.
A ground electrode is interposed between the two resonance electrodes.

The multilayer filter described in this publication is arranged so that the resonance electrodes overlap each other with a dielectric layer interposed therebetween when viewed in a plan view, that is, in the stacking direction. The short-circuited end and the inner end connected to the open end are open ends, and the linear portion on the outer periphery of the resonance electrode having the base end is connected to the input terminal and the output terminal, respectively. In this structure, by setting the actual line length to be 0.90 to 0.94 times as long as the theoretical line length, it is possible to obtain a multilayer filter with a small decrease in the Q value. It is described.

[0006]

However, according to this structure, since the resonance electrodes are arranged almost entirely at positions facing each other with the dielectric layer interposed therebetween, in order to obtain a steep characteristic, the resonance electrodes must It is necessary to interpose a ground electrode with a large area that is close to between the two resonance electrodes, so that the actual line length is not as short as expected, and the objective of miniaturization is not sufficiently obtained. There is a point.

[0007] In view of the above problems, the present invention has a structure capable of narrowing the interval between the resonance electrodes in the stacking direction to achieve a reduction in thickness, but it is possible to reduce capacitive coupling and steeply. It is an object of the present invention to provide a laminated filter having a configuration that can obtain a filter having specific characteristics and can easily achieve miniaturization.

[0008]

In order to achieve this object, the present invention provides a laminated filter having a rectangular parallelepiped shape using a pair of substantially λ / 4 resonators. A first shield electrode, a first resonance electrode, a ground electrode, a second resonance electrode, and a second shield electrode are laminated in this order via a dielectric layer, and the first resonance electrode And the second resonance electrode, each base end of which is connected to a ground terminal provided on the outer surface of the base, and the front end of both resonance electrodes has an open structure. The first resonance electrode and the second resonance electrode are electrically coupled to an input terminal and an output terminal provided on an outer surface.
Has a shape with the tips bent toward each other.
The portions other than the tip portions of the first resonance electrode and the second resonance electrode are arranged at different positions in plan view, and the tip portions of both resonance electrodes are arranged in overlapping positions in plan view. Between the resonance electrode and the tip of the second resonance electrode so as to shield a part of the region where both resonance electrodes overlap.
The ground electrode is interposed, the first, second shield electrode and the ground electrode is characterized by being connected to a ground terminal provided on the outer surface of the substrate to (claim 1).

Further, the laminated filter of the present invention is characterized in that the first filter
The second resonance electrode and the second resonance electrode have a shape that is inclined so as to gradually approach from the base end to the tip end ( Claim 2 ).

Further, the laminated filter of the present invention is characterized in that the first
Resonance electrode and the second resonance electrode is characterized by forming a T-shaped tip portion is projected on both sides (claim
3 ).

Further, the laminated filter of the present invention is characterized in that the first filter
The input terminal and the output terminal respectively electrically coupled to the resonance electrode and the second resonance electrode are provided on different side surfaces of the base ( Claim 4 ).

[0012]

According to the present invention, the paired resonance electrodes are arranged on different layers so that they do not overlap each other except at the tip.
Excessive capacitive coupling between both resonant electrodes can be prevented,
In addition, since the ground electrode is interposed only at the tip of the two resonance electrodes having strong capacitive coupling, the pass band width can be narrowed. In addition, since the ground electrode is interposed between the ends of the open structure, the resonance frequency can be effectively reduced. That is, the line length can be made shorter than λ / 4.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1A is a laminated structural view showing an embodiment of a laminated filter according to the present invention, FIG. 1B is an external view thereof, and FIG. 1C is an arrangement of a resonance electrode. It is the figure seen in the lamination direction.

As shown in FIG. 1B, in the laminated filter of this embodiment, a substrate 1 made of a ceramic dielectric has a substantially rectangular parallelepiped shape, and has ground terminals 2 and 3 on both end surfaces.
It has an input terminal 4 and an output terminal 5 on both sides.

As shown in FIG. 1A, this laminated filter is used for a first shield electrode 6a, a first resonance electrode 7, a ground electrode 8, a second resonance electrode 9, and a second shield electrode 6b. The dielectric green sheets 1a to 1e printed for a plurality of filters and the dielectric green sheets 1f forming the uppermost protective layer are stacked on top of each other, pressure-bonded and laminated, and cut or cut after firing. After baking, the chip is manufactured by forming the ground terminals 2, 3 and the input terminals 4 and the output terminals 5 for each chip by plating with another metal for facilitating baking and soldering of the conductor paste. You.

The conductive paste for forming the electrodes 6a, 6b, 7 to 9 is formed by mixing silver or silver-palladium with a binder and a solvent. As the dielectric green sheet, a material obtained by mixing glass as necessary in addition to the dielectric is used.

In addition to such a sheet lamination method, a laminate may be produced by a screen printing method.

The first shield electrode 6a and the second shield electrode 6b are formed from one end to the other end of the base 1 except for both sides of the dielectric green sheets 1a and 1e. Connected.

The first resonance electrode 7 and the second resonance electrode 9
The base electrodes 7a and 9a are exposed to the end surface of the base 1 and connected to the ground terminal 2, whereby the resonance electrodes 7 and 9 are short-circuited to each other, and the front ends 7b and 9b are bent open structures. In the part, the extraction electrode 7 exposed on the side surface
c and 9c. These lead electrodes 7c and 9c are connected to the input terminal 4 and the output terminal 5, respectively.

As shown in FIG. 1C, the first resonance electrode 7 and the second resonance electrode 9 do not overlap with each other except the tips 7b and 9b when viewed in a plan view, that is, when viewed in the stacking direction. So that In addition, the tip portions 7 of the two resonance electrodes 7 and 9
b and 9b are bent toward the other party, and are arranged so as to overlap with each other via the dielectric layer by bending.

The ground electrode 8 is connected to both resonance electrodes 7,
9 overlaps the two resonance electrodes 7 , 9 between the tip portions 7b, 9b.
The ground electrode 8 is connected to one ground terminal 3 so as to interpose a dielectric layer so as to shield a part of the area .

[0022] 2 (A) is an equivalent circuit diagram of the multilayer filter of Figure 1, the inductance component _L a of each resonance electrode 7, 9, _{L b} is electromagnetically coupled by mutual inductance M, The capacitor component C Are capacitively coupled. Capacitance components C _a and C _b are formed between the resonance electrodes 7 and 9 and the first shield electrode 6a and the second shield electrode 6b, respectively. Further, the tip portions 7b of the ground electrode 8 and the resonance electrodes 7,9, the capacitance component _C d which is formed between the 9b, is _{C e} the capacitance component _C a, is added to the _{C b.}

FIG. 2B shows an arrangement example of the resonance electrodes 7 and 9 of the multilayer filter shown as a comparative example.
When the resonance electrodes 7 and 9 are arranged at the same intervals as those in the above-described embodiment in the case of having the bent front end portions 7b and 9b as described above, in the structure of FIG. as shown in C), higher than the center frequency f _b to the center frequency becomes the target, obtained by setting the center frequency such that f _a, that is, if you set the length of the resonance electrodes 7 and 9, passage Although the bandwidth BW _a is widened, 1
As shown in FIG. 2 (C), by interposing the ground electrode 8 between the tip portions 7b, 9b of the resonance electrodes 7, 9 as shown in FIG.
As shown in the equivalent circuit diagram of FIG.
Inductance _L a, _{L b} capacitive component in parallel with _C d, _{C e} tip portion 7b, by effectively applied well in 9b, the resonance frequency decreases as _{f b,} and resonance electrodes 7, 9 with the Passband BW _b by weakening the capacitive coupling of
Can be narrowed.

According to the present invention, the center length of the resonance electrodes 7 and 9 in the width direction (the length of (a + b) in FIG. 1C)
Can be reduced to about 0.5 to 0.7 times the theoretical value (the length derived from the dielectric constant ε and the frequency of the propagating signal). In addition, a relatively long line length can be obtained with a small area by bending the tip portions 7b and 9b of the resonance electrodes 7 and 9.

FIG. 3A is a laminated structure diagram showing another embodiment of the present invention, and FIG. 3B is an example of the arrangement of the resonance electrodes. The resonance electrodes of the first and second resonance electrodes are shown. The first resonance electrodes 7A and 9A provided in correspondence with 7, 9 are respectively arranged in an inclined shape such that the tips gradually approach.
As shown in FIG. 3 (B), the two resonating electrodes 7A, 9A are overlapped with each other at the tips 7d, 9d.
Are provided with a ground electrode 8 interposed therebetween so as to shield a part of the overlapping area , and can be expressed as the same as that of FIG. 1B in appearance. Reference numerals 7e and 9e denote base ends of the resonance electrodes 7A and 9A, respectively.
e and 9e are connected to the ground terminal 2 and short-circuited to each other. 7f and 9f are extraction electrodes connected to the input terminal 4 and the output terminal 5, respectively.

According to the embodiment of FIG. 3, similarly to the case of FIG. 1, a capacitive component is efficiently formed between the ground electrodes 8 and the ground at the tip portions 7d and 9d, and the resonance electrodes 7A and 9A are formed. , It is possible to reduce the resonance frequency and narrow the pass bandwidth. Also, by disposing the resonance electrodes 7A and 9A obliquely,
A relatively long line length can be obtained with a small area.

FIG. 4A is a diagram showing a laminated structure showing another embodiment of the present invention, and FIG. 4B is an example of the arrangement of the resonance electrodes. , Second
In place of the resonance electrode 9 described above, a first resonance electrode 7B and a second resonance electrode 9B are formed in a T-shape in which respective tips 7g and 9g protrude on both sides, and as shown in FIG. The two resonance electrodes 7 are located between the protruding portions of the front end portions 7g and 9g.
The ground electrode 8 is interposed so as to shield a part of the region where B and 9B overlap . Note that, also in the resonance electrodes 7B and 9B of this example, the base ends 7i and 9i are the same as those in FIG.
And the extraction electrodes 7j and 9
j is connected to the input terminal 4 and the output terminal 5.

In the present embodiment, the tip portions 7g, 9
g, the capacitance components C _a and C _b between the first and second shield electrodes 6 a and 6 _b can be increased by the portions 7 h and 9 h protruding on the opposite side to the counterpart resonance electrode. This can contribute to lowering of the resonance frequency, and further downsizing can be achieved.

In practicing the present invention, the input terminal 4
And the first resonance electrodes 7, 7A, 7B or the output terminal 5 and the second resonance electrodes 9, 9A, 9B may be coupled by a capacitance component. The arrangement of the ground terminals 2 and 3 and the input terminals 4 and the output terminals 5 is not limited to the above-described embodiment, and may be on the outer surface of the base 1. These can be easily formed.

[0030]

According to the first aspect of the present invention, since the pair of resonance electrodes are arranged on different layers so that the portions other than the tip end are not overlapped, excessive capacitive coupling between the two resonance electrodes can be avoided. In addition, since the ground electrode is interposed only at the ends of the two resonance electrodes, capacitive coupling can be effectively avoided, and the pass band width can be narrowed. In addition, the interposition of the ground electrode can effectively reduce the resonance frequency, making it possible to use a resonance electrode that is considerably shorter than the theoretical line length, and is small and thin suitable for use in a high-frequency circuit of a mobile phone. It is possible to provide a laminated filter having good characteristics.

Further, the first resonance electrode and the second
Has a shape in which the tip portions are bent toward each other, so that a structure in which only the tip portions face each other can be easily realized, and the area occupied by the resonance electrodes can be reduced. The effect is further obtained.

According to the second aspect , the first resonance electrode and the second resonance electrode have a shape that is inclined so as to gradually approach from the base end to the front end.
The same effect as in claim 1 is obtained.

According to the third aspect , each of the first resonance electrode and the second resonance electrode has a tip end protruding to both sides.
In order to form a character, in addition to the effects of claims 1 and 2 ,
The addition of the capacitance has the effect of further reducing the line length of the resonance electrode.

According to the fourth aspect, the input terminal and the output terminal that are electrically coupled to the first resonance electrode and the second resonance electrode, respectively, are provided on different side surfaces of the base. The effect that the output terminal can be easily formed is further obtained.

[Brief description of the drawings]

FIG. 1A is a diagram showing a laminated structure showing an embodiment of a laminated filter according to the present invention, FIG. 1B is an external view of the laminated filter, and FIG.

FIG. 2A is an equivalent circuit diagram of the multilayer filter of FIG. 1,
(B) is a layout diagram of the resonance electrode of the comparative example, and (C) is a characteristic diagram illustrating the operation of the present invention, showing a change in the amount of attenuation with frequency.

FIG. 3A is a diagram showing a laminated structure showing another embodiment of the laminated filter according to the present invention, and FIG. 3B is a diagram showing the arrangement of the resonance electrodes in the laminating direction.

FIG. 4A is a diagram showing a laminated structure showing another embodiment of the laminated filter according to the present invention, and FIG. 4B is a diagram showing the arrangement of the resonant electrodes in the laminating direction.

[Explanation of symbols]

1: substrate, 1a to 1f: dielectric green sheet, 2,
3: ground terminal, 4: input terminal, 5: output terminal, 6a: first shield electrode, 7, 7A, 7B: first resonance electrode,
7a, 7e, 7i: base end, 7b, 7d, 7g: front end, 7c, 7f, 7j: lead electrode, 8: ground electrode, 9, 9A, 9B: second resonance electrode, 9a, 9e, 9
i: proximal end, 9b, 9d, 9g: distal end, 9c, 9f,
9j: Leader electrode

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-5-102703 (JP, A) JP-A-6-204703 (JP, A) JP-A 8-288706 (JP, A) 37508 (JP, A) JP-A-5-335810 (JP, A) JP-A-10-32402 (JP, A) JP-A-9-214204 (JP, A) JP-A-2-106701 (JP, U) (58) Field surveyed (Int.Cl. ⁷ , DB name) H01P 1/203 H01P 1/205

Claims (4)

(57) [Claims] 1. A rectangular parallelepiped using a pair of substantially λ / 4 resonators
A multilayer filter comprising: a first shield electrode; a second shield electrode;
A first resonance electrode, a ground electrode, a second resonance electrode,
A second shield electrode and a second shield electrode are laminated in this order via a dielectric layer.
Wherein the first resonance electrode and the second resonance electrode
Connect the base end to the ground terminal provided on the outer surface of the base, and
Make the tip of the resonance electrode an open structure, and
An input terminal and an output terminal, each having a space between the outer surfaces of the base
Electrically coupled toThe first resonance electrode and the second resonance electrode have a tip
Parts are bent toward each other,  Other than the tip of the first resonance electrode and the second resonance electrode
Parts are arranged at different positions in plan view,
The tips of both resonance electrodes are placed at the overlapping position in plan view
And between the first resonance electrode and the tip of the second resonance electrode,
So as to shield a part of the area where both resonant electrodes overlapThe group
The first and second shield electrodes with a land electrode interposed therebetween;
And the ground electrode is connected to a ground terminal provided on the outer surface of the base.
A laminated filter characterized by being connected. (2)A rectangular parallelepiped using a pair of approximately λ / 4 resonators
In the laminated filter comprising A first shield electrode and a first shield electrode are provided inside a dielectric body.
A first resonance electrode, a ground electrode, a second resonance electrode,
A second shield electrode and a second shield electrode are laminated in this order via a dielectric layer.
And The first resonance electrode and the second resonance electrode have respective
Base end on outer surface of base Connect to the provided ground terminal and
Make the tip of the resonance electrode an open structure, and
An input terminal and an output terminal, each having a space between the outer surfaces of the base
Electrically coupled to The first resonance electrode and the second resonance electrode are at a proximal end.
From tip to tip
Has a shape, Other than the tip of the first resonance electrode and the second resonance electrode
Parts are arranged at different positions in plan view,
The tips of both resonance electrodes are placed at the overlapping position in plan view
And Between the tip of the first resonance electrode and the tip of the second resonance electrode,
The group is set so as to shield a part of the area where the two resonance electrodes overlap.
With a land electrode interposed, The first and second shield electrodes and the ground electrode are
Connected to the ground terminal provided on the outer surface of the body Characterized by
Laminated filter. (3)A rectangular parallelepiped using a pair of approximately λ / 4 resonators
In the laminated filter comprising A first shield electrode and a first shield electrode are provided inside a dielectric body.
A first resonance electrode, a ground electrode, a second resonance electrode,
A second shield electrode and a second shield electrode are laminated in this order via a dielectric layer.
And The first resonance electrode and the second resonance electrode have respective
Connect the base end to the ground terminal provided on the outer surface of the base, and
Make the tip of the resonance electrode an open structure, and
An input terminal and an output terminal, each having a space between the outer surfaces of the base
Electrically coupled to The first resonance electrode and the second resonance electrode have a tip
The part has a T-shape protruding on both sides, Other than the tip of the first resonance electrode and the second resonance electrode
Parts are arranged at different positions in plan view,
The tips of both resonance electrodes are placed at the overlapping position in plan view
And Between the tip of the first resonance electrode and the tip of the second resonance electrode,
The group is set so as to shield a part of the area where the two resonance electrodes overlap.
With a land electrode interposed, The first and second shield electrodes and the ground electrode are
Connected to the ground terminal provided on the outer surface of the body Characterized by
Laminated filter. (4)In any one of claims 1 to 3,  Each of the first resonance electrode and the second resonance electrode
Input terminals and output terminals that are electrically coupled to each other
A laminated filter characterized by being provided on a side surface.