JP2002111309A - Laminated dielectric filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated dielectric filter whose Q and bandwidth can be set larger without increasing the insertion loss of the filter. SOLUTION: The laminated dielectric filter comprises a strip line 10a and 10b provided in parallel and opposition to ground electrodes formed on both main surface of a lamination, wherein the strip line consists of an induction electrode 1a and 1b, a via hole conductor 3, and a folded electrode 2a to 2d. In this laminated dielectric filter, the length of the electrode 2a is different from that of the electrode 2c, the length of the electrodes 2a and 2d, each electrode is connected to the strip line 10a and 10b adjusting to each other, is the same, and the length of the electrode 2b is equal to that of the electrode 2c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic resonator used as a high-frequency component and a TE such as a filter.
The present invention relates to a high-frequency component using an M (Transversed Electromagnetic Mode) mode.

[0002]

2. Description of the Related Art Conventionally, small filters are frequently used in devices such as mobile phones utilizing microwaves. Among them, a laminated dielectric formed by using a strip line resonator in which a plurality of dielectric layers are laminated is particularly used. Body filters have been widely used because they can be made thinner and more sophisticated.

[0003] Such a laminated dielectric filter will be described with reference to FIG. FIG. 6 is an exploded perspective view of a conventional laminated dielectric filter. As shown in the figure, a ground electrode 101a is formed on both main surfaces of a laminated body 106 in which a plurality of dielectric layers 106a to 106c are laminated, and a ground electrode 101b is formed on an end surface of the laminated body 106, and the ground electrode 101a and the ground electrode 101b are formed. Are connected to each other. Dielectric layer 1
Strip lines 102 and 103 are arranged in parallel with each other on the main surface of 06b, and the distance between the strip lines 102 and 103 is set to be S. One end of each of the strip lines 102 and 103 has an open end to which neither is connected, and input / output electrodes 104 and 105 are formed in the vicinity of both ends. The other sides of the strip lines 102 and 103 are connected to the ground electrode 101b to form a short-circuit end.

As a method of manufacturing a laminated dielectric filter, first, a slurry comprising a ceramic material and a glass material as a substrate, an organic binder and a solvent is cast by a doctor blade method or the like, and dried to produce a green sheet. Next, a conductor paste is printed on the green sheet according to the pattern of the internal wiring such as a strip line. After laminating and integrating a plurality of the printed green sheets, they are simultaneously fired at a time to form a laminate. Thereafter, a conductive paste serving as a ground electrode is printed and fired on the side surface, the short-circuited end, the open end, the upper surface, and the lower surface of the laminate, thereby forming a filter.

[0005]

In the laminated dielectric filter formed as described above, a design for simultaneously securing a desired center frequency, bandwidth and attenuation of the filter characteristics is required.

That is, a desired center frequency can be obtained by changing the dielectric constant of the dielectric layer and the shape such as the length dimension of the strip line, and the degree of magnetic field coupling between resonators formed by each strip line. Also, the passband width and the position of the attenuation pole are determined by the degree of electric field coupling.
For example, when the interval between the resonators is reduced, the magnetic field coupling is strengthened, which is one of the factors for widening the bandwidth.

However, in a laminated dielectric filter in which both magnetic field coupling and electrolytic coupling act, the magnetic field coupling becomes strong even if the gap between the strip lines is simply reduced to widen the pass band width of the filter. The insertion loss of the filter increases, and as a result, the filter characteristics deteriorate.

Therefore, in order to obtain good filter characteristics in the laminated dielectric filter, a filter structure that can provide a wide pass band width in the pass band and can obtain a larger amount of attenuation in the stop band. It has been demanded. Therefore, as a conventional method, a desired filter characteristic is obtained by changing the shape of the strip line while reducing the interval between the strip lines and appropriately adjusting magnetic field coupling and electric field coupling.

However, in recent years, in the field of mobile communication using a high-frequency band, the passband on the transmitting side and the stopband on the receiving side or the passband on the receiving side and the stopband on the transmitting side are close to each other and have large attenuation. There is a demand for a filter that requires a large amount, and there are cases in which it is not possible to cope with these methods only.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a filter capable of increasing a Q value and a bandwidth without deteriorating the insertion loss of the filter. is there.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a first and second earth electrodes formed on both main surfaces of a laminate formed by laminating a plurality of dielectric layers; A plurality of quarter-wave strip lines, which are formed so as to face each other between the same layers of the body and one end of which is connected to any of the first and second ground electrodes, are provided side by side. An induction electrode extending in a plane direction from a short-circuited end with the first and second ground electrodes;
A via-hole conductor extending to an arbitrary dielectric layer between the ground electrode and a first ground electrode connected to a tip of the via-hole conductor on the first ground electrode side and turned back to the induction electrode side to reach an open end;
In the laminated dielectric filter formed from a folded electrode and a second folded electrode connected to the tip of the via-hole conductor on the second ground electrode side and folded to the induction electrode side to reach the open end, the strip line includes: The length from the folded point of the first folded electrode to the open end of the first folded electrode is different from the length from the folded point of the second folded electrode to the open end of the second folded electrode, and one adjacent strip on one side is formed. The length of the first folded electrode of the line is equal to the length of the second folded electrode on the other side, and the first folded electrode of the adjacent other side strip line is
A laminated dielectric filter is provided, wherein the length of the folded electrode is equal to the length of the second folded electrode on one side.

Conventionally, as described above, in a laminated dielectric filter, when it is desired to widen the bandwidth of the filter, each quarter-wave resonator (hereinafter simply referred to as a resonator) constituted by each strip line. This was realized by reducing the distance between the resonators, but as a negative effect, as the distance between the resonators became smaller, the volume of the dielectric occupied by the resonators became smaller, and the Q value of the resonators decreased, resulting in a filter. Insertion loss was increased.

On the other hand, according to the present invention, as shown in FIG.
Length a of the folded electrode 2a ₁And folded electrode 2
length b of d_Two, And the return electrode 2b
Length a _TwoAnd the length b of the folded electrode 2c₁And equal
Therefore, the path lengths of the strip lines 10a and 10b are the same.
And the center frequency does not change. Moreover, the folded power
Poles 2a, 2c or 2b, 2d with different lengths
The strip line 10 adjacent to the area near the open end
In the case where the capacitance components of a and 10b have the same length of the folded electrode
Can be reduced compared to
Without strip lines 10a and 10b
Can change the bandwidth by changing the electric field coupling state of the
Wear.

Further, even when the size of the laminated dielectric filter is reduced by reducing the distance between the resonators, the pass band width of the filter can be maintained as compared with the conventional product, and the deterioration of the insertion loss of the filter can be suppressed. However, the size of the filter can be reduced.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a laminated dielectric filter of the present invention, FIG. 2 is an exploded perspective view for explaining an internal structure thereof, and FIG. 3 is a sectional view taken along line AA of FIG. In FIG. 1, F is a laminated dielectric filter of the present invention. The laminated dielectric filter F is composed of a laminated body 6 composed of a dielectric ceramic 4.
Is formed on substantially the entire surface thereof.

The dielectric porcelain 4 constituting the laminate 6 is shown in FIG.
As shown, the dielectric layers 4a to 4d are stacked in the thickness direction.
Low temperature firing with dielectric ceramic material
Oxide and low melting glass material
You. Specifically, as a dielectric ceramic material, for example,
For example, BaO-TiO_TwoSystem, Ca-TiO_TwoSystem, MgO-T
iO_TwoWhen the system or the like is used as an oxide for firing at a low temperature,
iVO_Four, CuO, Li _TwoO, B_TwoO_ThreeEtc. Dielectric layer
4a to 4d have a thickness of about 50 to 300 μm per layer.
Have. Also, a ground electrode is provided on the surface of the dielectric layer 4a.
5 is formed on the back surface of the dielectric layer 4d.
The lower surface electrode 5b forming the ground electrode 5 is located at the end of the laminate 6
End electrodes 5c forming the ground electrode 5 are provided on the entire surface, respectively.
Is formed. Further, the dielectric layers 4c to 4c
Strip line 10 (10
a, 10b) are parallel to each other in the upper electrode 5a and the lower electrode 5b.
Are formed facing each other. This strip rye
10 is folded with the induction electrodes 1a and 1b and the via-hole conductor 3.
And a return electrode 2. Induction electrodes 1a, 1b
Is formed on the surface of the dielectric layer 4c, and is
Are connected respectively to the end electrodes 5c of the potentials. Biahoo
The conductor 3 is closer to the tips of the induction electrodes 1a and 1b that are not short-circuited.
Formed in the thickness direction of the laminate 6, and from the tip
The dielectric layers 4b and 4d between the ground electrode 5a and 5b
It is formed to extend to the surface. Via-hole conductor 3
The shape is the same as the width of the strip line 10 as shown in the figure.
Slots of the same width are formed, but it is not limited to this
No connection is made through the end face facing the end face electrode 5c.
This is a concept that also includes conductors. The folded electrode 2 is a dielectric layer
4b (between the dielectric layers 4a and 4b), the induction electrode 1a,
Folded electrodes 2a, 2a that are folded back to the side
b and the surface of the dielectric layer 4d (between the dielectric layers 4c and 4d)
Is folded back to the induction electrodes 1a and 1b and reaches the open end.
It is composed of return electrodes 2c and 2d. Above
The strip line 10 extends from the end face electrode 5c and
Folded at any of the different dielectric layers 4 on the
Forming an open end. This forms an anchor
Have been. And the strip line 10a
And the distance a of the folded electrode 2a₁Of the folded electrode 2c
Distance b₁Is different in the strip line 10b.
Distance a of folded electrode 2b_TwoAnd the distance between the folded electrode 2d
b_TwoAre different. Moreover, the folded electrode 2
length a₁And the length b of the folded electrode 2d_TwoAnd equal
And the length a of the folded electrode 2b_TwoAnd folded electrode
2c length b₁And strip line 10
a and 10b are center lines passing between strip lines 10
Are arranged so as to be mirror symmetrical with respect to. In addition, next
Induction electrode 1 of strip lines 10a and 10b
The lengths of a and 1b in the extending direction are formed to be the same. This
By setting the length relationship as shown in FIG.
a and 10b have the same path length from the short-circuit end to the open end.
The resonance frequency does not change.

With such a configuration of the folded electrodes 2a to 2d, the wavelength can be substantially shortened and the size of the filter can be reduced while maintaining the function of a resonator that resonates at a wavelength of ４λ. Further, the length of the folded electrodes 2a to 2d is vertically different with respect to the induction electrodes 1a and 1b, that is, the length ratio of the folded electrodes 2a and 2c or 2b and 2d is changed, and the length of the folded electrodes 2a and 2d is changed. Since the distance between the folded electrodes 2b and 2c is equal, for example, the capacitance component formed by the adjacent folded electrode 2a and the folded electrode 2b has a reduced capacitance component as compared with the case where the ratio is equal to each other, thereby increasing the resonance frequency. Since the strip line 10 can be formed and the path length of the strip line 10 is the same in each of the adjacent strip lines 10a and 10b, the center frequency is maintained as it is and the resonance frequency is increased, thereby controlling the pass bandwidth. It becomes possible. Note that 7 is an input line, and 8 is an output line.

As described above, the material of the strip line 10, the folded electrode 2, the via hole 3, and the ground electrode 5 is made of a conductive material mainly composed of Ag, Ag-Pd, Cu or the like.

The laminated dielectric filter F having the above-described configuration is provided with the folded electrodes 2a to 2f of the strip line 10.
Are electrically open ends, and the other of the induction electrodes 1a and 1b is electrically short-circuited. Therefore, the capacitance component between the strip line 10, the folded electrode 2, the via hole 3, and the ground electrode 5 Inducible components are formed, respectively, 1/4
A resonator in which an LC resonance circuit of λ is configured. Also,
As shown in FIG. 2, two or more resonators composed of strip lines 10a and 10b can be coupled to obtain desired filter characteristics.

The present inventors have confirmed the effects of the present invention.
For the sake of convenience, the dimensions a shown in FIG.₁/ (A₁+ A_Two) Ratio
By changing the ratio, the medium in the laminated dielectric filter of FIG.
FIG. 4 shows the result of examining the change in the heart frequency. this
In the case, the strip line 10a and the strip line 10
b is mirror symmetric, so a₁/ (A₁+
a _Two) At a predetermined ratio, b₁/ (B₁+
b_TwoThe ratio changes in the same manner. from this result
As you can see, changing the ratio of the folded electrodes
It can be seen that the center frequency of the filter does not change.
This is because the strip lines 10a and 10b are mirror pairs of each other.
The path length does not change and the center frequency is
It is not expected to change.

Next, FIG. 5 shows the result of examining the relationship between the change in the ratio of the folded electrodes and the bandwidth of the filter.
In this case as well, the strip line 10a and the strip line 10b are mirror-symmetrical, so that a ₁ /
As the ratio changes at a predetermined ratio of (a ₁ + a ₂ ), b ₁ / a
The ratio of (b ₁ + b ₂ ) changes similarly. As understood from the result, the ratio a ₁ /
By making (a ₁ + a ₂ ) different, the bandwidth of the filter can be greatly improved.

From the above, it can be seen that the configuration of the present invention can improve only the bandwidth without changing the center frequency of the filter.

[0022]

As described above, according to the present invention, the distance between the folded electrode portions of the strip lines formed in an anchor shape is made to be different from each other in the upper and lower directions. Since the lines are mirror-symmetrical, it is possible to vary only the bandwidth without changing the center frequency of the filter without deteriorating the Q value, thereby increasing the degree of freedom in design.

[Brief description of the drawings]

FIG. 1 is an external perspective view of a multilayer dielectric filter of the present invention.

FIG. 2 is a diagram illustrating each layer structure of the multilayer dielectric filter of the present invention.

FIG. 3 is a cross-sectional view of the laminated dielectric filter of the present invention.

FIG. 4 is a diagram illustrating the relationship between the ratio of folded electrodes and the center frequency of a filter.

FIG. 5 is a diagram illustrating the relationship between the ratio of the folded electrodes and the center frequency of the filter.

FIG. 6 is a diagram illustrating each layer structure of a conventional laminated dielectric filter.

[Explanation of symbols]

 10 (10a, 10b): strip line 1a, 1b: induction electrode 3: via hole conductor 5a to 5c: ground electrode 4a to 4d: dielectric layer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5E082 AB02 AB03 AB06 BB02 DD07 EE01 EE17 EE23 EE31 FF05 FG06 FG26 GG10 KK06 KK08 PP08 5J006 HB05 HB13 HB21 HB22 JA01 LA02 LA05 LA11 NA04 NC02

Claims (1)

[Claims] 1. A first and a second ground electrode formed on both main surfaces of a laminated body formed by laminating a plurality of dielectric layers, opposing each other in the same layer of the laminated body, and having one end side of the first and second ground electrodes. A plurality of 1/2 formed to be connected to any of the second ground electrodes.
A four-wavelength strip line is provided side by side. Each of the strip lines has an inductive electrode extending in a plane direction from a short-circuited end with the first and second ground electrodes, and a tip of the inductive electrode and the first and second ground electrodes.
A via-hole conductor extending to an arbitrary dielectric layer between the first ground electrode and the second ground electrode; a first folded electrode connected to the tip of the via-hole conductor on the first ground electrode side and folded toward the induction electrode to reach the open end; A second folded electrode connected to the tip of the conductor on the side of the second earth electrode and folded back to the induction electrode side to reach the open end; And the length from the turning point to the open end of the first turning electrode
The length from the turning point of the turning electrode to the open end of the second turning electrode is made different, and the length of the first turning electrode of one adjacent strip line is made equal to the length of the second turning electrode on the other side. A laminated dielectric filter, wherein the length of the first folded electrode of the adjacent strip line on the other side is equal to the length of the second folded electrode on the one side.