JPH0697705A - Dielectric filter - Google Patents

Abstract

PURPOSE:To provide a dielectric filter which has a compact structure and a small area occupied for mounting. CONSTITUTION:The resonant lines 21a and 21b constructing partly a resonant element are set on a dielectric layer 12, and an inner ground electrode 30 is formed on a dielectric layer 13 which is put on the layer 12. The resonance lines 21b and 22b constructing partly the resonant element are set on a dielectric layer 14 which is put on the layer 13. The front end parts of both lines 21a and 21b are connected to each other via a through hole 91 filled with a conductor. Thus a 1/4 wavelength type strip line resonant element is obtained at the input side. Meanwhile the front end parts of both lines 22b and 22a are connected to each other via a through hole 92 filled with a conductor. Thus a 1/4 wavelength type strip line resonant element is obtained at the output side respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter,
In particular, the present invention relates to a high-frequency circuit filter used in a high-frequency circuit wireless device such as a mobile phone and a dielectric filter used in an antenna duplexer.

[0002]

18 and 19 are a schematic development view and a perspective view of a dielectric filter devised by the present inventors.

In this dielectric filter, as shown in FIG. 18, first, an input electrode 41 and one end portion of which one end portion overlaps a part of an input side resonance element 21 which will be described later are formed on the dielectric layer 11. The output electrode 42 is formed so as to partially overlap with the output-side resonance element 22, and one end of the output electrode 42 is formed on the dielectric layer 16 laminated on the dielectric layer 11.
Resonant elements 21 and 22 composed of quarter-wave strip line resonators electrically connected to the ground electrode 70 are formed at a predetermined interval, and one end is electrically connected to the ground electrode 70 and the other end is electrically connected to the ground electrode 70. The electrodes 121 and 122 facing the resonant elements 21 and 22 at a predetermined distance from the open ends of the resonant elements 21 and 22 are formed on the dielectric layer 16 to form the resonant element 2.
1 and 22 are inductively coupled to each other, the dielectric layer 15 is laminated on the dielectric layer 16 and then fired to form a laminated body 100 as shown in FIG.

Next, as shown in FIG. 19, a laminate 100 is formed.
The ground electrode 70 is formed on the front surface of the above, and the side surface and the back surface excluding the input terminal portion 61 and the output terminal portion 62.
00 is electrically insulated from the ground electrode 70 in the input terminal portion 61 formed on the side surface and the back surface of the input electrode 4 and
1, the input terminal 51 electrically connected to 1, and the laminated body 100.
In the output terminal portion 62 formed on the side surface and the back surface of the above, the output terminal 52 electrically insulated from the ground electrode 70 and electrically connected to the output electrode 42 is formed.

[0005]

However, in portable telephone terminals and the like in which such a dielectric filter is used, there is an increasing demand for miniaturization, and accordingly, the dielectric filter used therein is also miniaturized. Turned into
Although there is a strong demand for reducing the occupied area, in the dielectric filter having the above-mentioned structure, the resonant elements 21 and 22 are, for example, approximately 1/4 each.
Since it is necessary to have the wavelength length in the same plane,
It was difficult to reduce the occupied area.

Therefore, an object of the present invention is to provide a dielectric filter which is miniaturized and occupies a small area when mounted.

[0007]

According to the present invention, in a stripline type dielectric filter in which a resonance element is formed in a dielectric between ground electrodes, the resonance element is provided in two layers above and below. A dielectric filter having the above stripline type resonance line is obtained.

[0008]

In the present invention, since the resonance element is provided with the stripline type resonance line of two or more layers provided above and below, the area occupied by the resonance element can be reduced, and as a result, the area occupied by the dielectric filter is reduced. Can be made smaller.

The upper resonance line and the lower resonance line may be connected to each other by a connecting electrode provided on the side surface of the dielectric filter, or a dielectric layer between the upper resonance line and the lower resonance line may be connected. It may be performed by a via hole provided in a layer and filled with a conductor inside it, or it may be provided in a dielectric layer between an upper resonance line and a lower resonance line, and the inside thereof is not filled with a conductor. Alternatively, it may be performed by a through hole provided with a conductor on its side surface.

If the resonance line in the upper layer and the resonance line in the lower layer are connected by a via hole or a through hole, the resonance element formed by these is not exposed to the outside of the dielectric filter. The impact can be reduced. When the upper resonance line and the lower resonance line are connected by the connecting electrodes provided on the side surfaces of the dielectric filter, the front end of the upper resonance line and the lower end of the lower resonance line are connected to each other. Since it is exposed to the side surface of the dielectric filter, it is possible to shorten the length in the direction in which the resonance line of the dielectric layer in which the resonance line of the upper layer and the resonance line of the lower layer are respectively provided extends.

As the resonance element, a one-end short-circuit type resonance element in which one end is short-circuited and the other end is open, or a both-ends-open type resonance element in which both ends are open can be used. Further, the dielectric filter can be applied to a combline type filter having short-circuited ends arranged in the same direction, or an interdigital type filter having short-circuited ends alternately arranged.

When a single-ended short-circuit type resonance element is used as the resonance element, the thickness of the dielectric layer between the ground electrodes having the open end of the resonance element is set to the dielectric between the ground electrodes having the short-circuit end of the resonance element. By making it thinner than the thickness of the body layer, the open end portion of the resonant element becomes closer to the ground, and electrostatic capacitance is formed between the open end portion of the resonant element and the ground electrode. It is added to the capacitance of the parallel resonant circuit when the resonant element is equivalently converted. Therefore, if the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and as a result, the length of the resonance element and the length of the dielectric filter are shortened.

Further, among the two or more layers of resonance lines constituting the resonance element, the dielectric constant between the ground electrodes in which at least one layer of resonance lines is present is the dielectric constant of the dielectric layer, and the ground electrode in which the resonance lines of other layers are present. By making the dielectric constant smaller than that of the intervening dielectric layer, the coupling between the resonance lines existing in the dielectric layer having a small dielectric constant can be increased, so that the degree of freedom in design can be increased.

Further, when a single-ended short-circuit type resonant element is used as the resonant element, the dielectric constant of the dielectric layer having the open end and the dielectric constant of the dielectric having the short-circuited end are made different from each other to open the element. Since the characteristic impedance of the resonant line near the end and the characteristic impedance of the resonant line near the short-circuited end can be greatly different, the spurious characteristic of the dielectric filter can be improved.

The present invention can also be applied to a trap filter. In this case, the resonance element includes an inductance component constituted by two or more layers of resonance lines and a capacitance component formed by a gap between the resonance line and the input terminal. Composed of and.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic development view of the first embodiment of the present invention, FIG. 2 is a perspective view of the present embodiment, and FIG. 3 is FIG.
6 is a sectional view taken along line XX of FIG.

On the dielectric layer 11, an input electrode 41, one end of which overlaps with a part of an input side resonance line 21a, which will be described later, and an output electrode 42, one end of which overlaps with a part of an output side resonance line 22a, which will be described later. To form.

Dielectric layer 12 laminated on dielectric layer 11
A resonance line 21a, one end (rear end) of which is electrically connected to a ground electrode 70, which will be described later, and which constitutes a part of a 1/4 wavelength stripline resonance element on the input side, and one end (rear end). A resonance line 21b that is electrically connected to a ground electrode 70, which will be described later, and forms a part of the quarter wave type stripline resonance element on the output side is formed at a predetermined interval.

Dielectric layer 13 laminated on dielectric layer 12
An internal ground electrode 30 is formed on top. The dielectric layer 1
3 is provided with a via hole 91 for connecting the resonance line 21a and the resonance line 21b described later, and a via hole 92 for connecting the resonance line 22a and the resonance line 22b described later, which are electrically insulated from the internal ground electrode 30 respectively. The via holes 91 and 92 are filled with a conductor.

Dielectric layer 14 laminated on dielectric layer 13
A resonance line 21b forming a part of the 1/4 wavelength type stripline resonant element on the input side and a resonance line 22b forming a part of the 1/4 wavelength type stripline resonant element on the output side are arranged at predetermined intervals. Form. Resonance line 21
b and the resonance line 22b have rear ends of 1 on the input side, respectively.
They are the open end of the quarter-wavelength stripline resonant element and the open end of the quarter-wavelength stripline resonant element on the output side.

Resonant line 21 provided on dielectric layer 14
The front end portion of b and the front end portion of the resonance line 21a provided on the dielectric layer 12 are connected by a via hole 91 provided in the dielectric layer 13 and filled with a conductor, and a quarter-wave type on the input side. The stripline resonance element is formed, and the front end of the resonance line 22b provided on the dielectric layer 14 and the front end of the resonance line 22a provided on the dielectric layer 12 are provided inside the dielectric layer 13 and They are connected by via holes 92 filled with conductors to form a quarter-wave stripline resonant element on the output side.

Further, electrodes 121 and 122, one end of which is electrically connected to the ground electrode 70 and the other end of which faces the resonance lines 21 and 22 at a predetermined distance from the open ends of the resonance lines 21b and 22b, respectively. It is formed on the dielectric layer 14 to inductively couple the resonance element on the input side and the resonance element on the output side.

The dielectric layer 15 having the ground electrode 70 formed on the surface thereof is laminated on the dielectric layer 14, and the dielectric layers 11 and 1 are formed.
2, 13, 14 and 15 are integrally formed and then fired to form the laminated body 100.

Next, as shown in FIG. 2, a ground electrode 70 is formed on the front surface of the laminated body 100, and the side surface and the rear surface excluding the input terminal portion 61 and the output terminal portion 62, and the laminated body 10 is formed.
The input terminal 51 electrically insulated from the ground electrode 70 and the internal ground electrode 30 and electrically connected to the input electrode 41 in the input terminal portion 61 formed on the side surface and the back surface of 0, and the laminated body 100. An output terminal 52 electrically insulated from the ground electrode 70 and the internal ground electrode 30 and electrically connected to the output electrode 42 is formed in the output terminal portion 62 formed on the side surface and the back surface.

In the dielectric filter of this embodiment having the above-described structure, the quarter-wave type resonant element has the resonant lines 21a and 22a on the dielectric layer 12 and the dielectric layer 14.
The resonance lines 21a, 22a, 2a and 2b of the dielectric filter are constituted by the upper resonance lines 21b, 22b, respectively.
The length a in the extending direction of 1b and 22b becomes short, and therefore,
The area occupied during mounting can be reduced. Further, in this embodiment, the resonance lines 21a and 22a on the dielectric layer 12 and the resonance lines 21b and 22b on the dielectric layer 14 are connected to the dielectric layer 1.
A via hole 9 provided in 3 and filled with a conductor therein
Since they are connected by 1 and 92, respectively, the resonance element constituted by them is not exposed to the outside of the dielectric filter, so that the influence of the outside on the filter characteristics can be reduced.

Next, a method of manufacturing the dielectric filter according to the first embodiment of the present invention will be described.

This dielectric filter has resonance lines 21a and 22a.
a, 21b, 22b, the electrodes 121, 122, the input electrode 41 and the output electrode 42, the internal ground electrode 30, and the conductors in the via holes 91, 92 are completely built in the dielectric, so that the resonance lines 21a, 22a , 21b, 22
b, the electrodes 121 and 122, the input electrode 41 and the output electrode 42, the internal ground electrode 30, and the via hole 91,
It is desirable to use a conductor with a low loss and a low specific resistance as the conductor in 92, and it is preferable to use a low resistance Ag-based or Cu-based conductor.

As the dielectric to be used, a ceramic dielectric which is highly reliable and has a large dielectric constant εγ and thus can be miniaturized is preferable.

As the manufacturing method, a conductor paste is applied to a ceramic powder compact to form an electrode pattern, the compacts are laminated and fired to densify, and a conductor is laminated therein. It is desirable to integrate the ceramic dielectric with the ceramic dielectric.

When Ag-based or Cu-based conductors are used, the melting points of these conductors are low and it is difficult to co-fire with ordinary dielectric materials. Therefore, their melting points (1100 ° C. or less) are used. It is necessary to use a dielectric material that can be fired at lower temperatures. Also, due to the nature of the device as a microwave filter, the temperature characteristic (temperature coefficient) of the resonance frequency of the formed parallel resonance circuit is ± 50 ppm / ° C.
The following dielectric materials are preferred. Examples of such a dielectric material include glass-based materials such as a mixture of cordierite-based glass powder, TiO ₂ powder and Nd ₂ Ti ₂ O ₇ powder, and BaO—TiO ₂ —Re ₂ O.
_3- Bi ₂ O ₃ composition (Re: rare earth component) with some glass-forming components or glass powder added, barium oxide-titanium oxide-neodymium oxide dielectric magnetic composition powder with some glass powder added There is something I did.

As an example, BaO--TiO ₂ --Nd ₂ 2
₃ -Bi ₂ O ₃ system powder ZnO-B ₂ O ₃ -Si composition
O ₂ glass powder was mixed to obtain a mixed powder. Then
Acrylic organic binder, plasticizer,
Toluene and an alcohol-based solvent were added, and the mixture was thoroughly mixed with alumina cobblestone to form a slurry. Then, using this slurry, a doctor blade method was used to obtain 0.2 mm.
A green sheet having a thickness of 0.5 mm was prepared.

Next, in the case of the first embodiment, the conductor patterns shown in FIG. 1 are printed using silver paste as the conductor paste, and then the thickness of the green sheet on which these conductor patterns are printed is adjusted. Therefore, necessary green sheets were stacked and stacked so as to have the structure shown in FIG. 1, and after stacked, they were baked at 900 ° C. to obtain a stacked body 100. The relative permittivity εr of the dielectric material after firing was 80.

As shown in FIG. 2, a silver electrode is formed on the upper surface of the laminate 100 having the above-described structure, that is, the surface corresponding to the entire surface of the dielectric layer 15, and the side surface and bottom surface excluding the input terminal portion 61 and the output terminal portion 62. A ground electrode 70 composed of is printed, and a silver electrode electrically insulated from the ground electrode 70 and electrically connected to the input electrode 41 and the output electrode 42 separately is connected to the input terminal portion 61 and the output terminal portion 62. Printed as the input terminal 51 and the output terminal 52 inside, and the printed electrode is 8
It was baked at 50 ° C. to form the dielectric filter of this example.

In this embodiment, the thickness of the dielectric layer A where the open end of the resonant element exists and the thickness of the dielectric layer B where the short side of the resonant element exists are both 2 mm.
there were. In addition, the resonant lines 21a and 22 of the dielectric filter
The length a in the extending direction of a, 21b, and 22b was 3.5 mm, the width b of the dielectric filter was 5 mm, and the center frequency was 1800 MHz.

For comparison, the dielectric filters shown in FIGS. 18 and 19 were formed in the same manner as in this example using the materials used in this example. In this case, the length a of the resonant element of the dielectric filter in the extending direction was 6 mm, the width b of the dielectric filter was 5 mm, the thickness was 2 mm, and the center frequency was 1800 MHz. Comparing this result with the dimensions of the dielectric filter of the first embodiment, the thickness of the dielectric filter of the first embodiment is thick, but the length a in the extending direction of the resonant element is short, and therefore, It can be seen that the area occupied by the dielectric filter during mounting is also small.

Next, a second embodiment of the present invention will be described.

FIG. 4 is a schematic development view of the second embodiment of the present invention, FIG. 5 is a perspective view of this embodiment, and FIG. 6 is FIG.
6 is a sectional view taken along line XX of FIG.

In the first embodiment, the resonance line 2
The resonance element on the input side constituted by 1a and 21b and the resonance element on the output side constituted by the resonance lines 22a and 22b are one-side short-circuit type resonance elements, but in the present embodiment, the resonance lines 21a and 21b. Is different from the first embodiment in that the input-side resonance element and the output-side resonance element formed by the resonance lines 22a and 22b are open-ended resonance elements, but other configurations are the same as those of the first embodiment. This is similar to the first embodiment.

Also in this embodiment, since the resonance element is composed of the resonance lines 21a and 22a on the dielectric layer 12 and the resonance lines 21b and 22b on the dielectric layer 14, respectively, the resonance line 21a of the dielectric filter, 22a, 21
The length a of the b and 22b in the extending direction is shortened, so that the occupied area during mounting can be reduced. Also in this embodiment, the resonance lines 21a and 22a on the dielectric layer 12 and the resonance lines 21b and 22b on the dielectric layer 14 are connected to the dielectric layer 13.
A via hole 91 provided inside and filled with a conductor,
Since they are connected to each other by 92, the resonance elements constituted by them are not exposed to the outside of the dielectric filter, so that the influence of the outside on the filter characteristics can be reduced.

Also in this example, the same material as that used in the first example was used, and a dielectric filter was prepared by the same method as in the first example. As a result, the thickness A of the dielectric layer where the open end of the resonant element exists and the thickness B of the dielectric layer where the short side of the resonant element exists were both 2 mm. In addition, the resonance line 21 of the dielectric filter
a, 22a, 21b, 22b has a length a in the extending direction of 3.
5 mm, the width b of the dielectric filter is 5 mm,
The center frequency was 900 MHz.

Next, a third embodiment of the present invention will be described.

FIG. 7 is a schematic development view of the third embodiment of the present invention, FIG. 8 is a perspective view of the present embodiment, and FIG. 9 is FIG.
6 is a sectional view taken along line XX of FIG.

In the first embodiment, the thickness of the dielectric layer A where the open end of the resonant element exists and the thickness of the dielectric layer B where the short side of the resonant element exists are the same.
The resonant lines 21a and 22a on the dielectric layer 12 and the dielectric layer 1
4 are connected to the resonance lines 21b and 22b in the dielectric layer 13 by via holes 91 and 92 filled with conductors, respectively. The thickness of the body layer A is made smaller than the thickness of the dielectric layer B where the short-circuit side of the resonance element exists, and the resonance lines 21a and 22a on the dielectric layer 12 and the resonance lines 21b and 22b on the dielectric layer 14 are separated from each other. It differs from the first embodiment in that it is connected by connecting electrodes 81 and 82 provided on the side surface of the laminated body 100, but the other configurations are the same as those in the first embodiment.

In this embodiment, the thickness of the dielectric layer A where the open end of the resonant element exists is made smaller than the thickness of the dielectric layer B where the short side of the resonant element exists. Becomes closer to the ground, and a capacitance is formed between the open end of the resonant element and the ground electrode.
This capacitance is also added to the capacitance of the parallel resonant circuit when the resonant element is equivalently converted. Therefore, if the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and as a result, the length of the resonance element and the length of the dielectric filter are shortened.

Further, in this embodiment, the dielectric layer 12
Since the upper resonance lines 21a and 22a and the resonance lines 21b and 22b on the dielectric layer 14 are connected by the connecting electrodes 81 and 82 provided on the side surface of the laminated body 100, respectively.
Since the front ends of the resonance lines 21a and 22a on the dielectric layer 12 and the front ends of the resonance lines 21b and 22b on the dielectric layer 14 are exposed to the side surface of the dielectric filter, the resonance lines 21a and 22a and The length of the dielectric layers 12 and 14 provided with the resonance lines 21b and 22b in the direction in which the resonance lines extend can be shortened.

In the present embodiment, the connection electrodes 81 for connecting the resonance lines 21a and 22a on the dielectric layer 12 and the resonance lines 21b and 22b on the dielectric layer 14 to the front surface of the laminated body 100, respectively. , 82 are provided, the internal ground electrode 13 provided on the dielectric layer 13 is not extended to the front end portion of the dielectric layer 13 in order to prevent the connection electrodes 81, 82 from being grounded.

Next, a method of manufacturing the dielectric filter of this embodiment will be described. Also in this example, using the green sheet used in the first example, the conductor patterns shown in FIG. 7 were printed using silver paste as the conductor paste, and then the green sheet with the conductor pattern printed thereon was printed. After stacking the green sheets necessary for adjusting the thickness and stacking so as to have the structure of FIG. 7,
The laminate 100 was formed by firing at 900 ° C.

FIG. 2 shows the upper surface of the laminated body 100 configured as described above, that is, the surface corresponding to the entire surface of the dielectric layer 15, the left and right side surfaces except the input terminal portion 61 and the output terminal portion 62, the rear side surface and the bottom surface. As described above, the ground electrode 70 made of a silver electrode is printed, and the silver electrode electrically insulated from the ground electrode 70 and electrically connected to the input electrode 41 and the output electrode 42 is input terminal portion 61. , Output terminal 6
2 are printed as the input terminals 51 and the output terminals 52, and the resonance lines 21a and 22a on the dielectric layer 12 and the resonance lines 21b and 2b on the dielectric layer 14 are provided on the front surface of the laminated body 100.
The connection electrodes 81 and 82 for respectively connecting to 2b were printed, and the printed electrodes were baked at 850 ° C. to form the dielectric filter of this example.

In this embodiment, the thickness of the dielectric layer A where the open end of the resonant element exists is smaller than the thickness of the dielectric layer B where the short side of the resonant element exists, 0.5 mm, respectively.
It was 1.6 mm. In addition, the resonance line 2 of the dielectric filter
The length a in the extending direction of 1a, 22a, 21b, 22b was 2.5 mm, the width b of the dielectric filter was 5 mm, and the center frequency was 1800 MHz.

In this embodiment, the length a in the extending direction of the resonant element of the dielectric filter can be made shorter than that in the first embodiment, and a more compact dielectric filter can be obtained.

Next, a fourth embodiment of the present invention will be described.

FIG. 10 is a schematic development view of the fourth embodiment of the present invention, FIG. 11 is a perspective view of the present embodiment, and FIG.
FIG. 12 is a sectional view taken along line XX of FIG. 11.

In the first embodiment, the thickness of the dielectric layer A where the open end of the resonant element exists and the thickness of the dielectric layer B where the short side of the resonant element exists are the same.
In addition to the resonance lines 21b and 22b, one end of the resonance lines 21 and 22 is electrically connected to the ground electrode 70 on the dielectric layer 14 and the other end thereof is separated from the open ends of the resonance lines 21b and 22b by a predetermined distance. Electrodes 121 and 12 facing each other
However, in the present embodiment, the thickness of the dielectric layer A where the open end of the resonant element is present is made smaller than the thickness of the dielectric layer B where the short side of the resonant element is present, and the dielectric layer 14 is provided. The electrodes 121 and 122 are not provided on the resonance line 21.
The difference from the first embodiment is that only b and 22b are provided.
The other structure is similar to that of the first embodiment.

Also in this embodiment, by making the thickness of the dielectric layer A having the open end of the resonant element smaller than the thickness of the dielectric layer B having the short-circuit side of the resonant element, the open end of the resonant element is obtained. The part becomes closer to the ground, and a capacitance is formed between the open end part of the resonant element and the ground electrode, and this capacitance also becomes the capacitance of the parallel resonant circuit when the resonant element is equivalently converted. Will be added. Therefore,
If the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and as a result, the length of the resonance element is shortened and the length of the dielectric filter is also shortened.

Also in this example, the same material as that used in the first example was used, and a dielectric filter was prepared by the same method as in the first example. As a result, the thickness of the dielectric layer A having the open end of the resonant element was 0.5 mm, and the thickness of the dielectric layer B having the short side of the resonant element was 1.6 mm. The length a of the resonant lines 21a, 22a, 21b, 22b of the dielectric filter in the extending direction was 3.0 mm, the width b of the dielectric filter was 5 mm, and the center frequency was 1800 MHz.

In the present embodiment, the length a of the resonant element of the dielectric filter in the extending direction can be made shorter than that of the first embodiment, and a more compact dielectric filter can be obtained.

Further, in this embodiment, the dielectric layer 12
Since the upper resonance lines 21a and 22a and the resonance lines 21b and 22b on the dielectric layer 14 are provided in the dielectric layer 13 and the conductors are connected by the via holes 91 and 92 filled in the dielectric layers 13, respectively, the dielectric Although the length a of the resonance element of the filter in the extending direction is slightly longer than that of the third embodiment,
Since the resonance element constituted by the resonance lines 21a, 22a, 21b, 22b and the via holes 91, 92 is not exposed to the outside of the dielectric filter, it is possible to reduce the influence of the outside on the filter characteristics.

Next, a fifth embodiment of the present invention will be described.

The structure of the dielectric filter of this embodiment is shown in FIG.
Same as the third embodiment described with reference to 8 and 9, but the dielectric material used is slightly different.

That is, also in this embodiment, the third point is that the thickness of the dielectric layer A where the open end of the resonant element exists is smaller than the thickness of the dielectric layer B where the short side of the resonant element exists.
However, the dielectric layer A in which the open end of the resonant element exists is the same as the dielectric material used in the third embodiment, BaO—TiO ₂ —Nd ₂ 2 ₃ —Bi. ₂ O
A green sheet using a mixed powder of ZnO-B ₂ O ₃ -SiO ₂ -based glass powder mixed with powder of _3- based composition is used, but Ba is used for the dielectric layer B where the short-circuit end of the resonance element exists.
The powder O-TiO ₂ -ZnO-based composition ZnO-B ₂ O ₃
By using a green sheet made of a mixed powder mixed with —SiO ₂ glass, the dielectric layer B having the short-circuited end of the resonance element is more than the dielectric constant of the dielectric layer A having the open end of the resonance element. The difference from the third embodiment is that the dielectric constant is smaller.

When different dielectric materials are used in one dielectric filter as in this embodiment, the green used for the dielectric layer A is avoided in order to avoid warping and bending after firing. It is preferable that the shrinkage rates of the green sheets used for the sheet and the dielectric layer B do not differ greatly during firing.

Next, a method of manufacturing the dielectric filter of this embodiment will be described. In this embodiment, the above-mentioned 2
Using various kinds of green sheets, printing the conductor patterns shown in FIG. 7 using silver paste as the conductor paste,
Next, a green sheet necessary for adjusting the thickness of the green sheet on which the conductor pattern is printed is overlapped on these and laminated so as to have a structure of FIG. 7, and then baked at 900 ° C. to form a laminated body 100. . The dielectric layer A after firing has a relative permittivity of 80, the dielectric layer B has a relative permittivity of 32, and the resonant element is short-circuited more than the dielectric layer A having an open end of the resonant element. The dielectric constant of the dielectric layer B having the edges was smaller.

In the thus-formed dielectric filter, the thickness of the dielectric layer A where the open end of the resonant element exists is 0.5 mm, and the thickness of the dielectric layer B where the short side of the resonant element exists. Was 1.6 mm. The length a of the resonant lines 21a, 22a, 21b, 22b of the dielectric filter in the extending direction was 3.0 mm, the width b of the dielectric filter was 5 mm, and the center frequency was 1800 MHz.

Also in this embodiment, the length a in the extending direction of the resonant element of the dielectric filter can be shortened, and a more compact dielectric filter can be obtained.

Further, in this embodiment, since the dielectric constant of the dielectric layer B where the short-circuited end of the resonance element is present is made small, the coupling between the resonance elements becomes strong, and a wider band dielectric filter can be obtained. It was

Further, in this embodiment, the dielectric layer A having the open end of the resonant element has a large dielectric constant and the dielectric layer has a small thickness, whereas the short-circuited end of the resonant element exists. Since the dielectric layer B has a small dielectric constant and the thickness of the dielectric layer is large, the characteristic impedance on the open end side of the resonant element is smaller than the characteristic impedance on the short circuit end side, and the spurious characteristic of the dielectric filter can be improved. .

Next explained is the sixth embodiment of the invention. In the first to fourth embodiments, the case where the present invention is applied to the bandpass filter using the coupling between the resonance elements has been described, but in the present embodiment, the case where the present invention is applied to the dielectric trap filter will be described. To do.

FIG. 13 is a schematic development view of the sixth embodiment of the present invention, FIG. 14 is a perspective view of the present embodiment, and FIG.
FIG. 15 is a sectional view taken along line XX of FIG. 14.

On the dielectric layer 12, the resonance line 23a forming a part of the inductance component and the input terminal 53 forming a capacitance component with the resonance line 23a sandwiching the dielectric layer are formed. The rear end of the resonance line 23a is connected to the rear end of the resonance line 23b described later by a conductor in a via hole 93 described later.

Dielectric layer 13 laminated on dielectric layer 12
An internal ground electrode 30 is formed on top. The dielectric layer 1
A via hole 93 for connecting the resonance line 23a and a resonance line 23b, which will be described later, is provided at 3 electrically insulated from the internal ground electrode 30, and the via hole 93 is filled with a conductor.

Dielectric layer 14 laminated on dielectric layer 13
A resonance line 23b that forms an inductance component is formed on the resonance line 23a. The rear end of the resonance line 23b is connected to the rear end of the resonance line 23a by the conductor in the via hole 93, and the front end of the resonance line 23b is connected to the ground electrode 70 described later.

The dielectric layer 15 having the ground electrode 70 formed on the surface thereof is laminated on the dielectric layer 14, and the dielectric layers 12 and 1 are formed.
3, 14, and 15 are integrally formed, and then fired to form the laminated body 100.

Next, as shown in FIGS. 14 and 15, the ground electrode 70 is formed on the upper surface of the laminated body 100, the side surface excluding the front surface and the rear surface excluding the input terminal portion.
No. 00 on the front surface of the ground electrode 70 and the resonance element 23b and the ground electrode 71 connected to the front end of the internal ground electrode 30 and the ground electrode 71, respectively, and electrically connected to the input terminal 53. Input terminal 54 is formed, and the ground electrode 7 is formed on the back surface of the laminated body 100.
An input terminal 55 is formed that is electrically insulated from 0 and electrically connected to the input terminal 54.

FIG. 16 is an equivalent circuit diagram of the dielectric trap filter of this embodiment. The inductance component 212 is composed of the resonance lines 23a and 23b, and the capacitance component 211 is composed of a gap between the front end of the resonance line 23a and the input terminal 53. The filter configured in this way exhibits frequency characteristics as shown in FIG. 17, and by adding this filter in the circuit, a specific frequency signal can be greatly attenuated.

In the dielectric trap filter of this embodiment constructed as described above, the inductance component 2
Since 12 is constituted by the resonance line 23a on the dielectric layer 12 and the resonance line 23b on the dielectric layer 14, the lengths of the resonance lines 23a and 23b of the dielectric filter in the extending direction are shortened, and therefore the mounting is performed. The occupied area can be reduced. Also in this embodiment, the resonance line 23a on the dielectric layer 12 and the resonance line 23b on the dielectric layer 14 are connected in the dielectric layer 13 by the via holes 93 filled with the conductors. Therefore, since the resonance line constituted by these is not exposed to the outside of the dielectric filter, the influence of the outside on the filter characteristics can be reduced.

Next, a method of manufacturing the dielectric filter of this embodiment will be described. Also in this embodiment, the green sheets used in the first embodiment are used, the conductor patterns shown in FIG. 13 are printed using silver paste as the conductor paste, and then the green sheets having the conductor patterns printed thereon are printed. Green sheets necessary for adjusting the thickness were stacked and laminated so as to have the structure of FIG. 13, and then fired at 900 ° C. to form a laminated body 100.

As shown in FIGS. 14 and 15, the ground electrode 70 made of a silver electrode is printed on the upper surface of the laminated body 100 having the above-described structure, the side surface excluding the front surface and the back surface excluding the input terminal portion, In addition, on the front surface of the laminated body 100, a silver electrode connected to the front end of the ground electrode 70 and the resonance element 23b and the front end of the internal ground electrode 30 is used as the ground electrode 71 and electrically insulated from the ground electrode 70. A silver electrode electrically connected to the input terminal 53 is printed as the input terminal 54, and a silver electrode electrically insulated from the ground electrode 70 and electrically connected to the input terminal 54 is printed on the back surface of the laminate 100. Printed as the input terminal 55, the printed electrode was baked at 850 ° C. to form the dielectric filter of this example.

[0079]

According to the present invention, since the resonance element is provided with two or more layers of stripline type resonance lines provided above and below, the area occupied by the resonance element can be reduced.
As a result, the area occupied by the dielectric filter can be reduced.

When a single-ended short-circuit type resonance element is used as the resonance element, the thickness of the dielectric layer between the ground electrodes where the open end of the resonance element exists is determined by the dielectric layer between the ground electrodes where the short-circuited end of the resonance element exists. By making it thinner than the thickness of the body layer, the open end portion of the resonant element becomes closer to the ground, and electrostatic capacitance is formed between the open end portion of the resonant element and the ground electrode. It is added to the capacitance of the parallel resonant circuit when the resonant element is equivalently converted. Therefore, if the resonance frequencies are the same, the inductance of the parallel resonance circuit can be small, and as a result, the length of the resonance element and the length of the dielectric filter are shortened.

Further, among the two or more layers of resonance lines constituting the resonance element, the dielectric constant between the ground electrodes in which at least one layer of resonance line is present is determined by the dielectric constant of the dielectric layer between the earth electrodes in other layers. By making the dielectric constant smaller than that of the intervening dielectric layer, the coupling between the resonance lines existing in the dielectric layer having a small dielectric constant can be increased, so that the degree of freedom in design can be increased.

Furthermore, when a single-ended short-circuit type resonant element is used as the resonant element, the dielectric constant of the dielectric layer having the open end is made different from the dielectric constant of the dielectric layer having the short-circuited end to open the open end. Since the characteristic impedance of the resonant line near the end and the characteristic impedance of the resonant line near the short-circuited end can be greatly different, the spurious characteristic of the dielectric filter can be improved.

[Brief description of drawings]

FIG. 1 is a schematic development view for explaining a laminated dielectric filter according to a first embodiment of the present invention.

FIG. 2 is a perspective view for explaining the laminated dielectric filter according to the first embodiment of the present invention.

3 is a cross-sectional view taken along line XX of FIG.

FIG. 4 is a schematic development view for explaining a laminated dielectric filter according to a second embodiment of the present invention.

FIG. 5 is a perspective view for explaining a laminated dielectric filter according to a second embodiment of the present invention.

6 is a cross-sectional view taken along line XX of FIG.

FIG. 7 is a schematic development view for explaining laminated dielectric filters of third and fifth embodiments of the present invention.

FIG. 8 is a perspective view for explaining laminated dielectric filters of the third and fifth embodiments of the present invention.

9 is a cross-sectional view taken along line XX of FIG.

FIG. 10 is a schematic development view for explaining a laminated dielectric filter according to a fourth embodiment of the present invention.

FIG. 11 is a perspective view for explaining a laminated dielectric filter according to a fourth embodiment of the present invention.

12 is a cross-sectional view taken along line XX of FIG.

FIG. 13 is a schematic development view for explaining a laminated dielectric filter according to a sixth embodiment of the present invention.

FIG. 14 is a perspective view for explaining a laminated dielectric filter according to a sixth embodiment of the present invention.

15 is a sectional view taken along line XX of FIG.

FIG. 16 is an equivalent circuit diagram of a laminated dielectric filter according to a sixth embodiment of the present invention.

FIG. 17 is a diagram for explaining frequency characteristics of the laminated dielectric filter according to the sixth embodiment of the present invention.

FIG. 18 is a schematic development view for explaining a conventional dielectric filter devised by the present inventors.

FIG. 19 is a perspective view for explaining a conventional dielectric filter devised by the present inventors.

[Explanation of symbols]

11-16 ... Dielectric layer 21a, 21b, 22a, 22b, 23a, 23b ... Resonance line 21, 22 ... Resonance element 30 ... Internal earth electrode 41 ... Input electrode 42 ... Output electrode 53-55 ... Output terminal 70, 71 ... Ground electrode

Claims (3)

[Claims] 1. A stripline type dielectric filter in which a resonance element is formed in a dielectric between ground electrodes, the stripline type resonance line having two or more layers in which the resonance element is provided above and below. A dielectric filter characterized in that 2. The dielectric filter according to claim 1, wherein
The resonant element is a short-circuited resonant element, and the thickness of the dielectric layer between the ground electrodes where the open end of the resonant element is present is between the ground electrodes where the shorted end of the resonant element is present. A dielectric filter characterized by being thinner than the thickness of. 3. The dielectric filter according to claim 1, wherein the dielectric layer between the ground electrodes in which at least one layer of the resonant lines of the two or more layers constituting the resonant element exists. A dielectric filter having a coefficient smaller than that of a dielectric layer between ground electrodes in which a resonance line of another layer exists.