JPH098504A - Dielectric filter - Google Patents

Abstract

PURPOSE: To obtain the small sized dielectric with excellent filter characteristic. CONSTITUTION: A dielectric substrate 1 includes plural dielectric layers 11, 12 whose dielectric constant differs from each other. Each low dielectric constant dielectric layer 11 is placed between the high dielectric constant dielectric layers 12. Each of the dielectric resonators 21-24 is provided to the dielectric substrate 1, the high dielectric constant dielectric layer 12 is used for a dielectric layer to obtain a major filter characteristic and the low dielectric dielectric layer 12 is used for a coupling layer to be electrically coupled with the adjacent dielectric resonator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter.

[0002]

2. Description of the Related Art Dielectric filters are used, for example, in automobile telephones,
Used for mobile communication devices such as satellite communication or cordless telephones. As this type of dielectric filter, a configuration in which coaxial dielectric resonators are connected in a plurality of stages, a block dielectric filter in which a plurality of dielectric resonators are provided on one dielectric substrate, and the like have been conventionally known. It was However, miniaturization of the mobile communication device described above has been rapidly advanced, and miniaturization of the dielectric filter used as a component thereof is a very important issue. Further, it is also extremely important to improve electrical insulation to the outside, moisture resistance, and durability in order to meet the usage. The above-mentioned two types of dielectric filters cannot fully meet such demands.

The invention disclosed in Japanese Patent Application Laid-Open No. 4-144404 can be cited as one conventional technique that can be applied to miniaturization, electrical insulation to the outside, improvement in moisture resistance and durability. This prior art document discloses conductor protection by embedding a conductor inside an insulating support including a dielectric.
An object of the present invention is to provide a dielectric resonator having excellent electrical insulation with respect to the outside, moisture resistance and durability.

However, the technique described in this prior art document discloses a technique in the case where one dielectric resonator is provided. In order to improve the filter characteristics, the technology of the multi-stage connection studied in the dielectric filter in which the coaxial type dielectric resonators are connected in a plurality of stages, the block type dielectric filter, and the like is not disclosed.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a dielectric filter having excellent filter characteristics.

Another object of the present invention is to provide a small dielectric filter having excellent filter characteristics.

[0007]

In order to solve the above-mentioned problems, the dielectric filter according to the present invention has one dielectric substrate and a plurality of dielectric resonators. The dielectric substrate includes a plurality of dielectric layers having different dielectric constants, and the low dielectric constant dielectric layer is disposed between the high dielectric constant dielectric layers among the plurality of dielectric layers. Each of the dielectric resonators,
The high dielectric constant dielectric layer is provided on the dielectric substrate as a dielectric layer for obtaining main filter characteristics, and the low dielectric constant dielectric layer is used as a coupling layer to electrically couple with an adjacent dielectric resonator. Has been done.

Each of the plurality of dielectric resonators is provided on one dielectric substrate. Therefore, it is possible to obtain a dielectric filter which shares the dielectric substrate and has a filter characteristic according to the number of stages of the dielectric resonator.

The dielectric substrate includes a plurality of dielectric layers having different dielectric constants, and each of the dielectric resonators uses a high dielectric constant dielectric layer as a dielectric layer for obtaining main filter characteristics. Therefore, high filter characteristics can be ensured by the high dielectric constant of the high dielectric constant dielectric layer.

In the dielectric substrate, the low dielectric constant dielectric layer is disposed between the high dielectric constant dielectric layers, and each of the dielectric resonators has the low dielectric constant dielectric layer as a coupling layer and is adjacent to the dielectric. It is electrically coupled to the resonator. Therefore, the coupling capacitance between each of the dielectric resonators becomes a low value determined by the dielectric constant of the low dielectric constant dielectric layer. Therefore, the arrangement interval of the dielectric resonators can be reduced, and the overall shape can be downsized.
If the dielectric substrate is composed only of a high-dielectric-constant dielectric material required to obtain the main filter characteristics, the dielectric resonator is reduced in order to reduce the coupling capacitance between the dielectric resonators. The space between them must be increased, and the overall shape becomes large.

The dielectric filter according to the present invention can be manufactured by applying conventionally known manufacturing techniques such as printing technique and machining technique. Also, its use will be obvious to those skilled in the art.

Other objects, configurations and effects of the present invention will be described in more detail with reference to the accompanying drawings as embodiments.

[0013]

1 is a perspective view showing the appearance of a dielectric filter according to the present invention, FIG. 2 is a perspective view showing the electrode structure of the dielectric filter shown in FIG. 1, and FIG. 3 is a dielectric according to the present invention. A front view of the filter, FIG. 4 is a cross-sectional view taken along line A4-A4 of FIG. 3, FIG. 5 is a cross-sectional view taken along line A5-A5 of FIG. 4, and FIG. 6 is the dielectric shown in FIGS. The electrical connection diagram of the filter is shown respectively. As illustrated, the dielectric filter according to the present invention has one dielectric substrate 1 and a plurality of dielectric resonators 21-24. The dielectric substrate 1 includes a plurality of dielectric layers 11 and 12 having different dielectric constants (see FIG. 4).
In the following description, it is assumed that the dielectric constant ε1 of the dielectric layer 11 and the dielectric constant ε2 of the dielectric layer 12 have a relationship of ε1 <ε2, and the dielectric layer 11 is referred to as a low dielectric constant dielectric layer, The dielectric layer 12 will be referred to as a high dielectric constant dielectric layer.

Among the plurality of dielectric layers 11 and 12, the low dielectric constant dielectric layer 11 is arranged between the high dielectric constant dielectric layers 12. Each of the dielectric resonators 21 to 24 is provided in the dielectric substrate 1, and the high dielectric constant dielectric layer 12 is used as a dielectric layer for obtaining main filter characteristics, and the low dielectric constant dielectric layer 1 is used.
1 is a coupling layer and is electrically coupled to the adjacent dielectric resonators 21 to 24. Therefore, as shown in FIG. 6, a filter circuit in which the dielectric resonators 21 to 24 are sequentially connected by the coupling capacitors C1 to C3 based on the dielectric constant ε1 of the low dielectric constant dielectric layer 11 is obtained.

Each of the plurality of dielectric resonators 21 to 24 is provided on one dielectric substrate 1. For this reason,
A dielectric filter that shares the dielectric substrate 1 and has a filter characteristic according to the number of stages of the dielectric resonators 21 to 24 is obtained.

The dielectric substrate 1 includes a plurality of dielectric layers 11 and 12 having different dielectric constants, and each of the dielectric resonators 21 to 24 has a high dielectric constant dielectric layer 12 to obtain a main filter characteristic. Of the dielectric layer. Therefore, the high dielectric constant of the high dielectric constant dielectric layer 12 can ensure high filter characteristics.

In the dielectric substrate 1, the low dielectric constant dielectric layer 11 is disposed between the high dielectric constant dielectric layers 12, and each of the dielectric resonators 21 to 24 includes the low dielectric constant dielectric layer 11. It is electrically coupled to the adjacent dielectric resonators 21 to 24 as a coupling layer. Therefore, the coupling capacitance between each of the dielectric resonators 21 to 24 becomes a low value determined by the dielectric constant of the low dielectric constant dielectric layer 11. Therefore, the arrangement interval of the dielectric resonators 21 to 24 can be reduced, and the overall shape can be downsized. If the dielectric substrate 1 is composed of only a high dielectric constant dielectric material required to obtain the main filter characteristics, it is necessary to reduce the coupling capacitance between the dielectric resonators 21 to 24. The distance d between the dielectric resonators 21 to 24 must be increased, and the overall shape becomes large.

The low dielectric constant dielectric layer 11 and the high dielectric constant dielectric layer 12 can be made of an organic dielectric material, a ceramic dielectric material, or a composite dielectric material containing these as main components. Of these, ceramic dielectric materials are particularly desirable. The dielectric constant ε1 of the low dielectric constant dielectric layer 11 and the dielectric constant ε2 of the low dielectric constant dielectric layer 12 change depending on the coupling capacitance to be obtained, the coupling electrode structure, and the like. For example, the dielectric constant ε1 of the low-dielectric layer 11 is 4, and the high-dielectric layer 1 is
There may be a combination of dielectric constant ε2 = 200 of 2 and the like. Specific examples of the low-permittivity dielectric layer 11 are forsterite, glass, and the like, and the material of the high-permittivity dielectric layer 12 is a titanium oxide-based ceramic material that is widely used for capacitors and the like.

Next, other objects, configurations and effects of the present invention will be described in more detail with reference to the drawings. In the dielectric substrate 1, high dielectric constant dielectric layers 12 and low dielectric constant dielectric layers 11 are alternately provided along one direction and are integrated. Each of the dielectric resonators 21 to 24 has an electrode 2
11 to 241 are included. These electrodes 211-24
1 is embedded in the high dielectric constant dielectric layer 12.

Each of the dielectric resonators 21-24 has a coupling electrode 212-2 extended from the electrode 211-241.
42. The coupling electrodes 212 to 242 are embedded inside the low dielectric constant dielectric layer 11. Dielectric resonator 21
In the dielectric resonators 21 and 22, 22 and 23, and 23 and 24, which are adjacent to each other, the coupling electrodes 212 to 242 face each other in the low dielectric constant dielectric layer 11.
As a result, the required coupling capacitances C1 to C3 (see FIG. 6) are obtained. Specifically, between the dielectric resonator 21 and the dielectric resonator 22, the coupling electrode 212 and the coupling electrode 22 are provided.
The coupling capacitance C1 is obtained by 2 and. Dielectric resonator 22
And the dielectric resonator 23, a coupling capacitance C2 is obtained by the coupling electrode 223 and the coupling electrode 232. A coupling capacitance C3 is obtained between the dielectric resonator 23 and the dielectric resonator 24 by the coupling electrode 233 and the coupling electrode 242.

Of the dielectric resonators 21 to 24, the dielectric resonators 21 and 24 arranged on both sides are external electrodes 213 and 2, respectively.
43. The external electrodes 213 and 243 are provided on the outer surface of the dielectric substrate 1 at positions facing the electrodes 211 and 241. External electrodes 213 and 243
Is two terminal electrodes 21 provided on the outer surface of the dielectric substrate 1.
4 and 244, respectively. External electrode 213
And input (or output) due to overlap with electrode 211
The capacitor Cin (see FIG. 6) is obtained, and the external electrode 243 is obtained.
The output (or input) capacitor Cout (see FIG. 6) is obtained by the overlap between the electrode 241 and the electrode 241. External electrode 21
Since the electrodes 3 and 243 are provided on the outer surface of the dielectric substrate 1, the electrode area can be reduced, whereby the capacitance value of the input capacitor Cin or the output capacitor Cout can be adjusted. The area reduction of the external electrodes 213 and 243 can be performed by means such as laser or sandblast.

The illustrated dielectric filter has a ground terminal 3. The ground terminal 3 is formed on the end surface of the dielectric substrate 1. In each of the dielectric resonators 21 to 24, one end of the electrodes 211 to 241 is led to the end surface of the dielectric substrate 1 and is electrically connected to the ground terminal 3. As a result, as shown in FIG. 6, a circuit in which the ground sides of the dielectric resonators 21 to 24 are commonly connected by the ground terminal 3 is obtained.

Further, the illustrated dielectric filter has ground conductors 4 and 5. The ground conductors 4 and 5 are arranged so as to sandwich the plurality of dielectric resonators 21 to 24 from both sides. The ground conductors 4 and 5 are led out to the end surface of the dielectric substrate 1 and are electrically connected to the ground terminal 3. The ground conductors 4 and 5 can also be provided on the outer surface of the dielectric substrate 1.

The dielectric filter according to the present invention can be manufactured by applying a conventionally known manufacturing technique such as a printing technique. For example, as shown in FIG. 7, low dielectric constant dielectric layers 11 and high dielectric constant dielectric layers 12 are formed so as to be arranged alternately. As the forming means, the low dielectric constant dielectric layer 11
When the high dielectric constant dielectric layer 12 is made of a ceramic dielectric material, the ceramic dielectric paste forming the low dielectric constant dielectric layer 11 is screen-printed into a predetermined pattern, and then the high dielectric constant dielectric layer is formed. The ceramic dielectric paste forming 12 can be formed by means such as screen printing.

After the dielectric layer forming step is completed, electrodes 211, 221, 231, and 241 are formed by screen printing as shown in FIG. Depending on the pattern of the screen used at this time, the coupling electrodes 212, 222, 223, 232, 233 and 242.
Are also formed at the same time.

Before or after the step of forming the dielectric layer shown in FIG. 7, a low dielectric constant dielectric layer serving as a dielectric substrate, a step of forming ground conductors (4, 5), a firing step, and an earth. A terminal forming step, an external electrode applying step, a terminal electrode applying step and the like are added. Such a laminating process can be performed by applying a conventionally known laminating technique.

Although the dielectric filter according to the present invention has been described with reference to the preferred embodiments, the dielectric filter according to the present invention can take various modes based on the spirit and the teaching of the present invention. It will be obvious to those skilled in the art. For example, the number of dielectric resonators is arbitrary. The electrodes, the coupling electrodes and the external electrodes can have various modified patterns. Furthermore,
The present invention can also be applied to a block type dielectric filter as disclosed in JP-A-4-144404.

[0028]

As described above, according to the present invention, the following effects can be obtained. (A) It is possible to provide a dielectric filter having excellent filter characteristics. (B) It is possible to provide a compact dielectric filter having excellent filter characteristics.

[Brief description of drawings]

FIG. 1 is a perspective view showing an appearance of a dielectric filter according to the present invention.

2 is a perspective view showing an electrode structure of the dielectric filter shown in FIG. 1. FIG.

FIG. 3 is a front view of a dielectric filter according to the present invention.

4 is a sectional view taken along line A4-A4 of FIG.

5 is a cross-sectional view taken along the line A5-A5 of FIG.

FIG. 6 is an electrical connection diagram of the dielectric filter shown in FIGS.

FIG. 7 is a diagram showing part of the process of manufacturing the dielectric filter shown in FIGS. 1 to 6;

FIG. 8 is a diagram showing part of the process of manufacturing the dielectric filter shown in FIGS. 1 to 6;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric substrate 11 Low dielectric constant dielectric layer 12 High dielectric constant dielectric layer 21-24 Dielectric resonator 211-241 Electrode

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsuji Yasuda 1-13-1 Nihonbashi, Chuo-ku, Tokyo TDC Corporation

Claims (7)

[Claims] 1. A dielectric filter having one dielectric base and a plurality of dielectric resonators, wherein the dielectric base includes a plurality of dielectric layers having different permittivities. In the body layer, a low dielectric constant dielectric layer is disposed between high dielectric constant dielectric layers, and each of the dielectric resonators is provided in the dielectric base, and the high dielectric constant dielectric layer is provided. Is a dielectric layer for obtaining main filter characteristics, and the low dielectric constant dielectric layer is a coupling layer and is electrically coupled to an adjacent dielectric resonator. 2. The dielectric filter according to claim 1, wherein the dielectric substrate includes dielectric layers having a high dielectric constant and dielectric layers having a low dielectric constant alternately arranged along one direction. A dielectric filter in which each of the dielectric resonators has an electrode, and the electrode is embedded inside a dielectric layer having a high dielectric constant. 3. The dielectric filter according to claim 2, wherein each of the dielectric resonators has a coupling electrode extended from the electrode, and the coupling electrode has the low dielectric constant. A dielectric filter that is embedded in a dielectric layer, and in the adjacent dielectric resonators of the dielectric resonators, the coupling electrodes face each other in the low dielectric constant dielectric layer. . 4. The dielectric filter according to claim 2, wherein the dielectric resonators arranged on both sides of the dielectric resonator have external electrodes, and the external electrodes are A dielectric filter which is provided on the outer surface of the dielectric substrate at a position facing the electrode and is electrically connected to two terminal electrodes provided on the outer surface of the dielectric substrate. 5. The dielectric filter according to claim 2, further comprising a ground terminal, the ground terminal being formed on an end surface of the dielectric substrate, Each of them is a dielectric filter in which one end of the electrode is led to the end face of the dielectric substrate and is electrically connected to the ground terminal. 6. The dielectric filter according to claim 1, further comprising a ground conductor, wherein the ground conductor is arranged so as to sandwich the plurality of dielectric resonators from both sides. Body filter. 7. The dielectric filter according to claim 6, wherein the ground conductor is led out to an end surface of the dielectric base,
A dielectric filter connected to the ground terminal.