JPH06291509A - High frequency filter - Google Patents

Abstract

PURPOSE:To suppress the stray capacitance in a band pass filter containing a TEM mode dielectric resonator. CONSTITUTION:In a band pass filter constituted by coupling a first and a second dielectric resonators 1, 2 by a capacitance, a mutual coupling capacitance and an input and output coupling capacitance are constituted of a multi-layer substrate 3. A mutual interval of ground conductor layers 24, 64 and electrode conductor layers 43a, 47a is set so as to be larger than a mutual interval of the electrode conductor layers 43a, 47a for obtaining the mutual coupling capacitance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high frequency filter using a TEM mode dielectric resonator.

[0002]

2. Description of the Related Art First and second dielectric resonators are arranged on a substrate, an input coupling capacitance is provided between an input terminal and the first dielectric resonator, and an output terminal and a second dielectric resonator are provided. A filter having a configuration in which an output coupling capacitance is provided between the resonator and a mutual coupling capacitance is provided between the first and second dielectric resonators is known. In addition, the applicant of the present patent has attempted to construct the input coupling capacitance, the output coupling capacitance and the mutual coupling capacitance with a multi-layer substrate.

[0003]

By the way, in the case of disposing a plurality of dielectric resonators on a multilayer substrate, it is necessary to provide a ground conductor layer on both main surfaces of the multilayer substrate.
As a result, a stray capacitance is generated between the electrode conductor layer having the capacitance inside the multilayer substrate and the ground conductor layers on both main surfaces of the multilayer substrate. When this stray capacitance becomes large, a loss occurs here, and the attenuation characteristics on both sides of the pass band deteriorate.

Therefore, an object of the present invention is to provide a high frequency filter having a small stray capacitance in spite of using a multilayer substrate.

[0005]

In order to achieve the above object, the present invention provides a columnar dielectric having a resonance hole, an inner conductor provided in the resonance hole, and an outer conductor provided on the outer peripheral surface of the dielectric. And at least first and second dielectric resonators, respectively, and the first and second dielectric resonators formed so as to support the first and second dielectric resonators on one main surface. And a multi-layer substrate internally containing a mutual coupling capacitance connected between the dielectric resonators, wherein a pair of electrode conductor layers for obtaining the mutual coupling capacitance is First and second connections embedded in different positions in the thickness direction and for connecting the ground conductor layer and the inner conductors of the first and second dielectric resonators to the one main surface of the multilayer substrate. A conductor layer is provided, A ground conductor layer is provided on the other main surface, and one of the distance between one of the pair of electrode conductor layers and the one main surface and the distance between the other of the pair of electrode conductor layers and the other main surface. The present invention relates to a high frequency filter, wherein one or both of them is set to be larger than the mutual distance between the pair of electrode conductor layers. In addition, it is desirable to provide an input coupling capacitance and an output coupling capacitance on the multilayer substrate as described in claim 2.

[0006]

According to the present invention, either one or both of the mutual spacing between the electrode conductor layer on one side and the other side of the mutual coupling capacitance and the main surface on the one side and the other side of the multi-layered substrate are set to one side of the mutual coupling capacitance. Since it is set to be larger than the mutual spacing of the other electrode conductor layer, the stray capacitance between the electrode conductor layer and the ground conductor layer of the mutual coupling capacitance becomes small, the loss here also becomes small, and the frequency characteristic of the filter becomes small. Get better. That is, the attenuation characteristics on both sides of the pass band are improved.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a high frequency bandpass filter using a TEM mode dielectric resonator according to an embodiment of the present invention will be described with reference to FIGS.

As shown in FIG. 1, this bandpass filter includes first and second dielectric resonators 1 and 2 and a multilayer substrate 3 having a conductor layer for capacitance (capacitor) and a ground conductor layer. It is composed of a combination. As is clear from FIGS. 1 to 3, the first and second dielectric resonators 1 and 2 are composed of columnar or cylindrical porcelain having a relative permittivity of, for example, about 88. 5 and
First and second inner conductors 8 and 9 provided in the first and second resonance holes 6 and 7, and outer peripheral surfaces 10 and 11 of the dielectrics 4 and 5.
And outer conductors 12 and 13 provided on the. The first
The first and second connection conductors 14 and 15 are continuously provided on the first and second inner conductors 8 and 9. These first and second connection conductors 14 and 15 extend to the outer peripheral surfaces 10 and 11 through one end surfaces of the dielectric bodies 4 and 5. Also, the first
And the first and second inner conductors 8 and 9 for connecting the first and second inner conductors 8 and 9 to the first and second outer conductors 12 and 13 on the other end surfaces of the second and fourth dielectrics 4 and 5, respectively. Short-circuit conductors 16 and 17 are provided. Since the first and second dielectric resonators 1 and 2 are configured substantially the same, only the first dielectric resonator 1 is shown in detail in FIG. Detailed illustration is omitted. The inner conductors 8 and 9 and the outer conductor 1
2, 13, the connecting conductors 14, 15 and the short-circuit conductors 16, 1
Reference numeral 7 is composed of a conductive film which is coated with silver paste and baked. Note that each conductor may be formed by copper plating or the like.

In order to obtain this bandpass filter, an input coupling capacitance Ca, an output coupling capacitance Cb and a mutual coupling capacitance Cc are connected to the coaxial TEM mode dielectric resonators 1 and 2 as shown in FIG. Also, the first and second stray capacitances C1 and C2
Occurs. The input coupling capacitance Ca is connected between the signal input terminal T1 and one end of the first resonator 1, and the output coupling capacitance Cb is connected between one end of the second resonator 2 and the output terminal T2. Coupling capacitance Cc
Are connected between one ends of the first and second resonators 1 and 2. First and second stray capacitances C1, C
2 occurs between one end of the first and second resonators 1 and 2 and the ground. The other ends of the first and second resonators 1 and 2, that is, the outer conductors 12 and 13 are connected to the ground.

The multi-layer substrate 3 includes first, second, third, fourth and fifth dielectric layers made of the same material having the same relative permittivity as shown by a dashed line in FIGS. 18, 19,
It has 20, 21, 22 and various conductor layers. The multilayer substrate 3 is obtained by applying a conductive paste in a predetermined pattern on a green sheet (unfired porcelain sheet) having the same thickness to obtain the first to fifth dielectric layers 18 to 22, and laminating and firing. And the first to fifth dielectric layers 1 after firing
Although 8 to 22 are integrated, they are divided here for convenience of description.

As shown in FIG. 5, a ground conductor layer 24 and first and second connecting conductor layers 25 and 26 are provided on the flat surface 23 of the multilayer substrate 3, that is, the surface of the first dielectric layer 18. ing. The ground conductor layer 24 has a portion corresponding to the outer conductors 12 and 13 of the first and second resonators 1 and 2, and here, as shown in FIG. The outer conductors 12 and 13 of 1 and 2 are respectively fixed. The first and second connection conductor layers 25 and 26 are the first and second connection conductors 14 and 15 of the first and second resonators 1 and 2.
Corresponding to the first and second connection conductors 1
Nos. 4 and 15 are fixed by solder (not shown). Via holes are provided at four locations on the first dielectric layer 18 so as to extend from the front surface to the back surface.
7, 28, 29, 30 are filled.

The second dielectric layer 22 is provided for the purpose of reducing the stray capacitances C1 and C2, and the surface thereof has the via-hole conductor 27 of FIG.
Four connection conductor layers 31, which are connected to 28, 29, 30
32, 33, 34 are provided. Each connection conductor layer 3
1, 32, 33 and 34 have via holes filled with conductors 35, 36, 37 and 38, respectively.

As shown in FIG. 7, the third dielectric layer 20 is provided with ground connecting conductor layers 39, 40 and capacitance conductor layers 41, 42, 43a, 43b.
The ground connecting conductor layers 39 and 40 are arranged so as to be connected to the via hole conductors 35 and 36 of the second dielectric layer 19 of FIG. 6, and the via holes filled with the conductors 44 and 45 are also provided. Is provided. The input / output capacitance conductor layers 41 and 42 are arranged so as to be connected to the via-hole conductors 37 and 38 of the second dielectric layer 19 of FIG. A pair of input / output coupling capacitance conductor layers 41, 4
Via holes are provided in the second extension portions 41a and 42a, and conductors 46a and 46b are filled therein. In addition, a pair of input / output coupling capacitance conductor layers 42, 4
3 includes conductor layers 43a and 43b for mutual coupling capacitance.
Are connected. The pair of mutual coupling capacitance conductor layers 43a and 43b are the pair of mutual coupling capacitance conductor layers 47a and 47b on the surface of the fourth dielectric layer 21.
To form a mutual coupling capacitance Cc. The mutual coupling capacitance Cc is determined by the opposing conductor layers 43a, 4
It is also possible to obtain only one of 7a or 43b and 47b. However, in this embodiment, in order to improve the symmetry of the stray capacitance, each conductor layer 39, 4 is
0, 41a, 42, 42a, 43a, 43b are symmetrically arranged around the vertical center line and the horizontal center line in FIG. 7, and the mutual coupling capacitance Cc is obtained by the two conductor layers 43a, 43b. .

As shown in FIG. 8, the fourth dielectric layer 21 includes a pair of mutual coupling capacitance conductor layers 47a and 47b.
In addition, conductor layers 48 and 49 for ground connection and conductor layers 50 and 51 for input and output coupling capacitance are provided. The conductor 5 is formed on the rectangular conductor layers 48, 49, 50 and 51.
Via holes filled with 2, 53, 54, 55 are provided. The connecting conductor layers 48 and 49 of FIG. 8 are connected to the via hole conductors 44 and 45 of FIG. Also,
The mutual coupling capacitance conductor layers 47a and 47b of FIG.
Are connected to the via-hole conductors 46a and 46b in FIG. Mutual coupling capacitance conductor layers 47a and 4 of FIG.
7b is a conductor layer 43a for mutual coupling capacitance of FIG.
It faces 43b. The input / output coupling capacitance conductor layers 50 and 51 of FIG. 8 face the input / output coupling capacitance conductor layers 41 and 42 of FIG. 7. Therefore,
The patterns of the conductor layers of FIGS. 7 and 8 provide the capacitances Ca, Cb and Cc of FIG.

On the surface of the fifth dielectric layer 22 shown in FIG. 9, the via-hole conductors 52, 5 of the fourth dielectric layer 21 of FIG. 8 are formed.
3, 54, 55 to be connected to the conductor layer 56 for connection,
57, 58, 59 are provided on which conductors 6
Via holes filled with 0, 61, 62, 63 are provided. The back surface of the fifth dielectric layer 22, that is, the multilayer substrate 3
As shown in FIG. 10, a ground conductor layer 64 and first and second terminal conductor layers 65 and 66 are provided on the back surface of the.
The ground conductor layer 64 is the via-hole conductor 6 shown in FIG.
0, 61 connected to the first and second terminal conductor layers 65,
66 is connected to the via-hole conductors 62 and 63 shown in FIG. 9, respectively. The first and second terminal conductor layers 65 and 66 on the back surface of FIG. 10 correspond to the input terminal T1 and the output terminal T2 of FIG.

The conductor layers 43a and 43b and the multilayer substrate 3 shown in FIG.
Between the ground conductor layer 24 and the conductor layer 4 of FIG.
7a, 47b and the ground conductor layer 64 on the back surface of the multilayer substrate 3.
Between the stray capacitances C1 and C2 shown in FIG.
Occurs. However, the thickness of the third dielectric layer 20 for obtaining the mutual coupling capacitance Cc, that is, the conductor layers 43a, 4 and
Since the mutual distance between the ground conductor layer 24 and the conductor layers 43a and 43b and the mutual distance between the ground conductor layer 64 and the conductor layers 47a and 47b are set to be larger than the mutual distance between the 3b and the conductor layers 47a and 47b. The stray capacitances C1 and C2 have relatively small values.

A characteristic line A of FIG. 11 shows the frequency characteristic of the filter according to the present embodiment, and a characteristic line B omits the dielectric layers 19 and 21 of FIGS. 1 and 3 and shows the dielectric pattern of the surface of the dielectric layer 21. The frequency characteristic of the filter of the structure provided in the body layer 22 is shown. In the filter according to the present embodiment, since the stray capacitances C1 and C2 are small, the attenuation characteristics on both sides of the pass band are good.

[0018]

MODIFICATION The present invention is not limited to the above-mentioned embodiments, and the following modifications are possible. (1) Instead of providing the connection conductors 14 and 15, the inner conductors 8 and 9 are formed of conductor layers 25 and 26 of the multilayer substrate 3 by independent connection members.
Can be connected to. (2) The extension conductor layers of the first and second terminal conductor layers 65 and 66 and the extension conductor layer of the ground conductor layer 64 can be provided on the side surface of the multilayer substrate 3. (3) The present invention can be applied to a case where a dielectric resonator is further added to form a filter having three or more stages. (4) The half-wave resonators 1 and 2 can be configured by omitting the short-circuit conductor layers 16 and 17. (5) First, second, fourth, fifth dielectric layers 18, 19, 2
The relative dielectric constant of a part or all of the first and the second dielectric layers is set to the third dielectric layer 2
It can be set to a value smaller than the relative dielectric constant of 0. (6) As shown in FIG. 2, the multi-layer substrate 3 is composed of first, second and third dielectric layers 18a, 20a and 22a.
5, the same dielectric layer pattern as that shown in FIG. 5 is formed on the surface of the second dielectric layer 18a, and the same conductor layer pattern as that shown in FIG. 7 is formed on the surface of the second dielectric layer 20a. Layer 22a
It is possible to form the same conductor layer pattern as that shown in FIG. 8 on the front surface and the same conductor layer pattern as that shown in FIG. In FIG. 12, the first and third dielectric layers 18
Since the thicknesses of a and 22a are thicker than the thickness of the second dielectric layer 20a, the stray capacitance can be reduced. (7) A groove may be formed on the surface 23 of the multilayer substrate 3, and the first and second dielectric resonators 1 and 2 may be arranged in this groove to prevent the resonators 1 and 2 from being displaced. Also, the resonators 1, 2
It is possible to apply an insulating material (for example, glass paste) to a region surrounding the to form a convex portion of the insulator, and dispose the resonators 1 and 2 in the concave portion formed by the formation of the convex portion. Further, a dielectric layer based on a green sheet is further provided on the surface 23 having the ground conductor layer 24, holes corresponding to the resonators 1 and 2 are formed in this dielectric layer, and the resonator 1 is formed in this hole.
Two may be arranged. (8) Instead of the ground conductor layer 24 made of a thick film conductor, a metal plate may be fixed to the surface 23, and the outer conductors 12 and 13 of the resonators 1 and 2 may be connected thereto.

[Brief description of drawings]

FIG. 1 is a perspective view showing a filter of an embodiment.

FIG. 2 is a sectional view of a dielectric resonator.

3 is a central longitudinal sectional view showing the filter of FIG. 1 at a position corresponding to line AA in FIGS. 5 and 7. FIG.

FIG. 4 is an equivalent circuit diagram of the filter of FIG.

FIG. 5 is a plan view of a first dielectric layer.

FIG. 6 is a plan view of a second dielectric layer.

FIG. 7 is a plan view of a third dielectric layer.

FIG. 8 is a plan view of a fourth dielectric layer.

FIG. 9 is a plan view of a fifth dielectric layer.

FIG. 10 is a bottom view of a fifth dielectric layer.

FIG. 11 is a frequency characteristic diagram of filters of an example and a comparative example.

FIG. 12 is a cross-sectional view of a modified multilayer substrate.

[Explanation of symbols]

 1 First Dielectric Resonator 2 Second Dielectric Resonator 3 Multilayer Substrate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Mitsuyoshi Ito 6-16-20 Ueno, Taito-ku, Tokyo Within Taiyo Electric Co., Ltd. (72) Inventor Satoshi Kazama 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd. (72) Inventor Makoto Inoue 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Denki Co., Ltd.

Claims (2)

[Claims] 1. At least first and second dielectrics each having a columnar dielectric having a resonance hole, an inner conductor provided in the resonance hole, and an outer conductor provided on an outer peripheral surface of the dielectric. Body resonator, and mutual coupling capacitance formed to support the first and second dielectric resonators on one main surface and connected between the first and second dielectric resonators. Is a high-frequency filter comprising a multilayer substrate containing therein, a pair of electrode conductor layers for obtaining the mutual coupling capacitance is embedded in different positions in the thickness direction of the multilayer substrate, the one of the multilayer substrate Is provided with first and second connection conductor layers for connecting a ground conductor layer to the inner conductors of the first and second dielectric resonators, and the other main surface of the multilayer substrate A ground conductor layer is provided on the Either one or both of the distance between one of the electrode conductor layers and the one main surface and the distance between the other of the pair of electrode conductor layers and the other main surface is more than the mutual distance of the pair of electrode conductor layers. A high-frequency filter characterized in that is also set large. 2. An input terminal conductor layer and an output terminal conductor layer are provided on the other main surface of the multilayer substrate, and the input terminal conductor layer and the output terminal conductor layer are connected between the input terminal conductor layer and the first connection conductor layer. An input coupling capacitance and an output coupling capacitance connected between the output terminal conductor layer and the second connection conductor layer, and one electrode and the other electrode of the input coupling capacitance and the output coupling capacitance. 2. The high frequency filter according to claim 1, wherein conductor layers are provided on extension planes of the one and the other electrode conductor layers of the mutual coupling capacitance, respectively.