JPH06125206A - Dielectric filter - Google Patents

Abstract

PURPOSE:To provide a dielectric filter which can secure the satisfactory coupling capacitance with a coupling electrode kept in a small size and furthermore can easily attain a coupling substrate when both coaxial resonators are coupled together or a coaxial resonator is coupled to an input/output electrode via the coupling substrate. CONSTITUTION:A dielectric filter 1 contains the coaxial resonators 10 and 20 having their center conductors put in the rod-shaped ceramics 11 and 21. Both resonators 10 and 20 are connected to a coupling substrate 50 consisting of a multilayer substrate. This multilayer substrate includes a coupling electrode which connects the resonator 10 to the resonator 20 or a coupling electrode which connects the resonators 10 and 20 to an input/output electrode.

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 which a coaxial resonator in which a central conductor of a resonator is arranged in a rod-shaped ceramic is connected to a coupling substrate.

[0002]

2. Description of the Related Art As a conventional dielectric filter, a microfilm disclosed in Japanese Utility Model Application No. 1-117521 (3-5
Japanese Patent No. 6205) discloses a structure in which a coupling substrate is provided so as to be orthogonal to the central conductor of the resonator.

FIG. 9 is a perspective view showing this conventional example as a dielectric filter 6. That is, in the conventional dielectric filter 6, the coaxial resonator 10 in which the central conductor of the resonator is arranged in the rod-shaped ceramic 11 and the rod-shaped ceramic 21.
Coaxial resonator 20 in which the center conductor of the resonator is arranged
Are arranged side by side, and the coaxial type resonators 10 and 20 are coupled to each other.
They are connected to each other via 0. That is, the coaxial resonators 10 and 20 are arranged so that the axial direction of the central conductor is parallel to the surface of the substrate 40 of the external circuit, and the coaxial resonators 10 and 20 are arranged in the vicinity of the open end of the central conductor and the substrate 40 of the external circuit. On the substrate 40 of the external circuit so as to be orthogonal to
0 is set. Then, the electrode 32 is formed on the front surface 301 (shown in FIG. 9A) of the combined substrate 30.
33 is provided and the back surface 302 of the combined substrate 30 (see FIG.
The coupling electrode 35 is provided in (2), and the electrodes 32 and 33 and the electrode 35 are capacitively coupled.

[0004]

In the above-mentioned conventional example, if the combined substrate 30 is to have a predetermined strength, the combined substrate 30 needs to have a certain thickness, while the electrodes 32, 33 sandwich the thickness. When the electrode 35 and the electrode 35 are capacitively coupled, in order to secure the predetermined amount of the capacitance, the electrode 3
A large area is required for the electrodes 2 and 33 and the electrode 35, and the size of the combined substrate 30 itself becomes large, which eventually causes the size of the entire dielectric filter 6 to become large.

If the thickness of the combined substrate 30 is reduced, the distance between the electrodes is shortened. Therefore, electrostatic capacitance is not required even if the area between the electrodes 32 and 33 and the electrode 35 is increased (that is, the combined substrate 30 is not enlarged). The capacity can be increased. However, in this case, since the strength of the combined substrate 30 is reduced, a step of attaching a reinforcing substrate to the combined substrate 30 is necessary to reinforce the combined substrate 30, and the reinforcing step is complicated. There is a problem that is.

The same problem as described above also occurs when the coaxial resonator and the input / output electrodes are coupled.

According to the present invention, when the coaxial resonators are coupled to each other or the coaxial resonators and the input / output electrodes are coupled to each other by the coupling substrate, the coupling capacitance can be sufficiently ensured while keeping the coupling electrodes small. Moreover, it is an object of the present invention to provide a dielectric filter in which it is easy to manufacture a bonded substrate having sufficient strength.

[0008]

DISCLOSURE OF THE INVENTION The present invention relates to a dielectric filter in which a coaxial resonator having a resonator center conductor arranged in a rod-shaped ceramic is connected to a coupling substrate, and the coupling substrate is a multilayer substrate. A coupling electrode for coupling one coaxial resonator and another coaxial resonator or a coupling electrode for coupling the coaxial resonator and the input / output electrode is formed in the inner layer of the multilayer substrate. There is something.

[0009]

According to the present invention, the combined substrate is composed of a multilayer substrate.
Since a coupling electrode for coupling one coaxial resonator and another coaxial resonator, or a coupling electrode for coupling the coaxial resonator and the input / output electrode is formed on the inner layer of the multilayer substrate,
The distance between the coupling electrode that couples the coaxial resonators or the coupling electrode that couples the coaxial resonator and the input / output electrode can be made very short, and therefore a large electrostatic coupling capacitance can be obtained. The bonding capacity can be sufficiently ensured while keeping the size small, and it is easy to increase the thickness of the multilayer substrate before firing, so that the bonding substrate having sufficient strength can be easily manufactured.

[0010]

1 is a perspective view showing a dielectric filter 1 according to a first embodiment of the present invention, and FIG. 2 is an exploded perspective view of a main part of the first embodiment.

The dielectric filter 1 is a rod-shaped ceramic 1
The coaxial substrate 10 in which the central conductor 12 of the resonator is arranged in 1 and the coaxial resonator 20 in which the central conductor 22 of the resonator is arranged in the rod-shaped ceramics 21
0 is a dielectric filter coupled through 0.

The coupling substrate 50 is in close contact with the coaxial resonators 10 and 20, and the central conductor 1 of the coaxial resonators 10 and 20 is connected.
A combined substrate 50 is provided substantially orthogonal to 2 and 22. The coupling substrate 50 is formed of a multi-layer substrate, and the coupling electrode 55 that electrically couples the coaxial resonator 10 and the coaxial resonator 20 is formed as an inner layer of the multi-layer substrate.

That is, the combined substrate 50 is made of the ceramic 5
0a and 50b, the ceramic 50a is
Input / output electrodes 51 and 54, through holes 12h and 22h,
Electrodes 52 and 5 connected to two conductive pins (not shown) inserted into the through holes 12h and 22h, respectively.
3 are provided, and the through hole 12 is provided in the ceramics 50b.
h and 22h, and a coupling electrode 55 for electrically coupling the electrodes 52 and 53 are provided. Since the ceramics 50a is thin and the distance between the electrodes 52 and 55 and the distance between the electrodes 53 and 55 are sufficiently small, even if the electrodes 52, 53, 55 are small, the electrodes 52 and 55 are small.
It is possible to secure a sufficient capacity of the capacitor constituted by, and similarly, a sufficient capacitance of the capacitor constituted by the electrodes 53 and 55.

The ceramics 50a and 50b are called green sheets in the manufacturing stage. The electrodes 51 to 55 are formed by printing a conductive paste on the green sheets, and the center conductor 12 and
The combined substrate 50 has through holes 12h and 22h provided at positions corresponding to 22. These through holes 12h, 22h
A conductive pin not shown in the figure is inserted into the core conductor, one end of the conductive pin is soldered to the open end of the center conductor 12 or 22, and the other end of the conductive pin is soldered to the electrode 52 or 53. In the green sheet stage, via holes are provided at positions corresponding to the through holes 12h and 22h, a conductive paste is applied to the via holes, and the paste is baked, so that the conductive pins do not need to be used.

In the first embodiment, the combined substrate 50 is used.
Is composed of a multilayer substrate, and the coupling electrode 55 for coupling the coaxial resonator 10 and the coaxial resonator 20 is formed in the inner layer of the multilayer substrate, so that the coaxial resonators 10 and 20 are coupled to each other. The distance between the coupling electrodes 52 and 55 and the distance between the coupling electrodes 53 and 55 can be made very short, and therefore, the electrostatic coupling capacitance due to these coupling electrodes can be made large, so that the coupling electrodes can be kept small. The binding capacity can be sufficiently secured. Further, if the combined substrate 50 is thickened before firing, the strength of the combined substrate 50 can be sufficiently secured, and since the combined substrate 50 is composed of a multilayer substrate, it is easy to thicken the combined substrate 50 before firing. Therefore, a bonded substrate having sufficient strength can be easily manufactured.

FIG. 3 is an exploded perspective view of the dielectric filter 2 according to the second embodiment of the present invention.

This dielectric filter 2 is basically the same as the dielectric filter 1, but instead of the ceramic 50b in the dielectric filter 1, a ceramic 50b '.
Is provided. The ceramics 50a and 50b 'constitute a combined substrate 50'.

The ceramic 50b 'is one in which coupling electrodes 55, 56 and 57 are provided on the front surface of the green sheet in FIG. The coupling electrode 56 is for coupling the input / output electrode 51 and the electrode 52 to each other.
Reference numeral 7 connects the input / output electrode 54 and the electrode 53.

In the dielectric filter 2, the combined substrate 5
0'is composed of a multi-layer substrate, and the coupling electrode 56 for coupling the coaxial resonator 10 and the input / output electrode 51 is formed as an inner layer of the multi-layer substrate. Since the inter-electrode distance of the coupling electrode for coupling with the electrode 51 can be made very short, and therefore the electrostatic coupling capacitance can be made large, the coupling capacitance can be sufficiently secured while keeping the coupling electrode small. Further, if the combined substrate 50 ′ is thickened before firing, the strength of the combined substrate 50 ′ can be sufficiently secured. Since the combined substrate 50 ′ is composed of a multi-layer substrate, the combined substrate 50 ′ can be thickened before baking. It is easy and thus a bonded substrate having sufficient strength can be easily manufactured. The same applies to the coupling electrode 57 that couples the coaxial resonator 20 and the input / output electrode 54.

FIG. 4 is an exploded perspective view of the dielectric filter 3 according to the third embodiment of the present invention.

The dielectric filter 3 is provided with only the coaxial resonator 10 as the coaxial resonator (the coaxial resonator is 1
The bonded substrate 60 is made of ceramics 60.
It is composed of a and 60b, and couples the input / output electrode and the central conductor 12 of the coaxial resonator 10. The ceramics 60a includes the through hole 12h and the input / output electrodes 61, 6
3 and an electrode 62 connected to the central conductor 12 via a conductive pin (not shown) provided in the through hole 12h,
The ceramics 60b includes a through hole 12h, a coupling electrode 66 for coupling the input / output electrode 61 and the electrode 62, and an electrode 6
2 and a coupling electrode 67 for coupling the input / output electrode 63.

In the dielectric filter 3, the combined substrate 6 is used.
Since 0 is composed of a multi-layer substrate and the coupling electrodes 66 and 67 are formed in the inner layers of the multi-layer substrate, the electrodes 61 and 66 for coupling the coaxial resonator 10 and the input / output electrodes 61 and 63 are formed. And the distance between the electrodes 63 and 67 can be made very short, the electrostatic coupling capacitance due to these coupling electrodes can be made large, and the coupling capacitance can be sufficiently secured while keeping the coupling electrodes small. . In addition, the combined substrate 60 before firing
If the thickness of the combined substrate 60 is increased, the strength of the combined substrate 60 can be sufficiently secured. Since the combined substrate 60 is composed of a multi-layer substrate, it is easy to thicken the combined substrate 60 before firing, and thus the combined substrate having sufficient strength is obtained. Can be easily manufactured.

In the above embodiment, the combined substrate 5 is used.
0, 50 ', 60 are provided so as to be in close contact with the coaxial resonator 10 and the like and substantially orthogonal to the central conductor 12 of the coaxial resonator. It may be installed parallel to the center conductor 12 of the container,
It may be installed so as to intersect with the extension line of the central conductor 12 at a predetermined angle other than 0 and 90 degrees. Further, in the above embodiment, the coupling substrates 50, 50 ′ and 60 are the same as the coaxial resonator 1
Although it is installed on the open end side such as 0,
0 ′ and 60 may be installed on the short-circuit end side of the coaxial resonator.

FIG. 5 is a perspective view showing a dielectric filter 4 according to a fourth embodiment of the present invention, and FIG. 6 is an exploded perspective view showing a coupling substrate 70 in the dielectric filter 4.

The dielectric filter 4 is provided with the ground electrode G by printing or the like on the surface of the coaxial resonators 10 and 20 of the dielectric filter 1 (the surface other than the surface including the open end of the center conductor). Bonded substrate 5 in dielectric filter 1
Instead of 0, a combined substrate 70 is provided.

The combined substrate 70 is made of ceramics 70a, 7
0b, 70c, and ceramics 70a, 70b
Are the same as the ceramics 50a and 50b, respectively. The ceramics 70c has through holes 12h and 22h.
And the ground electrode G1 provided in the portion excluding the through holes 12h and 22h and the periphery thereof. When manufacturing the combined substrate 70, the ceramics 70a, 70b,
70c is called a green sheet. A conductive paste is printed on the green sheet to form each electrode, and at the same time, through holes 12h and 22h are provided, which are fired in a stacked state, and then the through holes are formed. Hole 12
Insert conductive pins into h and 22h to
Are connected to the electrodes 72 and 73, respectively.

The ground electrode G provided on the outer circumference of the coaxial resonators 10 and 20 is connected to the ground portion of the substrate 40 of the external circuit, and the ground electrode G provided on the surface of the coaxial resonators 10 and 20. The ground electrode G1 of the ceramics 70c is connected, and the input / output electrodes 71 and 74 are connected to a predetermined portion of the substrate 40 of the external circuit.

In the dielectric filter 4, the combined substrate 7
0 is provided with a ground electrode G1 and the coaxial resonator 1
Since the surfaces of Nos. 0 and 20 are covered with the ground electrodes G and the ground electrodes G and G1 are connected to each other, it is possible to shield without using a shield case, and it is easy to shield the dielectric filter. .

FIG. 7 is a perspective view showing a dielectric filter 5 according to a fifth embodiment of the present invention, and FIG. 8 is an exploded perspective view showing a coupling substrate 80 in the dielectric filter 5.

The dielectric filter 5 is basically the same as the dielectric filter 4, except that a combined substrate 80 is provided in place of the combined substrate 70, and ceramics 80a and 80b forming the combined substrate 80 are provided on the respective surfaces thereof. Ground electrode G2,
G3 is provided.

Input / output electrodes 8 are provided on the ceramics 80a.
1, 84, through holes 12h and 22h, through hole 12h,
Electrodes 82 and 83 respectively connected to two conductive pins (not shown) inserted into 22h and ground electrode G2 are provided, and ceramics 80b has through holes 12h and 22h and electrode 82. A coupling electrode 85 for electrically coupling 83 to each other and a ground electrode G3 are provided.

In the dielectric filter 5, the combined substrate 80
Since the ground electrodes G2 and G3 provided on the surface of the and the ground electrodes G provided on the surfaces of the coaxial resonators 10 and 20 are connected, it is possible to shield without using a shield case, and to use as a dielectric filter. The work of applying a shield is easy.

In the above embodiment, the bonded substrates 50, 5
0'60, 70, 80 are installed on the open end sides of the center conductors 12, 22 of the coaxial resonators 10, 20, but the coupling substrates 50, 50'60, 70, 80 are arranged on the center conductors 12,
It may be installed on the short-circuited end side of 22. For example, the center conductors 12 and 22 are formed of hollow cylindrical conductors, a rod-shaped conductor is provided in the hollow portion of the center conductors 12 and 22, and one end of the rod-shaped conductor is connected to the open end side of the center conductors 12 and 22.
The other end of the rod-shaped conductor is connected to the combined substrates 50, 50'60, 70, 8
You may make it connect to 0.

In the above embodiment, the dielectric filter is constructed by using one or two coaxial resonators, but the dielectric filter is constructed by using three or more coaxial resonators. You may do it.

[0035]

According to the present invention, when the coaxial resonators are coupled to each other or the coaxial resonators and the input / output electrodes are coupled by the coupling substrate, the coupling capacitance can be reduced with the coupling electrodes kept small. The effect is that it is easy to manufacture a bonded substrate that can be sufficiently secured and that has sufficient strength.

[Brief description of drawings]

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

FIG. 2 is an exploded perspective view of a main part of the dielectric filter 1.

FIG. 3 is an exploded perspective view of a dielectric filter 2 according to a second embodiment of the present invention.

FIG. 4 is an exploded perspective view showing a dielectric filter 3 according to a third embodiment of the present invention.

FIG. 5 is a perspective view showing a dielectric filter 4 according to a fourth embodiment of the present invention.

6 is an exploded perspective view of a combined substrate 70 in the dielectric filter 4. FIG.

FIG. 7 is a perspective view showing a dielectric filter 5 according to a fifth embodiment of the present invention.

FIG. 8 is an exploded perspective view of an essential part of the dielectric filter 5.

FIG. 9 is a perspective view showing an example of a conventional dielectric filter.

[Explanation of symbols]

1, 2, 3, 4, 5 ... Dielectric filter, 10, 20 ... Coaxial resonator, 11, 21 ... Rod-shaped ceramics, 12, 22 ... Central conductor, 40 ... External circuit substrate, 50, 50 ', 60 , 70, 80 ... Combined substrate, 51, 54, 61, 63, 71, 74, 81, 84 ... Input / output electrodes, 52, 53, 62, 72, 73, 82, 83 ... Electrodes, 55, 56, 57 , 66, 67, 75, 85 ... Coupling electrodes, G, G1, G2, G3 ... Ground electrodes.

Claims (3)

[Claims] 1. A dielectric filter in which a coaxial resonator in which a central conductor of a resonator is arranged in rod-shaped ceramics is connected to a coupling substrate, wherein the coupling substrate is a multilayer substrate, and one of the coaxial type resonators is provided. A coupling electrode that couples the resonator to the other coaxial resonator, or a coupling electrode that couples the coaxial resonator to the input / output electrode, is formed on the inner layer of the multilayer substrate. Characteristic dielectric filter. 2. The dielectric filter according to claim 1, wherein the coupling substrate is installed so as to be orthogonal to, parallel to, or intersect at a predetermined angle with the central conductor. 3. The coupling substrate according to claim 2, wherein the coupling substrate is provided in close contact with the coaxial resonator and substantially orthogonal to the central conductor, and the surface of the coaxial resonator is covered with a ground electrode. A ground electrode is provided on the surface or inside of the coupling substrate, and the ground electrode provided on the surface of the coaxial resonator is connected to the ground electrode provided on the surface of the coupling substrate or inside. Dielectric filter.