JPH07212103A - Dielectric filter - Google Patents

Abstract

PURPOSE:To obtain a dielectric filter in which the number of parts can be reduced and manufacturing man-hours can be reduced and which is inexpensively manufactured and miniaturized. CONSTITUTION:Dielectric coaxial resonators 10, 11, and 12 are connected in parallel, and a tip conductor 7 which separates an internal conductor 3 and an external conductor 4 from each other is provided in the neighborhood of the opening side end face of respective resonance holes 2, and an inductance electrode 6 which connects mutually adjacent tip conductors 7 is formed on the opening side end face. An input/output electrode 5 communicated with the tip conductor 7 is formed spreading over the opening side end face and the bottom of the dielectric coaxial resonators 10, 12 that is an input/output stage. Capacitance which constitutes a filter circuit can be obtained by capacitance formed between the tip conductor 7 and the internal conductor 3 and capacitance formed between the tip conductor 7 and the external conductor 4. Inductance which constitutes the filter circuit can be obtained by the inductance electrode 6 which connects the mutually adjacent tip conductors 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, a car telephone,
The present invention relates to a dielectric filter used in mobile communication devices such as mobile phones.

[0002]

2. Description of the Related Art For example, when a band elimination filter as shown in the equivalent circuit diagram of FIG. 5 is constructed, a trap capacitance Ct and an inductance L are added to each resonator R1, R2, R3, and a stray capacitance Cs is added. Is added. When constructing such a dielectric filter, conventionally, a structure as shown in FIG. 4 has been adopted. In this dielectric filter, three dielectric coaxial resonators 9, 9, 9 are arranged in parallel in a metal case (not shown),
A substrate 20 having a coupling electrode 21 and a ground electrode 22 formed on one surface thereof is disposed, a capacitor substrate 23 is connected to the coupling electrode 21 of the substrate 20, and the coupling electrode 2
1, a coil 24 is connected between them, a chip capacitor 25 is connected between the coupling electrode 21 and a ground electrode 22, and a coupling terminal is press-fitted into the resonator hole 2 of each dielectric coaxial resonator 9 on the capacitor substrate 23. 26 is connected.

The outer conductor 4 of each dielectric coaxial resonator 9
The ground electrode 22 of the substrate 20 and the ground electrode 22 of the substrate 20 are electrically connected to a metal case (not shown).
Input / output terminals 27 and 27 are connected to the terminals 1 and 21, respectively.

In the above-mentioned conventional dielectric coaxial resonator 9, one resonator hole 2 is formed so as to penetrate a pair of opposing surfaces of a substantially rectangular parallelepiped dielectric block 1, and an inner circumference of the resonator hole 2 is formed. An inner conductor 3 is formed on the surface, and an outer conductor 4 is formed on the other five surfaces of the resonator hole 2 except one opening surface (hereinafter, referred to as an open end surface). The inner conductor 3 is the outer conductor 4 on the open end surface.
And the resonator hole 2 that is separated (opened) and faces the open end surface.
The other opening surface (hereinafter referred to as the short-circuit side end surface) is electrically connected (short-circuited) with the outer conductor 4.

Here, the capacitor substrate 23 serves as the trap capacitance Ct shown in FIG. 5, the coil 24 serves as the inductance L, and the chip capacitor 25 serves as the stray capacitance (capacity falling to the ground) Cs.

[0006]

However, in the above-described conventional dielectric filter, is it necessary to use a capacitor element such as a capacitor substrate or a chip capacitor or an inductance element such as a coil for the capacitance component and the inductance component that form the filter circuit? Alternatively, an electrode formed on the substrate is used. Further, a coupling terminal is used for connecting the dielectric coaxial resonator and the filter circuit section, and an input / output terminal is used for the input / output section of the filter. For this reason, the number of parts is increased, and moreover, it is necessary to assemble and solder the parts. Therefore, there is a problem that miniaturization is difficult, the cost of parts is high, the number of manufacturing steps is large, and the manufacturing cost is high.

Therefore, an object of the present invention is to solve the above problems of the conventional dielectric filter, reduce the number of parts, reduce the number of manufacturing steps, and reduce the cost and reduce the size of the dielectric. To provide a body filter.

[0008]

In order to achieve the above object, the present invention provides a dielectric filter in which a plurality of dielectric coaxial resonators are connected in parallel to form a filter. A tip conductor separated from the inner conductor and the outer conductor is provided in the resonator hole in the vicinity of the open end surface, and an inductance electrode is formed on the open end surface of each dielectric coaxial resonator so as to conduct with the tip conductor. And the tip conductors of the adjacent dielectric coaxial resonators are connected to each other, and an input / output electrode that is electrically connected to the tip conductor is formed on the outer surface of the dielectric coaxial resonator corresponding to the input / output stage.

[0009]

According to the above structure, the capacitance component forming the filter circuit is obtained by the capacitance formed between the tip conductor and the inner conductor and the capacitance formed between the tip conductor and the outer conductor. , The inductance component of the filter circuit can be obtained by the inductance electrode connecting the adjacent tip conductors, and the filter can be configured only by the dielectric coaxial resonator without using an external capacitor element, inductance element or the like. it can.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the drawings showing the embodiments. In the figure, the same parts as those in the conventional example are designated by the same reference numerals. In the figure, the dot-filled portion indicates the exposed portion (conductor non-forming portion) of the base material of the dielectric block.

The construction of a dielectric filter which is an embodiment of the present invention is shown in FIGS. FIG. 1 (a) is an external perspective view of an end surface of a dielectric filter having three dielectric coaxial resonators joined together, and FIG. 1 (b) shows the dielectric filter shown in FIG. 1 (a) cut along a central horizontal plane. FIG. 3C is a perspective view showing the lower part, and FIG. 3C is an external perspective view showing the bottom surface of the dielectric filter of FIG. FIG. 2 is an external perspective view of each of the dielectric coaxial resonators forming the dielectric filter as viewed from the open end surface.

As shown in FIG. 1, the dielectric filter of this embodiment is constructed by arranging three dielectric coaxial resonators 10, 11 and 12 in parallel and electrically and mechanically joining them. .

The dielectric coaxial resonators 10, 11 and 12 constituting the dielectric filter of this embodiment are shown in FIGS.
As shown in FIG. 1, the dielectric block 1 having a substantially rectangular parallelepiped shape is penetrated between the opposing open-side end surface and short-circuiting side end surface, respectively.
The individual resonator holes 2 are formed, and the inner conductor 3 is formed on the inner peripheral surface of the resonator hole 2. An outer conductor 4 is formed on the outer surface of the dielectric block 1 excluding the open end surface, the input / output electrode 5 forming portion and the inductance electrode 6 forming portion.

The inner conductor 3 has, as shown in FIG.
An inner conductor non-forming portion is provided near the open end surface and deeper than the open end surface. That is, a part of the inner conductor is left as the tip conductor 7, and the tip conductor 7 is separated from the inner conductor 3 and the outer conductor 4. On the other hand, the inner conductor 3 is electrically connected (short-circuited) with the outer conductor 4 at the end face on the short-circuit side.

As shown in FIG. 1 (c), the input / output electrodes 5 and 5 are mounted on the substrate from the openings of the resonator holes 2 on the open end faces of the dielectric coaxial resonators 10 and 12, which are the input / output stages. It is formed across the bottom surface, which is the surface. This input / output electrode 5
Is electrically connected to the tip conductor 7 at the open end surface, and is separated from the outer conductor 4 by providing an outer conductor non-forming portion on the bottom surface thereof.

As shown in FIG. 2, the dielectric coaxial resonator 1
The inductance electrodes 6 formed on the conductors 0 and 12 are formed on the open side end faces of the dielectric coaxial resonators 10 and 12 so as to extend from the openings of the respective resonator holes 2 to one side surface serving as a joint surface. There is. The inductance electrode 6 is electrically connected to the tip conductor 7 on the open side end face, and is separated from the outer conductor 4 by providing an outer conductor non-formation portion around the side face serving as a joint surface. That is, the dielectric coaxial resonator 10 and the dielectric coaxial resonator 12 have a plane-symmetrical structure.

The inductance electrodes 6, 6 formed on the dielectric coaxial resonator 11 arranged in the center are formed from the opening of the resonator hole 2 on the open end face to both side surfaces serving as a joint surface. Has been done. This inductance electrode 6, 6
Also, one end of each of the open side end faces is electrically connected to the tip conductor 7, and the outer conductor non-formation portions are provided around the both side faces that are joint surfaces to be separated from the outer conductor 4.

As shown in FIG. 1, the dielectric coaxial resonators 10, 11 and 12 are electrically and mechanically joined to each other to form an integrated dielectric filter.
Specifically, the dielectric coaxial resonator 11 is located at the center, the dielectric coaxial resonators 10 and 12 are arranged on both sides of the dielectric coaxial resonator 11, and the outer conductor 4 and the inductance electrode 6 on the side surfaces serving as the respective joint surfaces are soldered. It is electrically and mechanically joined by attachment. That is, the dielectric coaxial resonators 10, 11, 12
The tip conductors 7 adjacent to each other are connected by continuous inductance electrodes 6 and 6, respectively.

With this structure, a band elimination filter having three stages of resonators of the equivalent circuit shown in FIG. 5 is formed. That is, as schematically shown in FIG. 1B, in the dielectric filter of the present embodiment, the trap capacitance Ct shown in FIG. 5 is set to the tip conductor 7 of each of the dielectric resonators 10, 11 and 12. The stray capacitance Cs is the capacitance formed between the inner conductor 3 and the stray capacitance Cs and is the capacitance formed between the tip conductor 7 and the outer conductor 4.

Further, the inductance L connecting between the resonators shown in FIG. 5 is defined by the dielectric coaxial resonators 10, 11, and 12.
Is formed by the inductance electrodes 6, 6 connecting the adjacent tip conductors 7 of.

As shown in FIG. 1 (c), the outer conductor 4 and the input / output electrodes 5 to be ground are formed on the bottom surface of the dielectric filter, so that the surface mounting is directly performed on the circuit board. can do.

In the above embodiment, when the leakage of the electromagnetic field from each resonator hole is taken into consideration, a metal cover having a substantially L-shaped cross section is soldered to the outer conductor on the upper surface of the dielectric filter. May be attached to cover the open end surface.

As described above, in the dielectric filter of this embodiment, the capacitance component and the inductance component that form the filter are formed only by the electrodes and conductors formed in the dielectric coaxial resonator that forms the dielectric filter. It is characterized by having done. Therefore, the coupling terminal, the external capacitor element and the inductance element required in the conventional dielectric filter are unnecessary, and the input for connecting to these elements and the dielectric coaxial resonator mounting board or an external circuit. The output terminal can be eliminated.

The value of the trap capacitance Ct can be adjusted by changing the width of the inner conductor non-forming portion separating the tip conductor 7 and the inner conductor 3, and the value of the stray capacitance Cs can be adjusted. It can be appropriately set by changing the width and the distance between the tip conductor 7 and the outer conductor 4.

The value of the inductance L connecting between the resonators can be appropriately set by changing its shape, line width and the like. That is, although the inductance electrode is formed in a wave shape in this embodiment, it is not limited to this and may be formed in a linear shape as shown in FIG. 3 or may have another shape.

Further, the shape and the forming position of the input / output electrodes are
It is not particularly limited, and as shown in FIG. 3, it may be formed so as to extend from the open end face of the dielectric coaxial resonator corresponding to the input / output stage to the bottom face and the side face.

Further, in the above-mentioned embodiment, the connection of the adjacent inductance electrodes is connected by soldering a part of the inductance electrodes extended to the joint surface, but the invention is not limited to this, and it is not limited to this. The inductance electrode on the open end face may be connected by a conductor such as a metal piece.

In this embodiment, the dielectric filter having a three-stage structure has been described, but the present invention can be applied to a dielectric filter generally constituted by connecting a plurality of dielectric coaxial resonators.

[0029]

As described above, in the dielectric filter according to the present invention, not only the capacitance component constituting the filter but also the inductance component is formed only by the electrodes and conductors of the dielectric coaxial resonator constituting the filter. Therefore, the filter can be constructed only by joining a plurality of dielectric coaxial resonators. That is, the filter can be formed without using the coupling terminal, the external capacitor element, the inductance element, the coupling substrate on which these external components are mounted, the input / output terminal for connecting to the external circuit, and the like.

Therefore, according to the present invention, it is possible to greatly reduce the number of parts, and thus it is possible to greatly reduce the parts cost and the manufacturing cost, and it is possible to obtain an inexpensive and small dielectric filter.

[Brief description of drawings]

1A is an external perspective view of an end face of an open side of a dielectric filter in which three dielectric coaxial resonators according to an embodiment of the present invention are joined, and FIG. 1B is a dielectric view of FIG. The perspective view which shows the lower part which cut | disconnected and isolate | separated the body filter by the central horizontal surface, (c)
FIG. 4A is an external perspective view showing the bottom surface of the dielectric filter of FIG.

FIG. 2 is an external perspective view of each of the dielectric coaxial resonators constituting the dielectric filter as viewed from the open end surface.

FIG. 3 is an external perspective view of the dielectric filter according to another embodiment of the present invention as viewed from the open end surface.

FIG. 4 is an external perspective view showing an example of a conventional dielectric filter (band elimination filter).

FIG. 5 is an equivalent circuit diagram of a band elimination filter using a general dielectric coaxial resonator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric block 2 Resonator hole 3 Inner conductor 4 Outer conductor 5 Input / output electrode 6 Inductance electrode 7 Tip conductor 10, 11, 12 Dielectric coaxial resonator

Claims (1)

[Claims] 1. A dielectric filter in which a plurality of dielectric coaxial resonators are connected in parallel to form a filter, wherein an inner conductor and an outer conductor are provided in the vicinity of an open end face in a resonator hole of each of the dielectric coaxial resonators. A separate tip conductor is provided, an inductance electrode is formed on the open end surface of each dielectric coaxial resonator so as to be electrically connected to the tip conductor, and the tip electrodes of adjacent dielectric coaxial resonators are connected by the inductance electrode. A dielectric filter, wherein an input / output electrode electrically connected to the tip conductor is formed on an outer surface of a dielectric coaxial resonator corresponding to an output stage.