JPH0865011A - Dielectric filter - Google Patents

Abstract

PURPOSE: To provide the inexpensive dielectric filter of a standardized shape capable of easily obtaining the filter characteristics of different stage numbers without changing the shape of a dielectric block. CONSTITUTION: In this dielectric filter for which coupling electrodes 6a-6d conducted with internal conductors 3 and separated from an external conductor 4 and the adjacent internal conductors 3 are formed corresponding to respective resonator holes 2a-2d on an open side end face and input/output electrodes 5 are formed adjacently to the coupling electrodes 6a and 6d equivalent to input/output stages, a pair of the adjacent coupling electrodes 6b and 6c are connected by a short-circuit electrode 7. By this constitution, one resonator is formed by the resonator holes 2b and 2c corresponding to the coupling electrodes 6b and 6c. That is, the dielectric filter of four-stage constitution is turned to three-stage constitution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric filter used in a mobile communication device such as a mobile phone, and more particularly, a plurality of dielectric resonators are integrally formed in a single dielectric block to cause resonance. The present invention relates to a dielectric filter having a pattern electrode formed on the opening surface of a device hole.

[0002]

2. Description of the Related Art A conventional dielectric filter having a pattern electrode composed of a plurality of electrodes formed on the opening surface of a resonator hole has, for example, a structure shown in FIG. In addition, in the following figures, the dot-filled portion indicates a portion where the base material of the dielectric block is visible (conductor non-formation portion).

In this dielectric filter, as shown in FIG. 5, for example, four resonator holes 2a to 2d are formed by penetrating a pair of opposing surfaces of a substantially rectangular parallelepiped dielectric block 1. Inner conductors 3 are formed on the inner surfaces of the resonator holes 2a to 2d. An outer conductor 4 is formed on substantially the entire outer surface of the dielectric block 1 except one opening surface (hereinafter, referred to as an open end surface) of the resonator holes 2a to 2d. Each inner conductor 3
Is electrically connected (short-circuited) to the outer conductor 4 at the other opening surface of the resonator holes 2a to 2d facing the open end surface (hereinafter referred to as the short-circuit end surface).

On the open side end face, a coupling electrode 6 is formed in the center thereof so as to be electrically connected to the inner conductors 3 of the resonator holes 2a to 2d.
a to 6d, and input / output electrodes 5 and 5 are formed on both side edges thereof so as to face the coupling electrodes 6a and 6d. On the lower surface (bottom surface) which is the mounting surface, the connecting portions of the input / output electrodes 5 and 5 are formed.

This dielectric filter is composed of coupling electrodes 6a to 6a.
Resonators formed for each resonator hole 2a to 2d due to each stray capacitance formed between 6d and the outer conductor 4 and each coupling capacitance formed between each coupling electrode 6a to 6d. Are coupled to each other, and a filter characteristic including four-stage resonators is obtained as shown in FIG. External coupling capacitors are formed between the coupling electrodes 6a and 6d and the input / output electrodes 5 and 5, respectively.

In this dielectric filter, the coupling relationship between the resonators is changed by changing the shapes of various electrodes formed on the open end face, the gaps between the various electrodes, and the values of stray capacitance and coupling capacitance. Capacitive coupling or inductive coupling) and the degree of coupling are adjusted and set to obtain a desired bandwidth or the like.

[0007]

In the conventional filter described above, if the number of stages of the filter, that is, the number of resonator holes is determined, the basic characteristics of the filter are almost determined. The number of resonator holes has been increased or decreased to change the number of filter stages. In other words, if you need dielectric filters with different characteristics,
Each time, a dielectric block is required according to the required characteristics, standardization of the dielectric block is difficult, and there is a problem that the manufacturing cost such as molding die cost and material management cost becomes high.

Further, there is a problem that the dimension between the input and output electrodes cannot be standardized, and the mounting substrate cannot be standardized.

Therefore, an object of the present invention is to solve the above-mentioned problems of the conventional dielectric filter and to easily obtain filter characteristics having different stages without changing the shape of the dielectric block. Therefore, it is possible to provide an inexpensive and standardized dielectric filter.

[0010]

In order to achieve the above object, the invention according to claim 1 forms a plurality of resonator holes between a pair of opposed end faces of a dielectric block, and A coupling electrode having an inner conductor formed on the inner surface thereof, an outer conductor formed on the outer surface of the dielectric block, and electrically connected to the inner conductor and separated from the outer conductor and an adjacent inner conductor at one opening surface of the resonator hole. In the dielectric filter having the structure described above, a short-circuit electrode is formed between the coupling electrodes, and adjacent coupling electrodes are connected by the short-circuit electrode.

The invention according to claim 2 is the invention according to claim 1, wherein an input / output electrode is formed adjacent to the coupling electrode corresponding to the input / output stage.

[0012]

In the invention according to claim 1, by connecting the coupling electrodes, which are electrically connected to the respective inner conductors of the adjacent resonator holes, by the short-circuit electrodes, a plurality of resonator holes connected by the short-circuit electrodes can be formed. A stage resonator is formed. As a result, a plurality of resonator holes can be formed in the dielectric block to form a dielectric filter having a smaller number of stages than the number of resonator holes.

According to the second aspect of the present invention, the input / output electrodes can be connected to the external circuit without using a connection terminal or the like.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings showing the embodiments thereof. In the figure, the same or corresponding parts and those having the same functions as those in the conventional example are designated by the same reference numerals.

The structure and filter characteristics of the dielectric filter according to the first embodiment of the present invention are shown in FIGS. FIG. 1 is an external perspective view of the dielectric filter as seen from the open end face side, and FIG. 2 is a diagram in which the center frequency is formed at about 830 MHz.
5 is a diagram showing frequency attenuation characteristics and frequency reflection loss of the dielectric filter shown in FIG.

As shown in FIG. 1, a short-circuit electrode 7 is formed between the coupling electrodes 6b and 6c which are electrically connected to the inner conductors 3 and 3 of the resonator holes 2b and 2c of the dielectric filter of this embodiment. The electrode 7 electrically connects the coupling electrodes 6b and 6c. Other structures are the same as those of the conventional dielectric filter shown in FIG. 5, and the description thereof is omitted. That is, this dielectric filter has four resonator holes 2
a to 2d are formed, and the outer dimensions, the shapes and dimensions of the input / output electrodes are the same as those shown in FIG.

In this structure, since the adjacent coupling electrodes 6b and 6c are connected by the short-circuiting electrode 7, one resonator is formed by the two resonator holes 2b and 2c corresponding to the two bonding electrodes 6b and 6c. As a result, as shown in FIG. 2, it was possible to obtain a filter characteristic including a three-stage resonator.

That is, this dielectric filter is composed of a resonator formed by the resonator hole 2a, a resonator formed by the resonator holes 2b and 2c, and a resonator formed by the resonator hole 2d.
It consists of two resonators. That is, FIG.
In the dielectric filter including the four-stage resonator shown in, the three-stage dielectric filter is configured by connecting the coupling electrodes that are electrically connected to the inner conductors of the pair of adjacent resonator holes with the short-circuit electrode. You can In this case, the characteristic impedance of the resonator equivalent to one resonator due to the short-circuit electrode is about 1 / about that of the other resonators.
It is considered to be 2.

The dielectric filter composed of the three-stage resonators thus obtained has three resonator holes.
It is possible to obtain an attenuation characteristic different from that of the filter including the resonators in stages. For example, the amount of attenuation outside the pass band can be increased.

Furthermore, by changing the shape and width of the short-circuit electrode, the filter characteristics such as the amount of attenuation outside the pass band can be changed, and desired filter characteristics can be easily obtained. This is considered to be due to the influence of the inductance component of the short-circuit electrode.

Next, FIG. 3 shows the structure of a dielectric filter according to the second embodiment of the present invention. FIG. 3 is a plan view of the open end surface of the dielectric filter. As shown in FIG. 3, short-circuit electrodes 7 and 7 are formed between the coupling electrodes 6a and 6b and between the coupling electrodes 6b and 6c of the dielectric filter of this embodiment. 6b and the coupling electrodes 6b and 6c are electrically connected. Other structures are the same as those of the conventional dielectric filter shown in FIG. 5, and the description thereof is omitted.

In this configuration, the two short-circuit electrodes 7,
By connecting adjacent coupling electrodes 6a, 6b, 6c at 7, one resonator is formed by the three resonator holes 2a, 2b, 2c corresponding to the three bonding electrodes 6a, 6b, 6c, and two resonators are formed. It is possible to obtain a dielectric filter composed of the resonator. That is, the dielectric filter including the four-stage resonator can be a two-stage dielectric filter.

Also in this configuration, it is possible to obtain a filter characteristic having a larger out-of-band attenuation than the two-stage dielectric filter formed by two resonator holes, and the shape and width dimension of the short-circuit electrode. By changing, the filter characteristic can be changed and the desired filter characteristic can be easily obtained.

In each of the above embodiments, the short-circuit electrode is formed by one straight line, but the present invention is not limited to this. For example, the shape of the short-circuit electrode is crank-shaped as shown in FIG. Alternatively, the filter characteristics may be further varied by changing the shape of the short-circuit electrode. The shape, number, and width dimension of the short-circuit electrodes are appropriately set according to the required filter characteristics.

In the above embodiment, the dielectric filter having four resonator holes formed in the dielectric block has been described, but the present invention is not limited to this, and the dielectric block may have two or more resonator holes. The present invention can be applied to the formed dielectric filter. For example, a dielectric filter composed of five-stage resonators in which five resonator holes are formed in a dielectric block has four stages,
The dielectric filter may have a three-stage structure, a two-stage structure, and a one-stage structure.

Further, in each of the above-mentioned embodiments, the input / output electrodes are formed for connection with the external circuit. However, the connection terminals may be used to connect to the external circuit without forming the input / output electrodes. Good. Further, in order to increase the stray capacitance formed between the coupling electrode and the outer conductor, the outer conductor may be formed on a part of the peripheral portion of the open side end face.

[0027]

As described above, according to the present invention,
Since one resonator can be obtained with a plurality of resonator holes corresponding to the plurality of coupling electrodes connected by the short-circuit electrode,
It is possible to easily realize a dielectric filter including resonators having a smaller number of stages than the number of resonator holes, without changing the shape and size of the dielectric block.

Therefore, a dielectric block having a different number of stages can be constructed with one shape of the dielectric block, and the dielectric blocks can be shared and standardized, so that the productivity is improved, the die cost and the cost are reduced. Material management costs and the like can be reduced, and thus manufacturing costs can be significantly reduced. Further, the standardization of the dielectric block standardizes the shapes and dimensions of the input / output electrodes, so that the pattern of the mounting board can be standardized, the mounting becomes easy, and the mounting cost can be reduced.

By appropriately setting and adjusting the shape, width dimension, etc. of the short-circuit electrode, various filter characteristics corresponding to the required characteristics can be easily obtained.

[Brief description of drawings]

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

FIG. 2 is a diagram showing filter characteristics of the dielectric filter shown in FIG.

FIG. 3 is a plan view of an open end face of a dielectric filter according to a second embodiment of the present invention.

FIG. 4 is a diagram showing a modification of the shape of the short-circuit electrode of the present invention.

FIG. 5 is an external perspective view of a conventional dielectric filter.

FIG. 6 is a diagram showing filter characteristics of the dielectric filter shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Dielectric block 2a-2d Resonator hole 3 Inner conductor 4 Outer conductor 5 Input / output electrode 6, 6a-6d Coupling electrode 7 Short-circuit electrode

Claims (2)

[Claims] 1. A plurality of resonator holes are formed between a pair of opposed end faces of a dielectric block, an inner conductor is formed on an inner surface of the resonator hole, and an outer conductor is formed on an outer surface of the dielectric block. A dielectric filter having a coupling electrode that is electrically connected to the inner conductor and is separated from the outer conductor and an adjacent inner conductor on one opening surface of the resonator hole, wherein a short-circuit electrode is formed between the coupling electrodes. A dielectric filter, wherein adjacent coupling electrodes are connected by the short-circuit electrode. 2. The dielectric filter according to claim 1, wherein an input / output electrode is formed adjacent to the coupling electrode corresponding to the input / output stage.