JP3071528B2 - Dielectric filter - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention related <br/> the dielectric filter obtained by forming a ground electrode and the resonance electrode dielectrics block.

[0002]

2. Description of the Related Art A dielectric resonator in which a resonance electrode (inner conductor) is formed inside a dielectric block and a ground electrode (outer conductor) is formed on the outer surface of the dielectric block, and a resonance electrode is formed on the surface of a dielectric substrate. A dielectric resonator in which a (strip line) is formed and an earth electrode is formed on the opposing surface is used, for example, as a band-pass filter in a microwave band.

FIGS. 26 and 27 show examples of a conventional dielectric resonator obtained by bonding two dielectric substrates.

FIG. 26 is an exploded perspective view of a dielectric resonator. In FIG. 26, reference numerals 1 and 2 denote dielectric substrates, respectively. The first principal surface (upper surface in the figure) of the dielectric substrate 1
The resonance electrodes 3a, 3b, 3c, 3d are provided, and the signal input / output electrodes 6a, 6b are formed from the first main surface of the dielectric substrate 1 to the second main surface via the side surface. In addition, ground electrodes 4 are formed on the four side surfaces excluding the signal input / output electrode formation portion and on the second main surface (the back surface in the figure). Ground electrodes 5 are formed on the second main surface (the surface in the figure) and four side surfaces of the dielectric substrate 2 except for the vicinity of the signal input / output electrodes 6a and 6b.

FIG. 27 is a perspective view of a dielectric resonator with the dielectric substrate 1 shown in FIG. 26 facing upward. Thus, FIG.
A dielectric resonator acting as a four-stage bandpass filter is formed by superposing and joining the two dielectric substrates 1 and 2 shown in FIG.

[0006]

By the way, the transmission / reception duplexer in the microwave band is provided with a transmission filter and a reception filter, and as the reception filter, the attenuation of the reception band is small and the attenuation of the transmission band is sufficiently large. Characteristics are required.

In general, a band-pass filter must be able to obtain a predetermined amount of attenuation in a band apart from the pass band width. To this end, an effective method is to provide a pole in the attenuation region (hereinafter referred to as polarization). Is effective. However, in the dielectric resonator having the structure shown in FIGS. 26 and 27, one or more resonators could not be skipped and the preceding and following resonators could not be directly electromagnetically coupled, and could not be polarized. . The resonance electrode is not closed in the two dielectric substrates as shown in FIG. 26. For example, a resonance electrode forming hole having a circular cross section is provided in the dielectric, and the resonance electrode is provided on the inner surface thereof. Polarization is possible by inserting a coupling terminal from the outside into the formation hole and coupling between the resonators of a predetermined stage, but a special component for directly coupling the resonators is required, For example, it is not suitable for a dielectric resonator of a surface mount type on a substrate.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an attenuation pole by polarization without adding any special parts , and to provide a circuit board surface
Another object of the present invention is to provide a dielectric filter which can be surface-mounted .

[0009]

[0010]

According to a first aspect of the present invention, there is provided a dielectric resonator comprising: a dielectric block having a plurality of through holes with two opposing surfaces as opening surfaces; In a dielectric resonator in which a resonance electrode is formed and a ground electrode and a signal input / output electrode are provided on an outer peripheral surface, a ground electrode is formed on the two opposing surfaces of the dielectric block, and one of the resonance electrodes is formed. places the end electrically connected to the grounding electrode on one opening surface of the through hole, in which each of the other end portion, recessed from the other opening face of the front SL through hole
An open end substantially equal to the inner diameter of the other opening surface;
And provided, on an outer peripheral surface of the dielectric block, the coupling electrodes for organic poling for each capacitive coupling in the vicinity of the open end of the predetermined two resonance electrodes that do not bind to the input and output electrodes of the plurality of resonance electrodes It is characterized by having been formed.

According to a second aspect of the present invention, there is provided a dielectric resonator, wherein a resonance electrode is formed inside each through hole with respect to a dielectric block having a plurality of through holes with two opposing surfaces as opening surfaces. In a dielectric resonator having a ground electrode and a signal input / output electrode provided on a surface thereof, ground electrodes are formed on the two opposite surfaces of the dielectric block, and one end of each of the resonance electrodes is provided with the through hole. while conducting the ground electrode at the opening surface of each of the other end portion, the other portion where recessed from the opening face of the front SL through hole, the other opening of the
An open end substantially equal to the inner diameter of the surface is provided, and on the outer peripheral surface of the dielectric block, a polarized coupling electrode capacitively coupled to a resonance electrode adjacent to a resonance electrode capacitively coupled to the signal input / output electrode is provided. It is characterized by being formed in a continuous electrode shape from the input / output electrodes.

[0012]

[Action] In the dielectric resonator of claim 1, wherein the dielectric Bro
Tsu coupling electrode for polarized into the outer peripheral surface of the click is provided at a part of the ground electrode formation region, the coupling electrode is a dielectric block
Are respectively coupled to the plurality of resonance electrodes formed inside the through holes . Therefore, the plurality of resonance electrodes are coupled via the capacitor. For example, in a band-pass filter having three or more stages, an attenuation pole is formed on the high band side of the pass band by capacitively coupling the first and second resonance electrodes through the coupling electrode. Further, for example, in a five-stage band-pass filter, if the second-stage and fourth-stage resonance electrodes are capacitively coupled via a coupling electrode, an attenuation pole is formed on the lower side of the pass band.

As described above, polarization can be performed only by separating a part in the formation region of the ground electrode as a coupling electrode, and no special component for polarization is required, and the characteristics are improved. Can be achieved. Also, the open end of the resonant electrode
A place deeper than one of the openings of the through hole of the electronic block
And a ground electrode is formed on the opening surface
Therefore, electromagnetic field leakage from the open end of the resonant electrode is extremely small.
Absent. Therefore, a special shielding member must be provided.
No, as a surface mount type dielectric filter
Can be used. That is, other components on the circuit board
Even when surface-mounted in close proximity to other components or circuit boards
Unnecessary coupling with the above wiring causes a signal leakage problem
Absent.

In the dielectric resonator according to the second aspect, since the signal input / output electrode is also used as a coupling electrode, the signal input / output electrode also serving as the coupling electrode is provided only by being provided in a part of the ground electrode formation. Can be performed. Normally, the signal input / output electrode is coupled to the first-stage resonance electrode and the last-stage resonance electrode. Can be capacitively coupled by the signal input / output electrodes, thereby obtaining a bandpass filter having an attenuation pole on the high frequency side. Dielectric filter having the above configuration
Is capacitively coupled to the signal input / output electrode of the plurality of resonance electrodes.
Between the resonant electrode and the adjacent resonant electrode
, And polarized with signal input / output electrode and its continuous shape
Can be provided in a limited space.
A coupling electrode for polarization can be formed together with signal input / output electrodes.
You. Therefore, a small dielectric filter with a small number of resonator stages
Even in the case of ruta, polarization is possible. Claim 1
As in the case of (1), the problem of electromagnetic field leakage does not occur.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, as a reference example, the configuration and characteristics of a four-stage bandpass filter are shown in FIGS.

FIG. 1 is an exploded perspective view of the filter. FIG.
, 1 and 2 are dielectric substrates, respectively. Four resonance electrodes 3a, 3b, 3c, 3d are provided on a first main surface (upper surface in the drawing) of the dielectric substrate 1, and a second main surface (lower surface in the drawing) is formed from two opposing side surfaces of the dielectric substrate 1. ), Two signal input / output electrodes are formed. Reference numeral 6a in the figure denotes a signal input / output electrode appearing on one side.
Except for these signal input / output electrode formation regions, ground electrodes 4 are formed on the four side surfaces and the second main surface of the dielectric substrate 1. On the other hand, the first main surface (the lower surface in the figure) of the dielectric substrate 2
No earth electrode 5 is formed on the four side surfaces and the second main surface (the upper surface in the drawing) except for the vicinity of the signal input / output electrode formation portion on the dielectric substrate 1 side.

FIG. 2 is a perspective view of a filter having the dielectric substrate 1 shown in FIG. 1 facing upward, and a comb line is formed by overlapping and joining the two dielectric substrates 1 and 2 shown in FIG. A four-stage bandpass filter of the type is obtained. 2, the signal input / output electrode 6b is capacitively coupled to the vicinity of the open end of the resonance electrode 3d shown in FIG. The signal input / output electrode 6a is shown in FIG.
Are capacitively coupled to the vicinity of each open end of the resonance electrodes 3a and 3b.

FIG. 3 is a vertical sectional view passing through the signal input / output electrode in FIG. However, hatching is omitted for clarity of the drawings (the same applies to other cross-sectional views referred to hereinafter). Thus, the signal input / output electrode 6a is connected to the resonance electrode 3b.
Of the electrode 6a
Act as coupling electrodes. That is, capacitive coupling is performed between the resonance electrodes 3a and 3b via the electrode 6a.

FIGS. 4 and 5 are equivalent circuit diagrams of the above filter. In FIG. 4, Ra to Rd are resonators formed by the resonance electrodes 3a to 3d shown in FIGS. 1 and 3, and Ca, Cb, and Cd are capacitances generated between each resonance electrode and the signal input / output electrode shown in FIG. In the equivalent circuit shown in FIG.
The equivalent circuit as shown in FIG. 5 is obtained by Δ-Y conversion of the coupling capacitance between the resonators Ra and Rb and the capacitances Ca and Cb formed between the resonance electrode and the signal input / output electrode. Thus, an attenuation pole is generated on the high frequency side due to the series resonance of the resonator Ra and the inductive reactance L1.

FIG. 6 is an attenuation characteristic diagram of the above filter.
In FIG. 6, P is an attenuation pole. Since the attenuation pole is generated on the high band side of the pass bandwidth in this way, the high band side of the pass bandwidth can be cut off sharply.For example, using this band pass filter as a reception filter, the frequency of the attenuation pole can be reduced. By making the transmission frequency band coincide with the lower side of the transmission frequency band, the transmission signal band can be sufficiently suppressed.

Next, a configuration of an interdigital type four-stage bandpass filter is shown in FIGS. 7 to 10 as another reference example .

FIG. 7 is an exploded perspective view of the filter. FIG.
, 1 and 2 are dielectric substrates, respectively. Four resonance electrodes 3a to 3d are provided on a first main surface (upper surface in the figure) of the dielectric substrate 1, and a second resonance electrode 3a to 3d is formed from two opposing side surfaces.
The signal input / output electrodes 6a,
6b is provided. Further, the signal input / output electrodes 6a, 6
Ground electrodes 4 are formed on the four side surfaces and the second main surface of the substrate excluding the region where b is formed. On the other hand, no electrodes are provided on the first main surface (the lower surface in the figure) of the dielectric substrate 2 and the dielectric substrate 1
The ground electrode 5 is formed on the four side surfaces and the second main surface (the upper surface in the drawing) except for the portion near the signal input / output electrode on the side.

FIG. 8 is a perspective view of the filter. Thus, an interdigital type four-stage bandpass filter is obtained by superposing and joining the two dielectric substrates 1 and 2 shown in FIG. In FIG. 8, the signal input / output electrode 6
b is inductively coupled to the resonance electrode 3d shown in FIG. Since the signal input / output electrode 6a of FIG. 8 extends to near the open end of the resonance electrode 3b, it is inductively coupled to the resonance electrode 3a of FIG. 7 and capacitively coupled to the resonance electrode 3b.

FIG. 9 is a vertical sectional view passing through the signal input / output electrode 6a in FIG. Thus, the signal input / output electrode 6a
Generates a capacitance Cb with the second-stage resonance electrode 3b and is capacitively coupled.

FIG. 10 is an equivalent circuit diagram of the above filter. In FIG. 10, Ra to Rd are resonators composed of the resonance electrodes 3a to 3d shown in FIGS. As described above, since the second-stage resonator is coupled to the signal input / output terminal via the capacitor Cb, an attenuation pole is generated on the high frequency side as in the case of the first embodiment.

[0026] <First Embodiment> Next, integral comb line type using a dielectric block 4
The configuration of the stage bandpass filter is shown in FIGS.

FIG. 11 is a perspective view of the filter. FIG.
, 8a to 8d are inner conductor forming holes. A comb line type inner conductor is formed in each of the inner conductor forming holes 8a to 8d. Signal input / output electrodes 6a and 6b are provided on a part of the outer surface of the dielectric block, and the outer conductor 7 is provided on the outer surface of the dielectric block except for the area where the signal input / output electrodes are formed.
Is formed.

FIG. 12 is a vertical sectional view passing through the signal input / output electrode in FIG. 12, reference numerals 3a to 3d denote inner conductors formed on the inner surfaces of the inner conductor forming holes 8a to 8d shown in FIG. The signal input / output electrode 6a is capacitively coupled to the vicinity of the open end of the inner conductor 3a, and the signal input / output electrode 6b is connected to the inner conductor 3c.
And 3d are capacitively coupled to the vicinity of the open end. Also in the band-pass filter according to the third embodiment, an attenuation pole is generated on the high frequency side similarly to the first and second embodiments.

Second Embodiment Next, an integrated comb line type 4 using a dielectric block is described.
The configuration of the stage bandpass filter is shown in FIGS.

FIG. 13 is a perspective view of the filter. FIG.
The difference from the example shown in FIG. 9 is that not only the signal input / output electrode 6b but also the coupling electrode 6a is used.

FIG. 14 is an equivalent circuit diagram. In FIG. 14, Ra to Rd are resonators formed by inner conductors provided in the inner conductor forming holes 8a to 8d. Ca and Cb are the resonators Ra,
The capacitance formed between Rb and the signal input / output electrode 6a, Cc,
Cd is a capacitance formed between the resonators Rc and Rd and the signal input / output electrode 6b. By doing so, two attenuation poles are generated on the higher side of the pass bandwidth.

Third Embodiment Next, the configuration of an integrated interdigital four-stage bandpass filter using a dielectric block will be described with reference to FIGS.
6 is shown.

FIG. 15 is a perspective view of the filter. FIG.
In the figures, reference numerals 8a to 8d denote inner conductor forming holes provided in the dielectric block, and inner conductors are formed on the inner surface in an interdigital type. Further, signal input / output electrodes 6a and 6b are formed in predetermined regions on the outer surface of the dielectric block.

FIG. 16 is a schematic plan view showing the positional relationship between the signal input / output electrodes and the inner conductor. In FIG. 16, 3a-3
d is an inner conductor, which is arranged in an interdigital type. The signal input / output electrode 6a is capacitively coupled to the vicinity of the open end of the inner conductor 3a. The signal input / output terminal 6b is capacitively coupled to the vicinity of the open end of the inner conductor 3c and the vicinity of the open end of the inner conductor 3d. With this structure, it functions as a band-pass filter having an attenuation pole on the high frequency side similarly to the filter shown in FIG. 11 as a comb-line type example.

Fourth Embodiment Next, the configuration of a band-pass filter having a plurality of inner conductors having a circular cross section by combining two dielectric substrates is shown in FIGS.

FIG. 17 is an exploded perspective view of the filter. In FIG. 17, reference numerals 1 and 2 denote dielectric substrates, respectively. The first main surface (upper surface in the figure) of the dielectric substrate 1 is provided with five grooves having a semicircular cross section, and the inner conductors are respectively provided on the inner surfaces thereof.
3e. Further, signal input / output electrodes are provided on two opposing side surfaces of the dielectric substrate 1. 6b is 1
Signal input / output electrodes appearing on the side. Except for these signal input / output electrode formation regions, outer conductors 4 are formed on the four side surfaces and the second main surface (the lower surface in the figure) of the dielectric substrate 1. On the other hand, the first main surface (the lower surface in the figure) of the dielectric substrate 2
Has five grooves having the same semicircular cross section, and has an inner conductor formed on the inner surface thereof. A coupling electrode 9 is provided on a predetermined region of the second main surface (the upper surface in the drawing) of the dielectric substrate 2.
Is formed. Further, the outer conductor 5 is formed on the four side surfaces and the second main surface of the substrate except for the coupling electrode forming region.

FIG. 18 is a perspective view of the filter. In this manner, the two dielectric substrates shown in FIG.
e.

FIG. 19 is a schematic plan view showing the positional relationship between the inner conductor and the coupling electrode. In FIG. 19, reference numerals 3a to 3e denote inner conductors formed in a comb line shape on the inner surfaces of the inner conductor forming holes 10a to 10e shown in FIG. As shown in the figure, the vicinity of the open ends of the inner conductors 3b and 3d is capacitively coupled to the coupling electrode 9, respectively.

FIG. 20 is an equivalent circuit diagram of the above filter. Here, Ra to Re are resonators constituted by the inner conductors 3a to 3e shown in FIGS. Cb,
Cd is the capacitance formed between the inner conductors 3b and 3d and the coupling electrode 9 shown in FIG. 19, and Ca and Ce are between the inner conductor 3a and the signal input / output electrode 6a and between the inner conductor 3e and the signal input / output electrode 6b. This is the capacity that is formed. As described above, the capacitive coupling between the second stage and the fourth stage of the five-stage band-pass filter causes the attenuation pole P to fall in the lower band of the pass bandwidth as shown in FIG.
Occurs.

Fifth Embodiment Next, an example of an interdigital band-pass filter having a plurality of inner conductors having a circular cross section by combining two dielectric substrates is shown in FIGS.

FIG. 22 is an exploded perspective view of the filter. 17 is different from the example shown in FIG. 17 in the arrangement of the inner conductors 3a to 3e of the interdigital type and the arrangement of the coupling electrode 9 for capacitively coupling the second to fourth inner conductors. FIG.
23 is formed by overlapping and joining two dielectric substrates shown in FIG.

FIG. 24 is a schematic plan view showing the positional relationship between the inner conductor and the coupling electrode of the filter shown in FIG. As described above, capacitance is generated between the open ends of the inner conductors 3b and 3d and the coupling electrode 9, respectively. With this configuration, as in the case of the sixth embodiment, an attenuation pole is generated on the low frequency side.

Sixth Embodiment Next, FIG. 25 shows an example in which a coupling electrode is formed on the same surface as a signal input / output electrode. 25 is different from the example shown in FIG. 18 in that the signal input / output electrodes 6a and 6b are
It is provided on the side. Thus, the coupling electrode 9 may be provided on the mounting surface side with respect to the substrate.

[0044]

According to the first aspect of the present invention, the dielectric resonator can be polarized without using any special parts. For example, in a band-pass filter, the high frequency side and / or the low frequency range are used. By providing an attenuation pole on the side, signals in unnecessary bands can be sufficiently attenuated. Also, the open end of the resonance electrode
A part deeper than one of the openings of the through hole of the dielectric block
Ground electrode on the opening surface.
Therefore, electromagnetic field leakage from the open end of the
Few. Therefore, it is necessary to provide special shielding members.
As a surface mount type dielectric filter
Can be used. That is, other parts on the circuit board
Even when surface-mounted close to the product, other components and circuit
Unwanted coupling with wiring on the board causes signal leakage
I do not. According to the second aspect of the present invention, a plurality of shared
A resonant electrode capacitively coupled to the signal input / output electrode
Signal input / output so that it straddles the adjacent resonant electrode
An electrode and a coupling electrode for polarization in a shape following it
Signal input / output electrodes in a limited space.
At the same time, a coupling electrode for polarization can be formed. for that reason,
In the case of a small dielectric filter with a small number of resonator stages
Can also be polarized.

[0045]

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a filter according to a reference example .

FIG. 2 is a perspective view of a filter according to a reference example .

FIG. 3 is a vertical sectional view passing through input / output electrodes 6a and 6b in FIG.

FIG. 4 is an equivalent circuit diagram of a filter according to a reference example .

FIG. 5 is an equivalent circuit diagram obtained by modifying FIG. 4;

FIG. 6 is a characteristic diagram of a filter according to a reference example .

FIG. 7 is an exploded perspective view of a filter according to another reference example .

FIG. 8 is a perspective view of a filter according to another reference example .

FIG. 9 is a vertical sectional view passing through a signal input / output electrode 6a in FIG.

FIG. 10 is an equivalent circuit diagram of a filter according to another reference example .

FIG. 11 is a perspective view of a filter according to the first embodiment.

FIG. 12 is a vertical sectional view passing through signal input / output electrodes 6a and 6b in FIG.

FIG. 13 is a perspective view of a filter according to a second embodiment.

FIG. 14 is an equivalent circuit diagram of the filter according to the second embodiment.

FIG. 15 is a perspective view of a filter according to a third embodiment.

FIG. 16 is a schematic plan view showing a positional relationship between an inner conductor and a signal input / output electrode of a filter according to a third embodiment.

FIG. 17 is an exploded perspective view of a filter according to a fourth embodiment.

FIG. 18 is a perspective view of a filter according to a fourth embodiment.

FIG. 19 is a schematic plan view showing a positional relationship between an inner conductor and a coupling electrode of a filter according to a fourth embodiment.

FIG. 20 is an equivalent circuit diagram of a filter according to a fourth embodiment.

FIG. 21 is a characteristic diagram of a filter according to a fourth embodiment.

FIG. 22 is an exploded perspective view of a filter according to a fifth embodiment.

FIG. 23 is a perspective view of a filter according to a fifth embodiment.

FIG. 24 is a schematic plan view showing a positional relationship between an inner conductor and a coupling electrode of a filter according to a fifth embodiment.

FIG. 25 is a perspective view of a filter according to a sixth embodiment.

FIG. 26 is an exploded perspective view of a conventional dielectric resonator.

FIG. 27 is a perspective view of a conventional dielectric resonator.

[Explanation of symbols]

 1,2-dielectric substrate 3a-3e-resonant electrode, inner conductor 4,5-ground electrode 6a, 6b-signal input / output electrode 7-outer conductor 8a-8d-inner conductor forming hole 9-coupling electrode 10a-10e- Inner conductor formation hole

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Yukihiro Kitaichi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Murata Manufacturing Co., Ltd. (56) References JP-A-3-212001 (JP, A) JP-A Heisei JP-A-2-295201 (JP, A) JP-A-3-125502 (JP, A) JP-A-3-6101 (JP, A) JP-A-61-230403 (JP, A) JP-A-61-172402 (JP, A A) JP-A-62-104201 (JP, A) JP-A-62-73801 (JP, A) JP-A-3-98506 (JP, U) JP-A-2-145804 (JP, U) JP-A-4 -116403 (JP, U) US Patent 4,418,324 (US, A)

Claims (2)

(57) [Claims] 1. A dielectric block provided with a plurality of through holes having two opposing surfaces as opening surfaces, a resonance electrode is formed inside each through hole, and a ground electrode and a signal input / output electrode are formed on an outer peripheral surface. In the dielectric resonator, ground electrodes are formed on the two opposing surfaces of the dielectric block, and one end of each of the resonance electrodes is connected to the ground electrode at one opening surface of the through hole. is conducted to each of the other end portion, the other portion where recessed from the opening face of the front SL through hole, substantially equal to the inside diameter of the other opening face
Correct provided as an open end, the the outer circumferential surface of the dielectric block, coupling for chromatic poling for each capacitive coupling in the vicinity of the open end of the predetermined two resonance electrodes that do not bind to the input and output electrodes of the plurality of resonance electrodes A dielectric filter having electrodes formed thereon. 2. A dielectric block provided with a plurality of through holes having two opposing surfaces as opening surfaces, a resonance electrode is formed inside each through hole, and a ground electrode and a signal input / output electrode are formed on the outer peripheral surface. In the dielectric resonator, ground electrodes are formed on the two opposing surfaces of the dielectric block, and one end of each of the resonance electrodes is connected to the ground electrode at one opening surface of the through hole. is conducted to each of the other end portion, the other portion where recessed from the opening face of the front SL through hole, substantially equal to the inside diameter of the other opening face
An open end, which is capacitively coupled to an outer peripheral surface of the dielectric block adjacent to a resonance electrode capacitively coupled to the signal input / output electrode and to a resonance electrode not coupled to another signal input / output electrode. A dielectric filter, wherein a coupling electrode for polarization is formed in an electrode shape continuous from the signal input / output electrode.