JP2561607Y2 - Dielectric band stop filter - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dielectric band rejection filter used for automobile telephones, portable telephones, satellite communications, and other mobile communications equipment.

[0002]

2. Description of the Related Art A plurality of dielectric resonator elements are arranged in parallel,
The dielectric filter in which the dielectric resonance elements are coupled by appropriate means is small and widely used particularly in the microwave band (for example, Japanese Utility Model Publication No. 2-47602).

When a band-pass filter is formed by combining a plurality of dielectric resonance elements, the dielectric resonance elements may be coupled by an interstage coupling capacitance or an inductor, and the number of components may be reduced. When a band rejection filter is configured by combining a plurality of dielectric resonance elements,
It is necessary to insert a capacitance for series resonance in series with each dielectric resonance element, and there is a problem that the number of components increases.

FIG. 9 shows a conventional dielectric band rejection filter.
This is an example, and FIG. 10 shows an equivalent circuit thereof. In these figures, A1 and A2 are quarter-wavelength coaxial dielectric resonance elements, which are formed on an inner peripheral surface of a rectangular cylindrical dielectric 2 with an inner conductor film 3 serving as a penetrating conductive portion 3A, and with an outer peripheral surface and The external conductor film 4 is formed on the short-circuit end face. Square cylindrical dielectric 2
The remaining surface is an open end surface where the dielectric is exposed,
The inner conductor film 3 and the outer conductor film 4 are connected at a short-circuit end face.

On the other hand, dielectric substrates B1 and B2 and dielectric plates D1 and D2 having conductor film electrodes formed on both surfaces thereof are used corresponding to the respective dielectric resonance elements.
The open end of the internal conductor film 3 serving as the penetrating conductive portion 3A of each of the dielectric resonance elements A1 and A2 is connected to the electrode 5 on the upper surface of D2 by soldering or the like via a connection conductor piece 6. The electrodes on the lower surfaces of the dielectric plates D1 and D2 are
Are connected and fixed to the electrode 7 on the upper surface of the substrate by soldering, a conductive adhesive or the like, respectively. Electrodes on the upper and lower surfaces of the dielectric plates D1 and D2 are used for the capacitances Ca ₁ and Ca ₂ for series resonance shown in FIG. Respectively. The dielectric resonator elements A1, A2
The external conductor film 4 and the electrodes on the lower surfaces of the dielectric substrates B1 and B2 are soldered to a metal case (or a ground conductor portion) (not shown) and connected and fixed with a conductive adhesive or the like. The capacitance C of FIG.
constitute a b _1, Cb _2. And the dielectric substrates B1, B
An air-core coil 8 as an inter-stage coupling inductance L in FIG. 10 is connected and fixed between the electrodes 7 on the upper surface 2 by soldering or the like. An input / output terminal 21 is connected and fixed to an end of each electrode 7 by soldering or the like.

[0006]

The conventional example shown in FIG. 9 uses a dielectric plate or a substrate having electrodes formed on both sides to form the respective capacitances Ca ₁ , Ca ₂ , Cb ₁ and Cb _2. In other words, in other words, it is necessary to use two dielectric plates or substrates constituting the capacitance for each dielectric resonance element, and the number of components is large, the number of assembly steps is increased, and the cost is increased. Further, since there is no means for adjusting the capacitance between the electrodes 7 on the upper surfaces of the dielectric substrates B1 and B2, when a chip inductor is used instead of the air-core coil 8, adjustment of the coupling coefficient (adjustment of the filter characteristics) ) Can not be done.

In view of the above, the present invention reduces the number of parts and the number of assembling steps by forming the capacitance required for a dielectric resonance element on a single dielectric substrate. Accordingly, an object of the present invention is to provide a low-cost and highly reliable dielectric band rejection filter.

[0008]

In order to achieve the above object, a dielectric band rejection filter according to the present invention comprises a plurality of dielectric resonators, and the same number of first capacitance electrodes as the number of the dielectric resonators. A second capacitor electrode formed on the first main surface and forming a capacitance between the second capacitor electrode and the first capacitor electrode on the second main surface opposite to the first main surface is the same in number as the first capacitor electrode. A common ground electrode that forms a capacitance between each of the first capacitance electrodes is formed on the second main surface, and a static ground electrode between adjacent first capacitance electrodes is formed.
The band-shaped extension electrodes for capacitance adjustment that constitute the capacitance
A dielectric substrate formed in close proximity to each of the first capacitance electrodes ; and an inductor connected between the adjacent first capacitance electrodes, wherein the dielectric resonance element is provided in the second capacitance electrode. The first electrodes respectively connected to capacitor electrodes and located at both ends of the dielectric substrate;
The input / output terminals are connected to the capacitance electrodes.

[0009]

[0010]

In the dielectric band rejection filter of the present invention, a capacitance for series resonance, a capacitance for grounding, and a static capacitance for adjusting inter-stage coupling are connected in series with each dielectric resonance element. Capacitance can be formed on one dielectric substrate, so that the number of parts can be greatly reduced and the number of assembly steps can be significantly reduced as compared with the conventional example. Also, by trimming the extension electrode portion for capacitance adjustment constituting the capacitance for interstage coupling, the coupling coefficient,
That is, the filter characteristics (mainly, the rejection bandwidth) can be easily adjusted.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a dielectric band rejection filter according to the present invention will be described below with reference to the drawings.

1 to 3 show a first embodiment of the present invention, and FIG. 4 shows an equivalent circuit thereof. In these figures,
First capacitor electrodes E1 and E2 corresponding to the dielectric resonator elements A1 and A2 are formed on the first main surface 11 which is the upper surface of the dielectric substrate 10, and the first capacitor electrodes E1 and E2 correspond to the lower surface (the surface opposite to the first main surface 11). Second capacitance electrodes F1 and F2 corresponding to the dielectric resonance elements A1 and A2 and one common ground electrode 13 are formed on the second main surface 12 respectively. A part of the first capacitance electrodes E1 and E2 and the second capacitance electrodes F1 and F2 are opposed to each other with the dielectric substrate 10 interposed therebetween to form the capacitances Ca ₁ and Ca ₂ of FIG. 4, respectively. Further, a part of the first capacitance electrodes E1 and E2 and the common ground electrode 13 are opposed to each other with the dielectric substrate 10 interposed therebetween, and constitute the capacitances Cb ₁ and Cb ₂ of FIG. 4, respectively.

The first capacitance electrodes E1 and E2 are integrally formed with a capacitance adjusting extension electrode portion 14 which constitutes the interstage coupling capacitance Cv between the first capacitance electrodes shown in FIG. . Each of the capacitance-adjusting extension electrode portions 14 has an elongated band shape, and is arranged at a position adjacent to and adjacent to each other. An air-core coil 15 as an inductance L for inter-stage coupling shown in FIG. 4 is connected and fixed between the first capacitance electrodes E1 and E2 by soldering or the like.

The second capacitor electrodes F1 and F2 are provided with an internal conductor film 3 serving as a penetrating conductive portion 3A of the dielectric resonance elements A1 and A2.
Are connected to each other by soldering or the like via connection conductor pieces 16. The configuration of each of the dielectric resonators A1 and A2 is the same as that of the conventional example, and
The second external conductor film 4 is connected and fixed to a metal case (or a ground conductor) (not shown) by soldering or using a conductive adhesive. It is necessary to keep a predetermined distance between the second main surface 12 of the dielectric substrate 10 and the inner surface of the metal case (or the ground conductor portion) facing the second main surface 12, so that the common ground electrode 13 and the metal case (or the ground conductor portion) are separated. ) Are connected directly or by another grounding member. Further, input / output terminals 21 are connected to the first capacitance electrodes E1 and E2 located at both ends in the longitudinal direction of the dielectric substrate 10 by soldering or the like.

According to the configuration of the first embodiment, the capacitance Ca _1, Ca _2, the capacitance of the ground for the series resonance connected in series to each dielectric resonator element A1, A2 C
Since b ₁ , Cb ₂ and the capacitance Cv for adjusting the coupling between stages can be formed on one dielectric substrate 10, the number of components can be greatly reduced and the number of assembly steps can be significantly reduced as compared with the conventional example.
In addition, by trimming the capacitance adjusting extension electrode portion 14 constituting the capacitance Cv for interstage coupling, the filter characteristics can be improved.
(Mainly the stop bandwidth) can be easily adjusted.

FIG. 5 shows a second embodiment of the present invention. In this case, a chip inductor 20 is used instead of the air-core coil 15, and the chip inductor 20 is connected to the first capacitance electrodes E1 and E1.
It is connected and fixed between the two by soldering or the like. In addition,
Conductive wires 22 for connection to input / output terminals are respectively connected to the first capacitance electrodes E1 and E2 located at both ends in the longitudinal direction of the dielectric substrate 10 by soldering or the like. Other configurations are the same as those of the first embodiment.

Also in this case, the filter characteristics can be easily adjusted by trimming the extension electrode portion 14 for capacitance adjustment which constitutes the capacitance Cv for interstage coupling.

FIG. 6 shows a third embodiment of the present invention. In this case, a dielectric band rejection filter is configured by using four dielectric resonator elements A1, A2, A3, and A4, and the electrodes on the dielectric substrate 10 side correspond to the increase in the number of dielectric resonator elements. Except that the number is also increased, it is the same as the first embodiment described above, and the same parts are denoted by the same reference numerals. That is,
First capacitance electrodes E1, E2, E3, and E4 corresponding to the dielectric resonator elements A1, A2, A3, and A4 are formed on the first main surface 11, which is the upper surface of the dielectric substrate 10, and the lower surface (first The second main surface, which is opposite to the main surface 11, has a dielectric resonance element A
Second capacitor electrodes and one common ground electrode corresponding to 1, A2, A3, and A4 are respectively formed by deposition.

FIG. 7 shows a third example using four dielectric resonance elements.
7 shows the frequency characteristics of the attenuation in the case of the embodiment, and shows the characteristics near the band rejection frequency band. FIG. 8 shows the frequency characteristic of the attenuation in the case of the third embodiment, which shows the characteristic over a wide frequency range. In FIG. 8, P is the original band rejection frequency band, and Q is the first capacitance electrodes E1, E2, E3, E
The attenuation effect as a low-pass filter is shown by the capacitance between the four common electrodes and one common ground electrode and the air-core coil 15 coupling between the stages.

Although the embodiments of the present invention have been described above, it is obvious to those skilled in the art that the present invention is not limited to the embodiments and various modifications and changes can be made within the scope of the claims. Would. For example, the number of dielectric resonator elements may be three or five or more, and each of the dielectric resonator elements may be cylindrical instead of square cylinder.

[0021]

As described above, according to the dielectric band rejection filter of the present invention, the required capacitance corresponding to the dielectric resonance element is formed on one dielectric substrate. In addition, the number of parts and the number of assembly steps can be reduced, and further, cost reduction and reliability can be improved. Also,
Extension electrode for capacitance adjustment that constitutes capacitance for interstage coupling
Is formed on the dielectric substrate, and the extension for adjusting the capacitance is formed.
Filter characteristics (mainly by trimming the electrode part)
Therefore, there is an advantage that the stop bandwidth can be easily adjusted.

[Brief description of the drawings]

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

FIG. 2 is a plan view showing the upper surface of the dielectric substrate used in the first embodiment.

FIG. 3 is a bottom view showing a part of the first embodiment in cross section.

FIG. 4 is an equivalent circuit diagram of the first embodiment.

FIG. 5 is a perspective view showing a second embodiment of the present invention.

FIG. 6 is a perspective view showing a third embodiment of the present invention.

FIG. 7 is a graph showing the frequency characteristics of the attenuation in the case of the third embodiment, showing the characteristics near the band rejection frequency band.

FIG. 8 is a graph showing the frequency characteristics of the attenuation amount in the case of the third embodiment, showing the characteristics over a wide frequency range.

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

FIG. 10 is an equivalent circuit diagram of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Dielectric substrate 11 1st main surface 12 2nd main surface 13 Common ground electrode 14 Capacity adjustment extension electrode part 15 Air core coil 16 Connection conductor piece 20 Chip inductor 21 Input / output terminal A1, A2, A3, A4 Dielectric resonance element E1, E2, E3, E4 First capacitance electrode F1, F2 Second capacitance electrode

Continuation of the front page (72) Inventor Kenji Endo 1-13-1 Nihonbashi, Chuo-ku, Tokyo Inside TDK Corporation (56) References JP-A-61-193501 (JP, A) JP-A-3-24801 ( JP, A)

Claims (1)

(57) [Scope of request for utility model registration] 1. A plurality of dielectric resonators, and the same number of first capacitance electrodes as the number of the dielectric resonators are formed on a first main surface, and a second main surface opposite to the first main surface is provided. Forming the same number of second capacitance electrodes as the first capacitance electrode with the first capacitance electrode, and forming a common ground electrode forming the capacitance with each of the first capacitance electrodes. An electrostatic capacitor formed on the second main surface and further between adjacent first capacitance electrodes;
The strip-shaped extension electrodes for capacitance adjustment that make up the volume
A dielectric substrate formed on each of the first capacitance electrodes, and an inductor connected between the adjacent first capacitance electrodes, wherein the dielectric resonance elements are respectively connected to the second capacitance electrodes. And an input / output terminal connected to each of the first capacitance electrodes located at both ends of the dielectric substrate.