JPH07297603A - Dielectric filter - Google Patents

Abstract

PURPOSE:To provide a compact and high quality dielectric filter which can improve its working environment together with its cost reduction and also has its characteristic that can be automatically controlled by providing the conductor electrodes to form a trimming capacitor on a ceramic substrate which includes a wiring conductor. CONSTITUTION:The conductor electrodes 7 and 8 are placed opposite to each other on both sides of a ceramic substrate 3. Thus both electrodes 7 and 8 hold the substrate 3 between them and form a trimming capacitor. The electrode 8 is connected to an inner conductor 1a of a resonator 1 via a connection lead wire 9, and the electrode 7 is connected to a frame 2 via a wiring conductor. The trimming capacitor consisting of both electrodes 7 and 8 is provided on each resonator 1. In regard of control of the filter characteristic, a slit 7' is added to the electrode 7 by a laser beam with use of an automatic laser trimming machine while the filter's general characteristic is observed. Thus the area of the electrode 7 is reduced and the electrostatic capacity of the electrode 7 is also reduced to its opposite electrode 8.

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 as a high frequency functional component for communication equipment.

[0002]

2. Description of the Related Art A dielectric filter using a plurality of dielectric resonators is a bandpass filter in a high frequency stage or an intermediate frequency stage of a wireless communication device, an antenna duplexer or a duplexer for transmitting / receiving one antenna. Many are used as wave instruments. FIG. 4 is a perspective view of a conventional dielectric filter (A).
FIG. 3B is a partial cross-sectional view (B), showing an antenna duplexer in which five dielectric resonators 1 are arranged on each of the transmitting side and the receiving side. In FIG. 4A, 2 is a metal frame for fixing the plurality of resonators 1. Reference numeral 4 is an antenna connection terminal, 5 is a transmission side terminal, and 6 is a reception side terminal, which are fixed to the printed wiring board 30 and are connected to a wiring conductor provided on the resonator side surface to form a filter circuit. There is. Reference numeral 35 is a screw for adjusting the filter characteristic, the details of which are shown in FIG.
Next, description will be made with reference to the partial sectional view shown in FIG.

A prismatic dielectric resonator 1 has a hole penetrating its center axis, and an inner conductor 1a is provided on the inner surface of the hole.
The outer conductor 1b is provided on the outer surface of the prism, and the inner conductor 1a and the outer conductor 1b are short-circuited by the conductor provided on the other end surface. There is no conductor on the end face facing the printed wiring board 30, and the open end 1c is formed. The outer conductor 1b of the dielectric resonator 1 arranged side by side on the frame 2 is fixed to the frame 2 by soldering. 31 is a wiring conductor provided on the printed wiring board 30;
Reference numeral 32 is a connecting conductor wire between the wiring conductor 31 and the inner conductor 1a of the resonator 1, 33 is a conductor continuous to the wiring conductor 31 and is a through-hole conductor for guiding the adjusting screw 35, and 34 is a guide for the adjusting screw 35. The bobbin 10 is a fixed capacitor. After the individual dielectric resonators 1 are adjusted and assembled as shown in FIG. 4A, the screw 35 is rotated to adjust the overall characteristics of the dielectric filter.

FIG. 2 is a partial electrical equivalent circuit diagram of the dielectric filter of FIG. 4, showing the vicinity of two resonators 1. The adjustment by the adjusting screw 35 described above corresponds to changing the capacitance value of the variable capacitor 11.

As a method for adjusting the overall characteristics of the filter, in addition to the method using the adjusting screw 35 described above, a high-speed diamond cutter is used without using the adjusting screw 35 to adjust the open end 1c of the dielectric resonator 1. A method for changing the resonance frequency of the resonator 1 by cutting the corners, or a method for changing the resonance frequency of the resonator 1
There is a method to change the capacitance value of.

[0006]

The above conventional structure has the following drawbacks when adjusting the overall characteristics of the filter. (1) Although the method using the adjusting screw 35 can be adjusted while observing the filter characteristics, the material cost and the processing cost of the screw 35 and its guide portion are required, and there is a large restriction for downsizing. Furthermore, after adjusting the characteristics, there is a risk that the characteristics will change due to loosening of the screws. (2) In the method using cutting, the filter characteristics cannot be observed during cutting and cutting and trying are required, so the experience and skill of the operator are required, and it is difficult to reduce the adjustment man-hours and the number of operators is limited. . Moreover, the cutting tool needs to be replaced frequently, resulting in poor workability and non-mass production.
Further, in the cutting process, a lot of dust is generated and scattered, and adheres to the product to deteriorate the quality and contaminate the working environment.

It is an object of the present invention to provide a dielectric filter which can avoid the above-mentioned conventional drawbacks, reduce the cost, reduce the size, improve the quality, improve the working environment, and can automatically adjust. It is in.

[0008]

In the dielectric filter of the present invention, all side surfaces except one end surface of the prismatic dielectric having a hole penetrating the central axis, the inner surface of the hole and the other end surface are A plurality of dielectric resonators covered with a conductor, the conductors on all the side surfaces are outer conductors, the conductor on the inner surface of the hole is an inner conductor, and the one end surface is an open end, and the plurality of dielectric resonators, A metal frame having the open ends juxtaposed side by side and fixed to the outer conductor surface by soldering, and fixed to the frame at a predetermined distance from the open end at a right angle to the frame. A ceramic substrate provided with a wiring conductor that electrically connects the plurality of dielectric resonators to each other to form a filter circuit on an end surface and a filter input terminal and an output terminal connected to the wiring conductor. The ceramic substrate, the plurality of Conductor electrodes for forming trimming capacitors are provided on both sides of the ceramic substrate at positions corresponding to the respective open ends of the electric resonators, and the conductor electrodes inside the conductor electrodes are respectively connected to the dielectric resonators. It is characterized in that it is connected to the inner conductor by a conductive wire, and the outer conductor electrode is connected to the frame by a wiring conductor.

[0009]

1 is a structural diagram showing an embodiment of the present invention,
(A) is a perspective view, (B) is a partial sectional view, and (C) is a partial front view. In the figure, the dielectric resonator 1, the metal frame 2, the antenna connection terminal 4, the transmission side terminal 5, the reception side terminal 6, and the fixed capacitor 10 are the same as those in the conventional configuration shown in FIG. Reference numeral 3 is a ceramic substrate which is a main part of the present invention. Reference numerals 7 and 8 denote conductor electrodes provided on both sides of the ceramic substrate 3 so as to face each other, and the electrodes 7 and 8 form a trimming capacitor with the ceramic substrate 3 interposed therebetween. Reference numeral 9 is a connecting conductor wire between the electrode 8 and the inner conductor 1a of the resonator 1. The electrode 7 is connected to the frame 2 by a wiring conductor.

A trimming capacitor formed by the electrodes 7 and 8 is provided in each resonator 1. The shaded portion of the electrode 7 is the portion to be trimmed, and the electrode portion is cut by the laser beam to reduce the electrode area. Reference numeral 7'denotes a slit indicating a portion cut by laser light, which is a portion cut by an automatic laser trimming machine while observing the overall characteristics of the filter. Therefore, the number and length of the slits 7 ′ of the plurality of electrodes 7 after the filter characteristic adjustment are
It is not constant and varies depending on the characteristics, and there are various things such as one without slit 7 ', one that cuts electrode 7, and one that has a plurality of slits 7'.

The electrical equivalent circuit of the dielectric filter according to the present invention is shown by the partial equivalent circuit shown in FIG.
The trimming capacitor 8 is represented by a variable capacitor 11. When the slit 7'is formed in the electrode 7 by the laser light, the capacitance with the opposing electrode 8 becomes small. From this, it is clear that the trimming capacitor according to the present invention corresponds to the trimming structure using the conventional adjusting screw 35. Therefore, it is possible to perform dynamic trimming to obtain desired characteristics by changing the electrostatic capacity by processing with laser light while observing the filter characteristics. Moreover, since there is no mechanically movable part such as a screw, the characteristics are adjusted stably, and there is no possibility that the characteristics will change after the adjustment is completed.

FIG. 3 is a block diagram showing a configuration example of an automatic adjustment system for a dielectric filter according to the present invention. A characteristic measuring device 2 for measuring the characteristics of the dielectric filter 20 embodying the present invention
1 is sequentially measured and input to the computer 22, and the necessity of adjustment is judged by comparing with a desired characteristic value preset in the computer 22, and when a characteristic difference is detected, the difference is 0.
The laser trimming device 23 is supplied with a control signal that causes the laser light 24 to irradiate the electrode 7 of the trimming capacitor of the dielectric filter 20 to control the cutting process. Since the laser light 24 does not affect the characteristics of the dielectric filter 20, the characteristics can be adjusted according to the processing amount. Since a very small amount of dust generated during processing is absorbed by the dust collector provided in the laser trimming device 23, there is no risk of adhering to the product or scattering to the surroundings and polluting the environment.

In the above-mentioned embodiments, the dielectric resonator 1 is composed of five filters, each of which has a transmitter filter and a receiver filter. It is obvious that the same effect can be obtained by applying the present invention to one or a plurality of mounted dielectric filters.

[0014]

As described in detail above, the following effects can be obtained by implementing the present invention. (1) Since there are no mechanically movable parts, the material cost and the processing cost are reduced, the size is reduced, and the quality is improved. (2) A small amount of dust is collected due to the laser processing, so that it is not attached to the product and environmental pollution can be prevented. (3) Since automatic trimming can be performed, a skilled worker for adjustment work is not required and mass productivity is improved.

[Brief description of drawings]

FIG. 1 is a structural diagram showing an embodiment of the present invention.

FIG. 2 is a partial electrical equivalent circuit of a dielectric filter.

FIG. 3 is a block diagram of an automatic trimming system showing an application example of the present invention.

FIG. 4 is a diagram showing an example of a conventional structure.

[Explanation of symbols]

 1 Dielectric Resonator 1a Inner Conductor 1b Outer Conductor 1c Open End 3 Ceramic Substrate 4, 5, 6 Terminal 7, 8 Electrode 7'Slit 8 Wiring Conductor 9 Connection Conductor 10 Fixed Capacitor 11 Variable Capacitor 20 Dielectric Filter 21 Characteristic Measuring Device 22 Computer 23 Laser Trimming Device 24 Laser Light 30 Printed Wiring Board 31 Wiring Conductor 32 Connection Conductive Wire 33 Through Hole 34 Guide Bobbin 35 Adjustment Screw

Claims (1)

[Claims] 1. Except for one end surface of a prismatic dielectric having a hole penetrating the central axis, all side surfaces, the inner surface of the hole and the other end surface are covered with a conductor, and the conductor on all the side surfaces is covered by an outer surface. A plurality of dielectric resonators which are conductors and whose inner surface is a conductor and whose one end surface is an open end; and a plurality of these dielectric resonators which are arranged side by side with their open ends aligned. Is fixed to the frame by soldering, and is fixed to the frame at a predetermined distance from the open end at a right angle to the frame, and the plurality of dielectric resonators are provided on the surface on the open end side. And a ceramic substrate provided with a wiring conductor that is electrically connected to form a filter circuit and an input terminal and an output terminal of the filter that are connected to the wiring conductor, and the plurality of dielectrics are provided on the ceramic substrate. Corresponding to each open end of the resonator Conductor electrodes for forming capacitors for trimming are provided on both sides of the ceramic substrate at a position, the conductor electrodes inside the conductor electrodes are connected to the inner conductors of the dielectric resonator by conductors, and the outer conductors A dielectric filter, wherein the electrodes are connected to the frame by wiring conductors.