CN115588830A

CN115588830A - Medium filter capable of optimizing in-band echo

Info

Publication number: CN115588830A
Application number: CN202211233619.8A
Authority: CN
Inventors: 朱琦; 何胜
Original assignee: Jiangsu Canqin Science And Technology Co ltd
Current assignee: Jiangsu Canqin Science And Technology Co ltd
Priority date: 2022-10-10
Filing date: 2022-10-10
Publication date: 2023-01-10

Abstract

The application discloses can optimize in-band echo's dielectric filter, include the body of being made by solid-state dielectric material and set up in this internal a plurality of resonant cavities, the coating of body surface has first conducting layer, the both ends of the electrode face of body are formed with the electrode contact face respectively, the electrode face is adjacent with the circuit face, two the electrode contact face extends to respectively circuit face, head and the tail the outside of resonant cavity is formed with input/output coupling hole respectively, two input/output coupling hole is located respectively two on the circuit face electrode contact face, input/output coupling hole inside be formed with connect in the second conducting layer of electrode contact face, head and the tail the inside of resonant cavity is formed with the third conducting layer. The invention can solve the problem of poor in-band echo index of a wide-band dielectric filter caused by weak tap coupling, thereby improving the overall performance of the filter.

Description

Medium filter capable of optimizing in-band echo

Technical Field

The application belongs to the technical field of communication, and particularly relates to a dielectric filter capable of optimizing in-band echo.

Background

The integrated dielectric filter is formed by sequentially forming N (N is more than or equal to 2) resonance through holes on a single dielectric, wherein the dielectric surface consists of an electrode surface, a circuit surface (open circuit surface) and a short circuit surface, and the dielectric surface and the resonance through holes are coated by a certain amount of silver layers. The electrode surface is composed of an input and output electrode silver layer and a grounding silver layer, the electrode is connected with the electrode of the circuit surface to form an input and output port, a coupling capacitor is formed between the input and output port silver layer and the head and tail resonant cavity silver layer on the circuit surface, tap coupling is commonly called, signals can enter the filter through the tap coupling to realize a filtering function, and the tap coupling strength of the filter directly influences the quality of in-band echoes of the dielectric filter.

Fig. 1 is a simulation diagram of a dielectric filter with a 5-cavity structure, the center frequency of the filter is-5500 MHz, the bandwidth of the filter is-700 MHz, a resistance welding groove of an electrode surface is designed into a U-shaped structure, an input/output port and a head-tail cavity are designed into a zigzag shape to maximize a tap coupling capacitance, and simulation optimization shows that the absolute value of an in-band echo index is only about 5dB, the effect is poor, and if the optimization is continuously performed on the basis of the existing design, the optimization is quite difficult.

The conventional structure design is adopted for the dielectric filter with smaller volume and wider passband, the area of a silver block which can be designed on the circuit surface is smaller, the tap coupling strength of the structure is mainly directly related to the distance between the silver layers of the input and output ports and the silver layers of the head and tail resonant cavities and the area of the silver layers, and the tap coupling strength required by the filter is in direct proportion to the passband width of the filter. In addition, the dielectric filter is limited by requirements of a processing technology, power and the like, the distance between the silver layers of the input/output port and the head and tail cavities of the dielectric filter cannot be designed to be too small, generally more than or equal to 0.1mm is recommended, the specific size is recommended to be determined according to the power requirement of a customer, and the design of the space between the too small silver layers has the risk of reliability.

Disclosure of Invention

The invention aims to provide a dielectric filter capable of optimizing in-band echo, which can solve the problem of poor in-band echo index caused by weak tap coupling of a class of broadband dielectric filters, thereby improving the overall performance of the filter.

The in-band echo is a main index for measuring whether signals in a filter pass band are well matched and transmitted, and the insertion loss and the in-band flatness in the pass band are directly influenced by the quality of the in-band echo index.

In order to achieve the purpose, the invention provides the following technical scheme:

the embodiment of the application discloses can optimize in-band echo's dielectric filter, include the body of making by solid-state dielectric material and set up in this internal a plurality of resonant cavities, the coating of body surface has first conducting layer, the both ends of the electrode face of body are formed with the electrode contact face respectively, the electrode face is adjacent with the circuit face, two the electrode contact face extends to respectively circuit face, head and the tail the outside of resonant cavity is formed with input/output coupling hole respectively, two input/output coupling hole is located respectively two on the circuit face electrode contact face, input/output coupling hole inside be formed with connect in the second conducting layer of electrode contact face, head and the tail the inside of resonant cavity is formed with the third conducting layer, the third conducting layer extends to the short-circuit face of body is formed with the fourth conducting layer, the third conducting layer extends to the circuit face connect in first conducting layer, the outside of fourth conducting layer be formed with the spaced resistance welding groove of first conducting layer.

Preferably, in the above dielectric filter that can optimize in-band echo, the resonant cavity is provided in plurality.

Preferably, in the above dielectric filter capable of optimizing in-band echo, two ends of the electrode surface are respectively formed with a U-shaped exposed surface through a de-conducting layer, and the U-shaped exposed surface and one edge of the electrode surface enclose the electrode contact surface.

Preferably, in the above dielectric filter capable of optimizing in-band echo, one side of the U-shaped exposed surface is the other edge of the electrode surface.

Preferably, in the above dielectric filter that can optimize in-band echo, the solid dielectric material is ceramic.

Preferably, in the above dielectric filter capable of optimizing in-band echo, the fourth conductive layer is circular or rectangular, and the shape of the solder resist trench is the same as that of the fourth conductive layer.

Preferably, in the above dielectric filter capable of optimizing in-band echo, the resonant cavity and the input-output coupling hole are circular, rectangular or other polygonal shapes.

Compared with the prior art, the invention has the advantages that: on the basis of the original structure, two sides of the structure are respectively added with a through hole as an input and output coupling hole of a signal, a silver layer of the coupling hole is connected with an electrode of a bottom circuit surface to perform short circuit treatment, a tap coupling capacitor is formed between the silver layers of the head and tail resonant cavities, and the size of the coupling capacitor is related to the distance between the two silver layers; the design distance between the input and output coupling holes at two sides and the head and tail resonant cavities also directly influences the size of the coupling capacitor, the minimum distance between the input and output through holes and the head and tail resonant through holes can be obtained through simulation in consideration of the processability of a medium body (the hole distance cannot be too small to influence the processing of the medium), and the head and tail resonant cavity silver layers on the front-end circuit surface need to be respectively connected with the upper surface, the side surfaces and the bottom surface for short-circuit treatment.

The circuit silver layer of the head-tail resonant cavity of the structure needs to be designed on a rear-end short-circuit surface, namely a parallel surface of a front-end circuit surface, and is subjected to open-circuit treatment (a way that the head-tail resonant cavity silver layer of the short-circuit surface is separated from a grounding silver layer by a resistance welding groove), the head-tail resonant cavity silver layer at the rear end of the filter can be designed into a circular ring shape or a rectangular shape, and the corresponding resistance welding groove can also be designed into a circular ring shape or a rectangular shape. The silver layer of the head-tail resonant cavity directly influences the frequency of the head-tail cavity, and the simulation can obtain that the frequency is reduced when the width of the solder resist groove of the rear-end head-tail resonant cavity is unchanged and the silver layer of the resonant cavity is increased; the width of the solder mask groove also influences the frequency of the head and tail cavities, and simulation shows that the frequency can be increased when the silver layer of the rear-end head and tail resonant cavity is unchanged and the width of the solder mask groove is increased.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments described in the present application, and other drawings can be obtained by those skilled in the art without creative efforts.

FIG. 1 is a simulation diagram in the background art;

FIG. 2 is a perspective view of a dielectric filter that optimizes in-band echo in an embodiment of the present invention;

FIG. 3 is a perspective view of another perspective of a dielectric filter that optimizes in-band echo in an embodiment of the present invention;

FIG. 4 is a simulation diagram illustrating an embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be described in detail below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without making any creative effort based on the embodiments in the present invention, belong to the protection scope of the present invention.

The following exemplifies a dielectric filter with a 5-cavity structure, the center frequency of the filter is 5500MHz, the bandwidth is-700 MHz, the center frequency is consistent with the index setting of the conventional scheme, the resistance welding groove of the electrode surface is designed into a U-shaped structure, through simulation adjustment, as shown in figure 4, the in-band echo index of the dielectric filter can be adjusted to a better state, and the in-band echo absolute value of the dielectric filter designed by the new scheme can be adjusted to about 20dB from 5dB of the conventional scheme, so that the performance index of the filter is improved to a greater extent.

Referring to fig. 2-3, the dielectric filter capable of optimizing in-band echo includes a body 100 made of a solid dielectric material and a plurality of resonators 101 opened in the body 100, an outer surface of the body 100 is coated with a first conductive layer 102, electrode contact surfaces 104 are respectively formed at two ends of an electrode surface 103 of the body 100, the electrode surface 103 is adjacent to a circuit surface 105, the electrode contact surfaces 104 respectively extend to the circuit surface 105, input and output coupling holes 106 are respectively formed at outer sides of the front-to-back resonators 101, the input and output coupling holes 106 are respectively located at the electrode contact surfaces 104 on the circuit surface 105, a second conductive layer connected to the electrode contact surfaces 104 is formed inside the input and output coupling holes 106, a third conductive layer is formed inside the front-to-back resonators 101, a fourth conductive layer 107 is formed at a short-circuited surface where the third conductive layer extends to the body 100, the third conductive layer extends to the circuit surface 105 and is connected to the first conductive layer 102, and a solder resist 108 spaced apart from the first conductive layer 102 is formed outside the fourth conductive layer 107.

The improved scheme can obtain larger performance improvement under the condition that the overall dimension of the dielectric filter is not changed or the smaller dimension is sacrificed, and mainly reflects the in-band echo index. The implementation mode of the scheme is as follows: on the basis of conventional design, two sides of the filter are respectively added with 1 input/output coupling through hole, the coupling through holes are connected with bottom input/output electrodes to perform short-circuit treatment to form input/output ports of the filter, coupling capacitors are formed between silver layers of the input/output ports and silver layers of front-end head-tail resonant cavities, and on the other hand, the coupling capacitors formed by mutual coupling between the coupling through holes and the head-tail resonant through holes are mutually superposed with the front-end head-tail resonant through holes, so that tap coupling of the dielectric filter can be increased to a greater extent, and the purpose of improving in-band echo indexes of the dielectric filter is achieved.

The circuit silver layer and the solder mask groove of the head-tail resonant cavity of the improved scheme are both arranged on the back end short circuit surface, and the frequency of the head-tail cavity can be adjusted by changing the size of the circuit silver layer of the head-tail resonant cavity or the width of the solder mask groove.

For a small-size broadband dielectric filter, the existing technology has high difficulty in implementation, mainly reflects the difference of in-band echo indexes, and is obviously limited in design, and the improved scheme can obtain great performance improvement by adding two coupling through holes in advance under the condition that the overall dimension of the dielectric filter is unchanged or the smaller dimension is sacrificed. The design is flexible, the processing is convenient, the process difficulty is avoided, and the filter is practical for the broadband dielectric filter.

The silver layer and the resistance welding groove on the head-tail resonant cavity circuit surface of the dielectric filter of the improved scheme can be designed into a circular ring shape, a rectangular shape or other irregular patterns, but the circular ring shape or the rectangular shape is preferably designed for convenient processing, and the circular ring shape is adopted in the above example.

The resonance through holes and the coupling through holes of the improved dielectric filter can be designed to be round, rectangular, oval and other polygons, but the round or oval shapes are also preferable for the convenience of processing, and the round shapes are adopted in the above examples.

Further, two ends of the electrode surface 103 are respectively formed into a U-shaped exposed surface 109 through the de-conducting layer, and the U-shaped exposed surface 109 and one edge of the electrode surface 103 enclose an electrode contact surface 104. One side of the U-shaped exposed face 109 is the other edge of the electrode face 103.

Further, the solid dielectric material is a ceramic.

The ceramic has high dielectric constant, hardness and high temperature resistance, so that the ceramic becomes a common solid dielectric material in the field of radio frequency filters.

Further, the conductive layer is silver.

The conductive layer is preferably a high-conductivity material such as silver.

It should be noted that, in this document, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising a … …" does not exclude the presence of another identical element in a process, method, article, or apparatus that comprises the element.

The foregoing is directed to embodiments of the present application and it is noted that numerous modifications and adaptations may be made by those skilled in the art without departing from the principles of the present application and are intended to be within the scope of the present application.

Claims

1. A dielectric filter capable of optimizing in-band echo comprises a body made of a solid dielectric material and a plurality of resonant cavities arranged in the body, wherein a first conductive layer is coated on the outer surface of the body, electrode contact surfaces are formed at two ends of an electrode surface of the body respectively, the electrode surface is adjacent to a circuit surface, and the two electrode contact surfaces extend to the circuit surface respectively.

2. The dielectric filter for optimizing in-band echoes according to claim 1, wherein the resonant cavity is provided in plurality.

3. The dielectric filter of claim 1, wherein the two ends of the electrode surface are each formed with a U-shaped exposed surface by a de-conducting layer, the U-shaped exposed surface and an edge of the electrode surface defining the electrode contact surface therebetween.

4. The dielectric filter of claim 3, wherein one side of the U-shaped exposed surface is the other edge of the electrode face.

5. The optimizable in-band echo dielectric filter of claim 1, wherein the solid dielectric material is ceramic.

6. The dielectric filter capable of optimizing in-band echo according to claim 1, wherein the fourth conductive layer is circular or rectangular, and the solder resist groove has the same shape as the fourth conductive layer.

7. The dielectric filter of claim 1, wherein the resonator and the input-output coupling aperture are circular, rectangular or other polygonal shapes.