KR20020006098A - An integrated dielectric filter - Google Patents

Abstract

PURPOSE: An integrated dielectric filter is provided to improve attenuation property and minimize insertion loss by forming a conductive pattern to surround resonant holes. CONSTITUTION: A dielectric filter consists of a dielectric block(101) which includes a front surface(105) facing a rear surface, and side surfaces between the front surface and the rear surface. A conductive material is coated on the rear surface and the side surfaces to form a ground electrode(103). The front surface(105) is not coated with a conductive material, to form an open surface. A plurality of resonant holes(107a,107b,107c) are formed inside the dielectric block(101) to substantially pass through the front surface(105) and the rear surface in a parallel manner. An internal electrode is coated on an inside surface of the resonant holes(107a,107b,107c) to form a resonator. Input/output pads are formed on a side surface of the dielectric block(101) to be shorted to the ground electrode. The input/output pads are inserted from the ground electrode in a form that a part of the ground electrode is removed. An open area where a conductive material is not coated is formed between the input/output pads and the ground electrode so as to be isolated from each other. The second pattern(115) having a predetermined width is formed on the front surface and takes a closed curve form surrounding the resonant holes(107a,107b,107c) and the first conductive patterns(111a,111b,111c).

Description

Integrated dielectric filter {AN INTEGRATED DIELECTRIC FILTER}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated dielectric filter, and more particularly, to an integrated dielectric filter capable of forming a strong attenuation pole on the low frequency side by forming a conductor pattern surrounding a resonance hole on an open surface of the dielectric block.

In general, a dielectric filter is obtained by connecting a plurality of dielectric blocks provided with a coaxial resonator to obtain desired passband characteristics. An integrated dielectric filter is an advanced filter in the dielectric filter, and a plurality of coaxial resonators in one dielectric block. To simplify the structure.

The dielectric filter is used as a bandpass filter in order to obtain a signal of a desired channel band only in a mobile communication device such as a car phone or a mobile phone using a high frequency band as a communication band. Therefore, the dielectric filter is miniaturized. , Light weight and high impact resistance are required, and the bandpass characteristic of 20-30MHz is required.

1 to 3 show a conventional general integrated dielectric filter. 1 relates to an integrated dielectric filter in which coupling holes 9 are formed between resonance holes 7 and 8, and the mutual inductance and mutual capacitance between the resonators are adjusted by the coupling holes. The integrated dielectric filter of the above structure is made of a dielectric block, and the side and rear surfaces of the integrated dielectric filter except for the open surface of the front surface are coated with a conductive material. A coupling hole 9 is formed between the resonance holes 7 and 8 of the open surface, and the mutual inductance and mutual capacitance are determined by the size, length, position, etc. of the coupling hole 9. However, in the integrated dielectric filter, since the coupling holes 9 must be formed by a mechanical method, it is difficult to form the dielectric filter and the mechanical strength is lowered. As a result, it is difficult to meet the requirements of current mobile communication devices. have.

2 and 3 are diagrams illustrating dielectric filters in which coupling holes are not formed between the resonance holes 7 and 8, unlike the integrated dielectric filters illustrated in FIG. 1. In the figure, in the integrated dielectric filter shown in Figs. 2 and 3, the resonator is coupled by processing the resonant holes instead of forming the coupling holes between the resonant holes 7,8. First, in the integrated dielectric filter illustrated in FIG. 2, as shown in FIG. 2B, the resonator holes 7 and 8 have different inner diameters and are coupled between the resonators. That is, as shown in the figure, when the resonant holes (7, 8) are formed by varying the size of the inner diameter is coupled between the resonators by the difference in characteristic impedance due to the inner diameter difference. Since the dielectric filter having such a shape must have a different internal diameter of a resonance hole having a relatively smaller size than that of the dielectric filter shown in FIG. 1, it is complicated to manufacture and it is difficult to obtain a uniform molded body.

In addition, unlike other dielectric filters, another dielectric filter illustrated in FIG. 3 forms an electrode by applying a conductive material to all surfaces of the dielectric block 1 without an open surface, and forms the electrodes in the resonance holes 7 and 8. The electrodes of the specific portions 17 and 18 are removed to form a resonance period. This dielectric filter has a problem that it is difficult to accurately remove the electrode at any position on the inner surface of the small resonance holes 7 and 8.

In general, nowadays, when the distance between communication channels is getting closer, higher attenuation characteristics are required for the dielectric filter, and especially in the case of being very close such as a transmission channel and a receiving channel, a higher attenuation ratio is required in a specific band. For example, in the case of a dielectric filter having a transmission channel as a pass band, a higher attenuation ratio is required in the low frequency region so that a signal of a reception channel close to the low frequency region is not mixed with respect to the pass band. The dielectric filter has not been able to meet these requirements and is difficult to manufacture, and thus has practical limitations.

In view of this point, the integrated dielectric filter provided in recent years is a dielectric filter as shown in FIG. As shown in the figure, in the dielectric filter, conductor patterns 11a and 11b of a predetermined size are formed around the open surface of the dielectric block 1, that is, around the resonance hole of the front surface 5. The conductor patterns 11a and 11b are connected to internal conductive materials coated in the resonance holes 7a and 7b to form coupling capacitances between the resonators to form attenuation poles in the low frequency region of the pass band. In the above dielectric filter, the manufacturing method is simplified because the resonator is coupled by simply forming the conductor patterns 11a and 11b around the resonant holes 7a and 7b of the dielectric block 1 opening surface 5. Although there is an advantage, in order to form a coupling capacitance of a predetermined size or more, the area of the conductor patterns 11a and 11b must be enlarged, so there is a problem in forming a small dielectric filter.

In order to solve this problem, various types of integrated dielectric filters can be provided, and as an example, Patent Application No. 98-27437 filed by the applicant of the present invention has been proposed. As shown in FIG. 5, the patent application No. 98-27437 discloses a conductive pattern 15 having a predetermined width along the arrangement direction of the resonance holes 7a, 7b, and 7c in the open surface 5 of the dielectric block 1. ), The coupling capacitance between adjacent resonators is strengthened by the conductor pattern 15, thereby forming a stronger attenuation pole in the low frequency region of the pass band.

However, in the conventional integrated dielectric filters, when the strong attenuation poles are formed in the low frequency region of the pass band, that is, when the attenuation poles are transferred to the pass band to form an ideal pass band having a characteristic waveform of a square wave shape, the transition of the attenuation poles is performed. As the passband is shifted, the desired passband cannot be obtained. In this process, the insertion loss of the passband increases.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. An integrated dielectric filter capable of improving attenuation characteristics and minimizing insertion loss by forming a conductor pattern shorted to the ground electrode on the front open surface of the dielectric block to surround the resonance hole. The purpose is to provide.

In order to achieve the above object, the integrated dielectric filter according to the present invention has at least a portion of the front surface of which the conductive material is not applied and at least a portion of the rear surface of which the conductive material is coated and a ground electrode coated with the conductive material between the front and the rear surface. A roughly rectangular dielectric block having the formed side surface, a plurality of through holes penetrating substantially parallel to the front and rear surfaces of the dielectric block, and having internal electrodes formed on the inner surface thereof, and formed around the front and through holes of the dielectric block. A plurality of first conductor patterns connected to the internal electrodes to form a resonator; and a closed curve formed on a front surface of the dielectric block to short-circuit with the ground electrode and surrounding at least one resonance hole and the first conductor pattern. It consists of a second conductor pattern which forms a coupling capacitance between the resonators.

1 is a view showing a conventional integrated dielectric filter.

Figure 2 (a) is a perspective view of another conventional one-piece dielectric filter.

(B) is sectional drawing of FIG.

Figure 3 (a) is a perspective view of another conventional dielectric filter.

(B) is sectional drawing of FIG.

4 is a view showing a conventional integrated dielectric filter in which a conductor pattern around a resonance hole in a dielectric block opening surface is formed;

5 is a diagram illustrating a conventional dielectric filter in which a conductor pattern is disposed along an arrangement direction of a resonance hole on a dielectric block opening surface;

6 illustrates an integrated dielectric filter in accordance with an embodiment of the present invention.

7 (a) to 7 (e) show another embodiment of the present invention.

8 is a graph showing characteristic curves of the integrated dielectric filter and the conventional dielectric filter according to the present invention.

Explanation of symbols on the main parts of the drawings

101: dielectric block 103: ground electrode

105: front side (open side) 107: resonance hole

111: first conductor pattern 115: second conductor pattern

The present invention provides an integrated dielectric filter having a strong attenuation pole in the low frequency region of the pass band and having a desired pass bandwidth. That is, since the passband is not reduced while the attenuation pole is formed closer to the passband, the insertion loss of the passband can be minimized.

In order to form such a strong attenuation electrode, in the present invention, a conductor pattern is formed on the open surface of the dielectric block to reinforce the attenuation electrode. The conductor pattern is basically formed in a closed curve surrounding at least the resonance hole, but such a shape is not limited. That is, a closed curve surrounding one or two resonance holes may also be used in the present invention.

Hereinafter, an integrated dielectric filter according to the present invention will be described in detail with reference to the accompanying drawings.

6 is a view showing a preferred embodiment of the integrated dielectric filter according to the present invention. As shown in the figure, the dielectric filter of the present invention is composed of a dielectric block 101 composed of a front surface 105 and a rear surface facing each other and a side between the front surface 105 and each other. A conductive material is applied to the rear and side surfaces to form the ground electrode 103, and the front surface 105 forms an open surface to which the conductive material is not applied. In addition, a plurality of resonance holes 107a, 107b, and 107c penetrate substantially parallel to the front surface 105 and the rear surface of the dielectric block 101, and although not shown in the drawings, the resonance holes 107a, 107b and 107c have internal electrodes made of a conductive material on their inner surfaces to form resonators.

Although not shown in the drawing, an input / output pad shorted to the ground electrode is formed on the side of the dielectric block 101. The input / output pads 110a and 110b are insulated from the ground electrode by removing a part of the ground electrode, and are formed over the other surface adjacent to one surface of the side surface. That is, an open area to which the conductive material is not applied is formed between the input / output pad and the ground electrode and is shorted to each other.

The front surface 105 of the dielectric block 101 forms an open surface to which no conductive material is applied, and is connected to the conductive material inside the resonance holes 107 and 108 around the resonant holes 107a, 107b and 107c of the front surface 105. The first conductor patterns 111a, 111b, and 111c having a predetermined size are formed. The first conductor patterns 111a, 111b, and 111c add a load capacitance to the resonator, and form a coupling capacitance between adjacent resonators to couple the resonators.

In addition, a second width of the second conductive pattern 115 is formed on the front surface 105 of the dielectric block 101. As shown in the figure, the second conductor pattern 115 is formed in a closed curve so as to surround the resonance holes 107a, 107b, and 107c and the first conductor patterns 111a, 111b, and 111c, and a dielectric block. It is short-circuited with the ground electrode 103 formed in the side surface (101). The second conductor pattern 115 forms a coupling capacitance between adjacent resonators. That is, in the integrated dielectric filter of the present invention, not only the first conductor patterns 111a, 111b, and 111c but also the second conductor pattern 115 also form coupling capacitance to form dielectrics having only the first conductor patterns 111a, 111b, and 111c. It is different from the filter.

FIG. 8 shows characteristic curves of the integrated dielectric filter of the present invention in which the first conductor pattern and the second conductor pattern are formed, and the conventional integrated dielectric filter in which only the first conductor pattern is formed. In the figure, the characteristic curve ⓐ is the characteristic curve of the integrated dielectric filter in which only the first conductor pattern is formed, and the characteristic curve ⓑ is the characteristic curve of the integrated dielectric filter in which the first conductor pattern and the second conductor pattern are formed. As shown in the figure, in the characteristic curve ⓐ formed by the coupling capacitance of only the first conductor pattern, the attenuation pole (marked as Δ in the figure) is formed far from the pass band BW, while the second conductor pattern is formed. It can be seen that in the characteristic curve ⓑ formed by, the attenuation electrode approaches the pass band by Δf as compared with the characteristic curve ⓐ. Also, in this case, it can be seen that the bandwidth is the same as the characteristic curve ⓐ despite the movement of the attenuation poles. This indicates that the attenuation electrode is moved toward the pass band by the second conductor pattern, so that the attenuation characteristic is improved, but insertion loss due to the decrease of the pass bandwidth does not occur.

As described above, in the integrated dielectric filter of the present invention, the attenuation characteristic of the dielectric filter is greatly improved by the second conductor pattern surrounding the resonance hole on the open surface of the dielectric block, and the insertion loss in the bandwidth does not occur. Has

In the integrated dielectric filter of the present invention, the second conductor pattern formed on the open surface of the dielectric block is not limited to the shape shown in FIG. 6 and may have various shapes. 7 (a) to 7 (e) show another embodiment of the present invention. In the drawing, since the entire dielectric block has the same structure and only the second conductor patterns 111a, 111b, and 111c of the front surface 105 of the dielectric block are different, only the front surface 105 of the dielectric block 101 will be described. do.

First, in the integrated dielectric filter of FIG. 7A, the second conductor pattern 115 is formed around the resonant holes 107a, 107b, and 107 in the open surface of the front surface 105 of the dielectric block 105. Not only surround the first conductor patterns 111a, 111b and 111c connected to the internal electrodes on the inner surface of the resonant holes 107a, 107b and 107c, but also the respective resonant holes 107a, 107b and 107c and the first conductor pattern. Conductor patterns are also formed between (111a, 111b, 111c). That is, the three resonant holes 107a, 107b, and 107c and the first conductor patterns 111a, 111b, and 111c are not only surrounded by the ground electrode of the dielectric block and the second conductor pattern 115 which is shorted, but also the respective resonances. The holes 107a, 107b and 107c and the first conductor patterns 111a, 111b and 111c are also separated from the adjacent resonance holes by the second conductor pattern 115.

Like the dielectric filter shown in FIG. 6, the dielectric filter having the second conductor pattern 115 having such a shape has an advantage that the attenuation characteristic of the filter is improved and the insertion loss of the pass bandwidth is not reduced.

In the dielectric filter illustrated in FIG. 7B, unlike FIG. 7A, one resonance hole 107b and the first conductor pattern 111b are surrounded by the second conductor pattern 115. In addition, the second conductor pattern 115 is connected to the conductor pattern surrounding the resonance hole 107b and is formed on the bottom surface of the resonance holes 107a, 107b, and 107c along the arrangement direction of the resonance holes 107a, 107b, and 107c. It consists of arranged conductor patterns. The dielectric filter illustrated in FIG. 7C includes a conductor pattern in which the second conductor pattern 115 is disposed on the bottom surface of the resonance holes 107a, 107b, and 107c along the arrangement direction of the resonance holes 107a, 107b, and 107c. Consists of a conductor pattern surrounding the outer resonant holes (107a, 107c), the integral dielectric filter shown in Figure 7 (d) is a second conductor pattern 115 surrounding the two resonant holes (107b, 107c). It is included. In this case, although the second conductor pattern 115 surrounds the central resonance hole 107b and the right resonance hole 107c in FIG. 7 (d), the second resonance pattern 107b and the left resonance hole 107a are formed. The same effect may be obtained by forming the enclosing second conductor pattern 115.

In addition, in FIG. 7E, conductor patterns disposed on upper and lower surfaces of the resonance holes 107a, 107b, and 107c along the arrangement direction of the resonance holes 107a, 107b, and 107c, and the resonance holes 107a, 107b, and 107c. The second conductor pattern 115 formed of a conductor pattern formed between the first and second ends is formed. The resonance hole 107b in the center is surrounded by the second conductor pattern 115 by the second conductor pattern 115.

As described above, in the present invention, the attenuation characteristic of the integrated dielectric filter is improved by forming a closed curved conductor pattern which surrounds at least one resonance hole on the open surface of the dielectric block and is shorted with the ground electrode formed on the side of the dielectric block. At the same time, it is possible to minimize the insertion loss caused by the reduction of the bandwidth.

Claims (5)

A substantially rectangular dielectric block having at least a portion of a front surface not coated with a conductive material and at least a portion of a rear surface coated with a conductive material and a side surface of the ground electrode coated with a conductive material between the front surface and the rear surface; A plurality of through holes penetrating substantially parallel to the front and rear surfaces of the dielectric block and having internal electrodes formed on inner surfaces thereof; A plurality of first conductor patterns formed on the front surface of the dielectric block and around the through holes and connected to the internal electrodes to form a resonator; And An integrated dielectric filter formed on a front surface of the dielectric block to have a short circuit with the ground electrode and having a closed curve surrounding at least one resonant hole and the first conductor pattern to form a coupling capacitance between the resonators. . The dielectric filter of claim 1, wherein the second conductor pattern surrounds both the plurality of resonance holes and the first conductor pattern. The method of claim 1, wherein the second conductor pattern is connected to at least one of the conductor pattern and the third conductor pattern formed on at least one of the four corners or the bottom of the resonance hole along the direction of the resonance hole and the at least one resonance hole and the first conductor pattern. A dielectric filter comprising a surrounding fourth conductor pattern. The method of claim 1, wherein the second conductor pattern is characterized in that the third conductor pattern surrounding the resonance hole and the first conductor pattern and the fourth conductor pattern formed integrally with the third conductor pattern between the resonance hole. Dielectric filter. The method of claim 1, wherein the second conductor pattern is formed of a third conductor pattern formed on the bottom and bottom of the resonance hole along the direction of the resonance hole and a fourth conductor pattern integrally formed with the third conductor pattern between the resonance hole. A dielectric filter characterized by the above-mentioned.