KR200230864Y1 - Dielectric Filters which have good attenuation characteristics - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic dielectric filter that forms a plurality of holes penetrating the upper and lower surfaces of one dielectric block and selectively plate the outer surface of the dielectric block to transmit a signal of a specific frequency. At least one metal pattern is placed between the resonator and the resonator on the open side of the resonator so that a small amount of field coupling occurs between the non-adjacent resonators as well as the field coupling of the adjacent resonator period. By providing the characteristics of the elliptic filter generated in the present invention provides an excellent filter that can improve the damping characteristics.

Description

Dielectric Filters which have good attenuation characteristics

In the present invention, at least one metal pattern is formed on the open surface between the resonator and the resonator of the filter, and the metal pattern is combined so that the combination of the metal pattern and the resonance period affects not only the resonator adjacent to the metal pattern but also the non-adjacent resonator. It is an object of the present invention to provide a filter having an improved attenuation characteristic without increasing the number of resonators by adjusting the size of a to have a plurality of attenuation poles in the stopband of a specific frequency desired.

The present invention relates to a bandpass filter used in a high frequency circuit next to an antenna of a wireless communication system to pass a signal of a desired frequency and to remove a signal of an undesired frequency. A ceramic dielectric filter having attenuation characteristics.

In the conventional ceramic dielectric filter, an integrated filter using a quarter wave resonator having one end shorted is frequently used. The integrated filter forms a resonator by drilling a plurality of holes penetrating the upper and lower surfaces of the dielectric block in one dielectric block, and plating the inner wall of the lower surface, side surfaces, and holes of the dielectric block except the upper surface of the dielectric block with a highly conductive material. The upper surface of the dielectric block is formed by selectively plating a metal pattern and a metal pattern for an input electrode and an output electrode to facilitate electric field coupling or magnetic field coupling between the resonator and the resonance period. Has

In general, a large number of resonators penetrating through the dielectric block can provide a filter having excellent attenuation characteristics, but has a disadvantage in that the size of the filter increases and the insertion loss of the filter increases.

The dielectric filter 100 of FIG. 1 drills six holes 103 to 109 penetrating from the upper surface 101 to the lower surface 102 of one dielectric block, and the lower surface 102 and the side surface 110 except for the upper surface 101. ) To form a ground plane and plate the inner wall of the hole with a conductive metal to form a resonator. On the upper surface of the dielectric block, a metal pattern 113 for coupling the input / output electrodes 111 and 112 to the resonator and the resonator period Was plated selectively. In particular, the input electrode 111 and the output electrode 112 extend to the transmission line 114 to the side of the dielectric block so as to be easily mounted on the PCB substrate, so that the filter can be easily miniaturized by a dielectric filter that can be directly mounted on the PCB substrate. It is simple to manufacture. Since the hole formed in FIG. 1 operates as a quarter-wave resonator with one end shorted, a hole and a resonator will be used below.

Referring to the principle of operation of Figure 1 as follows. The microwave signal transmitted to the input electrode 111 is electric field coupled to the first resonator 103 and the second resonator 104 by the capacitance formed between the first resonator 103 and the second resonator 104. The first resonator 103 is a resonator for forming an attenuation pole, and when a signal having a desired attenuation pole frequency propagates as an input signal, the signal does not propagate to an output terminal but flows to the ground plane. The microwave signal propagated from the input electrode 111 to the second resonator 104 resonates near the resonant frequency of the second resonator 104 and generates a high electric field at the open end of the second resonator 104. Therefore, the second resonator 104 and the ground plane are electric field-coupled by the metal pattern 113 selectively plated on the upper surface of the dielectric block, and the second resonator 104 and the third resonator 105 are electric field-coupled and magnetic field-coupled. do. The amount of field coupling and magnetic field coupling of the resonator affects the resonant frequency of the microwave resonator. The microwave signal propagates to the sixth resonator 109 in the same manner as the combination of the second resonator 104 and the third resonator 105, and the resonant signal of the sixth resonator 109 propagates to the output electrode 112 to FIG. 1. Dielectric filter 100 is operated as a filter.

In the dielectric filter of FIG. 1, the frequency of the attenuation pole has one frequency since the electric field coupling of the adjacent resonance period is made of a simple metal pattern. In addition, since an additional resonator is formed adjacent to the input electrode 111 to form an additional attenuation pole frequency, the size of the filter is increased. In addition, there is a problem in that the metal pattern formed on the upper surface of the dielectric block is complicated to determine the accurate resonance frequency, which is difficult to manufacture.

Figure 2 shows another shape of the metal pattern formed on the upper surface of the ceramic dielectric filter of the prior art. FIG. 2A is a metal pattern shape for capacitive coupling. In this case, since the ground pattern is formed between the resonator and the resonator, the resonance period coupling is a pure magnetic coupling, and the attenuation pole frequency is formed at a position higher than the resonance frequency, and thus requires a high stopband characteristic at a position higher than the pass band. It is a structure suitable for a filter. FIG. 2B is a metal pattern for resonant period capacitive coupling. In this case, when the resonant period capacitive coupling is greater than the resonant period magnetic coupling, the resonant period coupling becomes capacitive coupling, and the attenuation pole frequency is lower than the resonant frequency. It is a structure suitable for a filter that is formed in the filter and requires high stopband characteristics at a position lower than the passband. 2C is characterized in that the metal pattern 201 is formed between the resonator and the resonator to facilitate the control of the resonance period coupling amount. Due to the change in the size of the metal pattern 201 formed between the resonator and the resonator, the field coupling amount of the resonance period may be changed, and the frequency of the attenuation pole may be changed.

In the case of FIGS. 2A and 2B, the resonance period coupling which has a significant influence on the resonance characteristics and the attenuation characteristics of the filter is composed of the coupling between the metal pattern and the ground plane of adjacent resonance periods. In addition, in the case of FIG. 2C, the metal pattern 201 formed between the resonator and the resonator functions to adjust the amount of electric field coupling between adjacent resonators.

In the dielectric filter of FIG. 2, the coupling amount is determined by the coupling amount of the resonance periods in which the resonance period electromagnetic coupling is adjacent to each other. Therefore, such a filter has a disadvantage in that it is difficult to obtain the stopband characteristics of a wide band because the attenuation pole frequency determined by the resonance period inverter circuit is located at a substantially similar frequency.

Accordingly, the present invention is provided to solve the problems of the prior art as described above, wherein at least one metal pattern is formed in the filter opening between the resonator and the resonator, and the resonant field coupling is performed by the metal pattern. By adjusting the size of the metal pattern so that fine field coupling is generated not only in the resonator immediately adjacent to the pattern but also in the non-adjacent resonator, it has a large number of attenuation poles in the stop band of a specific frequency, so that the attenuation characteristics are increased without increasing the number of resonators It is an object to provide a filter having a stopband characteristic of a wide band.

1 is a structural diagram of an integrated filter using a ceramic dielectric according to the prior art,

2 is a shape of a metal pattern formed on the upper surface of the integrated filter using a ceramic dielectric according to the prior art,

3 is a structural diagram of a dielectric filter according to a first embodiment of the present invention,

4 is an equivalent circuit diagram of a dielectric filter according to a first embodiment of the present invention;

5 is a frequency transfer characteristic of a dielectric filter according to a first embodiment of the present invention,

6 is a structural diagram of a dielectric filter according to a second embodiment of the present invention;

7 is a structural diagram of a dielectric filter according to a third embodiment of the present invention;

8 is a structural diagram of a dielectric filter according to a fourth embodiment of the present invention.

<Description of Symbols for Major Parts of Drawings>

300: dielectric filter 301: upper surface

302: side 303: side

304, 305, 306, 307, 308: Resonator 310: Metal Pattern

320: input electrode 320: output electrode

According to the present invention for achieving the above object, to form a resonator by drilling a plurality of holes through the upper and lower surfaces of the dielectric block, and to form a ground plane by plating the lower and side surfaces of the dielectric block with a conductive metal, The inner wall of the hole is plated with a conductive metal to be connected to the conductive metal formed on the bottom surface of the dielectric block to form a short end to operate as a quarter-wave resonator with one end shorted, and an electric field coupling between the resonators or A dielectric filter composed by selectively plating a metal pattern for facilitating magnetic field coupling and other metal patterns for the input electrode and the output electrode, wherein at least one metal pattern is placed between the resonator and the resonator so that Small amounts of field coupling occur not only in the field coupling but also between non-adjacent resonators The dielectric filter is provided to be.

Further, according to the present invention, a metal pattern completely enclosing at least one or more holes in the holes is placed on the upper surface of the dielectric block, so that not only the electric field coupling of the resonator surrounded by the metal pattern and the resonance period adjacent to the metal pattern is provided. In addition, a dielectric filter is provided so that electric field coupling occurs in a resonator not adjacent to the metal pattern.

Further, according to the present invention, in the dielectric filter in which at least two or more metal patterns surrounding the predetermined area between the holes and the holes are formed between the holes on the upper surface of the dielectric block and the holes, the predetermined holes between the holes and the holes are provided. There is provided a dielectric filter formed in connection with a ground plane that is a side of a dielectric block having a predetermined region between metal patterns surrounding the region of.

Further, according to the present invention, in the dielectric filter formed between the hole and the hole on the upper surface of the dielectric block, at least two or more metal patterns surrounding the predetermined region between the hole and the hole, There is provided a dielectric filter formed by connecting a hole existing between a metal pattern surrounding a predetermined area and a metal pattern completely interposed between the holes and the ground pattern, which is a side surface of the dielectric block.

In the following, a preferred embodiment of a dielectric filter having a plurality of attenuation poles according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a structural diagram of a dielectric filter according to a first embodiment of the present invention. As shown in FIG. 3, the ceramic dielectric filter 300 of the present invention includes an upper surface 301, a lower surface 302, and a side surface 303. The lower surface and the side surface include a dielectric block formed of parallelepipeds plated with a conductive metal to form a ground plane. The dielectric block is formed with four holes 304 to 307 penetrating through the upper surface 301 and the lower surface 302 of the dielectric block, and the inner walls of the holes 304 to 307 are plated with a conductive metal to form the dielectric block. It is connected to the conductive metal formed on the lower surface 302 to form a short end.

In addition, the metal patterns 322 having a predetermined region are selectively plated on the upper surface 301 of the dielectric filter on the input / output electrodes 320 and 321 and the holes 304 to 307 disposed on the upper surface 301. , 321 is configured to extend directly to the transmission line 330 to the side surface 303 of the dielectric block to be mounted on the PCB substrate, so that it can be mounted directly on the PCB substrate, in particular, the upper surface (301) The top surface of the dielectric filter is a block diagram of a dielectric filter in which a metal pattern 310 is formed between the hole 305 and the hole 306 which surround the predetermined area of the hole 305 and the hole 306. The metal pattern 310 formed on the 301 is part of the metal pattern such that not only the electric field coupling of the resonators 305 and 306 adjacent to the metal pattern 310 but also the electric field coupling is performed to the non-adjacent resonators 304 and 307. Is not adjacent to the top surface 301 of the dielectric filter By increasing the size of the elements 304 and 307 to surround a predetermined area of the adjacent resonators 305 and 306, a small amount of capacitance is formed between the non-adjacent resonators 304 and 307 and the metal pattern 310. It is a structure.

In order to examine the operation principle of FIG. 3 in detail, the electrical equivalent circuit of FIG. 3 is presented. The four holes 304 to 307 of FIG. 3 are represented by resonators 404 to 407 shorted at one end in FIG. 4, and the input capacitance for transferring the input signal to the first resonator 404 is 420, the fourth. Output capacitances for transmitting the microwave signal propagated to the resonator 407 to the output terminal are represented by 421, respectively. The capacitances 423 to 426 are parallel capacitances respectively generated between the metal pattern 322 and the ground plane formed on the resonator on the upper surface of the dielectric block of FIG. 3. Also, capacitances 427 and 428 are series capacitances for electric field coupling between the resonator 304 and the resonator 305 and the resonator 306 and the resonator 307 on the top surface of the dielectric block of FIG. 3. Capacitances 429 and 430 are capacitances generated between the second resonator 305 and the third resonator 306 and the metal pattern 310 of FIG. 3, and the capacitances 440 and 441 are the first resonator 304 and It is a capacitance formed between the fourth resonator 307 and the metal pattern 310 of FIG. The capacitance 431 is a capacitance formed between the metal pattern 310 and the ground plane of FIG. 3.

The operation principle of the ceramic dielectric filter 300 shown in FIG. 3 will now be described in detail. The microwave signal transmitted to the input electrode 320 is field-coupled with the first resonator 304 by the capacitance formed between the input electrode 320 and the first resonator 304, and the resonant frequency of the first resonator 304. Microwave signals with nearby frequencies are resonated by the first resonator 304. As a result, a strong local electric field is generated around the opening of the first resonator 304 to couple the electromagnetic field with the adjacent second resonator 305. In addition, a part of the signal is formed between the metal pattern 310 formed between the second resonator 305 and the third resonator 306 to be electric field-coupled by a small amount of capacitance 440. The microwave signal near the resonant frequency propagated by the first resonator 304 is resonated at the resonant frequency of the second resonator 305. In this case, as in the first resonator 304, a strong local electric field is generated around the opening of the second resonator 305, and the local electric field signal is generated by the metal pattern 310 and the third resonator 306 adjacent to the second resonator 305. ) And electric field and magnetic field combination. In addition, the electric field signal propagated to the metal pattern 310 is electric field coupled to the third resonator 306, which is an immediate resonator, and some signals of the metal pattern 310 are electric field coupled to the ground plane to propagate the ground plane signal. do. In addition, a portion of the signal is coupled to the fourth resonator 307 which is not adjacent to the metal pattern 310 by electric field coupling due to the capacitance formed between the metal pattern 310 and the resonator 307. Propagation to the third resonator 306 The microwave signal resonates at the resonant frequency of the third resonator 306 and propagates to the fourth resonator 307 by the same method. The signal propagated to the fourth resonator 307 is propagated to the output electrode 321 by the same method, so that the ceramic dielectric filter 300 operates as a microwave filter to flow a signal of a specific frequency well.

FIG. 5 is a frequency transfer characteristic curve of the ceramic dielectric filter of FIG. 3 according to the first embodiment of the present invention, and the curve indicated by the dotted line is between the first resonator 304 and the fourth resonator 307 and the metal pattern 310 of FIG. 3. Shows the frequency transfer characteristics when no capacitance is generated in the curve, and the curve indicated by the solid line shows the frequency generated when the capacitance generated between the first resonator 304 and the fourth resonator and the metal pattern in FIG. 3 is 0.025 pF. The transfer characteristics are shown. When no capacitance occurs between the first resonator and the fourth resonator of FIG. 3 and the metal pattern, one attenuation pole Fp1 is generated at a frequency lower than the passband, while the first resonator and the fourth resonator are generated between the metal pattern and the first resonator. When the capacitance value is present, it can be seen that the attenuation poles Fp2, Fp3, Fp4 occur at a position lower than the pass band. Therefore, as shown in FIG. 5, when there is a small amount of electric field coupling with the resonator which is not immediately adjacent to the metal pattern formed between the resonator and the resonator according to the present invention, a plurality of attenuation poles are formed in the stop band requiring high attenuation. It can be seen that the stop band of the broadband is formed.

Accordingly, the ceramic dielectric filter 310 is formed by the capacitance 440 formed between the resonator 304 and the metal pattern 310 of FIG. 3 and the capacitance 441 formed between the resonator 307 and the metal pattern 310. The coupling of the resonance periods of not only causes the electromagnetic coupling of the resonance periods adjacent to each other, but also the electromagnetic coupling of the resonance periods not adjacent to each other. Therefore, the microwave filter by the resonance period coupling method has the characteristics of an elliptical filter that can form a plurality of attenuation poles in the stopband. Therefore, the microwave filter 300 operates as a filter forming a plurality of attenuation poles in the stop band.

FIG. 6 is a structural diagram of a dielectric filter 600 according to a second embodiment of the present invention, in which a metal pattern 610 completely enclosing the second resonator 602 is formed on an upper surface of the dielectric block. As a result, not only electric field coupling between the first resonator 601 and the second resonator 602 but also electric field coupling between the first resonator 601 and the third resonator 603 is generated. Electric field bonds are formed. Other components and operation principles can be described in the same manner as in FIG.

FIG. 7 is a structural diagram of a dielectric filter 700 according to a third embodiment of the present invention, and includes a ground pattern 720 for preventing electric field coupling between two metal patterns 710 and 711 formed between a resonator and a resonator. ) Is formed between two metal patterns 710 and 711 on the upper surface of the dielectric block. When the field coupling between the metal pattern is generated during the resonator and the resonance period, not only the resonance characteristic of the filter is bad but also the attenuation characteristic is degraded. Other components and operation principles can be described in the same manner as in FIG.

FIG. 8 is a structural diagram of a filter 800 according to a fourth embodiment of the present invention, in which a resonator and a resonance period are completely prevented from generating electric field coupling between two metal patterns 810 and 811 formed between a resonator and a resonator. A ground pattern 820 is formed between two metal patterns on the top surface of the dielectric block. In this case, the electric field coupling between the metal patterns 810 and 811 formed in the resonance period is completely blocked. However, since the electric field coupling of the resonance period not adjacent to the metal pattern is a three-dimensional formation having a resonator length, the resonance period not adjacent to the metal pattern 810 even though the ground pattern 820 completely covers the resonance period. Electric field coupling occurs. Therefore, even if there is a ground pattern 810 completely separating the resonance period, by adjusting the size of the metal pattern formed between the resonators, it is possible to determine the coupling amount between the adjacent resonance periods and the non-adjacent resonance periods necessary for forming the resonance band and the attenuation characteristics of the resonator. have. Other components and operation principles can be described in the same manner as in FIG.

As described in detail above, the present invention can be used for a filter having excellent attenuation in the case of a duplexer used in a mobile communication terminal, and has a feature of having a plurality of attenuation poles at a position higher or lower than a passband without increasing the number of resonators. As a result, a compact filter can be provided, and a bandpass filter and duplexer having excellent insertion loss characteristics can be provided due to the small number of resonators.

The technical idea of the dielectric filter of the present invention has been described above with the accompanying drawings, but this is only illustrative of the best embodiment of the present invention and is not intended to limit the present invention.

In addition, it is obvious that any person skilled in the art can make various modifications and imitations without departing from the scope of the technical idea of the present invention.

Claims (4)

A plurality of holes penetrating the upper and lower surfaces of the dielectric block are formed, and the lower and side surfaces of the dielectric block are plated with a conductive metal to form a ground plane, and the inner wall of the hole is plated with a conductive metal to form a lower surface of the dielectric block. It forms a short-circuit by connecting with the formed conductive metal to operate the holes as a quarter-wave resonator short-circuited at one end, and the metal pattern and the input electrode and the output to facilitate the field coupling or magnetic field coupling between the resonators A dielectric filter configured by selectively plating a metal pattern for an electrode, wherein at least one metal pattern is formed between the resonator and the resonator to facilitate electric field coupling with not only adjacent resonators but also non-adjacent resonators. The metal pattern of claim 1, wherein a metal pattern completely surrounding at least one or more resonator holes in the holes is formed between another resonator and the resonator on the upper surface of the dielectric block, and the metal pattern is surrounded by the metal pattern. And a metal pattern for forming an electric field coupling not only with the resonator adjacent to the resonator but also with the resonator not adjacent to the metal pattern. In claim 1, at least two metal patterns exist between the resonator and the resonator, and a dielectric formed between the resonator and the resonator to facilitate electric field coupling with the non-adjacent resonator as well as electric field coupling with the immediately adjacent resonator. A filter comprising: a metal pattern having a predetermined region between a metal pattern formed between a resonator and a resonator is connected to a ground plane that is a side surface of a dielectric block. The method of claim 1, wherein at least two or more metal patterns exist between the resonator and the resonator, and the metal pattern connected to the ground plane, which is a side surface of the dielectric block having a predetermined area between the two or more metal patterns, may reduce the resonator and the resonance period. Dielectric filter including metal pattern formed completely apart