JP2002261507A - Dielectric filter and antenna shared apparatus using the same, and communications equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of the thickness differing at the central section and peripheral section of an electrode in a resonator electrode, an interstage coupling-capacity electrode or an input/output coupling-capacity electrode or the like formed by the printing of the conventional conductive paste, and the Q-factor of a resonator becoming lowered and filter characteristics becoming deteriorated by the pointing of the end section of an electrode peripheral section, when a dielectric substrate is laminated. SOLUTION: A shielding electrode 12a is placed on the top face of a ground- electrode dielectric substrate 11b, the interstage coupling-capacity electrode 13 on the top face of an interstage coupling-capacity dielectric substrate 11c, and the resonator electrodes 14a and 14b composed of metal foil on the top face of a resonator dielectric substrate 11d respectively. The input/output coupling-capacity electrodes 15a and 15b are formed on the top face of an input/output coupling-capacity dielectric substrate 11e and a shielding electrode 12b on the top face of the ground-electrode dielectric substrate 11f respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a small-sized dielectric filter mainly used in high-frequency radio equipment such as a portable telephone, particularly a strip line type resonance electrode arranged on a dielectric substrate and electromagnetically coupled to each other. The present invention relates to a dielectric filter having a reduced structure.

[0002]

2. Description of the Related Art In recent years, a large number of dielectric filters have been used as high-frequency filters for portable telephones. Filters hold promise. Hereinafter, an example of a planar dielectric filter will be described with reference to the drawings.

FIG. 8 is an exploded perspective view showing the structure of a planar laminated type dielectric filter. The basic configuration of the laminated type dielectric filter shown in the figure is firstly six dielectric substrates 1a to 1f. A shield electrode 2a on an upper surface of the dielectric substrate 1b, an inter-stage coupling electrode 3 on an upper surface of 1c,
Resonator electrodes 4a and 4b are formed on an upper surface of 1d, input / output coupling capacitance electrodes 5a and 5b are formed on an upper surface of 1e, and a shield electrode 2b is formed and stacked on an upper surface of 1f.

On the left and right side surfaces of the laminated dielectric substrate, end electrodes 6a and 6b which are connected to the shield electrodes 2a and 2b to form ground terminals are provided. On the rear surface of the laminated dielectric substrate, the shield electrodes 2a and 2b and the resonance electrodes are provided. An end face electrode 7 serving as a ground terminal is formed corresponding to the common open end of the device electrodes 4a and 4b. The end face electrode 8 formed on the front surface of the laminated dielectric substrate is connected to the respective short-circuited ends of the resonator electrodes 4a and 4b and connected to the shield electrodes 2a and 2b. The end surface electrodes 9a and 9b on the left and right side surfaces of the laminated dielectric substrate are the input / output coupling electrodes 5.
a, 5b to form input / output terminals.

[0005]

However, in the planar laminated dielectric filter having the above-mentioned structure, the interstage coupling capacitance electrode including the resonator electrode and the input / output coupling capacitance electrode are all made of conductive paste or the like. Therefore, it was difficult to uniformly form the resonator electrode with a sufficient thickness.

FIG. 9 is a cross-sectional view showing the laminated state of the dielectric substrates 1c and 1d shown in FIG. 8. As shown in the figure, the center portions of the resonator electrodes 4a and 4b are thicker, and the thickness increases toward the periphery. Tended to be thinner. In addition, when laminating dielectric substrates on which electrodes are printed, the electrode ends are sharp, and high-frequency currents are concentrated on the ends, so that the Q value of the resonator is reduced and the filter characteristics deteriorate. Further, when printing a conductive paste using a metal powder as a conductor, the occurrence of surface irregularities due to the mesh of the printing screen is inevitable, and there is a problem that the filter characteristics are deteriorated.

An object of the present invention is to solve the above problems and to provide a low-loss dielectric filter by forming a resonator electrode having a uniform thickness.

[0008]

According to the present invention, there is provided a dielectric filter comprising a plurality of resonator electrodes, wherein the plurality of resonator electrodes are electromagnetically coupled to each other. Since the device electrode is made of metal foil, the Q value of the resonator can be improved, and low loss and high attenuation characteristics can be provided.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises a plurality of resonator electrodes, an inter-stage coupling capacitance electrode, and an input / output coupling capacitance electrode. A dielectric filter configured by coupling, wherein at least a plurality of resonator electrodes are configured by metal foil,
Since a resonator electrode having a uniform thickness and an arc-shaped end face can be formed, the Q value of the resonator can be improved.

The invention described in claim 2 of the present invention is claim 1
Wherein the plurality of resonator electrodes are shaped such that one of the resonator electrodes has a short-circuited end and the other has an open end.

[0011] The invention described in claim 3 of the present invention is the invention claimed in claim 3.
1. The dielectric filter according to 1, wherein both ends of the plurality of resonator electrodes are open ends.

According to a fourth aspect of the present invention, there is provided the dielectric filter according to the second or third aspect, wherein a wide portion is provided on the open end side of the resonator electrode, which is generated between the resonators. By arbitrarily controlling the amount of electromagnetic field coupling, the degree of freedom in filter design can be improved.

According to a fifth aspect of the present invention, the resonator electrode is formed of a metal foil containing at least one of gold, silver and copper as a main component, and a resonator having high conductivity is obtained. This is effective in reducing insertion loss.

According to a sixth aspect of the present invention, there is provided the dielectric filter according to any one of the first to fifth aspects, wherein the cross-section of the resonator electrode has a rounded corner having an arc formed at the corner. It has a square shape or an arc shape, so that the concentration of high-frequency current flowing through the end of the resonator electrode can be reduced, and the Q value of the resonator can be improved.

The invention described in claim 7 of the present invention is claim 1.
7. The dielectric filter according to any one of items 1 to 6, wherein the thickness of the resonator electrode is in a range of 10 μm to 400 μm, and the thickness and shape of the resonator electrode can be arbitrarily and accurately designed. .

According to an eighth aspect of the present invention, there is provided the dielectric filter according to any one of the first to seventh aspects, wherein the surface of the resonator electrode is polished or plated, and the surface is smoothed. Therefore, a resonator having a high Q value can be obtained.

According to a ninth aspect of the present invention, there is provided the dielectric filter according to any one of the first to eighth aspects, wherein the average surface roughness of the resonator electrode is 0.5 μm to 0.01 μm. Thus, a resonator having an extremely high Q value can be obtained.

According to a tenth aspect of the present invention, there is provided
Forming a resonator electrode made of a metal foil containing at least one of silver and copper as a main component, embedding the resonator electrode inside a dielectric substrate, and forming a resonator dielectric substrate; Laminating a body substrate and at least an inter-stage coupling capacitance dielectric substrate, an input / output coupling capacitance dielectric substrate, and a ground electrode dielectric substrate to form a laminated dielectric substrate, a method of manufacturing a dielectric filter, A dielectric filter having low loss and high attenuation characteristics can be provided.

According to an eleventh aspect of the present invention, there is provided a method for manufacturing a dielectric filter according to the tenth aspect, wherein the step of forming a resonator electrode includes at least one of gold, silver and copper as a main component. After forming a photomask on both sides of the metal foil to be etched and etching from both sides, an electrode frame is formed by using a chemical polishing method or an electrolytic polishing method to form an end face of the resonator electrode with a rounded square shape or an arc shape. This is a process, and the end face of the resonator electrode can be given an arbitrary shape.

According to a twelfth aspect of the present invention, there is provided a method for manufacturing a dielectric filter according to the tenth aspect, wherein the step of forming a resonator dielectric substrate is performed on a green dielectric ceramic substrate. This is a step of embedding the resonator electrode formed by the manufacturing method described in 11 and can be used when the dielectric filter is made of a high dielectric constant ceramic material, so that it is small and has excellent filter characteristics. A dielectric filter can be provided.

According to a thirteenth aspect of the present invention, there is provided a resonator ceramic dielectric substrate in the form of a green sheet formed by the manufacturing method according to the twelfth aspect, and at least a green sheet-like interstage coupling capacitor ceramic dielectric. A substrate substrate and a green sheet-shaped input / output coupling ceramic dielectric substrate are sandwiched from above and below by a green sheet-shaped grounded electrode ceramic dielectric substrate, laminated and fired simultaneously to form a laminated dielectric substrate This is a method for manufacturing a dielectric filter including a process. Since all of the dielectric filters can be formed of a high dielectric constant ceramic substrate, it is possible to obtain a small dielectric filter with low loss.

According to a fourteenth aspect of the present invention, there is provided a method of manufacturing a dielectric filter according to the tenth aspect, wherein the step of forming a resonator dielectric substrate is performed on an uncured composite substrate. After embedding the resonator electrode obtained by the manufacturing method described in (1), it is a step of heating and curing, which is effective in reducing the manufacturing cost.

According to a fifteenth aspect of the present invention, there is provided a resonator composite dielectric substrate formed by the manufacturing method according to the fourteenth aspect, at least a fired interstage coupling capacitance ceramic dielectric substrate, A method for manufacturing a dielectric filter comprising a step of forming a laminated dielectric substrate having a composite structure by laminating an input / output coupling capacitance ceramic dielectric substrate and a plurality of grounded electrode ceramic dielectric substrates. After the composite dielectric substrate and the other ceramic dielectric substrate are manufactured in different processes, they can be integrated, which is effective in improving the manufacturing yield.

According to a sixteenth aspect of the present invention, there is provided an antenna duplexer using the dielectric filter according to any one of the first to ninth aspects as one or both of a transmitting filter and a receiving filter. Therefore, an extremely miniaturized duplexer can be obtained.

According to a seventeenth aspect of the present invention, a dielectric filter formed by the manufacturing method according to any one of the tenth to fifteenth aspects is used as one or both of a transmission filter and a reception filter. An antenna duplexer is provided, and an extremely miniaturized antenna duplexer can be obtained.

According to an eighteenth aspect of the present invention, the antenna duplexer according to the sixteenth or seventeenth aspect is used for a communication device such as a mobile phone, and has excellent characteristics and extremely miniaturized communication. Equipment can be realized.

Hereinafter, the dielectric filter of the present invention will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is an exploded perspective view showing the structure of a dielectric filter according to a first embodiment of the present invention. The basic structure of the dielectric filter is the same as that shown in FIG. Similarly, the resonator dielectric substrate 11d, which is composed of six dielectric substrates 11a to 11f and on which resonator electrodes are mounted, is made of a resin substrate or a resin component by a manufacturing method described later, in addition to a high dielectric constant ceramic substrate. In some cases, a composite substrate composed of an inorganic filler and an inorganic filler is selected.

First, a shield electrode 12a is provided on the upper surface of the ground electrode dielectric substrate 11b,
The inter-stage coupling capacitance electrode 13 is formed on the upper surface of the substrate, and the thickness is 10 μm to 400 μm on the upper surface of the resonator dielectric substrate 11 d.
The resonator electrodes 14a and 14b, which are made of a metal foil containing silver or copper as a main component and have round cross-sections having no sharp corners, are mounted. The input / output coupling capacitance electrode 15 is provided on the upper surface of the body substrate 11e.
The shield electrodes 12b are formed on the upper surface of the ground electrode dielectric substrate 11f, and these dielectric substrates are integrally laminated to form a dielectric filter.

End electrodes 16a and 16b and input / output coupling capacitance electrodes 15a and 1
5b, an end face electrode 19a forming an input / output terminal,
19b is similar to the conventional one in that end electrodes 17 and 18 are respectively formed on the back and front surfaces of the laminated dielectric substrate.

The feature of the present invention in the above configuration lies in the configuration of the resonator electrode, and as shown in FIG. 1, the resonator electrode 1 formed on the upper surface of the resonator dielectric substrate 11d.
4a and 14b are formed of a metal foil containing at least one of gold, silver and copper as a main component.

FIG. 2 (a) shows a cross section of the laminated dielectric substrates 11c, 11d and 11e taken along the line AA shown in FIG. 1. The upper surface of the resonator dielectric substrate 11d will be described later. Resonator electrodes 14a and 14b made of metal foil containing at least one of gold, silver and copper produced in another step are arranged. An inter-stage coupling capacitance electrode 13 is provided on the upper surface of the inter-stage coupling capacitance dielectric substrate 11c.
Input / output coupling capacitance electrodes 15a and 15b are respectively formed on the upper surface of the input / output coupling capacitance dielectric substrate 11e by printing a conductive paste. The inter-stage coupling capacitance electrode 13
In addition, the input / output coupling capacitance electrodes 15a and 15b can be formed of metal foil as in the case of the resonator electrodes 14a and 14b.

The resonator electrode 14 in the present embodiment
As shown in FIG. 2 (b), an enlarged cross section of each of a and 14b is preferably formed in an arc shape at a corner or in an arc shape at an end face of the resonator electrode in terms of electrical characteristics. Such a rounded square shape can be formed by etching an electrode frame described later into the shape of the resonator electrodes 14a and 14b, and then subjecting the end faces of the resonator electrodes 14a and 14b to chemical polishing or electrolytic polishing. Further, the surfaces of the resonator electrodes 14a and 14b are polished or metal-plated to provide a surface having a thickness of 0.5 μm.
It is preferable to provide a smooth surface having a surface roughness of m to 0.01 μm.

By forming the resonator electrodes 14a and 14b with a metal foil having a flat surface, a resonator having a high Q value can be formed, and a dielectric material having low loss and excellent attenuation characteristics can be obtained. A filter can be obtained.

The planar shapes of the resonator electrodes 14a and 14b are not limited to those having a uniform electrode width as shown in FIG.
As shown in FIG. 2C, the wide portion 14aw, 1
A shape having 4 bw can also be formed corresponding to the required filter characteristics.

In this embodiment, the thickness is 1
Although the case where a strip line made of a metal foil of 0 μm to 400 μm is used is shown, the present invention is not limited to this. When a dielectric filter is used at a high frequency, the high-frequency current does not flow uniformly in the thickness direction but may concentrate on the line surface, and the degree of concentration, that is, the concentrated thickness is referred to as “skin depth”. Then
The conductor thickness must be greater than the skin depth. In the case of a stripline, the high-frequency current flows on the upper and lower surfaces, so the conductor thickness is required twice. Considering the skin depth, it depends on the frequency, conductivity, etc., but in the frequency range of several GHz, it is about 1-3 μm. The metal foil preferably has a thickness of 10 μm or more. On the other hand, from the experimental results, the Q value of the resonator is monotonously improved to 100 μm, but 200 μm.
When it comes to m, it will be almost flat or will rise slightly,
Considering that the thickness of the dielectric filter increases as the thickness increases, the thickness of the metal foil is preferably 400 μm or less.

In the above embodiment, when a metal foil mainly composed of copper and silver and having an electrode thickness of 100 μm is used as the resonator electrode, the Q value is 28.
On the other hand, when a resonator electrode having an electrode thickness of 40 μm is formed by the printing method as shown in the conventional example, the Q value becomes 240. A high value resonator can be provided.

(Embodiment 2) Next, a method of manufacturing a dielectric filter according to the present invention will be described.

FIG. 3 is a process chart showing a method of manufacturing a dielectric filter according to a second embodiment of the present invention. First, a method of manufacturing a resonator electrode in another step will be described.

FIG. 3A is a cross-sectional view taken along line AA in the plan view of FIG. 3B, and is provided on both surfaces of a metal foil 21 containing at least one of gold, silver and copper as a main component. An etching resist film 22 having exactly the same pattern is formed by photolithography. This is etched from both sides of the metal foil 21, and the etched end face is subjected to chemical polishing or electrolytic polishing to obtain a structure shown in FIG.
As shown in the plan view of (b), an electrode frame 24 in which a plurality of pairs of resonator electrodes 23 are formed can be obtained.
Reference numeral 25 denotes a positioning guide provided on both inner sides of the electrode frame 24.

FIG. 3C shows a cross section of the electrode frame 24 formed in this manner.
As shown in (d), the electrode frame 24 and Bi-Ca-Nb-O
Green sheet 26 made of high dielectric constant material
3 (e), the electrode frame 24 is embedded in the green sheet 26 as shown in FIG. 3 (e), and then cut into individual pieces.
The resonator dielectric substrate 27 shown in (f) can be obtained.

FIG. 4 shows a dielectric filter using a resonator dielectric substrate 27 (corresponding to 11d in FIG. 1) provided with resonator electrodes (14a, 14b) made of metal foil formed in this manner. It shows the manufacturing process to be formed,
The same parts as those in FIG. 1 are described with the same numbers.

First, as shown in FIG. 4A, a protective ceramic dielectric substrate 11a serving as a protective material and a shield electrode 12a
Are formed, the inter-stage coupling capacitor ceramic dielectric substrate 11c on which the inter-stage coupling capacitance electrode 13 is formed, and the metal foil resonator electrodes 14a and 14b obtained in the process of FIG. An embedded resonator ceramic dielectric substrate 11d, an input / output coupling capacitance ceramic dielectric substrate 11e having input / output coupling capacitance electrodes 15a and 15b formed thereunder, and a ground electrode ceramic dielectric substrate having a shield electrode 12b formed thereon 11f are arranged and pressurized as shown by the arrows, and the respective electrodes are embedded in the ceramic dielectric substrates in the form of green sheets and laminated, whereby the laminated dielectric substrate 28 shown in FIG. Then, the laminated dielectric substrate 28 is fired in a reducing atmosphere at a temperature of about 900 ° C. and sintered to form a laminated ceramic dielectric. Filter can be obtained.

In this embodiment, the material of each of the above dielectric substrates is Bi-Ca-Nb-O-based, Ba-Ti-O-based, [Zr (M
g, Zn, Nb)] TiO ₄ + MnO ₂ or Ba-Nd-Ti-O high dielectric constant ceramic material can be used, and forsterite, alumina borosilicate glass is used for components that do not form a capacity It is also possible to use a low dielectric constant ceramic substrate.

(Embodiment 3) Next, a method of manufacturing a dielectric filter according to a third embodiment of the present invention will be described. This embodiment is different from the second embodiment in that a thermosetting resin made of an epoxy resin and Al ₂ O ₃ , Mg are used as a dielectric substrate for embedding a resonator electrode made of a metal foil.
The point is that a composite material mixed with an inorganic filler made of a powder such as O is used.

As the thermosetting resin, a phenolic resin, a cyanate resin or the like can be used as a resin component of the composite material in addition to the epoxy resin.

FIG. 5 is a schematic process diagram for explaining the essential points of the manufacturing method according to the present embodiment. First, as shown in FIG. 5A, a protective ceramic dielectric substrate 31a in the form of a green sheet serving as a protective material and a shield are provided. A green sheet-shaped ground electrode ceramic dielectric substrate 31b having an electrode 32a and a green sheet-shaped inter-stage coupling capacitance ceramic dielectric substrate 31c having an inter-stage coupling capacitance electrode 33 are superposed and pressed and laminated in the direction of the arrow. This is fired at about 900 ° C. to form the first dielectric block 34 shown in FIG. 5B. Next, as shown in FIG. 5C, a green sheet-shaped input / output coupling ceramic dielectric substrate 36 having input / output coupling capacitance electrodes 35a and 35b and a shield electrode 3
The green dielectric ceramic substrate 37 on which the green sheet 2b is formed is superposed, pressurized, laminated, and fired at about 900 ° C. to form the second dielectric block 38 shown in FIG. To form

Next, as shown in FIG. 5E, a process similar to the method of forming the resonator electrode described in FIG. 3 is used between the first dielectric block 34 and the second dielectric block 38. Then, pressure is applied in the direction of the arrow across the resonator composite dielectric substrate 40 in which the resonator electrodes 39a and 39b are embedded in a composite sheet in which an epoxy resin and an inorganic filler made of a powder such as Al ₂ O ₃ or MgO are mixed. The input / output coupling capacitance electrodes 35a and 35b are embedded in the lower surface of the resonator composite dielectric substrate 40, and are integrated by heating at a curing temperature of 150 ° C. to 200 ° C. of the composite material, as shown in FIG. A dielectric filter can be obtained.

In the present embodiment, in addition to the above-mentioned Al ₂ O ₃ and MgO, Bi-Ca-Nb-O-based, Ba-Ti-O-based, [Zr (Mg, Zn, Nb) )] T
Excellent filter characteristics can be obtained by forming a resonator composite dielectric substrate 40 by mixing a high dielectric constant ceramic powder of iO ₄ + MnO ₂ system or Ba—Nd—Ti—O system at a high filling amount. .

As described above, according to the present embodiment, since the resonator electrodes 39a and 39b made of metal foil are embedded in the composite material containing the resin component, the dielectric material can be formed in a relatively easy manufacturing process shown in FIG. A filter can be formed.

In this embodiment, as an example of the content of the filler in the composite material, the content of the filler is set to about 70 to 90% in order to match the thermal expansion coefficient with the ceramic material used at the same time. preferable.

When it is desired to increase the dielectric constant of the composite material, it is preferable to increase the content of the filler as much as possible. Conversely, if the adhesion is taken into consideration, the content of the filler may be smaller than the above range. I do not care.

(Embodiment 4) Next, a method of manufacturing a dielectric filter according to a fourth embodiment of the present invention will be described. The present embodiment is an improvement of the manufacturing method of the third embodiment in which a dielectric filter can be provided by a relatively easy manufacturing method, and is shown in FIG. 3 as shown in FIG. The electrode frame 24 and a composite material 41 having substantially the same thickness as the electrode frame are crimped, and FIG.
As shown in (b), the gap material 42 of the electrode frame 24 is filled with the composite material 41 to form the electrode composite substrate 43.

Next, as shown in FIG. 6C, FIG.
A dielectric substrate 44 made of a high-permittivity ceramic material in the form of a green sheet is placed on the upper surface of the second dielectric block 38 in the form of a green sheet formed in FIG. Third dielectric block 45 formed by stacking and firing under the same conditions as in the third embodiment.
Then, the electrode composite substrate 43 is cut into individual pieces, and a resonator composite dielectric substrate 46 obtained is sandwiched between the substrate and the substrate, and pressed into contact with the input / output coupling capacitance electrodes 35a and 35b as shown in FIG. A dielectric substrate 44 made of a high dielectric constant material can be interposed between the device electrodes 39a and 39b, and a dielectric filter with an improved Q value can be obtained while being an effective manufacturing method for cost reduction. .

Instead of using the electrode composite substrate 43 in the present embodiment, the resonator electrode 3 is formed on the upper surface of the third dielectric block 45 in the step shown in FIG.
9a and 39b are placed, and a liquid resin of at least one of an epoxy resin, a phenol resin, a cyanate resin, a polyphenylene phthalate resin, and a polyphenylene ether resin is used as an adhesive.
It is also possible to manufacture a dielectric filter by filling in 2 and joining the dielectric block 34. Alternatively, instead of the resin adhesive, a paste made of glass frit may be filled in the gap portion 42 of the electrode frame 24, fired at about 900 ° C., and sealed with glass.

FIGS. 3A to 3E and FIG.
The formation of the resonator electrodes by the electrode frames shown in (a) and (b) describes the case of multi-cavity formation in which a plurality of resonator electrodes are formed at the same time, and the other steps are individually described to simplify the drawings. Has been described.

The surface of the resonator electrode made of a metal foil in each of the embodiments of the present invention is polished or Au, A
g, Cu, etc., can be formed into a smooth surface having an average surface roughness of about 0.5 μm to about 0.01 μm by plating, and the average surface roughness of the resonator electrode obtained by printing a conventional conductive paste is 1 μm. As compared with a thickness of up to 3 μm, an electrode surface with extremely excellent flatness can be obtained, so that the Q value of the resonator can be improved and excellent filter characteristics can be obtained.

In each of the above embodiments, a plurality of resonator electrodes made of metal foil according to the present invention have been described with respect to a resonator composed of two resonator electrodes. However, three or more resonator electrodes are formed. The same effect can be obtained even when the above operation is performed.

Further, the thickness of the conventional resonator electrode formed by printing a conductive paste is limited, but the resonator electrode made of a metal foil according to the present invention can be formed by etching the metal foil by photolithography. Since the thickness can be freely designed according to the required filter characteristics and the conductor loss can be reduced, it can be effectively used for miniaturization of communication equipment and the like.

(Embodiment 5) Next, a fifth embodiment of the present invention will be described. In the present embodiment, the dielectric filter according to the first to fourth embodiments is used as a transmission filter or a reception filter of an antenna duplexer that separates a transmission wave and a reception wave of a communication device such as a mobile phone. By arranging the dielectric filters according to the present invention at both ends of the matching circuit connected to the antenna as shown in FIG. 7, the coaxial resonance with a large space factor used in the conventional antenna duplexer is realized. Since the antenna can be eliminated, an extremely miniaturized antenna duplexer can be obtained.

Further, by using a dielectric filter having a resonator electrode made of a metal foil according to the present invention or the above antenna duplexer for a communication device such as a mobile phone, excellent characteristics and an extremely miniaturized communication device are obtained. Can be realized.

[0062]

According to the present invention, as is apparent from the above embodiment, a plurality of resonator electrodes are provided, and the plurality of resonator electrodes of a dielectric filter formed by electromagnetically coupling the resonator electrodes to each other are made of metal. It is made of foil, and the thickness of the metal foil resonator electrode is made uniform, and the Q value of the resonator is improved by further improving the flatness of the electrode surface, with low loss and high attenuation characteristics. And a dielectric filter having high-precision filter characteristics can be obtained without increasing the manufacturing cost.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a dielectric filter according to a first embodiment of the present invention.

2A is a cross-sectional view of the laminated dielectric substrate taken along the line AA in FIG. 1; FIG. 2B is an enlarged cross-sectional view of the resonator electrode; FIG. 2C is a resonator having a resonator electrode having a wide portion; Perspective view of dielectric substrate

FIGS. 3A to 3F are first-half process diagrams illustrating a method for manufacturing a dielectric filter according to a second embodiment of the present invention; FIGS.

FIGS. 4 (a) and (b) are second half process charts in the same manufacturing method.

FIGS. 5A to 5F are process diagrams illustrating a method for manufacturing a dielectric filter according to a third embodiment of the present invention.

FIGS. 6A to 6D are process diagrams illustrating a method for manufacturing a dielectric filter according to a fourth embodiment of the present invention.

FIG. 7 is a schematic block diagram of an antenna duplexer and a communication device according to a fifth embodiment of the present invention.

FIG. 8 is an exploded perspective view of a conventional dielectric filter.

FIG. 9 is a sectional view of a resonator electrode formed in the dielectric filter.

[Explanation of symbols]

 11a to 11f Dielectric substrate 12a, 12b Shield electrode 13 Interstage coupling capacitance electrode 14a, 14b Resonator electrode 15a, 15b Input / output coupling capacitance electrode

Continued on the front page (72) Inventor Tohru Yamada 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. 5J006 HB04 HB05 HB17 HB21 JA01 JA31 LA02 LA26 NA04 NB07 NC03

Claims (18)

[Claims] 1. A dielectric filter comprising a plurality of resonator electrodes, an inter-stage coupling capacitance electrode, and an input / output coupling capacitance electrode, wherein at least one of the resonator electrodes is electromagnetically coupled to each other. A dielectric filter, wherein the plurality of resonator electrodes are made of metal foil. 2. The dielectric filter according to claim 1, wherein the plurality of resonator electrodes are resonator electrodes having one of a short-circuited end and the other an open end. 3. The dielectric filter according to claim 1, wherein the plurality of resonator electrodes are resonator electrodes having both ends open. 4. The dielectric filter according to claim 2, wherein in the planar shape of the resonator electrode, a wide portion is provided on an open end side of the resonator electrode. 5. The dielectric filter according to claim 1, wherein the resonator electrode is made of a metal foil containing at least one of gold, silver, and copper as a main component. 6. The end shape of the cross section of the resonator electrode is as follows:
6. The dielectric filter according to any one of 1 to 5, wherein the dielectric filter has a rounded square shape or an arc shape in which an arc is formed at a corner. 7. The thickness of the resonator electrode is from 10 μm to 40 μm.
The dielectric filter according to any one of claims 1 to 6, wherein the thickness is in a range of 0 µm. 8. The dielectric filter according to claim 1, wherein the surface of the resonator electrode is polished or plated. 9. The resonator electrode having an average surface roughness of 0.5 μm
9. The method according to claim 1, wherein the thickness is set to 0.01 μm.
The dielectric filter according to any one of the above. 10. A step of forming a resonator electrode made of a metal foil containing at least one of gold, silver and copper as a main component, and embedding the resonator electrode in a dielectric substrate. Forming, and laminating the resonator dielectric substrate, at least the inter-stage coupling capacitance dielectric substrate, the input / output coupling capacitance dielectric substrate, and the ground electrode dielectric substrate to form a laminated dielectric substrate. Of producing a dielectric filter. 11. A step of forming a resonator electrode includes forming a photomask on both surfaces of a metal foil containing at least one of gold, silver and copper as a main component and etching the metal mask from both surfaces, and then performing a chemical polishing method or 11. The method of manufacturing a dielectric filter according to claim 10, comprising a step of forming an electrode frame in which the end faces of the resonator electrodes are rounded square or arc using an electropolishing method. 12. The step of forming a resonator dielectric substrate,
12. A green sheet-shaped ceramic dielectric substrate.
The method for manufacturing a dielectric filter according to claim 10, wherein the resonator electrode is formed by embedding a resonator electrode formed by the manufacturing method according to (1). 13. A green sheet-shaped resonator ceramic dielectric substrate formed by the manufacturing method according to claim 12, at least a green sheet-shaped inter-stage coupling capacitance ceramic dielectric substrate, and a green sheet-shaped input / output. A dielectric filter comprising a step of forming a laminated dielectric substrate by sandwiching and laminating a coupling capacitor ceramic dielectric substrate and a plurality of green sheet-shaped ground electrode ceramic dielectric substrates from above and below, and firing them simultaneously. Production method. 14. The step of forming a resonator dielectric substrate,
12. The method of manufacturing a dielectric filter according to claim 10, wherein the resonator electrode obtained by the manufacturing method according to claim 11 is embedded in an uncured composite substrate, followed by heating and curing. Method. 15. A resonator composite dielectric substrate formed by the manufacturing method according to claim 14, at least a baked inter-stage coupling capacitor ceramic dielectric substrate, and an input / output coupling capacitor ceramic dielectric substrate. A method for manufacturing a dielectric filter, comprising a step of forming a laminated dielectric substrate having a composite structure by laminating a plurality of grounded electrode ceramic dielectric substrates. 16. An antenna duplexer, wherein the dielectric filter according to claim 1 is used for one or both of a transmitting filter and a receiving filter. 17. An antenna duplexer, wherein the dielectric filter formed by the manufacturing method according to claim 10 is used for one or both of a transmission filter and a reception filter. 18. A communication device using the antenna duplexer according to claim 16 or 17.