JP2003087074A - Multilayer filter - Google Patents

Abstract

(57) [Summary] When a plurality of coils are arranged close to each other, they are mutually inductively coupled to each other. Therefore, the magnitude of the coupling changes depending on the arrangement of the coils, and sufficient attenuation characteristics cannot be obtained. SOLUTION: An insulating layer and a conductor pattern are laminated to form an LC filter having a plurality of coils in a laminated body. The plurality of coils of this LC filter are formed with their winding axes shifted so as not to overlap each other, and the adjacent coils are formed such that the directions of magnetic flux generated by signals transmitted through the LC filter become the same. You.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LC filter formed by laminating an insulating layer and a conductor pattern in a laminated body,
The present invention relates to a laminated filter mounted on a mobile communication terminal or a high frequency communication device.

[0002]

2. Description of the Related Art There is a conventional laminated filter in which an insulator layer and a conductor pattern are laminated to form an LC filter as shown in FIG. 4 in the laminated body. FIG. 4 shows a low-pass filter, which has a coil L between the input terminal 41 and the output terminal 42.
3 and the capacitor C6 are connected in parallel, and the capacitor C7 is connected between the input terminal 41 side of the coil L3 and the ground,
A capacitor C is connected between the output terminal 42 side of the coil L3 and the ground.
8 are connected. This type of low-pass filter is mainly connected immediately after the output of the power amplifier of a high-frequency communication device,
It is used to remove unnecessary harmonic components generated in the F section. In recent years, high-frequency communication devices are required to have high attenuation in the stop band. However, since such a conventional multilayer filter has a low order, even if the inductance value of the coil or the capacitance value of the capacitor is adjusted, unnecessary harmonic components cannot be sufficiently attenuated in the stop band.

In order to solve such a problem, it is considered to increase the circuit configuration of the filter as shown in FIG. The laminated filter shown in FIG. 5 has an insulating layer and a conductor pattern laminated, and a parallel circuit of a coil L4 and a capacitor C9 between an input terminal 51 and an output terminal 52 in the laminated body.
A parallel circuit of the coil L5 and the capacitor C10 is connected in series, and a capacitor C12 is connected between the parallel circuit of the coil L4 and the capacitor C9, a connection point of the parallel circuit of the coil L5 and the capacitor C10, and the ground, and a parallel circuit of the coil L4 and the capacitor C4. Capacitor C11 between the input terminal side of the circuit and ground
To form a low-pass filter in which a capacitor C13 is connected between the output terminal side of the parallel circuit of the coil L5 and the capacitor C10 and the ground.

[0004]

Such a conventional multilayer filter tends to have a narrower space between the respective elements constituting the circuit as the size thereof is reduced, and in particular, the coils L4 and L
If the 5's are placed close together, the two coils will be inductively coupled to each other. Therefore, in the conventional multilayer filter, the size of the coupling may change depending on how the coils are arranged, and sufficient attenuation characteristics may not be obtained.

An object of the present invention is to provide a laminated filter capable of obtaining a sufficient attenuation characteristic even if a plurality of coils forming the filter are arranged close to each other.

[0006]

The laminated filter of the present invention is formed so that the directions of the magnetic flux of adjacent coils are the same while the winding axes of a plurality of coils constituting the LC filter are offset from each other. By doing so, the aforementioned problems are solved. That is, an LC filter having a plurality of coils is formed by stacking an insulator layer and a conductor pattern,
The plurality of coils are arranged with their winding axes displaced from each other so as not to overlap each other, and the adjacent coils are formed so that the directions of magnetic flux generated by the signals transmitted in the LC filter are the same. Further, the plurality of coils are connected in series between the input terminal and the output terminal.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In the laminated filter of the present invention, an LC filter having two coils is formed by laminating an insulating layer and a conductor pattern. In this LC filter, a first coil and a second coil are connected in series between an input terminal and an output terminal, a first capacitor is connected in parallel with the first coil, and a second capacitor is connected in parallel with the second coil. A capacitor is connected to each of them, a third capacitor is connected between the connection point of the first coil and the second coil and the ground, and a fourth capacitor is connected between the input terminal side of the first coil and the ground. A fifth capacitor is connected between the output terminal side of the second coil and the ground to form a low-pass filter. The first coil and the second coil are formed side by side so as not to overlap each other, and the winding direction is set so that the directions of the magnetic flux generated by the signal transmitted through the low pass filter are the same. . Therefore, the laminated filter of the present invention is the first
The magnetic flux of the coil and the magnetic flux of the second coil interfere with each other,
Mutual inductive coupling can be reduced.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The laminated filter of the present invention will be described below with reference to FIGS. FIG. 1 is an exploded perspective view showing an embodiment of the laminated filter of the present invention. In FIG. 1, 11
A to 11H are insulator layers, and 12 to 19 are conductor patterns. The insulator layers 11A to 11H are made of an insulating material such as a dielectric material or a magnetic material. The ground conductor pattern 12 is formed on the surface of the insulator layer 11A. This earth electrode 1
2 is drawn to the opposite side surfaces of the insulator layer 11A. On the surface of the insulator layer 11B, the capacitor conductor pattern 1 is formed.
3, 14 are formed. The capacitance conductor pattern 13 and the capacitance conductor pattern 14 are formed at positions facing the grounding conductor pattern 12. The lead-out end of the capacitance conductor pattern 13 and the lead-out end of the capacitance conductor pattern 14 are drawn to different side surfaces. The conductor pattern 12 for grounding is formed on the surface of the insulator layer 11C. The ground electrode 12 is led out to the opposite side surfaces of the insulator layer 11C. The conductor pattern 15 for capacitance is formed on the surface of the insulator layer 11D. The capacitance conductor pattern 15 is formed at a position facing the ground conductor pattern 12 of the insulator layer 11C. Capacitor conductor patterns 16 and 17 are formed on the surface of the insulator layer 11E. The capacitance conductor pattern 16 and the capacitance conductor pattern 17 are formed at positions facing the capacitance conductor pattern 15. The lead-out end of the capacitance conductor pattern 16 and the lead-out end of the capacitance conductor pattern 17 are drawn to different side surfaces. Insulator layer 11F
The coil conductor patterns 18A and 19A are formed on the surface of the. The coil conductor pattern 18A and the coil conductor pattern 19A are formed by arranging the patterns of less than one turn side by side with an interval so as not to contact each other. One end of the coil conductor pattern 18A and one end of the coil conductor pattern 19A are connected to the capacitor conductor pattern 15 through through holes, respectively. Insulator layer 11
Coil conductor patterns 18B and 19B are formed on the surface of G. The coil conductor pattern 18B and the coil conductor pattern 19B are formed by arranging the patterns of less than one turn side by side so as to be spaced from each other so as not to contact each other. One end of the coil conductor pattern 18B is connected to the coil conductor pattern 1 through the through hole of the insulator layer 11G.
It is connected to the other end of 8A. Coil conductor pattern 19B
One end of is connected to the other end of the coil conductor pattern 19A through a through hole of the insulator layer 11G. The other end of the coil conductor pattern 18B and the coil conductor pattern 19
The other end of B is pulled out to different side surfaces. In this way, the coil conductor pattern 18A and the coil conductor pattern 18B are connected to form the coil L1. Further, the coil conductor pattern 19A and the coil conductor pattern 19
B is connected to form the coil L2. This coil L
1 and the coil L2 are connected in series via the conductor pattern 15 for capacitance. At this time, the coil L1 and the coil L2 are
The winding direction, the drawing direction, and the connection position with other elements are set so that the magnetic fluxes generated by the signals flowing between the input and output terminals are in the same direction. As shown in FIG. 2, terminal electrodes 21, 22, 23, on the side surface of the laminated body in which the insulating layers 11A to 11G are sequentially laminated and covered with the protective insulating layer 11H,
24, 25, 26 are formed. Then, the terminal electrode 22
Thus, the capacitance conductor pattern 13, the capacitance conductor pattern 16 and the other end of the coil conductor pattern 19B of the insulator layer 11G are connected. The terminal electrode 25 connects the capacitance conductor pattern 14, the capacitance conductor pattern 17, and the other end of the coil conductor pattern 18B of the insulator layer 11G. Further, the ground conductor pattern 12 of the insulator layer 11A and the ground conductor pattern 12 of the insulator layer 11C are connected by the terminal electrodes 21, 23, 24, and 26.

A low-pass filter as shown in FIG. 3 is formed in the laminated body thus formed. That is,
The coil L1 formed by the coil conductor patterns 18A and 18B and the coil L2 formed by the coil conductor patterns 19A and 19B are connected between the input terminal 31 and the output terminal 32. Further, the capacitor C1 is connected in parallel to the coil L1 by the capacitance formed between the capacitance conductor pattern 15 and the capacitance conductor pattern 17, and the capacitor C2 is formed by the capacitance formed between the capacitance conductor pattern 15 and the capacitance conductor 16. It is connected in parallel to the coil L2. Further, due to the capacitance formed between the capacitance conductor pattern 13 and the ground conductor patterns 12 on both sides thereof, a capacitor C3 is provided between the input side of the coil L1 and the ground, and between the capacitance conductor pattern 14 and the ground conductor patterns 12 on both sides thereof. Due to the formed capacitance, the capacitor C5 is provided between the output side of the coil L2 and the ground, and the capacitor conductor pattern 15 and the insulating layer 1 are provided.
The capacitor C4 is connected between the connection point of the two parallel circuits and the ground by the capacitance formed between the 1C ground conductor patterns 12.

The multilayer filter thus formed has two
Two coils are placed side by side in the stack,
The direction of the magnetic flux generated in the coil L1 by the signal input from the terminal electrode 25 configuring the input terminal 31 is the same as the direction of the magnetic flux generated in the coil L2 by the signal output from the terminal electrode 22 configuring the output terminal 32. become.

Although the embodiment of the laminated filter of the present invention has been described above, the present invention is not limited to this embodiment. For example, the two coils may be formed so that the directions of the magnetic flux of the adjacent coils are the same in a state where the winding axes are offset from each other so as not to overlap each other. Each of the two coils is formed by a spiral coil conductor pattern. May be done.
Further, the coil conductor pattern forming one coil and the coil conductor pattern forming the other coil may be formed on different insulating layers. Furthermore, although the winding axis of the coil is perpendicular to the mounting surface in the embodiment, the winding axis of the coil may be horizontal to the mounting surface. The present invention can also be applied to an LC filter having three or more coils.

[0012]

As described above, in the laminated filter of the present invention, an LC filter having a plurality of coils is formed by laminating an insulating layer and a conductor pattern, and the plurality of coils are superposed on each other. The coils are arranged so that the winding axes are offset so that the adjacent coils are formed so that the directions of the magnetic fluxes generated by the signals transmitted in the LC filter are the same, so the magnetic fluxes of the adjacent coils interfere with each other. Then
Mutual inductive coupling can be reduced. Therefore, the multilayer filter of the present invention can obtain a sufficient attenuation characteristic even if a plurality of coils forming the filter are arranged close to each other.
Further, in the laminated filter of the present invention, a plurality of coils constituting the filter can be arranged close to each other, so that the laminated filter can be made smaller than the conventional one. Further, the laminated filter of the present invention does not need to consider the influence of mutual inductive coupling, which facilitates the design.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing an embodiment of a laminated filter of the present invention.

FIG. 2 is a perspective view showing an embodiment of the laminated filter of the present invention.

FIG. 3 is a circuit diagram of FIGS. 1 and 2.

FIG. 4 is a circuit diagram of a conventional multilayer filter.

FIG. 5 is a circuit diagram of another conventional multilayer filter.

[Explanation of symbols]

11A-11H Insulator layer 12-19 conductor pattern

Continued front page    F term (reference) 5E070 AA05 CB02 CB13                 5J024 AA01 BA01 CA03 DA01 DA29                       EA01

Claims (4)

[Claims] 1. An LC filter having a plurality of coils is formed by stacking an insulating layer and a conductor pattern,
The plurality of coils are arranged with their winding axes displaced from each other so as not to overlap each other, and adjacent coils are formed so that the directions of magnetic flux generated by signals transmitted through the LC filter are the same. Characteristic multilayer filter. 2. The multilayer filter according to claim 1, wherein the plurality of coils are connected in series between an input terminal and an output terminal. 3. The multilayer filter according to claim 1, wherein the LC filter is a low pass filter. 4. An LC filter having two coils is formed by stacking an insulator layer and a conductor pattern,
The LC filter has a first coil and a second coil connected in series between an input terminal and an output terminal, a first capacitor in parallel with the first coil and a second capacitor in parallel with the second coil. Two
Of the first coil and the second coil.
A third capacitor is connected between the connection point of the coil and the ground, a fourth capacitor is connected between the input terminal side of the first coil and the ground, and a fifth capacitor is connected between the output terminal side of the second coil and the ground. To form a low-pass filter, the first coil and the second coil are arranged with their winding axes displaced from each other so as not to overlap each other, and are transmitted between the input terminal and the output terminal. The multilayer filter is formed so that the directions of magnetic fluxes generated by the signals that are generated are the same.