JPH0818376A - Distribution factor type noise filter - Google Patents

Abstract

PURPOSE:To obtain the distribution factor type noise filter which has a wide band and superior high frequency characteristics. CONSTITUTION:Insulators 1b-1f are laminated so that signal line conductor coil patterns 2b-2g and ground line conductor coil patterns 3b-3g are arranged substantially opposite each other across the insulator layers 1b-1f. This distribution factor type noise filter has a magnetic coupling between coefficient >=0.6 the signal line conductor coil patterns 2b-2g and ground line conductor patterns 3b-3g.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distributed constant type noise filter, and more particularly to a noise filter capable of controlling arbitrary filter characteristics in a wide band.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 4-37005, which is an example of a distributed constant type noise filter, discloses a signal line conductor coil pattern and a ground line conductor coil pattern that are substantially opposed to each other via an insulating layer. Further, a distributed constant type noise filter formed by stacking the insulators is disclosed. As a means for varying the filter characteristic, the number of layers of coils and the number of turns are changed to change the coil area in order to change the equivalent inductance. Was going on.

[0003]

However, in the above-mentioned distributed constant type noise filter, the attenuation pole characteristic is determined by the equivalent inductance or equivalent capacitance. Even if the control is performed based on the calculation, it is difficult to perform the accurate control.

As in the conventional case, it is difficult to independently control the number of laminated layers and the number of turns of the coil in order to change the equivalent inductance, only by changing the coil area, the primary attenuation pole and the secondary attenuation pole, Especially, the setting of the secondary attenuation pole on the higher frequency side than the primary attenuation pole was not stable.

Generally, the attenuation pole frequency fr = k × 1 / (L ₁
XC ₁ ) ^1/2 (k is a proportional constant, L ₁ is an equivalent inductance, and C ₁ is an equivalent capacitance). The equivalent inductance L ₁ is given by the sum of the self-inductance of the signal line side coil, the self-inductance value of the ground line side coil, and the mutual inductance M, and the equivalent capacitance C ₁ is between the signal line side coil and the ground line side coil. Given by capacity.

However, according to various experiments conducted by the present inventors, the linear coupling coefficient is determined by the self-inductance L _{S of the} coil on the signal line side, the self-inductance L _{G of the} coil on the ground line side, and the mutual inductance M. It has been found that the fluctuation of the attenuation pole can be reduced and only the fluctuation of the secondary attenuation pole can be controlled.

That is, in the above-mentioned conventional technique, only the primary attenuation pole can be changed actually, and it is difficult to control the secondary attenuation pole, but if the above magnetic coupling coefficient is appropriately selected. Therefore, a wideband noise filter having arbitrary characteristics can be easily achieved.

The present invention has been devised on the basis of the above findings, and an object thereof is to provide a wide band distributed constant type noise filter in which the control of the secondary attenuation pole is easy.

[0009]

According to the present invention, an insulator layer is provided between a plurality of signal line conductor coil patterns and a plurality of ground line conductor coil patterns in a laminate formed by laminating a plurality of insulator layers. In the distributed constant type noise filter in which the signal line side coil and the ground line side coil are formed so as to be substantially opposed to each other, the magnetic coupling coefficient between the signal line side coil and the ground line side coil is 0. It is a distributed constant type noise filter having a value of 6 or more.

[0010]

According to the present invention, in a distributed constant type noise filter in which a signal line side coil and a ground line side coil are formed by interposing an insulator layer between the signal line conductor coil pattern and the ground line conductor coil pattern,
Although the attenuation pole frequency is defined by the equivalent inductance L ₁ and the equivalent capacitance C ₁ , in particular, the self-inductance L _{S of the} coil on the signal line side, the self-inductance L _{G of the} coil on the ground line side, and the mutual inductance that give the equivalent inductance L ₁ If the inductances M are properly set, the fluctuation of the primary attenuation pole can be reduced and the secondary attenuation pole can be arbitrarily set on the high frequency side.

That is, when the coupling coefficient defined by the self-inductance L _{S of the} coil on the signal line side, the self-inductance L _{G of the} coil on the ground line side, and the mutual inductance M is set to 0.6 or more, the secondary attenuation pole is primary attenuated. It shifts to a high band relatively to the pole, and has a wide band filter characteristic.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the drawings. FIG. 1 is a sectional view of a distributed constant type noise filter of the present invention, and FIGS. 2A and 2B respectively show a conductor film serving as a signal line conductor coil pattern formed on an insulating sheet serving as an insulator layer, It is a top view of a conductor film used as a ground line conductor coil pattern.

The distributed constant type noise filter of the present invention comprises, for example, a laminated body 1 formed by laminating seven insulator layers 1a to 1g, and an input / output terminal electrode 6 formed on the outer surface of the laminated body 1. , 7 and the ground terminal electrode 8 are mainly included.

The laminated body 1 includes, for example, seven insulating layers 1a to 1a.
1g, and signal line conductor coil patterns 2b to 2g and ground line conductor coil patterns 3b to 3g are juxtaposed on each of the insulating layers 1a and 1b, 1b and 1c ... 1f and 1g. , The respective signal line conductor coil patterns 2 in the thickness direction of each of the insulator layers 1b to 1f.
Via-hole conductors 4b to 4f connecting one end of b to 2f and the other end of the signal line conductor coil patterns 2c to 2g adjacent in the thickness direction, and one end of each ground line conductor coil pattern 3b to 3f. And via-hole conductors 5b to 5f that connect the ground line conductor coil patterns 3c to 3g adjacent to each other in the thickness direction to the other ends.

That is, the laminated body 1 includes, for example, an insulating sheet to be the insulating layers 1b, 1d, 1f shown in FIG.
Insulator sheets to be the insulator layers 1c, 1e, and 1g shown in FIG. 2B are alternately laminated. Incidentally, FIG.
FIG. 2 (a) shows each coil pattern formed on the insulator sheet that will be the insulator layer 1b, and FIG. 2 (b) shows each coil pattern that was formed on the insulator sheet that will be the insulator layer 1c. The pattern is shown.

In FIG. 2 (a), a substantially U-shaped signal line conductor coil pattern 2b is arranged between the insulating layers 1a and 1b on an insulating sheet which becomes the insulating layer 1b.
And the ground line conductor coil pattern 3b is formed. Further, one end portion of the signal line conductor coil pattern 2b penetrates the thickness of the insulator layer 1b, and FIG.
A via-hole conductor 4b for connecting to the other end of the signal line conductor coil pattern 2c arranged between the insulating layers 1b and 1c shown in FIG. In addition, one end of the ground line conductor coil pattern 3b penetrates the thickness of the insulator layer 1b, and the insulator layer 1b shown in FIG.
And 1c, a conductor serving as a via-hole conductor 5b for connecting to the other end of the ground line conductor coil pattern 3c arranged between the layers is formed.

Further, in FIG. 2B, the insulator layer 1c
A signal line conductor coil pattern 2c and a ground line conductor coil pattern 3c, which are substantially U-shaped and arranged between the insulating layers 1b and 1c, are formed on the insulating sheet. Also, the signal line conductor coil pattern 2
A via-hole conductor 4c for penetrating the thickness of the insulating layer 1c and connecting to the other end of the signal line conductor coil pattern 2d arranged between the insulating layers 1c and 1d is formed at one end of c. Has been done. Further, one end of the ground line conductor coil pattern 3c is connected to the other end of the ground line conductor coil pattern 3d which penetrates the thickness of the insulator layer 1c and is arranged between the insulator layers 1c and 1d. A conductor to be the via-hole conductor 5c is formed.

The insulator layer 1a has a via hole conductor 4a connected to the other end of the signal line conductor coil pattern 2b, and the insulator layer 1g has a via hole connected to one end of the signal line conductor coil pattern 2f. A conductor 4g and a via-hole conductor 5g connected to one end of the ground line conductor coil pattern 3f are respectively formed.

Further, the input / output terminal electrodes 6 and 7 and the ground terminal electrode 8 are formed on the outer surface of the laminated body 1, that is, the end surface or both main surfaces (both main surfaces in the figure). For example, the output terminal electrode 7 is connected to the via-hole conductor 4a, the input terminal electrode 6 is connected to the via-hole conductor 4g, and the ground terminal electrode 8 is connected to the via-hole conductor 5g.

With the above structure, the output terminal electrode 7 is provided on the other end of the signal line conductor coil pattern 2b via the via-hole conductor 4a, and the input terminal electrode 6 is provided on the via-hole conductor 4g.
Since the ground terminal electrode 8 is connected to one end of the signal line conductor coil pattern 2g via the via hole conductor 5g and the one end of the ground line conductor coil pattern 2g via the via hole conductor 5g, as shown in FIG. Between the input / output terminal electrodes 6 and 7, the via hole conductor 4a, the other end of the signal line conductor coil pattern 2b, one end of the signal line conductor coil pattern 2b, the via hole conductor 4b, the signal line conductor coil pattern 2c, and the like. End-One end of signal line conductor coil pattern 2c-Via hole conductor 4c
-The other end of the signal line conductor coil pattern 2d-One end of the signal line conductor coil pattern 2d-Via hole conductor 4d-The other end of the signal line conductor coil pattern 2e-One end of the signal line conductor coil pattern 2e-The via hole conductor 4e -The other end of the signal line conductor coil pattern 2f-One end of the signal line conductor coil pattern 2f-The via hole conductor 4f-The other end of the signal line conductor coil pattern 2g-One end of the signal line conductor coil pattern 2g-The via hole conductor 4g A series of coils on the signal line side, which are electrically connected to each other and have a predetermined inductance value, are formed.

On the ground potential side, the other end of the ground line conductor coil pattern 3b-one end of the ground line conductor coil pattern 3b-via hole conductor 5b-
The other end of the ground line conductor coil pattern 3c-one end of the ground line conductor coil pattern 3c-via hole conductor 5c-the other end of the ground line conductor coil pattern 3d-one end of the ground line conductor coil pattern 3d-via hole conductor 5d- The other end of the ground line conductor coil pattern 3e-one end of the ground line conductor coil pattern 3e-via hole conductor 5e-the other end of the ground line conductor coil pattern 3f-one end of the ground line conductor coil pattern 3f-via hole conductor 5f- The other end of the ground line conductor coil pattern 3g-one end of the ground line conductor coil pattern 3g-the via hole conductor 5g-the ground terminal electrode 8 is electrically connected to form a series of ground line coils having a predetermined inductance value. Ru It becomes door.

In addition, the signal line conductor coil pattern 2b
~ 2g and ground line conductor coil pattern 3b ~ 3g
Causes a capacitance corresponding to an equivalent capacitance to occur through each of the insulator layers 1b to 1f.

The laminate 1 having the above structure is manufactured by the following manufacturing method.

[0024] First, insulating sheets made of a dielectric material layer 1a~1g laminate 1, BaTiO ₃ which is a dielectric material, T
A ceramic powder containing at least iO ₃ and an organic vehicle are homogeneously kneaded to have a predetermined thickness (20 μm to 100 μm).
Insulator layer 1a formed by molding the above tape and cutting it to a specified size
Create a sheet that weighs ~ 1 g.

Next, through holes (hole diameter 50 μm to 200 μm) to be the via hole conductors 4a to 4g, 5b to 5g are formed at predetermined positions of the insulating sheet by punching or the like.

Next, metal powders of Ag-based materials (Ag simple substance, Ag alloys such as Ag-Pd) and Cu-based materials and, if necessary, a low-melting-point glass frit and an organic vehicle are homogenized in the through holes. The conductive paste obtained by mixing is filled to form the conductors that become the via-hole conductors 4a to 4g and 5b to 5g, and the conductor film and the ground that become the signal line conductor coil patterns 2b to 2g on the surface of the sheet. The conductor film to be the line conductor coil patterns 3b to 3g is formed by screen printing the above-mentioned conductive paste to a thickness of 1 μm.
It is formed by m to 20 μm. Here, the insulator layers 1b, 1
The insulating sheets to be d and 1f have a pattern as shown in FIG. 2A, and the insulating sheets to be the insulating layers 1c, 1e and 1g have a pattern as shown in FIG. Will have. Although not shown in the figure, an insulating sheet that serves as the insulating layer 1a is basically a flat sheet that is filled with a conductor that serves as the via-hole conductor 4a.

Next, the respective sheets are selectively stacked in consideration of the stacking order and integrated by thermocompression bonding. After that, if necessary, it is cut into the final dimension in consideration of the sintering shrinkage, or a dividing groove for dividing is formed in the final step.

Next, a laminated body composed of each insulating sheet is
Bake at a specified atmosphere and a specified peak temperature. When an Ag-based conductive paste is used as the above-mentioned conductive paste, the treatment is carried out in an oxidizing atmosphere and a neutral atmosphere, and when a Cu-based conductive paste is used, it is treated in a reducing atmosphere and a neutral atmosphere. The peak temperature is set to a temperature required for the insulating sheet to undergo a sintering reaction, and the metal component of the conductive paste is adjusted to withstand this temperature. For example, when Ag alone or Cu alone is used for the conductive paste, the peak temperature is 1
When the firing temperature is 050 ° C. or lower and the firing temperature is higher than this, an alloy such as Pd is used.

Further, in the process of raising the firing temperature to about 1000 ° C., the organic vehicle components contained in the insulating sheet, the conductor film and the conductor are burnt off at about 500 ° C.

The laminate 1 fired in this way
To the via-hole conductor 4a exposed on the outer surface of the laminated body 1.
Terminal electrodes 6, 7, and 8 are formed on the exposed portions of 4 g and 5 g by baking a conductive paste. Note that the conductor films to be the terminal electrodes 6, 7, and 8 may be formed before firing the laminated body 1 and subjected to firing treatment simultaneously with the laminated body.

Such a distributed constant type noise filter is
The equivalent circuit configuration shown in FIG. 4 is obtained.

Here, the characteristic of the present invention is that the signal line side coil composed of the signal line conductor coil patterns 2b to 2g and the ground line conductor coil pattern 3b.
That is, the magnetic coupling coefficient with the coil on the ground line side made of 3 g is set to 0.6 or more.

According to various experiments conducted by the present inventors, the change of the magnetic coupling coefficient is caused by the signal line conductor coil pattern 2b.
~ 2g and ground line conductor coil pattern 3b ~ 3g
It has been found that it is determined by the distance between, and the thickness of the insulating layers 1b to 1f.

Furthermore, the present inventors created two types of distributed constant type noise filters having magnetic coupling coefficients of 0.58 and 0.80 and having the structure shown in FIG. 1, and transmitted with a network analyzer at input and output 50Ω. The characteristics were investigated.

As a result, in the distributed constant type noise filter having a magnetic coupling coefficient of 0.58 (comparative example), the primary attenuation pole is around 160 MHz and the secondary attenuation pole is 2 as shown in FIG.
It is around 80 MHz, the difference is about 120 MHz, and the attenuation amount is -20 dB or more in most of the range on the higher frequency side than the secondary attenuation pole, and the noise filter has a narrow band and a small attenuation amount. turn into.

On the other hand, in the distributed constant type noise filter (in the present invention) having a magnetic coupling coefficient of 0.6 or more, for example, 0.80, the primary attenuation pole is 160 MH as shown in FIG.
Near z, the secondary attenuation pole is around 410 MHz, the difference is about 250 MHz, and the attenuation amount is -20 dB or less in most of the range on the higher frequency side than the secondary attenuation pole, and as a noise filter, Wide band and large attenuation.

Further, the relationship between the primary attenuation pole and the secondary attenuation pole due to the variation of the magnetic coupling coefficient was investigated. FIG. 7 shows the result. In FIG. 7, the primary attenuation pole is shown by a dotted line and the secondary attenuation pole is shown by a solid line. As a result, the primary attenuation pole does not basically change even if the magnetic coupling coefficient changes, whereas the secondary attenuation pole shifts to a high frequency side especially when the magnetic coupling coefficient becomes 0.6 or more. However, it can be seen that the difference between the primary attenuation pole and the secondary attenuation pole becomes large. Therefore, in the distributed constant type noise filter, the signal line conductor coil patterns 2b to 2g and the ground line conductor coil pattern 3 are used.
By setting the magnetic coupling coefficient between b and 3g to be 0.6 or more, a wide band filter can be obtained, and as shown in FIG. 6, the amount of attenuation on the high frequency side can be increased, and excellent filter characteristics can be obtained. It becomes a noise filter.

One of the concrete means for setting the magnetic coupling coefficient to 0.6 or more is to adjust the thickness of the insulating layers 1b to 1g. For example, although it is slightly related to the magnetic permeability of the insulating layers 1b to 1g, the magnetic permeability of the insulating layer is generally 1, and if the layer thickness at the magnetic permeability is 45 μm or less, the coupling coefficient is 0.6 or more. Further, the coupling coefficient becomes smaller when the layer thickness is made thinner.

FIG. 8 is a structural sectional view of a laminated body 81 showing another embodiment of the present invention. The terminal electrodes are omitted.

The laminated body 81 includes, for example, eight insulating layers 81.
a to 81h. This embodiment is characterized by the insulating layers 81a and 81b, 81b and 81c, 81c and 81.
between the signal line conductor coil pattern 82b and the signal line conductor coil pattern 82b.
Only 82d is formed, and the ground line conductor coil pattern is not formed.

That is, only the conductor film which becomes the signal line conductor coil pattern in FIG. 2A is formed on the insulator sheet which becomes the insulator layers 81b and 81d, and the insulator sheet which becomes the insulator layer 81c. In FIG. 2, only the conductor film to be the signal line conductor coil pattern in FIG. 2B is formed.

Further, between the insulating layers 81d and 81e, 81e and 81f, 81f and 81g, 81g and 81h,
Signal line conductor coil patterns 82e to 82h and ground line conductor coil patterns 83e to 83h are formed.

That is, as shown in FIG. 2 (b), the insulator sheet to be the insulator layers 81e and 81g has an insulator layer 81.
A pattern as shown in FIG. 2A is formed on the insulating sheets f and 81h.

In the sectional view of FIG. 8, the signal line conductor coil patterns 82e and 82g and the ground line conductor coil patterns 83f and 83h are omitted because they do not appear in the drawing.

In the basic circuit of this distributed constant type noise filter, as shown in FIG. 9, the self-inductance of the signal line side coil and the self-inductance of the ground line side coil are different.

That is, by superposing the signal line conductor coil pattern formed between the insulator layers on the laminated body 81, only the self-inductance of the signal line side coil is set to a predetermined value without changing the equivalent capacitance. It can be set and in practice the coupling coefficient can be easily controlled.

Although the terminal electrodes 6, 7, 8 formed on the laminated body 1 are formed on both main surfaces of the laminated body in the above-mentioned embodiment, the other ends of the signal line conductor coil patterns 2b, 82b, One ends of the signal line conductor coil patterns 2g and 82h and one ends of the ground line conductor coil patterns 3g and 83h are led out from the end faces of the laminated bodies 1 and 81, and the terminal electrodes 6 and 7 are attached to the end faces of the laminated bodies 1 and 81. , 8 may be formed.

Further, the laminated structure, the number of laminated layers and the like can be arbitrarily changed.

[0049]

According to the present invention, since the magnetic coupling coefficient between the coil formed of the signal line conductor coil pattern and the coil formed of the ground line conductor coil pattern is set to 0.6 or more, the fluctuation of the primary attenuation pole is reduced. It is possible to simply shift only the secondary attenuation pole to the high frequency side, and a wide band distributed constant type noise filter can be achieved.

Further, the attenuation characteristic on the higher frequency side than the secondary attenuation pole can be increased, and an excellent distributed constant type noise filter having high selectivity can be easily achieved.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a distributed constant type noise filter of the present invention.

2A and 2B are schematic plan views showing respective coil patterns of an insulating sheet.

FIG. 3 is a schematic diagram showing a connection state of substantial coil patterns of the noise filter shown in FIG.

FIG. 4 is a circuit diagram equivalent to the distributed constant type noise filter shown in FIG.

FIG. 5 is a characteristic diagram of a distributed constant type noise filter having a magnetic coupling coefficient of 0.58.

FIG. 6 is a characteristic diagram of a distributed constant type noise filter having a magnetic coupling coefficient of 0.80.

FIG. 7 is a characteristic diagram showing the relationship between the magnetic coupling coefficient and the primary and secondary attenuation poles.

FIG. 8 is a sectional view showing another embodiment of the present invention.

9 is a circuit diagram equivalent to the distributed constant type noise filter shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Laminated body 1a-1g ... Insulator layer 2b-2g ... Signal line conductor coil pattern 3b-3g ... Ground line conductor coil pattern 4a-4g, 5b-5g ...・ Via hole conductors 6, 7 ・ ・ ・ I / O terminal electrodes 8 ・ ・ ・ ・ Ground side terminal electrodes

Claims (1)

[Claims] 1. A laminated body formed by laminating a plurality of insulator layers so that a plurality of signal line conductor coil patterns and a plurality of ground line conductor coil patterns are substantially opposed to each other with an insulator layer interposed therebetween. In the distributed constant noise filter in which the signal line side coil and the ground line side coil are formed by arranging the coil, the magnetic coupling coefficient between the signal line side coil and the ground line side coil is set to 0.6 or more. Distributed constant type noise filter.