JP2005079883A - Filter element, and electronic module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter element without requiring classification between an input terminal and an output terminal by making the frequency characteristic of impedance viewed from the input terminal come close to that viewed from the output terminal without deteriorating the characteristic as the filter element, and to provide an electronic module. <P>SOLUTION: Distribution capacitance is generated via each insulation body layer between first coil forming conductors 4b, 4d, 4f and second coil forming conductors 4a, 4c, 4e. By the sum of the capacitance of the first coil forming conductors and the capacitance of the second coil forming conductors, a first capacity is generated. Inductance is generated between a terminal 2a to be the input of a signal line and a terminal 2i to be the output of the signal line, so as to acquire the filter characteristic. Through the use of the structure, electric conductivity of the first coil forming conductors 4b, 4d, 4f and/or the second coil forming conductors 4a, 4c, 4e is made to be 5×10<SP>4</SP>(S/m) to 10<SP>6</SP>(S/m), so that the resistance component of the inductance is increased. Resonance is suppressed, so that the value of impedance viewed from an input side is made to be close to that of impedance viewed from an output side over wide frequencies. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a filter element and an electronic module, and particularly to a filter element used for noise removal and the like, which utilizes parallel resonance and series resonance of inductance and capacitance of a conductor pattern formed in a laminated insulator layer. The present invention relates to a filter element that can obtain a predetermined attenuation at a specific frequency and an electronic module using the filter element.

Conventionally, when coil pieces are formed in a plurality of insulator layers and the respective insulator layers are laminated, the coil pieces are connected to form a coil, and the inductance of the coil and the coil There is known an example in which a multilayer filter element is realized by using a capacitance formed between a conductive pattern formed on an insulator layer.
As this multilayer filter element, an element that actively utilizes distributed constant capacitance between element internal circuits has been proposed (for example, see Patent Document 1). In this filter element, double coils L1 and L2 are formed in the element, signal input terminals and output terminals are provided at both ends of the coil L1, the coil L2 is connected to the ground, the inductance of the coil L1, and the coil A low-pass filter is formed by using a distributed constant capacitance between L1 and coil L2.

The low-pass filter having this structure can obtain a predetermined attenuation at a specific frequency (cutoff frequency) by appropriately adjusting the capacitance and inductance of each part.
Japanese Unexamined Patent Publication No. 04-2108 JP 2001-53571 A

This filter element is different in impedance as viewed from the input side and impedance viewed from the output side due to the wiring structure, and when used, it is necessary to distinguish between the input side and the output side. When the input and output of the filter are used in reverse, the matching condition with the device connected before or after the filter changes, and the attenuation characteristic may deteriorate depending on the frequency.
Therefore, since it is necessary to identify the input terminal and the output terminal in the conventional filter element, marking for displaying the direction is necessary. For this reason, there has been a problem that the cost for marking is increased in the mounting process, the packaging process, and the like.

 The object of the present invention is to distinguish between the input terminal and the output terminal by bringing the frequency characteristic of the impedance viewed from the input terminal close to the frequency characteristic of the impedance viewed from the output terminal without impairing the characteristics as a filter element. It is providing the filter element and electronic module which do not have.

The filter element of the present invention has a coil-forming conductor formed on a plurality of insulator layers, and the coil-forming conductors are electrically connected to each other in a state where the respective insulator layers are laminated. Both ends of the conductor for conductor are extended to the end face as input and output of the signal line, the coil-forming conductor is grounded through the capacitance of the insulator layer, and the conductivity of the coil-forming conductor is 5 × 10 ⁴ [S / m] to 10 ⁶ [S / m]. S is Siemens and is the reciprocal of Ω (ohms).

The filter element according to the present invention includes a first coil-forming conductor and a second coil-forming conductor that are alternately formed on a plurality of insulator layers, and a laminate of each insulator layer. The first coil-forming conductors formed every other layer are electrically connected to each other, and the second coil-forming conductors formed every other layer in a state where the respective insulator layers are laminated. Are electrically connected, and both ends of the first coil forming conductor are extended to an end face as input and output of a signal line, and between the first coil forming conductor and the second coil forming conductor. A distributed capacitor is formed through each insulator layer, a first capacitor is formed by the sum of the distributed capacitors, and the second coil forming conductor is grounded directly or through the second capacitor of the insulator layer. The first coil-forming conductor and / or the second coil-forming conductor. Wherein the conductivity takes a value from ^{5 × 10 4 [S / m} ] to 10 ⁶ [S / m].

Hereinafter, the “first coil forming conductor” and the “second coil forming conductor” may be collectively referred to as “coil forming conductor”.
In such a filter element, the coil-forming conductor forms an inductance between the signal line input terminal and the signal line output terminal, and forms a distributed capacity via the capacity of the insulator layer. Thus, filter characteristics can be obtained.

Further, the resistance component of the coil is increased by setting the conductivity of the coil forming conductor to 5 × 10 ⁴ to 10 ⁶ [S / m]. As a result, resonance and anti-resonance are suppressed, and the impedance value seen from the input side and the impedance value seen from the output side can be made close to each other over a wide frequency range.
In the filter element of the present invention, since the impedance values seen from the input / output side can be made substantially equal, it is not necessary to identify the terminals that are input to the signal line for connection to the external circuit and the terminals that are the output of the signal line. . Therefore, these terminals can be formed in substantially the same shape, marking for indicating the direction as in the conventional filter element is unnecessary, and an increase in equipment burden and cost in the mounting process, packing process, etc. can be avoided. it can.

The coil forming conductor can be made of a conductor containing Ag as a main component, for example.
The filter element of the present invention employs a structure in which the coil forming conductor is formed on every other insulator layer, and the upper and lower layer connecting conductors are formed on the insulator layer interposed therebetween. be able to.

In this case, the coil forming conductor and the upper and lower layer connecting conductors can be connected by via conductors in the insulator layer.
When two types of coil forming conductors are provided, the first coil forming conductors are electrically connected to each other by via conductors in the insulator layer, and the second coil forming conductors are connected to the insulator. A structure in which the via conductors in the layers are electrically connected can be employed.

When two types of coil forming conductors are provided, upper and lower layers are connected to the insulator layer on which the first coil forming conductor is formed and the insulator layer on which the second coil forming conductor is formed. A structure in which a conductor is formed can be employed.
When forming the upper and lower layer connecting conductors in this way, the first coil forming conductor and the upper and lower layer connecting conductors are connected by via conductors in an insulator layer, and the second coil forming conductor and The upper and lower layer connecting conductors can be connected by via conductors in the insulator layer.

If the above connection structure using via conductors is adopted, there is no need to provide a connection conductor on the surface of the element, so that the surface of the element can be used widely. Therefore, the size of the input / output terminals and connection terminals for connection to the external circuit and the distance between them can be widened, so that defects such as short circuits between the external terminals are reduced, and the filter element can be easily downsized.
An electronic module according to the present invention includes the above-described filter element. Since such an electronic module can be mounted with a small filter having excellent characteristics, the entire electronic module can be reduced in size and improved in characteristics.

  As described above, in the present invention, since the impedance viewed from the input terminal and the impedance viewed from the output terminal can be brought close to each other, even when the input terminal and the output terminal are reversed, the external circuit is caused by the difference in reflection characteristics. There is no problem such as malfunction. Therefore, an easy-to-use filter element having a steep attenuation characteristic over a wide frequency can be realized.

Hereinafter, the noise filter of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an external perspective view of the filter element of the present invention. 2 is a cross-sectional view of the filter element taken along the line XX, and FIG. 3 is an exploded perspective view showing a laminated structure of dielectric ceramic layers.
As shown in FIG. 1, the filter element of the present invention includes a ceramic laminate 1 composed of a plurality of dielectric ceramic layers, an input terminal 2a of a signal line formed on the outer surface thereof, an output terminal 2i, It is a chip component composed of terminals 3 of the GND line.

As shown in FIG. 2, the ceramic laminated body 1 has a nine-layer laminated structure from the lowermost dielectric ceramic layer 1a to the uppermost dielectric ceramic layer 1i. The present invention is not limited to nine layers as long as a plurality of layers are laminated.
In the filter element of the present invention, two coils L1 and L2 are formed, and a capacitance is formed between them. The coil forming conductor constituting the coil L1 is referred to as a “first type coil forming conductor”, and the coil forming conductor constituting the coil L2 is referred to as a “second type coil forming conductor”.

This filter element has a structure in which dielectric ceramic layers in which first-type coil forming conductors are arranged and dielectric ceramic layers in which second-type coil forming conductors are arranged are alternately stacked. Therefore, the first type coil forming conductors and the second type coil forming conductors are arranged in every other layer in the dielectric ceramic layer.
The structure of the filter element will be described below. 2 and 3, a GND conductor 3a is formed on the lowermost dielectric ceramic layer 1a, and terminals are provided in two directions from the GND conductor 3a, which are connected to the GND terminal 3. doing. The dielectric ceramic layer 1a is formed with an input conductor 2b connected to the input terminal 2a.

  A second type coil forming conductor 4a is formed on the next dielectric ceramic layer 1b, and an upper and lower layer connecting conductor 2c is formed separately from the second type coil forming conductor 4a. The second-type coil forming conductor 4a is substantially H-shaped in plan view, and makes a signal approximately 3/4 turn between the lower ends of the H legs. This constitutes a part of the inductance of the coil L2. The upper and lower layer connection conductors 2c are substantially I-shaped in plan view, and include an input conductor 2b for the lower dielectric ceramic layer 1a and a first-type coil forming conductor 4b for the upper dielectric ceramic layer 1c. Connecting.

  In the next dielectric ceramic layer 1c, a first type coil forming conductor 4b is formed, and an upper and lower layer connecting conductor 2d is formed separately from the first type coil forming conductor 4b. The positional relationship between the first type coil forming conductor 4b and the upper and lower layer connecting conductor 2d is opposite to the positional relationship between the lower second type coil forming conductor 4a and the upper and lower layer connecting conductor 2c. The first type coil forming conductor 4b is substantially H-shaped in plan view, and makes a signal approximately 3/4 turn between the lower ends of the H legs. Since the signal is turned approximately ¼ turn by the upper / lower layer connection conductor 2c of the lower dielectric ceramic layer 1b, the signal circulates almost one turn together with the ¾ turn of the first type coil forming conductor 4b. (The same shall apply hereinafter.) The upper and lower layer connecting conductors 2d are substantially I-shaped in plan view, and are used for forming the second type coil forming conductor 4a of the lower dielectric ceramic layer 1b and the second type coil forming of the upper dielectric ceramic layer 1d. The conductor 4c is connected. Since the signal is turned approximately ¼ turn by the upper and lower layer connecting conductor 2d, the signal circulates almost one turn together with the ¾ turn of the second type coil forming conductor 4a (the same applies hereinafter).

  In the next dielectric ceramic layer 1d, a second type coil forming conductor 4c is formed, and an upper and lower layer connecting conductor 2e is formed. The positional relationship between the second type coil forming conductor 4c and the upper and lower layer connecting conductor 2e is opposite to the positional relationship between the lower first type coil forming conductor 4b and the upper and lower layer connecting conductor 2d. Therefore, it is in the same direction as the positional relationship between the second type coil forming conductor 4a and the upper and lower layer connecting conductor 2c. The second type coil forming conductor 4c is substantially H-shaped in plan view, and makes the signal approximately 3/4 turn between the lower ends of the H legs. The upper and lower layer connection conductors 2e are substantially I-shaped in plan view, and are used for forming the first type coil forming conductor 4b of the lower dielectric ceramic layer 1c and the first type coil forming of the upper dielectric ceramic layer 1e. The conductor 4d is connected.

  In the next dielectric ceramic layer 1e, a first type coil forming conductor 4d is formed, and an upper and lower layer connecting conductor 2f is formed. The positional relationship between the first type coil forming conductor 4d and the upper and lower layer connecting conductor 2f is opposite to the positional relationship between the lower second type coil forming conductor 4c and the upper and lower layer connecting conductor 2e. Therefore, it is in the same direction as the positional relationship between the lower first type coil forming conductor 4b and the upper and lower layer connecting conductor 2d. The first-type coil forming conductor 4d is substantially H-shaped in plan view, and makes a signal approximately 3/4 turn between the lower ends of the H legs. The upper and lower layer connection conductors 2f are substantially I-shaped in plan view, and the second type coil forming conductor 4c of the lower dielectric ceramic layer 1d and the second type coil forming of the upper dielectric ceramic layer 1f. The conductor 4e is connected.

  In the next dielectric ceramic layer 1f, a second type coil forming conductor 4e is formed, and an upper and lower layer connecting conductor 2g is formed. The positional relationship between the second type coil forming conductor 4e and the upper and lower layer connecting conductor 2g is opposite to the positional relationship between the lower first type coil forming conductor 4d and the upper and lower layer connecting conductor 2f. Therefore, it is in the same direction as the positional relationship between the lower second type coil forming conductor 4c and the upper and lower layer connecting conductor 2e. The second-type coil forming conductor 4e is substantially H-shaped in plan view, and makes the signal approximately 3/4 turn between the lower ends of the H legs. The upper and lower layer connection conductors 2g are substantially I-shaped in plan view, and the first type coil forming conductor 4d of the lower dielectric ceramic layer 1e and the first type coil forming of the upper dielectric ceramic layer 1g. The conductor 4f is connected.

  In the next dielectric ceramic layer 1g, a first type coil forming conductor 4f is formed, and an upper and lower layer connecting conductor 2h is formed. The positional relationship between the first type coil forming conductor 4f and the upper and lower layer connecting conductor 2h is opposite to the positional relationship between the lower second type coil forming conductor 4e and the upper and lower layer connecting conductor 2g. Therefore, it is in the same direction as the positional relationship between the lower first type coil forming conductor 4d and the upper and lower layer connecting conductor 2f. The first-type coil forming conductor 4f is substantially H-shaped in plan view, and makes a signal approximately 3/4 turn between the lower ends of the H legs. The upper and lower layer connection conductors 2h are substantially I-shaped in plan view, and are connected to the second type coil forming conductor 4e of the lower dielectric ceramic layer 1f.

An output conductor 2i connected to the output terminal 2i is formed on the top dielectric ceramic layer 1h. The output conductor 2i has a hook shape in a plan view, and makes a signal substantially half a circle.
Finally, a protective dielectric ceramic layer 1i (not shown in FIG. 3) is laminated on the dielectric ceramic layer 1h.
Between the dielectric ceramic layers, via conductors (shown schematically by thin lines in FIG. 3) 5a to 5g are provided so as to penetrate the dielectric ceramic layer, and the input conductor 2b, the upper and lower layer connection conductors 2c, The first type coil forming conductor 4b, the upper and lower layer connecting conductor 2e, the first type coil forming conductor 4d, the upper and lower layer connecting conductor 2g, the first type coil forming conductor 4f, and the output conductor 2i are these vias. The conductors 5a to 5g are connected. Therefore, the input terminal 2a and the output terminal 2i are connected in series by the first type coil forming conductor, the via conductor, and the upper and lower layer connecting conductors. The coil L1 is constituted by these members.

  Furthermore, via conductors (schematically shown by thin lines in FIG. 3) 6a to 6e are provided between the dielectric ceramic layers so as to penetrate the dielectric ceramic layer. By the via conductors 6a to 6e, the second type coil forming conductor 4a, the upper and lower layer connecting conductor 2d, the second type coil forming conductor 4c, the upper and lower layer connecting conductor 2f, the second type coil forming conductor 4e, and the upper and lower layers The connecting conductor 2h is connected in series. These second type coil forming conductors, via conductors, and upper and lower layer connecting conductors constitute the coil L2.

What is characteristic of the present invention is that the first type coil forming conductors 4b, 4d and 4f, the second type coil forming conductors 4a, 4c and 4e, the via conductors 5a to 5g, and the via conductors 6a to 6e are made of Ag or the like. That is, it is composed of a conductor material as a main component. The component composition of the conductor material is selected so that its conductivity is 5 × 10 ⁴ to 10 ⁶ [S / m]. Specifically, Ag is 60 to 90% by weight and Pd is 10 to 40% by weight. Further, it may be an alloy containing at least two of Ag, Ni, Pd, Pt, Ti, and Re, or a mixture thereof.

The terminal electrodes 2a and 2i are composed of a base conductor mainly composed of Ag and a layer such as Ni plating or solder plating formed on the surface thereof.
The coil L2 is floating without being connected to any terminal, forms a capacitance C1 with the coil L1 formed between the input terminal 2a and the output terminal 2i, and between the GND conductor 3a. A capacitor C2 is formed. The capacitance C1 is the sum of the capacitances (distributed capacitances) formed between the first type coil forming conductor and the second type coil forming conductor.

  FIG. 4 is an equivalent circuit diagram of the above filter element. Since the filter element has the above-described structure, the three-turn and half-turn coil L1 and the three-turn coil L2 are formed in a nine-layer laminated structure. Then, as shown in FIG. 4, a distributed capacitance is formed between the coil L1 and the coil L2, the sum thereof becomes a capacitance C1, and a capacitance C2 is formed between the coil L2 and the ground. The capacitors C1 and C2 formed in this way are represented by hatched portions C1 and C2 in FIG. 2, respectively. The hatched portion C1 represents a capacitance C1 that is a sum of distributed capacitances formed between the first type coil forming conductors 4b, 4d, 4f and the second type coil forming conductors 4a, 4c, 4e, and the hatched portion C2 represents a capacitance C2 formed between the second type coil forming conductor 4a and the GND conductor 3a.

  With the above configuration, the coil L1 formed by the first type coil forming conductors 4b, 4d, 4f, etc. exists between the input terminal 2a of the signal line and the output terminal 2i. A capacitance is formed between the coil L2 formed by the second type coil forming conductors 4a, 4c, 4e and the like, and a capacitance is further formed between the coil L2 and the GND line. Therefore, a low-pass filter element made of LC can be configured. A noise removal function or the like can be realized by this filter element.

The coil L2 is floating without being connected to any terminal, but a via conductor is provided to connect the second type coil forming conductor 4a to the GND conductor 3a. It is also possible to adopt a structure in which the coil L2 is directly grounded.
Next, the manufacturing method of the above filter element is demonstrated easily.
The raw materials for the dielectric ceramic layers 1a to 1i are dielectric ceramic materials such as alumina (Al ₂ O ₃ ), barium titanate (BaTiO ₃ ), titanium dioxide (TiO ₂ ), or crystallization with these dielectric ceramic materials. It consists of a mixture such as glass.

The first type coil forming conductors 4b, 4d, and 4f, the second type coil forming conductors 4a, 4c, and 4e, the GND conductor 3a, and the connection via conductors 5a to 5g and 6a to 6e are mainly composed of Ag or the like. A conductive material is used.
The input / output terminals 2a and 2i and the terminal 3 of the GND line are composed of a base conductor mainly composed of Ag and a layer such as Ni plating or solder plating attached to the surface thereof.

First, a binder or the like is mixed with a mixture containing the dielectric ceramic material as a main raw material, a green sheet is formed by press working, and a via hole is formed through a predetermined position.
In order to form the first type coil forming conductors 4b, 4d, 4f, the second type coil forming conductors 4a, 4c, 4e, and the GND conductor 3a on the green sheet with via holes, a conductor mainly composed of Ag. The paste is printed in a predetermined pattern. Further, the conductor paste is embedded in the via hole. And each green sheet is laminated | stacked in a predetermined order, and after pressing and integrating, it cuts into each shape.

  By firing it at around 900 ° C., a rectangular parallelepiped ceramic laminate 1 as shown in FIG. 1 is produced. Furthermore, the input / output terminals 2a and 2i and the GND terminal 3 are formed on the surface of the ceramic laminate 1 by a printing method or a DIP method using a conductive paste mainly composed of Ag. The input / output terminals 2a and 2i and the GND terminal 3 are baked and subjected to Ni and solder plating, whereby a filter element chip is manufactured.

In the filter element described above, the first-type coil forming conductors 4b, 4d, and 4f formed every other layer in a state where the respective insulator layers are stacked are for upper and lower layer connection formed in an intermediate layer. The second-type coil forming conductors 4a, 4c, 4e connected via the conductors 2e, 2g are connected via the upper and lower layer connecting conductors 2d, 2f formed in the middle layer. It had been.
However, the upper and lower layer connection conductors are omitted, and the first type coil forming conductors 4b, 4d, 4f formed every other layer are directly connected by via conductors, and the second type formed every other layer. The coil forming conductors 4a, 4c, and 4e can be directly connected by via conductors.

  FIG. 5 is an exploded perspective view showing a laminated structure of dielectric ceramic layers in which such coil forming conductors are directly connected by via conductors. The same members as those shown in FIG. 3 are denoted by the same reference numerals, and repeated description is omitted. However, the difference from FIG. 3 is that the input conductor 2b and the first type coil forming conductor 4b are connected. A via conductor 7a is provided, a via conductor 7b that connects the first type coil forming conductors 4b and 4d is provided, and a via conductor 7c that connects the first type coil forming conductors 4d and 4f is provided. That is, a via conductor 8a that connects the second type coil forming conductors 4a and 4c is provided, and a via conductor 8b that connects the second type coil forming conductors 4c and 4e is provided.

  These via conductors 7a to 7c, 8a, and 8b must be connected to the coil forming conductor in a state of penetrating through the dielectric ceramic layer that overlaps the two layers. For example, the via conductor 7a connecting the input conductor 2b and the first type coil forming conductor 4b straddles the dielectric ceramic layers 1b and 1c. For this reason, when manufacturing the filter element, it is necessary to form via holes so that the two green sheets are overlapped with each other so that the green sheets are located at the same position, and to embed the conductor paste across the upper and lower via holes. is there.

  In addition, in the coil forming conductors alternately formed every other layer, when the connection points of both lower ends of the H legs connected to the via conductor are in the same position in plan view, unless the via conductor is formed obliquely This makes it impossible to form a circular coil. Since it is difficult to form the via conductors at an angle, the positions E1, E2, and E3 of the connection points of the coil forming conductors are shifted little by little in the embodiment of FIG. Accordingly, it is possible to configure the circular coil while forming the via conductor vertically.

Thus, in the filter element of FIG. 5, the upper and lower layer connecting conductors can be omitted, so that the shape of the printed pattern of the conductor can be simplified and the area of the dielectric ceramic layer can be reduced.
On the other hand, when the upper and lower layer connection conductors are used as shown in FIG. 3, the positions of the connection points of the coil forming conductors can be formed at the same position in each layer. The number of masks for printing can be reduced, which is effective in reducing the price.

Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention.
For example, the present invention can be applied even when a circular coil is formed in a laminated structure using only one type of coil forming conductor. FIG. 7 shows a structure using only one type of coil forming conductor. According to this figure, three-and-a-half times using one type of coil forming conductors 12c, 12e, 12g, and 12h and upper and lower layer connecting conductors 12b, 12d, and 12f in the eight-layer laminated structures 1a to 1h. A winding coil is formed. Reference numerals 14a to 14c are floating conductors for forming an intermediate capacitance.

Also in this case, the coil forming conductors 12c, 12e, 12g, and 12h and the upper and lower layer connecting conductors 12b, 12d, and 12f are made of a conductive material mainly composed of Ag or the like, and the conductivity is 5 × 10 ^4. If selected to be 10 ⁶ [S / m], the resistance component of the coil can be increased. As a result, resonance and anti-resonance are suppressed, and the impedance value viewed from the input side and the impedance value viewed from the output side can be made close to each other over a wide frequency range.

  An electronic module that realizes various functions can be manufactured by mounting such a filter element on a mother board or the like.

In order to evaluate the input / output impedance characteristics of the filter element having the structure shown in FIGS. 1 to 3 manufactured as described above, a simulation of electromagnetic field analysis was performed.
The conductivity of the conductive material inside the filter element is (a) 5.8 × 10 ⁷ [S / m]
(B) 5.8 × 10 ⁶ [S / m]
(C) 5.8 × 10 ⁵ [S / m]
(D) 5.8 × 10 ⁴ [S / m]
The reflection coefficient S11 when viewed from the input side and the reflection coefficient S22 when viewed from the output side are represented in the Smith chart in the frequency range of 0.1 GHz to 6 GHz.

  The result is shown in FIG. Smith chart values are normalized to 50Ω. At a frequency of 0.1 GHz, it can be seen that both the reflection coefficients S11 and S22 are at the center of the Smith chart and are approximately 50Ω. As the frequency is increased, the reflection coefficients S11 and S22 each move away from the center of the chart while drawing a clockwise loop. When it is on the left side from the center of the chart, the impedance is small, and when it is on the right side, the impedance is large. The ideal state of the impedance seen from the input side and the impedance seen from the output side is that S11 and S22 do not change from the vicinity of the center (50Ω) of the chart. However, it is very difficult to realize this state over a wide frequency range. Next, it is desirable that the trajectories of S11 and S22 are biased to the left side of the chart. When the locus swells greatly to the right from the center, the impedance becomes very large.

According to the analysis of FIG. 6, in FIGS. 6 (a) and 6 (b), which are outside the scope of the present invention, S22 swells considerably to the right from the center of the chart, and the difference in impedance from S11 increases by an order of magnitude. ing.
On the other hand, in FIGS. 6 (c) and 6 (d) within the scope of the present invention, both S11 and S22 are in the left side of the chart (region G surrounded by a dotted line), and viewed from the input side and viewed from the output side. The impedances are both low impedance and the difference between them is quite small.

  As described above, according to the structure of the present invention, the impedance viewed from the input side and the impedance viewed from the output side can be made close to each other over a wide frequency range.

It is an external appearance perspective view of the filter element of this invention. It is sectional drawing of the filter element of this invention. It is a structure perspective view when a dielectric ceramic layer is laminated. It is an equivalent circuit diagram of the filter element of the present invention. By omitting the upper and lower layer connecting conductors, the first type coil forming conductors formed every other layer are directly connected by direct via conductors, and the second type coil forming conductors formed every other layer are directly via. It is a disassembled perspective view which shows the laminated structure of the dielectric ceramic layer directly connected by the conductor. Regarding the filter elements (a) and (b) outside the scope of the present invention and the filter elements (c) and (d) of the present invention, the reflection coefficient S11 when viewed from the input side and the reflection coefficient S22 when viewed from the output side. Is a diagram showing a Smith chart in a frequency range of 0.1 GHz to 6 GHz. It is an external perspective view of the filter element of the present invention using only one type of coil forming conductor.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Ceramic laminated body 1a-1h Dielectric ceramic layer 2a Input terminal 2c-2h Upper / lower layer connection conductor 2i Output terminal 3 GND terminal 4b, 4d, 4f 1st type coil formation conductor 4a, 4c, 4e 2nd type coil formation Conductor 5a-5g Via conductor 6a-6e Via conductor 7a-7c Two-layer through via conductors 8a, 8b Two-layer through via conductors 12c, 12e, 12g, 12h Coil forming conductors 12b, 12d, 12f Upper and lower layer connection conductors

Claims (11)

Having a coil-forming conductor formed on a plurality of insulator layers;
In the state where each insulator layer is laminated, the coil-forming conductors are electrically connected,
Both ends of the coil forming conductor are extended to the end face as input and output of the signal line,
The coil-forming conductor is grounded through the capacitance of the insulator layer;
A filter element, wherein the coil-forming conductor has a conductivity of 5 × 10 ⁴ [S / m] to 10 ⁶ [S / m]. Having a first coil forming conductor and a second coil forming conductor alternately formed in every other layer in a plurality of insulator layers;
In the state where the respective insulator layers are laminated, the first coil forming conductors formed every other layer are electrically connected,
In a state where the respective insulator layers are laminated, the second coil forming conductors formed every other layer are electrically connected,
Extending both ends of the first coil forming conductor to the end face as input and output of a signal line,
Forming a distributed capacitance between the first coil-forming conductor and the second coil-forming conductor via each insulator layer, and forming the first capacitance with the sum,
The second coil forming conductor is directly grounded or grounded via the second capacitor of the insulator layer,
The filter characterized in that the conductivity of the first coil forming conductor and / or the second coil forming conductor has a value of 5 × 10 ⁴ [S / m] to 10 ⁶ [S / m]. element.   The filter element according to claim 1, wherein a terminal serving as an input of the signal line and a terminal serving as an output of the signal line have substantially the same shape.   The filter element according to claim 1, wherein the coil forming conductor is made of a conductor containing Ag as a main component.   The filter element according to claim 2, wherein the first coil forming conductor and / or the second coil forming conductor is made of a conductor containing Ag as a main component.   The filter element according to claim 1, wherein upper and lower layer connection conductors are formed in an insulator layer interposed between the insulator layers on which the coil forming conductors are formed.   The filter element according to claim 6, wherein the coil forming conductor and the upper and lower layer connecting conductors are connected by via conductors in the insulator layer.   The first coil forming conductors are connected by via conductors in the insulator layer, and the second coil forming conductors are connected by via conductors in the insulator layer. Filter element.   3. The filter according to claim 2, wherein upper and lower layer connection conductors are respectively formed in the insulator layer in which the first coil forming conductor is formed and the insulator layer in which the second coil forming conductor is formed. element.   The first coil forming conductor and the upper and lower layer connecting conductor are connected by a via conductor in the insulator layer, and the second coil forming conductor and the upper and lower layer connecting conductor are an insulating layer. The filter element according to claim 9, wherein the filter element is connected by an inner via conductor.   An electronic module comprising the filter element according to any one of claims 1 to 10.

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