JP2005051432A - Filter element and electronic module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a filter element which obtains a steep attenuation and realizes desired attenuation characteristics around a cut-off frequency because a distributed inductance formed by first coil forming conductors 4b, 4d, 4f between an input and an output of a signal line is gradually changed from the first coil forming conductor 4b closer to an input terminal to the first coil forming conductor 4f closer to an output terminal, and also to provide an electronic module using the filter element. <P>SOLUTION: The stacked filter element is formed as a low pass filter wherein double coils L1, L2 are formed, a signal input terminal and a signal output terminal are respectively provided to both terminals of the coil L1, and the low pass filter is formed by using a capacitance between the coil L2 and ground and a distributed constant capacitance between the coils L1 and L2. The length of the first coil forming conductors 4b, 4d, 4f for forming the coil L1 is gradually increased from the conductor 4b closer to the input terminal to the conductor 4f closer to the output terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a filter element and an electronic module, and more particularly to a filter element used for noise removal and the like, using parallel resonance and series resonance of inductance and capacitance formed by a conductor pattern of laminated insulator layers. The present invention relates to a filter element capable of obtaining a steep attenuation at a specific frequency and an electronic module using the filter element.
[0002]
[Prior art]
Conventionally, when coil pieces are formed in a plurality of insulator layers and each insulator layer is laminated, the coil pieces are connected to form a coil, and the inductance of the coil and the insulator layer There is known an example in which a multilayer filter element is realized by using a capacitance formed between the conductive pattern and the conductive pattern.
[0003]
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, and between the coils L1 and L2. A low-pass filter is formed using the distributed constant capacitance.
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.
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 04-2108
[Problems to be solved by the invention]
However, what kind of capacitance and inductance should be set to obtain a steep attenuation at the cutoff frequency, and how to realize the capacitance and inductance when a specific structure is determined There were many unknown factors, and it was a big design problem.
In particular, control of the attenuation per unit frequency in the filter transmission characteristics and reflection characteristics is an important point for realizing the desired attenuation characteristics, but it is difficult to control the attenuation as desired. It was.
[0006]
In view of the above, an object of the present invention is to provide a filter element capable of obtaining a steep attenuation amount and realizing a desired attenuation characteristic, and an electronic module using the filter element.
[0007]
[Means for Solving the Problems]
The filter element of the present invention includes a first coil-forming conductor and a second coil-forming conductor that are alternately formed on every other insulating layer, and a ground that is formed on any of the insulating layers. The first coil forming conductors formed every other layer are electrically connected to each other in a state in which the respective insulating layers are laminated, and in the state in which the respective insulating layers are laminated, Second coil forming conductors formed every other layer are electrically connected to each other, both ends of the first coil forming conductor are extended to the end face as input and output of signal lines, and the first coil is formed. A distributed capacitor is formed between each conductor layer and the second coil-forming conductor via each insulator layer, and a first capacitor is formed by the sum, and the second coil-forming conductor and the second coil-forming conductor Configured to form a second capacitance with the ground conductor; The distributed inductance formed by the first coil forming conductor on the insulator layer gradually changes from the first coil forming conductor close to the input terminal to the first coil forming conductor close to the output terminal. It is characterized by that.
[0008]
In such a filter element, the distributed inductance formed by the first coil forming conductor between the input and output of the signal line has a first inductance close to the output terminal from the first coil forming conductor close to the input terminal. Since it gradually changes over the coil forming conductor, the amount of attenuation can be made steep and desired attenuation characteristics can be satisfied in the vicinity of the cutoff frequency.
The term “gradually changing” includes both a monotonically increasing distributed inductance and a monotonically decreasing one.
[0009]
The change in the distributed inductance can be realized by making the circumference, circumference, or conductor width of the first coil forming conductor on the insulator layer different.
Further, the filter element of the present invention may be configured such that the distributed inductance formed by the first coil-forming conductor on the insulator layer is changed to a configuration in which the distribution inductance is gradually changed, or in addition to the configuration, on the insulator layer. The distributed inductance formed by the second coil forming conductor gradually changes from the second coil forming conductor close to the input terminal to the second coil forming conductor close to the output terminal. Also good.
[0010]
The coil formed by the second coil-forming conductor is not connected between the input terminal and the output terminal, but by gradually changing the distributed inductance, the attenuation can be made steep and near the cutoff frequency. Thus, the desired attenuation characteristic can be satisfied.
The change of the distributed inductance can be realized by changing the circumference, radius, or conductor width of the second coil forming conductor on the insulator layer.
[0011]
Here, it is preferable that the ground conductor is formed on the uppermost layer or the lowermost insulator layer because the configuration of the filter element can be simplified.
Furthermore, in the filter element of the present invention, 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. It is desirable. When the upper and lower layer connecting conductors are respectively formed on 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, 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 in the insulator layer. It is desirable that the via conductors be connected.
[0012]
In the filter element adopting such a connection structure with via conductors, it is not necessary 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.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
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.
[0014]
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.
[0015]
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.
[0016]
What is characteristic of the present invention is that the circumference of the first-type coil forming conductor is not uniform and becomes longer each time the upper layer is formed. That is, when the dielectric ceramic layers are counted in the stacking direction, the length of the first-type coil forming conductor 4b formed on the dielectric ceramic layer 1c located relatively below is relatively short, and the inductance is also small. small. The first type coil forming conductor 4d formed on the dielectric ceramic layer 1e located in the center has a medium length and a medium inductance. The first-type coil forming conductor 4f formed on the dielectric ceramic layer 1g positioned relatively above has a relatively long length and a large inductance.
[0017]
The structure of such a filter element will be described in detail 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. is 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 has a substantially H shape in plan view, and makes the signal approximately 3/4 turn between the lower ends of the H shape. 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.
[0018]
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 both lower ends of the H-shape. This constitutes a part of the inductance of the coil L1.
[0019]
However, the distance from the base of the H-shaped central piece to the lower ends is shorter than that of the other first type coil forming conductors, and the conductor length for which the signal is approximately 3/4 turns is short. Accordingly, the partial inductance formed by the first type coil forming conductor 4b has a relatively small value.
Since the signal is turned approximately ¼ turn by the upper / lower layer connection conductor 2c of the lower dielectric ceramic layer 1b, the dielectric ceramic layer 1b is combined with the ¼ turn of the first type coil forming conductor 4b. , 1c orbits approximately one turn (the same applies hereinafter).
[0020]
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 connection conductor 2d, it is made to circulate almost one turn at the dielectric ceramic layers 1b and 1c together with the ¾ turn of the second type coil forming conductor 4a. (Same below).
[0021]
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 both lower ends of the H-shape. This constitutes a part of the inductance of the coil L2. 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.
[0022]
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 the signal approximately 3/4 turn between both lower ends of the H-shape. This constitutes a part of the inductance of the coil L1.
[0023]
However, the distance from the base of the H-shaped central piece to both lower ends is longer than that of the first type coil forming conductor 4b. As a result, the conductor length for which the signal is approximately 3/4 turns is also obtained. It is getting longer. Therefore, the partial inductance formed by the first type coil forming conductor 4d has a larger value than the inductance formed by the first type coil forming conductor 4b. 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.
[0024]
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 both lower ends of the H-shape. This constitutes a part of the inductance of the coil L2. 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.
[0025]
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 the signal approximately 3/4 turn between both lower ends of the H-shape. This constitutes a part of the inductance of the coil L1.
[0026]
In this case, the distance from the base of the H-shaped central piece to both lower ends is longer than that of the first type coil forming conductor 4d, and as a result, the conductor on which the signal is turned approximately 3/4. The length is even longer. Accordingly, the partial inductance formed by the first type coil forming conductor 4f has a larger value than the inductance formed by the first type coil forming conductor 4d. 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.
[0027]
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-hole conductors (schematically shown 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 via holes. 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 hole conductor, and the upper and lower layer connecting conductors. The coil L1 is constituted by these members.
[0028]
Furthermore, via hole conductors (shown schematically 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-hole 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-hole conductors, and upper and lower layer connecting conductors constitute the coil L2.
[0029]
However, the coil L2 is floating without being connected to any terminal, forms a capacitor C1 between the coil L1 formed between the input terminal 2a and the output terminal 2i, and is connected to the GND conductor 3a. A capacitor C2 is formed between them. 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 exploded plan view showing an exploded structure of eight layers from the lowermost dielectric ceramic layer 1a to the dielectric ceramic layer 1h. In particular, the first type coil forming conductor 4b. 4d. It shows that the distances A, B, C from the base of the central piece of the 4f H shape to both lower ends are gradually increased. Therefore, as described above, the partial inductance formed by the first type coil forming conductor 4d is larger than the partial inductance formed by the first type coil forming conductor 4b. The inductance partially formed by the seed coil forming conductor 4f is larger than that. That is, the distributed inductance of the coil L1 gradually increases from the input terminal 2a to the output terminal 2i. In other words, the first type coil forming conductor that forms a distributed capacity with the second type coil forming conductor. Is gradually increased from the input terminal 2a to the output terminal 2i.
[0030]
FIG. 5 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. As shown in FIG. 5, the inductance of the coil L1 is represented by the sum of the distributed inductances L11, L12, and L13. A distributed capacitance is formed between the coil L1 and the coil L2, and the sum is the capacitance C1. Further, a capacitor 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. The distributed inductances L11, L12, and L13 of the coil L1 are gradually increased from the input terminal 2a to the output terminal 2i as described above.
[0031]
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 effect of the uneven distribution of the distribution inductance will be described later while looking at the simulation results.
[0032]
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, 4f, the second type coil forming conductors 4a, 4c, 4e, the GND conductor 3a, and the connection via-hole conductors 5a-5g, 6a-6e are mainly composed of Ag or the like. A conductive material is used.
[0033]
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.
[0034]
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.
[0035]
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. For example, in addition to changing the distributed inductance of the first type coil forming conductor, a means of changing the distributed inductance of the second type coil forming conductor can be taken.
FIG. 6 is an exploded plan view showing an exploded structure of eight layers from the lowermost dielectric ceramic layer 1a to the dielectric ceramic layer 1h. Type 2 coil forming conductor 4a. 4c. The distances D, E, and F from the base of the H-shaped central piece of 4e to the lower ends are gradually shortened. For this reason, the distributed inductance of the type 2 coil forming conductor gradually decreases from the lower layer to the upper layer.
[0036]
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 connecting conductors are omitted, and the first type coil forming conductors 4b, 4d, 4f formed every other layer are directly connected by via-hole conductors, and the second type formed every other layer. The coil forming conductors 4a, 4c, and 4e can be directly connected by via-hole conductors.
[0037]
FIG. 7 is an exploded plan view showing a laminated structure of dielectric ceramic layers in which such coil-forming conductors are directly connected by via-hole conductors. The same members as those shown in FIG. 4 are denoted by the same reference numerals, and overlapping description is omitted. However, the difference from FIG. 4 is that the input conductor 2b and the first type coil forming conductor 4b are connected. A via hole conductor 7a, a via hole conductor 7b for connecting the first type coil forming conductors 4b and 4d, and a via hole conductor 7c for connecting the first type coil forming conductors 4d and 4f; A via hole conductor 8a that connects the second type coil forming conductors 4a and 4c and a via hole conductor 8b that connects the second type coil forming conductors 4c and 4e are provided.
[0038]
These via-hole conductors 7a to 7c, 8a, and 8b connect the coil-forming conductors in a state of penetrating the dielectric ceramic layer that overlaps the two layers. For example, the via-hole 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, via holes are formed so that the two green sheets are overlapped with each other so as to be in the same position, and the conductive paste is embedded over the upper and lower via holes.
[0039]
In addition, in the coil forming conductors that are alternately formed every other layer, if the connection points of both lower ends of the H legs connected to the via hole conductor are in the same position in plan view, the via hole conductor is not formed diagonally. This makes it impossible to form a circular coil.
Since it is difficult to form the via hole conductors obliquely, in the embodiment of FIG. 7, the positions E1, E2, E3, F1, F2, and F3 of the connection points of the coil forming conductors are shifted little by little. Thereby, it is possible to form a circular coil while forming the via-hole conductor vertically.
[0040]
Thus, in the filter element of FIG. 7, since the upper and lower layer connecting conductors can be omitted, the shape of the printed pattern of the conductors can be simplified.
On the other hand, when the upper and lower layer connection conductors are used as shown in FIGS. 3 and 4, the positions of the connection points of the coil forming conductors can be formed at the same position in each layer, so the pattern of the coil forming conductors is the same. Thus, the number of masks for printing the pattern can be reduced, which is effective for reducing the price.
[0041]
FIG. 8 is a filter element in which the distributed inductance of the coil L2 formed by the second type coil forming conductor is gradually reduced from the second type coil forming conductors 4a to 4e, and the upper and lower layer connection conductors are omitted. The first type coil forming conductors 4b, 4d, 4f are directly connected by via hole conductors, and the second type coil forming conductors 4a, 4c, 4e are directly connected by via hole conductors. FIG.
[0042]
In this structure, the second type coil forming conductors 4a. 4c. The distance from the base of the H-shaped central piece of 4e to both lower ends is gradually shortened, and the distributed inductance of the second type coil forming conductor is gradually decreased from the lower layer to the upper layer. At the same time, the upper and lower layer connecting conductors are omitted, the input conductor 2b and the first type coil forming conductor 4b are connected by the via hole conductor 7a, and the first type coil forming conductors 4b and 4d are connected by the via hole conductor 7b. The first type coil forming conductors 4d and 4f are connected by a via hole conductor 7c, the second type coil forming conductors 4a and 4c are connected by a via hole conductor 8a, and the second type coil forming conductor 4c is connected. And 4e are connected by a via-hole conductor 8b. The fact that the via-hole conductor penetrates the two layers of the dielectric ceramic layer and that the positions E1, E2, E3, F1, F2, and F3 of the connection points of the coil-forming conductors are shifted little by little. The structure is the same.
[0043]
【Example】
In order to evaluate the characteristics of the filter element produced in this manner and having the coil L1 having distributed inductance, S parameters were simulated.
FIG. 9A to FIG. 9D are equivalent circuit diagrams of filter elements to be simulated. A coil L1 is formed between the input / output terminals, and a distributed capacitor C1 is formed between the coil L1 and the coil L2.
[0044]
FIG. 9A shows an equivalent circuit diagram as a comparative example when the second type coil forming conductor 4a at the end of the coil L2 is dropped directly to the ground, and FIG. 9B shows the second type coil formation. An equivalent circuit diagram as a comparative example in which a capacitor C2 is formed between the conductor 4a and the ground is shown. In the above, the coil forming conductor is formed in the same shape for each dielectric ceramic layer.
In FIG. 9C, the inductance of the second type coil forming conductor is made the same for each dielectric ceramic layer, but the inductance of the first type coil forming conductor is gradually changed for each dielectric ceramic layer. The equivalent circuit diagram of the present invention in which the coil L1 is formed by distributed inductances L11 to L16 is shown. In FIG. 9D, the inductance of the first type coil forming conductor is made the same for each dielectric ceramic layer, but the inductance of the second type coil forming conductor is gradually changed for each dielectric ceramic layer. The equivalent circuit diagram of the present invention in which the coil L is formed by distributed inductances L21 to L25 is shown.
[0045]
Various constants are as follows.
FIG. 9A: R1 = R2 = 50Ω, C1 = 10 pF × 5 = 50 pF,
L1 = 0.3 nH × 6 = 1.8 nH,
L2 = 0.3nH × 5 = 1.5nH
FIG. 9B: R1, R2 and C1 are the same as above. C2 = 15 pF,
L1 = 0.5 nH × 6 = 3.0 nH,
L2 = 0.5nH × 5 = 2.5nH
FIG. 9 (c): R1, R2, C1, and C2 are the same as above.
L11 = 0.3 nH, L12 = 0.3 nH, L13 = 1 nH,
L14 = 1.5nH, L15 = 1.5nH, L16 = 0.5nH
L2 = 0.3nH × 5 = 1.5nH
L16 is the inductance of the output terminal 2i.
[0046]
FIG. 9 (d): R1, R2, C1, C2 are the same as above.
L1 = 0.8 nH × 6 = 4.8 nH,
L21 = 0.8 nH, L22 = 0.8 nH, L23 = 0.6 nH,
L24 = 0.2nH, L25 = 0.2nH
10 (a) to 10 (d) are diagrams showing the frequency characteristics of the S parameter. The horizontal axis represents the frequency (GHz), and the vertical axis represents the absolute value of the S parameter insertion loss (S21) (solid line). ) (Unit dB).
[0047]
FIG. 10A is a frequency characteristic diagram of the S parameter of the filter element in which the capacitor C2 corresponding to FIG. 9A is short-circuited. The attenuation amounts per unit frequency of the pass band and the stop band are circled in the graph. As shown in the part surrounded by, it is gradual. FIG. 10B is a frequency characteristic diagram of the S parameter of the filter element that forms the capacitor C2 corresponding to FIG. 9B, and the attenuation per unit frequency of the passband and stopband is shown in FIG. ).
[0048]
FIG. 10C is a frequency characteristic diagram of the S parameter of the filter element of the present invention in which the coil L1 corresponding to FIG. 9C is formed by distributed inductances L11 to L16, and unit frequencies of the passband and stopband. As shown in a circled portion in the graph, the per-damping amount is steeper than that in FIG.
FIG. 10D is a frequency characteristic diagram of the S parameter of the filter element of the present invention in which the coil L2 corresponding to FIG. 9D is formed by distributed inductances L21 to L25, and unit frequencies of the passband and stopband. As shown in a circled portion in the graph, the per-damping amount is steep as in FIG.
[0049]
From the above results, in the filter element manufactured with the structure of the present invention, a steep attenuation characteristic of the passband and stopband in the vicinity of the cutoff frequency can be obtained.
With this structure, a filter having excellent attenuation characteristics can be realized at low cost.
An electronic module that realizes various functions can be manufactured by mounting such a filter element on a mother board or the like.
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. For example, in the filter element of the present invention, it is possible to change both the distributed inductance of the first type coil forming conductor and the distributed inductance of the second type coil forming conductor. In addition, the inductance of the coil forming conductor can be changed not only by the circumference and radius of the conductor but also by the conductor width. In addition, various modifications can be made within the scope of the present invention.
[0050]
【The invention's effect】
As described above, in the filter element of the present invention, the distributed inductance formed by the first or second coil forming conductor is applied from the coil forming conductor close to the input terminal to the coil forming conductor close to the output terminal. By gradually changing, the amount of attenuation can be made steep, and a filter element having excellent characteristics satisfying the required attenuation characteristics near the cutoff frequency can be realized.
[Brief description of the drawings]
FIG. 1 is an external perspective view of a filter element of the present invention.
FIG. 2 is a cross-sectional view of the filter element of the present invention.
FIG. 3 is a structural perspective view when a dielectric ceramic layer is laminated.
FIG. 4 is an exploded plan view showing an exploded structure of eight layers from a dielectric ceramic layer 1a located at the bottom to a dielectric ceramic layer 1h.
FIG. 5 is an equivalent circuit diagram of the filter element of the present invention.
FIG. 6 is an exploded plan view showing an exploded structure of eight layers from a dielectric ceramic layer 1a located at the bottom to a dielectric ceramic layer 1h.
7 is an exploded plan view showing a laminated structure of dielectric ceramic layers in which coil forming conductors are directly connected by via-hole conductors without providing upper and lower layer connecting conductors. FIG.
FIG. 8 is an exploded plan view showing a laminated structure of dielectric ceramic layers in which coil forming conductors are directly connected by via-hole conductors without providing upper and lower layer connecting conductors.
FIG. 9 is an equivalent circuit diagram of a filter element to be simulated. (A), (b) shows a comparative example, (c), (d) shows the Example of this invention.
10 is a frequency characteristic diagram of S parameters obtained by simulation for the filter elements (a) to (d) in FIG. 9;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Ceramic laminated body 1a-1i 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-hole conductor 6a-6e Via-hole conductor 7a-7c Two-layer through via-hole conductor 8a, 8b Two-layer through-via-hole conductor

Claims (12)

A first coil-forming conductor and a second coil-forming conductor formed alternately in every other layer in a plurality of insulator layers;
A ground conductor formed on any insulator layer,
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,
Both ends of the first coil forming conductor are extended to an end face as input and output of a signal line, and each insulator layer is interposed between the first coil forming conductor and the second coil forming conductor. Forming a distributed capacitance, forming a first capacitance with the sum thereof, and forming a second capacitance between the second coil forming conductor and the ground conductor;
The distributed inductance formed by the first coil forming conductor on each insulator layer gradually changes from the first coil forming conductor close to the input terminal to the first coil forming conductor close to the output terminal. The filter element characterized by having carried out. 2. The filter according to claim 1, 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. 2. The filter element according to claim 1, wherein the change in the distributed inductance is realized by changing a circumference, a radius, or a conductor width of the first coil forming conductor on the insulator layer. 2. 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. 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 2, wherein the filter element is connected by an inner via conductor. A first coil-forming conductor and a second coil-forming conductor formed alternately in every other layer in a plurality of insulator layers;
A ground conductor formed on any insulator layer,
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,
Both ends of the first coil forming conductor are extended to an end face as input and output of a signal line, and each insulator layer is interposed between the first coil forming conductor and the second coil forming conductor. Forming a distributed capacitance, forming a first capacitance with the sum thereof, and forming a second capacitance between the second coil forming conductor and the ground conductor;
The distributed inductance formed by the second coil forming conductor on each insulator layer gradually changes from the second coil forming conductor close to the input terminal to the second coil forming conductor close to the output terminal. The filter element characterized by having carried out. 7. The filter according to claim 6, wherein upper and lower layer connection conductors are respectively formed on the insulator layer on which the first coil forming conductor is formed and on the insulator layer on which the second coil forming conductor is formed. element. The filter element according to claim 6, wherein the change in the distributed inductance is realized by changing a circumference, a radius, or a conductor width of the second coil forming conductor on the insulator layer. 7. 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. 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 7, wherein the filter element is connected by an inner via conductor. The filter element according to any one of claims 1 to 10, wherein the ground conductor is formed in an insulator layer which is an uppermost layer or a lowermost layer. An electronic module comprising the filter element according to any one of claims 1 to 11.

Images