JPH04196804A - Lc filter - Google Patents

Abstract

PURPOSE:To increase an inductance, and to increase an insertion loss by forming a capacitor of both opposed conductors with interposed a dielectric layer, and positively utilizing a distributed capacity generated between them. CONSTITUTION:An LC filter A1 is a plate-shaped material (chip) constituted of a first spiral-shaped inductor conductor 1 provided on one side, a conductor 21 for capacitor provided on the other side, with interposed a dielectric layer 4, and a second spiral-shaped inductor conductor 22 provided on the first inductor conductor 1 with interposed an insulator layer 32. Then, the inductance and a capacitance are prepared by positively utilizing the distributed capacitor generated between the inductor conductors 1 and 22. Thus, the inductance which can not freely be obtained due to the miniaturization of the LC filter, can be increased, and the insertion loss can be increased.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is used as a high frequency noise filter in a signal passing circuit 3 power supply circuit of an electronic device. Regarding LC filters.

[Prior Art] In an LC filter, lead terminals of a pair of signal lines are connected to one electrode portion disposed on a disk-shaped capacitor. Further, a ground terminal is connected to the other electrode on the opposite side of the capacitor. In addition, the above L
Since the C filter has three terminals, it is a three-terminal type L
It is called a C filter.

Furthermore, ferrite beads are inserted into the lead terminals to increase inductance.

Incidentally, in recent years, there has been a strong demand for LC filters to have a wider frequency band and be more compact, especially for capacitors and sensors.

However, the above LC filter has a noise attenuation characteristic (
Insertion loss) is not sufficient, and since ferrite beads are inserted into the lead terminals, they must be manufactured using a combination of different materials, making them expensive. Further, since the shape becomes larger due to the insertion of the ferrite beads, a large mounting space is required when mounting on a single circuit board or the like. Therefore, it cannot meet the demand for more compact electronic components.

Therefore, in order to solve the above problems,
As shown in the figure, a spiral electrode 8 is formed on one side of a dielectric layer 91, a signal terminal 5.6 is connected to both terminals 81, 82 of the electrode 8, and a spiral electrode is formed on the other side 90. LC filter 9 with earth terminal 7 connected to 80 (
A low-pass filter) has been proposed (Japanese Patent Laid-Open No. 62-2
33911).

The LC filter 9 consists of an inductor conductor L whose two ends are connected to a signal terminal 5.6 as shown in the equivalent circuit of FIG.
+ and an inductor conductor LO connected to the ground terminal 7, including a capacitor C that generates a monodistributed capacitor.

(Problem to be Solved) However, the LC filter 9 proposed in the above publication has a first-order problem.

That is, since the LC filter 9 is small, the spiral electrodes 8 and 80 are minute, and therefore there is a limit to the number of turns of the electrodes. Therefore, with such an electrode 8.80, a large inductance cannot be obtained, and the insertion loss is relatively small at about -35 dB, as shown in FIG.

The present invention has been made in view of these conventional problems, and has a large insertion loss and is compact.

It is intended to provide an LC filter.

[Means for Solving the Problems] The present invention provides a spiral first inductor conductor provided on one side with a dielectric layer interposed therebetween, a capacitor conductor provided on the other side, and an insulator on the first inductor conductor. A plate-shaped LC filter consisting of a spiral second inductor conductor provided through layers, the first inductor conductor and the second inductor conductor being connected in series, with signal terminals connected to both ends thereof. Further, there is an LC filter characterized in that the capacitor conductor is connected to a ground terminal (first invention).

The first and second inductor conductors are conductor layers that are connected to signal terminals and allow signals to pass therethrough. Also, connect the capacitor conductor to the ground terminal.

And these inductor conductors are made of one material, for example silver.

It is formed by thick film printing or the like using a conductive paste containing metal powder such as gold, silver/palladium, or copper.

Further, the capacitor conductor and the first inductor conductor are located on both sides of the dielectric layer. Therefore, 3, for example, a dielectric is formed on one side on a dielectric layer.

It is also possible to form the other layer on the insulator layer and laminate the two dielectric layers so that they are located on both sides of the dielectric layer (see Figure 1).
. Further, the spiral capacitor conductor is formed by thick film printing or the like, similarly to the first and second inductor conductors.

Further, the capacitor conductor, the first and second inductor conductors, and the signal terminal are electrically connected to each other via a conductor such as a through hole or a conductor circuit.

Next, another LC filter different from the above includes a spiral first inductor conductor provided on one side with a dielectric layer interposed therebetween, and a capacitor conductor provided on the other side.
A plate-shaped L comprising a spiral second inductor conductor further provided on the capacitor conductor via a dielectric layer.
C filter, characterized in that the first inductor conductor and the second inductor conductor are connected in series, signal terminals are connected to both ends thereof, and the capacitor conductor is connected to a ground terminal. (Second
invention).

Furthermore, as another LC filter, a spiral first inductor conductor provided on one side of the dielectric layer through the dielectric layer;
A capacitor conductor provided on the other side, and a spiral-shaped second conductor provided on the capacitor conductor with a dielectric layer interposed therebetween.
The first inductor conductor and the second inductor conductor are connected in parallel, and signal terminals are connected to both ends thereof, and the capacitor conductor is connected to a ground terminal. There exists an LC filter characterized in that it is connected (third invention).

What is most noteworthy about the third invention is as follows.

In the second invention, the first inductor conductor and the second inductor conductor are connected in parallel, signal terminals are connected to both ends thereof, and the capacitor conductor is connected to a ground terminal.

Next, for the dielectric layer, it is preferable to use a composite ceramic made of borosilicate glass and lead titanate (PbTiO3) having a dielectric constant (ε) of 10 or more.

Further, the dielectric layer is preferably a film formed by screen printing and having a thickness of 20 to 80 μm.

Further, the insulating layer is made of Cao-A, which is a low-temperature firing material.
1.03-51Oz-Bz O, based glass and alumina (
It is preferable to use a composite ceramic consisting of AltOs). This thing is a silver conductor.

It has the effect of being able to be fired simultaneously with the silver thread conductor.

The insulating layer is preferably composed of a ceramic green sheet for low-temperature fired substrates with a thickness of 0.05 to 0.3 degrees, which is said to have sufficient strength as a flat chip. have an effect.

Moreover, the above ceramic green sheet has a temperature of 1000°C.
Ceramic and crystal glass that can be fired with:

It is made of a material containing one or more types of insulator layer materials such as alumina.

Moreover, the LC filter shown in the said 1st invention.

It is also possible to stack them in multiple layers and connect them in parallel as one unit, as shown in FIG. This reduces the inductance and gear pantance of the LC filter. The resistance value can be set relatively freely. This is the second point. The same applies to the LC filter of the third invention.

[Operations and Effects] In the LC filter according to the first invention, a capacitor is formed by the dielectrics facing each other with the dielectric layer in between, and the stray (distributed) capacitance generated between the parentheses is actively utilized. . As a result, it is possible to increase the inductance, which has been difficult when making the LC filter compact, and to increase the insertion loss by 1, for example, nearly 1 OdB, compared to the conventional LC filter.

In addition, in the LC filter according to the second invention, since the spiral second inductor conductor faces the grounded capacitor conductor via the dielectric, the capacitor capacity is twice that of the conventional LC filter. can be increased to Further, the insertion loss can be increased by 1, for example, nearly 1 OdB, compared to a conventional LC filter.

Further, in the LC filter according to the third invention, the first
The inductor conductor and the second inductor conductor are connected in parallel, and the ground terminal is connected to the capacitor conductor sandwiched between the first and second inductor conductors. Therefore, although the inductance is slightly reduced, the resistance value between the signal terminals is half that of the conventional LC filter. Also, the L
The capacitor capacity of the C filter is twice that of the conventional one. The low resistance value is an important characteristic for an LC filter inserted into a signal line.

Also, the insertion loss is lower than that of conventional LC filters.

For example, it can be increased by nearly 10 dB.

Moreover, in the first to third inventions, the first and second inductor conductors and the capacitor conductor are arranged with a dielectric layer or an insulator layer interposed therebetween.

Therefore, by changing the thickness and material of the dielectric layer,
By increasing or decreasing the capacitance of the capacitor, the capacitance and noise attenuation characteristics of the entire LC filter can be arbitrarily set.

In addition, since the above derivative is formed in a spiral shape,
Large inductance and distributed capacitance can be obtained.

Furthermore, in the first to third aspects of the invention, since a relatively thin dielectric layer is formed, the thickness of the LC filter can be made thin. Therefore.

The LC filter can be made more compact. Also.

Since the insulator layer is also relatively thin, it is easy to make the LC filter compact as described above. and.

Since the insulator layer uses a material for a low-temperature fired substrate, it can be simultaneously fired (integrated firing) at a relatively low temperature, for example, 800°C to 1000°C, and is easy to manufacture.

As described above, according to the first to third inventions, by forming inductance and capacitance, inductance, which could not be freely obtained due to the small size of the LC filter (element), can be increased, resulting in large insertion loss and wide attenuation band. I had it. An LC filter with sharp cutoff frequency characteristics can be obtained.

〔Example〕

First example Regarding the L'C filter according to the embodiment of the first invention.

This will be explained using FIGS. 1 to 3.

That is, one example of LC filter A1 has the following characteristics as shown in FIG.
, a spiral first inductor conductor l provided on one side of the FA dielectric layer, a capacitor conductor 21 provided on the other side, and an insulator layer 32 placed on the first inductor conductor 1. It is a plate-like object (chip) made up of a spiral second inductor conductor 22 provided therein.

The first inductor conductor 1 and the second intertarter conductor 22 are connected in series, and signal input terminals 5 are connected to both ends thereof.
1 and the signal output terminal 61 are connected, and the capacitor conductor 21 is connected to the ground terminal 71.

The first inductor conductor 1 is formed by thick film printing on the dielectric layer 4 using a conductor paste containing Ag powder. Further, the dielectric layer 4 is made of borosilicate glass and lead titanate (Pb
A film having a thickness of approximately 30 μm is formed on an insulator layer 33 on which a capacitor conductor 21 is formed by screen printing using composite ceramics with T i Ox ).

The capacitor conductor 21 is formed by thick film printing on the insulator layer 33 using a conductor paste containing Ag powder.

Further, the insulator layer 33 is made of Ca0-Alz 03 S
A ceramic green sheet made of iOxBzOs glass and 81203 composite ceramic is formed on a substrate with a thickness of about 0.25cm.

Further, the second inductor conductor 22 is formed on the insulating layer 32 in the same manner as the capacitor conductor 21. Further, the insulator layer 32 is similar to the insulator layer 33.

Moreover, on the second inductor conductor 22.

An insulator layer 31 similar to the insulator layer 33 is laminated.

A signal input terminal 51 made of a conductor and a signal output terminal 61 are provided at both ends of the insulator layers 31, 32, and 33. Moreover, the insulator layers 31, 32, and 33 are.

A ground terminal 71 made of a conductor is provided at one end of the center.

Further, the first inductor conductor l and the second inductor conductor 22 are connected in series through a through hole 24. Further, the conductor 1 has one end 11 connected to an insulating layer 33.
It is connected to the signal circuit 331 formed above through the through hole 24. In addition, the capacitor conductor 21 has one end 2
11 is connected to the ground terminal 71. The insulator layers 31, 32, and 33 are laminated into an integral layer and heated to about 900°C.
Fired at low temperature to integrate.

As a result, as shown in FIG.
．． A ceramic green sheet in which No. 33 was integrally fired at a low temperature was used. A plate-shaped LC filter A1 is obtained. Also,
As shown in FIG. 3, the LC filter A1 includes an inductor conductor L3 for signal passage connected to the signal conductor 55.65.
．． L4 and the first inductor conductor connected to the ground terminal 71.

, an equivalent circuit consisting of capacitor C is formed.

Next, three effects will be explained.

In the LC filter according to this example, the dielectric layer 4
A capacitor is formed by the side conductors of the first inductor conductor 1 and the second inductor conductor 22, which face each other with the capacitor in between, and the distributed capacitance generated therebetween is actively utilized. As a result, as shown in Fig. 14, the inductance, which has been difficult to miniaturize the LC filter AI, can be increased, and the insertion loss can be reduced by 1% compared to the conventional LC filter.
It can be increased by nearly 0 dB.

Further, the LC filter A1 is plate-shaped.

A compact chip-type LC filter can be obtained.

That is, 5 the side conductors of the first inductor conductor l and the second inductor conductor 22 are arranged between the thin dielectric layer 4 or the insulating layer 32.

Therefore, the mLc filter A1 can be made compact.

Further, the second intertalor conductor 22 and the first inductor conductor 1 are arranged with a dielectric layer 4 interposed therebetween. Therefore, by changing the thickness and material of the dielectric layer 4,
By increasing the capacitance of the capacitor by Kffl, the capacitance and insertion loss of the entire LC filter can be increased or decreased as desired.

Further, since the side conductor is formed in a spiral shape, a large inductance and distributed capacitance can be obtained.

Therefore, according to this example, it is possible to obtain a compact LC filter with a large insertion loss and a characteristic represented by an attenuation curve consisting of two or more attenuation poles and a wide attenuation width.

In addition, the insulator layers 31, 32, and 33 are made of materials for low-temperature firing substrates, so the temperature is relatively low.

For example, simultaneous firing (integral layer) can be performed at 800 to 1000°C. Furthermore, a silver conductor or silver thread conductor material with a relatively low resistance value can be used. Therefore, manufacturing of the LC filter is easy.

Second example The LC filter of this example relates to the first and second inventions.

As shown in FIG. 4, this is the same as the first embodiment described above, in which the second inductor conductor 22 is provided with a dielectric layer 4 interposed therebetween. Further, a capacitor conductor 21 is arranged between the first inductor conductor 1 and the second inductor conductor 22.

In addition, the first inductor conductor 1 and the second inductor conductor 22
are connected in series and have signal terminals 51 and 61 at both ends.
The capacitor conductor 21 is connected to the ground terminal 71.

The other configurations are the same as those of the first embodiment.

That is, first, the second inductor conductor 22 is formed in a spiral shape by thick film printing on the dielectric layer 4 using an Ag conductive paste, as shown in FIG.

Further, above the second inductor conductor 22.

An insulator layer 32 and an insulator layer 31 are stacked above it.

The insulator layer 32 has a signal circuit 321.

The signal circuit 321 is connected to the center terminal 222 of the second inductor conductor 22 via the through hole 24. Further, the other terminal 221 of the second inductor conductor 22 is connected in series with the terminal 213 of the first inductor conductor 1 via a through hole 24.41.

On the other hand, the absolute layer 3 on which the first inductor conductor 1 is formed
An insulator layer 34 is laminated below "3.

The insulator layer 34 has a signal circuit 341, and the signal circuit 3
41 is connected to the center terminal 212 of the first inductor conductor 1 via the signal conductor 24. These are then fired at a low temperature into an integral layer in the same manner as in the first embodiment. As a result, a compact plate-shaped LC filter is obtained.

As shown in FIG. 5, the above LC filter is @
An inductance L is connected to the signal input terminal 51 by the signal circuit 341, an inductance L is connected to the ground terminal 7, and an inductance L is connected to the output terminal 61 by the signal circuit 321. signal conductor 2
The inductance connected by 4 and the capacitor C
,,C! Form an equivalent circuit consisting of

In the above circuit, a spiral second inductor conductor 22 is further provided on the first inductor conductor 1 with a dielectric layer 4 interposed therebetween. Therefore, the capacitor capacity of the LC filter is twice that of the conventional LC filter. Further, the insertion loss can be increased by nearly 1 odB compared to a conventional LC filter.

Other effects similar to those of the first embodiment can be obtained.

Third embodiment The LC filter of this example relates to the third invention.

In this case, as shown in FIG. 6, the first inductor conductor and the second inductor conductor are connected in parallel instead of being connected in series in the second embodiment. Further, the ground terminal is connected to the first inductor conductor. The other configurations are the same as those of the second embodiment.

That is, the center terminals 212 and 222 of the first inductor conductor 1 and the second inductor conductor 22 are respectively connected to the signal input terminal 51 by the signal conductor 24 and the signal circuit 321 and 341, as shown in FIG. Further, the signal input terminal 51 and the signal output terminal 61 are connected to the signal conductor 55.65.
Connect by.

On the other hand, the other terminals 213 and 223 of the first inductor conductor 1 and the second inductor conductor 22 are directly connected to the signal output terminal 6.
Connect to 1. As a result, an LC filter having one equivalent circuit as shown in FIG. 7 is obtained.

As shown in FIG. 7, the LC filter has an inductor L, which has a signal input terminal 51 connected to a signal circuit 321, 341 and a signal conductor 24, and terminals 213 and 223 connected to a signal output terminal 61. , and inductor L16 connected to ground terminal 7.

An equivalent circuit consisting of capacitors C, ,C, is formed.

In the above circuit, the first inductor conductor l and the second
The inductor conductor 22 is connected in parallel.

A capacitor conductor 21 connected to the ground terminal 7 is sandwiched between these inductor conductors. Therefore, the resistance value between the signal terminals is one-half that of a conventional LC filter.

Further, the capacitor capacity of the LC filter is twice that of a conventional LC filter.

As described above, a low resistance value between the transmission signal passing terminals is an important characteristic for an LC filter inserted into a signal line.

Other effects similar to those of the first embodiment can be obtained.

Fourth example The LC filter of this example is as shown in FIG.

The LC filter A1 in the first embodiment is stacked in three layers, and the signal input terminal 51 and signal output terminal 61 formed at both ends of the layers are connected in parallel. The other configurations are the same as those of the first embodiment.

As a result, as shown in FIG. 9, an LC filter A4 in which five layers of LC filters A1 are laminated is obtained.

Further, according to the multilayer LC filter of this example, the inductance, capacitor capacity, and resistance value of the LC filter can be freely increased and adjusted by f:IIi. Also.

The same effects as in the first embodiment can be obtained.

In one example, instead of the LC filter A1, the LC filters in the second and third embodiments can be stacked to obtain the same LC filter as in the two examples.

[Brief explanation of the drawing]

1 to 3 show the LC filter according to the first embodiment, FIG. 1 is a developed view thereof, FIG. 2 is a perspective view thereof, FIG. 3 is an equivalent circuit diagram thereof, and FIGS. The figure shows an LC filter according to a second embodiment. Fig. 4 is its development diagram, and Fig. 5 is its equivalent circuit diagram. 6 and 7 show an LC filter according to the third embodiment, FIG. 6 is a developed diagram thereof, and FIG. 7 is an equivalent circuit diagram thereof,
8 and 9 show an LC filter according to a fourth embodiment, and FIG. 8 is a developed view thereof. FIG. 9 is a perspective view thereof, FIGS. 10 to 13 show a conventional example, FIGS. 10 and 12 are front and back views of the conventional LC filter, and FIG. 11 is a side view thereof. FIG. 13 is an equivalent circuit diagram of a conventional LC filter, and FIG. 14 is an insertion loss curve diagram of the LC filter. 111. First inductor conductor. 21. Conductor for capacitor. 22, second inductor conductor. 31-34. ,,insulator layer. 416. dielectric layer. 51, signal input terminal. 61, signal output terminal. 71, Ground terminal.

Claims (7)

[Claims] (1) A spiral first inductor conductor provided on one side with a dielectric layer interposed therebetween, a capacitor conductor provided on the other side, and a spiral first inductor conductor provided above the first inductor conductor with an insulating layer interposed therebetween. The first inductor conductor and the second inductor conductor are connected in series, with signal terminals connected to both ends thereof, and a capacitor conductor is connected in series. An LC filter characterized by being connected to a ground terminal. (2) A spiral first inductor conductor provided on one side with a dielectric layer interposed therebetween, a capacitor conductor provided on the other side, and a spiral first inductor conductor provided on the capacitor conductor with another dielectric layer interposed therebetween. The first inductor conductor and the second inductor conductor are connected in series with signal terminals connected to both ends thereof, and the first inductor conductor and the second inductor conductor are connected in series, and a signal terminal is connected to both ends of the first inductor conductor. An LC filter characterized in that the conductor is connected to a ground terminal. (3) A spiral-shaped first inductor conductor provided on one side with a dielectric layer interposed therebetween, a capacitor conductor provided on the other side, and a spiral-shaped first inductor conductor provided on the capacitor conductor with a dielectric layer interposed therebetween. The first inductor conductor and the second inductor conductor are connected in parallel, and signal terminals are connected to both ends thereof, and the capacitor conductor is connected in parallel to the second inductor conductor. An LC filter characterized by being connected to a ground terminal. (4) The LC filter according to any one of claims 1 to 3, wherein the dielectric layer is a composite ceramic made of borosilicate glass and lead titanate. (5) In the first to third claims, the dielectric layer has a thickness of 2
An LC filter characterized in that it is a film formed by screen printing with a thickness of 0 to 80 μm. (6) In the first to third claims, the insulating layer is a low temperature firing material CaO-Al_2O_3-SiO_2-B_
2. An LC filter characterized by being made of composite ceramics consisting of O_3 glass and alumina. (7) In the first to third claims, the insulating layer has a thickness of 0.
．． L characterized by being constructed using a ceramic green sheet for low-temperature firing substrates of 0.05 to 0.3 mm.
C filter.