JPH1070429A - Lc filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LC filter using a distributed constant line whose characteristic is maintained independently of an input and output impedances. SOLUTION: This LC filter is constituted by providing a conductor member 5 enclosed by magnetic materials 4, 6 laterally to an upper face of a dielectric body 3 on a lower electrode 2 in a meandering way so as to form a capacitive component in a distribution way between an inductive component of the conductor member 5 and the lower electrode 2 of the conductor member 5. Thus, the filter without being affected by input output impedance is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a filter for EMI (Electro Magnetic Interference) used in an electronic circuit, and more particularly to an LC filter using a distributed constant line which does not depend on input / output impedance.

[0002]

2. Description of the Related Art Conventionally, feed-through type LC filters are mainly used as distributed constant type LC filters, and there are filters used for connectors and the like. 8A and 8B show a feed-through type low-pass filter showing a configuration example of a conventional distributed constant type LC filter. FIG. 8A shows a cross-sectional view, and FIG. 8B shows an equivalent circuit. In the LC filter shown in FIG.
A conductive true wire 12 is inserted into the conductive outer cover 11, and the true wire 12 is covered with a magnetic body 13 such as ferrite, and is covered with a dielectric 14 from above. That is, by wrapping the solid line 12 with the magnetic body 13, the inductance induction component L1 per unit length is distributedly increased. In addition, a capacitance (capacitance) component C1 per unit length is distributedly formed by the dielectric material interposed between the solid line 12 and the outer cover 11. Therefore, an LC filter is formed by the distributed inductance component L1 and capacitance component C1.

As shown in FIG. 8B, an equivalent circuit includes a resistance component R1 and an inductance component L1 per unit length formed by a solid line 12 and a magnetic body 13 on a line from a start point to an end point. Are distributed in series. Further, a magnetic body 13 is provided between the solid line 12 and the outer skin 11.
The capacitance component C1 formed by the dielectric 14 and the leakage resistance G1 per unit length are connected in parallel in a distributed manner.

[0004]

In the equivalent circuit shown in FIG. 8 (b), when a traveling wave such as a pulse square wave enters from the beginning (left end) of the filter, the following problem occurs. Occur. For example, when the characteristic impedance (L / C) of the filter is ZF and the characteristic impedance (output impedance of the filter) of a load (another line or circuit) connected to this circuit is Z0,
It is known that when ZF ≠ Z0, a reflected wave is generated on the filter side and a transmitted wave is generated on the load side.
(Z0) / (ZF + Z0) = m is the reflection coefficient. For example,
When ZF = Z0 / 2, the reflection coefficient m is-／. In this case, if a pulse square wave of V0 is incident on the filter, the transmitted wave transmitted to the load side becomes (2/3) V0, and (1/3) V0 is reflected to the filter side as a reflected wave.

That is, the feed-through type low-pass filter has a structure in which the attenuation of the filter is obtained by reflection. When the output impedance changes, the value of the reflection coefficient m also changes. The same is true for the case where the filter is connected to the input side of the filter, and the amount of attenuation in the conventional distributed constant type filter largely depends on the influence of input / output impedance. Therefore, when lines of electronic devices having different impedances are connected, attenuation may not be performed as expected. In order to prevent this, it is necessary to add a line having an appropriate characteristic impedance in the meantime to achieve matching.

An object of the present invention is to solve the above-mentioned conventional problems, and to provide an LC filter using a distributed constant line which can maintain its characteristics without depending on input / output impedance. It is an object.

It is a further object of the present invention to provide an LC filter using a distributed constant line, which is manufactured as a chip type filter, thereby minimizing the number of layers and suppressing the manufacturing cost.

[0008]

An LC filter according to the present invention comprises an electrode body, a dielectric provided on the electrode body, a magnetic member provided on the dielectric, and a conductive member embedded in the magnetic member. Having a capacitance component distributedly formed by the dielectric between the conductive member and the electrode body,
An inductance component formed distributedly in the magnetic member and the conductive member, and a resistance component that is distributedly increased compared to the low frequency region in a high frequency region exceeding a cutoff frequency from a low frequency region in the magnetic member. It has.

[0009] In the LC filter having such a configuration, for a signal in a frequency range lower than a frequency (cutoff frequency) at which the signal level incident on the filter inserted into the circuit causes an attenuation of 3 dB from the reference level, this signal is Since the signal passes through the inductance component, the signal can be passed by functioning as an LC filter. Further, the LC filter of the present invention becomes an RC distributed constant line after the cutoff frequency. Since the RC distributed constant line is a distributed constant line having a loss due to a resistance component, the higher the frequency (shorter wavelength), the greater the vibration when passing from the entrance to the exit of the line, and the signal is attenuated. Thus, a higher signal is attenuated and can function as a filter.

As described above, the LC filter using the distributed constant line according to the present invention does not depend on the difference between the specific impedance of the filter and the input / output impedance, and is not sensitive to signals in a frequency range lower than the cutoff frequency. , And functions as an LC filter for signals in a higher frequency range than the cutoff frequency.

In the present invention, the cutoff frequency is 500M
It is preferably in the range of not more than Hz. When the values of the inductance component and the capacitance component are reduced in order to increase the cutoff frequency of the LC filter, the stray capacitance due to the magnetic member and the conductive member and the electrode member due to the magnitude of the inductance component and the capacitance component are reduced. The above range is desirable because the inductance becomes large, so that a sufficiently large attenuation cannot be obtained.

Further, in the present invention, it is preferable that the conductive member is formed in a meandering shape or a spiral shape.

With this configuration, the length of the conductor per unit area can be set to be large.
The amount of signal attenuation by the filter can be increased,
An LC filter having excellent attenuation characteristics can be provided.

Further, in the present invention, it is preferable that a resistor is provided on the magnetic member in parallel with the resistance component so as to set the cutoff frequency by changing the resistance component.

[0015] Thereby, fine adjustment can be made in the direction of decreasing the cutoff frequency.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an LC filter according to the present invention will be described with reference to the drawings. (Embodiment 1) FIG. 1 shows an example of the configuration of an LC filter using a distributed constant line according to the present invention.
2B is a front view, FIG. 2C is a cross-sectional view taken along line AA of FIG. 2A, and FIG. 2 is an equivalent circuit diagram of the LC filter shown in FIG. In the LC filter in FIG. 1, a lower electrode body 2 and a dielectric 3 are stacked on the upper surface of a substrate 1. Also,
A conductive member 5 encapsulated by a lower magnetic member 4 and an upper magnetic member 6 is formed on the upper surface of the dielectric 3 in a so-called meandering shape. As the conductive member 5, for example, a thin copper film or the like can be used.

The lower magnetic member 4 and the upper magnetic member 6
An iron-based microcrystalline material that becomes a microcrystalline material after heat treatment in an amorphous state during film formation, for example, Fe-MO is used.
Note that Fe is iron, O is oxygen, and M is Zr (zirconium).
And the like, and can increase the inductance value of the conductive member 5 encapsulated in the lower magnetic member 4 and the upper magnetic member 6. An insulating film 7 coated with a resist material such as photosensitive polyimide is formed in a predetermined shape on the upper portion by a predetermined operation process.

The ends 5a and 5b of the conductive member 5 are drawn upward in the figure and are electrically connected to the bump electrodes 8a and 8b formed on the surface of the insulating film 7. further,
From the lower electrode body 2, a conductive member (not shown) is formed in a region where the lower magnetic member 4 and the upper magnetic member 6 are not formed.
Are drawn upward in the figure and are electrically connected to the bump electrodes 9 and 9 formed on the surface of the insulating film 7.

In the LC filters shown in FIGS. 1A and 1B,
With the above configuration, the inductance component of the conductive member 5 and the capacitance C of the dielectric 3 interposed between the conductive member 5 and the lower electrode body 2 can be distributed. Further, by manufacturing the filter as a chip type filter, the LC filter using the distributed constant line can be reduced in size, and can be easily incorporated into a circuit board or the like.

In the equivalent circuit of FIG. 2, in addition to the inductance component inherently included in the conductive member 5, the inductance component formed by the magnetic material (the lower magnetic member 4 and the upper magnetic member 6) enclosing the conductive member 5 is used. The inductance component L0 as the total value on which is superimposed is shown. The conductive member 5 has the inductance component L
Although there is a resistance R due to the conductive member 5 in series with 0, by enclosing the conductive member 5 with a magnetic material (the lower magnetic member 4 and the upper magnetic member 6), the resistance R is further reduced in parallel with the inductance component L0. The component r can be present.

Next, a method of forming an LC filter according to the present invention on a substrate will be described. First, an electrode body 2 made of copper is formed on a substrate 1 made of glass by sputtering.
A dielectric 3 made of Ta ₂ O ₅ was formed on the electrode body 2 to a thickness of 0.6 μm. Substrate 1
May be quartz, soda glass, etc.,
It is preferable to use a silicon substrate in terms of processability, cost, and the like. As the dielectric 3, SiO ₂ , Si ₃ N _{4 and the} like are effective.

Next, a FeZrO film is formed on the dielectric 3 to a thickness of 2 μm by a sputtering method, and the meandering lower magnetic member 4 is formed to a width of 84 μm by a lift-off method.
Was formed so that the total length of the ribbons was 9 mm with a pitch of 94 μm. Here, as the Fe-based microcrystalline material, Fe ₆₁ Z
r ₁₂ O ₂₇ (Fe at 61 at%, Zr at 12 at%, O at 27 at%) was used, but it is an Fe-based microcrystalline material that is in an amorphous state at the time of film formation by sputtering and then becomes a microcrystalline state by heating. If it has a large magnetic permeability, it is effective to set the inductance component to a large value. For example, Hf,
Fe-based oxides containing at least one of Y, Ce and Ti are preferred.

Next, a conductive layer made of copper is formed to a thickness of 0.7 μm on the lower magnetic member 4 by a sputtering method, and then a conductive layer having a width of 32 μm is formed along the center line of the lower magnetic member 4 by a lift-off method. The member 5 was formed. Then, an Fe ₆₁ Zr ₁₂ O ₂₇ film is formed with a thickness of 2 μm on the conductive member 5 by a sputtering method, and then the upper magnetic member 6 covers the conductive member 5 and completely overlaps the lower magnetic member 4. It was formed by patterning. Thus, the conductive member 5
The structure is embedded in the lower magnetic member 4 and the upper magnetic member 6. The substrate 1 thus obtained was annealed at 300 ° C. for 3 hours while applying a magnetic field in a vacuum. As a result, Fe ₆₁ which was in an amorphous state at the time of sputter deposition was formed.
The inductance value was increased by making the Zr ₁₂ O ₂₇ film in a microcrystalline state.

Next, polyimide (manufactured by Nissan Chemical Industries, Ltd .: Sanever RN8) is applied to the entire surface of the substrate 1 by spin coating.
The insulating film 7 made of 12) was formed with a thickness of 5 μm. Next, in a region where the lower magnetic member 4 and the upper magnetic member 6 are not formed, two holes from the surface of the insulating film 7 to the lower electrode body 2 are formed with a diameter of 80 μm by photolithography, and both ends of the conductive member 5 are formed. On the portions 5a and 5b, two holes from the surface of the insulating film 7 to the conductive member 5 through the upper magnetic member 6 were formed with a diameter of Φ80 μm. Next, these 4
One hole is filled with copper by an electroplating method, and then bump electrodes 8a, 8b, 9, 9 for connecting to external terminals are formed on the filled copper to form the LC filter of the present invention. did.

Here, the lower magnetic member 4 is formed in a meandering shape, but may be formed in a linear or spiral shape. By the way, in order to increase the attenuation without changing the size of the LC filter, it is necessary to increase the length of the conductive member 5 per unit area. Therefore, the conductive member 5 has a meandering or spiral shape. Preferably, it is formed.

Further, the LC filter according to the present invention comprises a substrate 1
Electrode body 2, dielectric 3, lower magnetic member 4, conductive member 5 on top
It is preferable to adopt a structure in which the upper magnetic member 6 and the upper magnetic member 6 are sequentially stacked. In such a structure, since the dielectric 3 can be formed on the flat electrode body 2, the dielectric 3 can be formed with a smaller thickness without causing a withstand voltage failure. Therefore, the inductive component distributedly increased by the dielectric 3 between the electrode body 2 and the conductive member 5 can be set to a large value, so that the cutoff frequency of the LC filter is set to a lower frequency range. Can be.

Further, according to the present invention, the cutoff frequency is 500M
It is preferably in the range of not more than Hz. When the values of the inductance component and the capacitance component are reduced in order to increase the cutoff frequency of the LC filter, the stray capacitance due to the magnetic member and the conductive member and the inductance due to the electrode body are reduced with respect to the magnitude of the inductance component and the capacitance component. Becomes large, so that a large amount of attenuation cannot be obtained. With such a configuration, an LC having excellent attenuation characteristics even when the cutoff frequency is set in a high frequency region.
A filter can be provided.

On the other hand, in the LC filter in which the lower magnetic member 4, the conductive member 5, the upper magnetic member 6, the dielectric 3 and the electrode body 2 are sequentially laminated on the substrate 1, the dielectric 3 has a film thickness of the upper magnetic member. 6 is formed thin at the corners. Therefore, according to this structure, insulation failure is likely to occur between the electrode body 2 formed on the dielectric 3 and the lower magnetic member 4, so that the thickness of the dielectric 3 must be set larger. For this reason, the induction component distributed and increased by the dielectric 3 between the electrode body 2 and the conductive member 5 cannot be increased, and it becomes difficult to set the cutoff frequency of the LC filter to a high value.

In consideration of applying the LC filter according to the present invention to a chip component, it is preferable that the conductive member 5 has a meandering shape. Generally, the bump electrode forming position of the chip component is set to the bump electrode 8 shown in FIG.
a, 8b, 9, and 9. Here, in the case where the conductive member 5 has a meandering shape, both end portions 5a and 5b of the conductive member 5 can be set on the substrate 1 so as to be located immediately below the bump electrodes. In addition, both ends 5a, 5b of the conductive member 5 and the bump electrodes 8a, 8b can be easily and electrically connected. On the other hand, when the conductive member 5 has a spiral shape, the central portion of the spiral from which the electrode is to be extracted cannot be pulled out to the position of the bump electrode on the substrate 1, so that a new process for drawing out the electrode is required. It is necessary to add a mask and an insulating film.

Next, the measurement results of the electrical characteristics of the LC filter of the present invention will be described. First, the relationship between the insertion attenuation and the frequency of this LC filter was measured using a network analyzer (8753B manufactured by HP). Here, the input impedance was measured at 50Ω and the output impedance was measured at 50Ω, and the input impedance was measured at 50Ω and the output impedance was measured at 3KΩ. For comparison, a conventional LC filter was also measured under the same conditions. The result is shown in FIG.

In FIG. 3, the vertical axis represents the insertion attenuation (d
B), and the horizontal axis is frequency (MHz). Code (1)
(2) shows an example of the measurement result of the conventional LC filter, and symbols (3) and (4) show the measurement result of the LC filter according to the present invention. Also, the signs (1) and (3) are 50
Ω-50Ω, and the symbols (2) and (4) indicate 50Ω-3KΩ. For example, “50Ω−50Ω” is measured when the input impedance of the LC filter is 50Ω and the output impedance is 50Ω.

The conventional LC filter has an input / output impedance dedicated to 50Ω, and therefore exhibits excellent characteristics when the input / output impedance shown by reference numeral (1) is 50Ω-50Ω. However, the sign (2)
As shown by, when the output impedance is 3 KΩ, it has a peak at the position of the point (A) (around the cutoff frequency of 13 MHz). That is, the conventional filter has a predetermined output impedance (50 in this example).
Ω) cannot be handled, and the characteristics of the filter have changed depending on the input / output impedance.

On the other hand, in the filter of the present invention, as shown by the reference numerals (3) and (4), even if the output impedance is 50Ω or 3KΩ, for example, the cut-off frequency is the same as that of the conventional filter. There is no peak in the vicinity, and the signal can be attenuated in almost the same manner, although there is some difference in gain. That is, the filter of the present invention is not affected by the output impedance.

FIG. 4 shows an example of a signal response waveform when the output impedance is changed, and FIG.
The system (b) is a 50Ω-3KΩ system. In FIG.
The vertical axis represents current (A), and the horizontal axis represents time (μsec). In FIG. 4, when a conventional LC filter is inserted ((8) and (10)) with respect to the fundamental wave (signs (7) and (10)) when a current of 2 MHz and 1 A flows to the output impedance side before the filter is inserted. (11)) shows the measurement results when the LC filter of the present invention is inserted ((9) and (12)). Symbols (8) and (9) indicate the case where the output impedance is 50Ω, and symbols (11) and (12) indicate the case where the output impedance is 3KΩ.

As shown in FIG.
At 0 Ω), the waveform (8) of the conventional filter with respect to the fundamental wave (7) is a filter dedicated to 50 Ω, and has almost no attenuation (about 0.98 A), indicating excellent characteristics. On the other hand, in the filter of the present invention, about 0.86 A
Although slightly inferior, the gain is -20 Log ₁₀ (0.8
6) = approximately -1.31 dB, not reaching a cutoff frequency of -3 dB, which is not so inferior to the conventional filter.

However, in FIG. 4B (output impedance: 3 KΩ), the conventional filter generates vibrations for both the rise and fall of the signal with respect to the fundamental wave (10). On the other hand, in the filter of the present invention, although the rise and fall times are somewhat dull due to the time constant, the filter exhibits characteristics superior to those of the output impedance of 50Ω. Therefore, it can be seen from the measurement results that the filter of the present invention can function without being affected by the input / output impedance without changing the output waveform even when different output impedances are connected. . That is, this LC
When the filter is used, it can be said that the input and output impedances are not considered.

(Embodiment 2) This embodiment is different from Embodiment 1 in that the thickness of the dielectric 3 is set to 1.2 μm. For other configurations, an LC filter was prepared under the same conditions as in Example 1, and the measurement of the electrical characteristics of the LC filter was performed in the same manner as in Example 1.

FIG. 3 shows the relationship between the insertion attenuation and the frequency of the LC filter according to this embodiment, and FIG. 5 shows an example of the signal response waveform when the input impedance and the output impedance are different. In FIG. 3, (5),
(6) shows the relationship between the insertion attenuation and frequency of the LC filter according to the present embodiment. Also, in FIG.
3) and (15) are fundamental waves when a current of 20 MHz and 1 A flows to the output impedance side.
4) and (16) show the measurement results when the LC filter according to the present embodiment is inserted.

As is apparent from FIGS. 3 (5) and (6), the LC filter according to the present embodiment cuts off even if the output impedance is, for example, 50Ω or 3KΩ as in a conventional filter. There is no peak near the frequency, and although there is some gain difference, it can be attenuated almost in the same way. Also, as is apparent from FIG. 5, the signal response waveform when the output impedance is changed shows the influence of the input / output impedance even when different output impedances are connected, similarly to the LC filter of the first embodiment. It turned out to be able to function without receiving it.

As is apparent from the above description, the capacitance component distributedly formed by the dielectric 3 and the inductance component distributedly formed in the lower magnetic member 4, the upper magnetic member 6 and the conductive member 5 are described in the embodiment. Even when a value different from 1 was set, it was found that the LC filter according to the present invention had the same effect as that of the first embodiment.

(Embodiment 3) FIG. 6 shows an LC according to the present invention.
9 shows another configuration example of the filter. 6A is a plan view, FIG. 6B is a front view, and FIG. 6C is a partially enlarged cross-sectional view along the line BB. FIG. 7 shows the LC according to this embodiment.
It is an equivalent circuit of a filter. In this embodiment, the same components as those in the first embodiment are denoted by the same reference numerals as those in the first embodiment. The difference between the LC filter according to the present embodiment and the LC filter according to the first embodiment is that the lower magnetic member 4
And the resistance bar 10 is formed on the upper magnetic member 6 so that the lower magnetic member 4 and the upper magnetic member 6 extend laterally in a meandering direction.

Next, a method of forming an LC filter according to the present invention on a substrate will be described. First, an electrode body 2 made of copper is formed with a thickness of 3 μm on a substrate 1 made of glass by a sputtering method, and then Ta ₂ O ₅ is formed on the electrode body 2.
Was formed in a thickness of 0.6 μm. Next, an Fe ₆₁ Zr ₁₂ O ₂₇ film is formed on the dielectric material 3 to a thickness of 2 μm by a sputtering method.
It was formed so that the total length was 9 mm at m pitches.

Then, after a conductor layer made of copper is formed to a thickness of 2 μm on the lower magnetic member 4 by a sputtering method, a conductive member having a width of 32 μm is formed along the center line of the lower magnetic member 4 by a lift-off method. 5 was formed. Next, a Fe ₆₁ Zr ₁₂ O ₂₇ film is formed on the conductive member 5 by sputtering at a thickness of 2 μm, and an upper magnetic member 6 having the same shape as the lower magnetic member 4 is formed by a lift-off method.
And formed so as to completely overlap the lower magnetic member 4. The substrate 1 thus obtained was annealed at 300 ° C. for 3 hours while applying a magnetic field in a vacuum. As a result, Fe ₆₁ which was in an amorphous state at the time of sputter deposition was formed.
The inductance value was increased by making the Zr ₁₂ O ₂₇ film in a microcrystalline state.

Next, over the entire surface of the substrate 1, Fe ₆₁ Zr
_After a resistor layer made of a ₁₂ O ₂₇ film was formed with a thickness of 0.2 μm, a resistance bar 10 was formed with a width of 10 μm by a lift-off method. As shown in FIG. 6, the resistance bar 10 is formed on the lower magnetic member 4 and the upper magnetic member 6 so that the lower magnetic member 4 and the upper magnetic member 6 extend laterally in a meandering direction.

Next, polyimide (manufactured by Nissan Chemical Industries, Inc .: Sunever RN) is applied to the entire surface of the substrate 1 by spin coating.
812) was formed. Next, in a region where the lower magnetic member 4 and the upper magnetic member 6 are not formed, two holes from the surface of the insulating film 7 to the lower electrode body 2 are formed with a diameter of 80 μm by a photolithography method.
Two holes from the surface of the insulating film 7 to the conductive member 5 through the upper magnetic member 6 were formed on both ends 5a and 5b of the conductive member 5 with a diameter of 80 μm. Thereafter, copper is filled into these four holes by an electrolytic plating method, and bump electrodes 8a, 8b, 9, 9 for connection to external terminals are formed so as to be electrically connected to the filled copper. Thus, an LC filter of the present invention was prepared.

FIG. 7 shows an equivalent circuit of the LC filter according to this embodiment. By inserting the resistor bar 10, the resistor is inserted in parallel with the resistor r on the equivalent circuit shown in FIG. Therefore, the value of the resistance component r in parallel with the inductance component L0 decreases, so that the cutoff frequency can be reduced.

The cutoff frequency of the LC filter according to the present embodiment obtained above was measured and found to be 25 MHz.
On the other hand, the cutoff frequency of the LC filter without the resistance bar 10 was 63 MHz. Also, for example, by setting the length of the resistance bar 10 to half, 1/4, or the like, the resistance r of the conductive member formed in a meandering shape can be arbitrarily set, and the cutoff frequency can be more finely adjusted. Can be set.

[0048]

As described above, according to the LC filter of the present invention, the electrode body, the dielectric provided on the electrode body, the magnetic member provided on the dielectric, and the magnetic member embedded in the magnetic member. And a conductive component formed in the low frequency region by the magnetic member and the inductance component distributed in the magnetic member and the conductive member. Since it has a resistance component that is distributedly increased in comparison with the low-frequency region in the high-frequency region beyond the cutoff frequency, without depending on the difference between the specific impedance and the input / output impedance,
It can function as an LC filter for signals in the lower frequency range than the cutoff frequency, and can function as an RC filter for signals in the higher frequency range than the cutoff frequency.

[Brief description of the drawings]

FIGS. 1A and 1B show an example of a configuration of an LC filter using a distributed constant line according to the present invention, wherein FIG. 1A is a plan view, FIG. 1B is a front view, and FIG. FIG.

FIG. 2 is an equivalent circuit diagram of the LC filter of FIG.

FIG. 3 is a frequency characteristic diagram showing insertion attenuation of a filter according to the present invention and a conventional filter.

FIG. 4 shows a signal response waveform when the output impedance is changed with respect to the LC filter according to the first embodiment;
(A) is a signal response waveform diagram of a 50Ω-50Ω system, and (b) is a signal response waveform diagram of a 50Ω-3KΩ system.

FIG. 5 shows a signal response waveform when the output impedance is changed for the LC filter according to the second embodiment;
(A) is a signal response waveform diagram of a 50Ω-50Ω system, and (b) is a signal response waveform diagram of a 50Ω-3KΩ system.

FIG. 6 is a configuration diagram showing one configuration example for lowering the cut-off frequency of the filter of the present invention, where (a) is a plan view,
(B) is a front view, (c) is a cross-sectional view along the line BB of (a).

FIG. 7 is an equivalent circuit diagram of the LC filter of FIG. 6;

8A is a cross-sectional view of a feed-through low-pass filter showing a configuration example of a conventional coaxial distributed constant filter, and FIG. 8B is an equivalent circuit diagram of FIG.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 electrode body (lower electrode body) 3 dielectric 4 lower magnetic member 5 conductive member 6 upper magnetic member 7 insulating film 8a, 8b, 9 bump electrode 10 resistance bar L inductance component per unit length C capacitance per unit length Component R Resistance per unit length G Leakage resistance per unit length

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Satoshi Waga Inside Alps Electric Co., Ltd. 1-7 Otsuka-cho, Yukitani, Ota-ku, Tokyo

Claims (4)

[Claims] An electrode body, a dielectric provided on the electrode body, a magnetic member provided on the dielectric, and a conductive member embedded in the magnetic member, wherein the conductive member and the electrode A capacitance component distributedly formed by the dielectric between the body, an inductance component distributedly formed in the magnetic member and the conductive member, and a high frequency exceeding a cutoff frequency from a low frequency region in the magnetic member. An LC filter having a resistance component distributedly increased in a region as compared with the low frequency region. 2. The LC filter according to claim 1, wherein said cutoff frequency is in a range of 500 MHz or less. 3. The LC filter according to claim 1, wherein the conductive member is formed in a meandering or spiral shape. 4. The LC according to claim 1, wherein a resistor is provided on the magnetic member so as to change a resistance value of the resistance component in parallel with the resistance component.
filter.