CN101232274A - Filter circuit for reducing differential signal electromagnetic interference - Google Patents
Filter circuit for reducing differential signal electromagnetic interference Download PDFInfo
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- CN101232274A CN101232274A CNA200710002530XA CN200710002530A CN101232274A CN 101232274 A CN101232274 A CN 101232274A CN A200710002530X A CNA200710002530X A CN A200710002530XA CN 200710002530 A CN200710002530 A CN 200710002530A CN 101232274 A CN101232274 A CN 101232274A
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Abstract
The invention relates to a filter circuit for lowering the electromagnetic interference caused by a differential signal. The filter circuit comprises a first passive component group, a second passive component group and a third passive component group. The first passive component group comprises a first input/output side and a second input/output side; the second passive component group is connected across a positive signal end and a negative signal end of the first input/output side; and the third passive component group is connected across the positive signal end and the negative signal end of the second input/output side. By using the filter circuit, the electromagnetic interference of an input signal is lowered without affecting the signal transmission speed.
Description
Technical field
The invention relates to a kind of signal processing apparatus, and particularly relevant for a kind of filter circuit that reduces the differential wave electromagnetic interference.
Background technology
In the evaluation criteria of various electronic installations, all kinds of audio-visual household electrical appliances such as personal computer, TV, sound equipment such as, Electromagnetic Compatibility is the quality index of a key.In modern advanced country, the assessment report of Electro Magnetic Compatibility is more and more paid attention to.Because the signaling rate of electronic installation is more and more fast, can be more serious to such an extent as to be arranged at the electromagnetic interference that the electronic building brick of electronic installation inside itself caused, and influence the normal operation of electronic installation.
The assessment of Electro Magnetic Compatibility comprises electromagnetic interference (EMI) and anti-electromagnetic interference (EMS).Electromagnetic interference has approach such as conduction and radiation, and the electromagnetic interference of radiation solves with the configuration mode of change circuit or assembly usually.In known technology, in order to reduce the influence that electromagnetic interference is brought, the designer often uses assemblies such as electric capacity, resistance and inductance, or or even Tao Tie magnetic bead (Ferrite Bead), the coupled circuit design, for example circuit models such as L type, T type, ∏ type are combined into the filter circuit that is enough to resist electromagnetic interference.
Figure 1 shows that the Organization Chart of the box-like anti-electromagnetic interface filter of known group.Please refer to Fig. 1, L type, T type and ∏ mode filter are arranged among Fig. 1, these filters all comprise electric capacity (C) and inductance (L), can be described as compound LC mode filter again.These filters are to utilize Bart this (Butterworth) or Chai Bixuefu (Chebyshev) Filter Design principle difficult to understand, hinder high frequency characteristics according to the logical high frequency resistance low frequency of electric capacity and the logical low frequency of inductance, with electric capacity and the synthetic circuit of inductive bank, make it have certain filter function.Yet, in the anti-electromagnetic interface filter of composite type,, the Insertion Loss performance of filter is descended rapidly, so only be applicable to the interference that blanketing frequency is relatively low because its electric capacity and inductance are subject to effects of distribution parameters when high frequency, even resonance phenomena takes place.
Known technology is only applicable to the relatively low interference of blanketing frequency, for present various electronic installation, want to reduce comprehensively and effectively electromagnetic interference, be practically impossible, and the circuit framework of known technology may make signaling rate slack-off, cause system works to postpone, reduce system effectiveness.
Summary of the invention
In view of this, purpose of the present invention just provides a kind of filter circuit, utilizes the design of passive component group and coupled circuit, improve the problem of electromagnetic interference (EMI), and can select suitable assembly for use according to input signal characteristics, allow the influence of electromagnetic interference minimize.
The present invention proposes a kind of filter circuit, comprises the first passive component group, the second passive component group and the 3rd passive component group.This first passive component group has the first I/O side and the second I/O side, and first and second I/O side all has positive signal end and negative signal end.Wherein, the positive signal end of the first I/O side and negative signal end are coupled to each other by the second passive component group.Similarly, the positive signal end of the second I/O side and negative signal end then are to be coupled to each other by the 3rd passive component group.
According to the described filter circuit of preferred embodiment of the present invention, the first above-mentioned passive component group comprises first passive component and second passive component.Wherein, the corresponding respectively positive signal end that is coupled to the first I/O side and the second I/O side of first end of first passive component and second end, the then corresponding respectively negative signal end that is coupled to the first I/O side and the second I/O side of first end of second passive component and second end.
In addition, the second passive component assembly places between the positive signal end and negative signal end of the first I/O side, and it comprises the 3rd passive component and the 4th passive component.Wherein, an end of the 3rd passive component is coupled to the positive signal end of the first I/O side by this 3rd passive component, and the other end of the 4th passive component then is coupled to the negative signal end of the first I/O side.And the 3rd passive component group is disposed between the positive signal end and negative signal end of the second I/O side, and it comprises the 5th passive component and the 6th passive component.Wherein, an end of the 5th passive component is coupled to the positive signal end of the second I/O side by this 5th passive component, and the other end of the 6th passive component then is coupled to the negative signal end of the second I/O side.
From another viewpoint, the present invention proposes a kind of filter circuit, comprises first passive component, second passive component, the 3rd passive component, the 4th passive component, first electric capacity and second electric capacity.Wherein, an end of first electric capacity couples first end of first passive component, and the other end then is coupled to first end of second passive component by the 3rd passive component.One end of second electric capacity couples second end of first passive component, and the other end then is coupled to second end of second passive component by the 4th passive component.
According to the described filter circuit of preferred embodiment of the present invention, first and second above-mentioned passive component comprises that choking-winding, inductance, resistance and Tao Tie magnetic bead are wherein a kind of, and the 3rd and the 4th passive component comprises that inductance, resistance and Tao Tie magnetic bead are wherein a kind of.When passive component was resistance, the Standard resistance range of resistance was chosen between 1-330 ohm (Ω); When passive component was the Tao Tie magnetic bead, the Standard resistance range of Tao Tie magnetic bead was chosen between 10-330 ohm (Ω), and the capacitance scope of first and second electric capacity is chosen between the 3-330 pico farad (pF).
Effect of the present invention:
The present invention receives a differential wave because of adopting the passive component group, make electromagnetic interference that input signal produces the time by this component groups, cancel each other because of induced field, therefore can effectively reduce electromagnetic interference, and utilize the series connection collocation of passive component group, allow input signal avoid flowing directly into electric capacity, therefore signal is passed through fast, the solution signaling rate is slack-off, causes the problem of system delay.
For above and other objects of the present invention, feature and advantage can be become apparent, preferred embodiment cited below particularly, and cooperate appended graphicly, be described in detail below.
Description of drawings
Figure 1 shows that the Organization Chart of the box-like anti-electromagnetic interference (EMI) filter of known group.
Figure 2 shows that Organization Chart according to a kind of filter circuit 200 of a preferred embodiment of the present invention.
Fig. 3 A is depicted as the discrete signal figure of the digital video interface that does not use filter circuit 200.
Fig. 3 B is depicted as the discrete signal figure of the digital video interface that uses filter circuit 200.
Embodiment
Figure 2 shows that Organization Chart according to a kind of filter circuit 200 of a preferred embodiment of the present invention.Please refer to Fig. 2, filter circuit 200 comprises passive component group 230, passive component group 240 and passive component group 250.Passive component group 230 has I/O side 210 and 220, is used for receiving respectively or exporting a differential wave.In addition, two I/O sides all have the positive signal end, as S11 and S21, and the negative signal end, as S12 and S22.Positive signal end S11 and negative signal end S12 are coupled to each other by passive component group 240.Similarly, positive signal end S21 and negative signal end S22 are coupled to each other by passive component group 250.
Passive component group 230 can comprise passive component 231 and 232.First end of passive component 231 and second end correspondence respectively are coupled to positive signal end S11 and S21, and first end of passive component 232 and second end respectively correspondence be coupled to negative signal end S12 and S22.
In general, passive component 231 and 232 can utilize choking-winding, resistance, inductance or Tao Tie magnetic bead to realize.And in the present embodiment, passive component 231 and passive component 232 all are to utilize choking-winding to realize, right the present invention is not as limit.
In addition, passive component group 240 also can comprise passive component 241 and 242.One end of passive component 241 is coupled to positive signal end S11, and the other end then is coupled to negative signal end S12 by the 4th passive component 242.In the present embodiment, passive component 241 can be resistance, inductance or Tao Tie magnetic bead, and passive component 242 then can be an electric capacity.
In preferred embodiment, when passive component 241 was resistance, its Standard resistance range can be between 1-330 ohm (Ω).When passive component 241 was the Tao Tie magnetic bead, then Standard resistance range was between 10-330 ohm (Ω).In addition, when passive component 242,252 was electric capacity, its capacitance scope was between 3-330 pico farad (pF).
Similar with passive component group 240, passive component group 250 comprises passive component 251 and 252.One end of passive component 251 is coupled to the second positive signal end S21, and the other end then is coupled to negative signal end S22 by passive component 252.
Though the above-mentioned structure that preferred embodiment of the present invention is provided is known the knowledgeable as can be known usually yet association area of the present invention has, the arrangements of components in the passive component group 240 and 250 of being lifted in the present embodiment is not limited to above-mentioned structure.That is to say that the position of passive component is interchangeable, can be not influential in spirit of the present invention.
More specifically, in the present invention, not special the qualification is to receive or export differential wave by I/O side 210 or 220, and promptly when I/O side 210 was signal receiving end, 220 of I/O sides were output, and vice versa.The filter circuit 200 that preferred embodiment of the present invention provided can be according to user's demand, and the differential wave that electronic installation or circuit produced that is used for handling.For example, preferred embodiment of the present invention can be handled the differential wave that connector modules such as comprising digital video interface (DVI) connector, local area network connector, universal serial bus connector, IEEE 1394 connectors and Low Voltage Differential Signal connector is exported.In addition, preferred embodiment of the present invention also is applicable to and handles the differential wave that high-speed chip produced.
Fig. 3 A is depicted as the discrete signal figure of the digital video interface that does not use filter circuit 200.Fig. 3 B is depicted as the discrete signal figure of the digital video interface that uses filter circuit 200.Please merge with reference to figure 3A and Fig. 3 B, locate in Fig. 3 A medium frequency 755.9 and 971.9 megahertzes (MHz), signal is above standard as can be seen, and can find out that in Fig. 3 B signal obviously improves.
In sum, filter circuit provided by the present invention is because adopt the passive component group, and makes electromagnetic interference that input signal produces by this component groups the time, cancels each other because of induced field, therefore can effectively reduce electromagnetic interference, avoid the electronic installation running not normal.
In addition, high speed signal is because amplitude is little, the time that discharges and recharges is short, so can transmit fast, so embodiments of the invention utilize second and third passive component group, allow input signal avoid flowing directly into electric capacity, increase and discharge and recharge the time, and make the transmission rate of signal slack-off, cause system delay, so can solve the slack-off problem of signal transmission rate.
Though the present invention discloses as above with preferred embodiment; right its is not in order to limiting the present invention, anyly has the knack of this skill person, without departing from the spirit and scope of the present invention; when can doing a little change and retouching, so protection scope of the present invention is as the criterion when looking claims person of defining.
Claims (21)
1. a filter circuit is characterized in that, comprising:
One first passive component group, have one first I/O side and one second I/O side, the wherein above-mentioned first I/O side has one first positive signal end and one first negative signal end, and the above-mentioned second I/O side then has one second positive signal end and one second negative signal end;
One second passive component group is disposed between above-mentioned first positive signal end and the above-mentioned first negative signal end; And
One the 3rd passive component group is disposed between above-mentioned second positive signal end and the above-mentioned second negative signal end.
2. filter circuit according to claim 1 is characterized in that, the wherein above-mentioned first passive component group comprises:
One first passive component, one end couple the above-mentioned first positive signal end, and the other end then couples the above-mentioned second positive signal end; And
One second passive component, one end couple the above-mentioned first negative signal end, and the other end then couples the above-mentioned second negative signal end.
3. filter circuit according to claim 2 is characterized in that, wherein above-mentioned first passive component and second passive component are choking-winding, inductance, resistance or Tao Tie magnetic bead.
4. filter circuit according to claim 1 is characterized in that, the wherein above-mentioned second passive component group comprises:
One the 3rd passive component; And
One the 4th passive component, the one end is coupled to the above-mentioned first positive signal end by above-mentioned the 3rd passive component, and the other end of above-mentioned the 4th passive component then is coupled to the above-mentioned first negative signal end.
5. filter circuit according to claim 4 is characterized in that, wherein above-mentioned the 3rd passive component is a resistance, an inductance or a Tao Tie magnetic bead.
6. filter circuit according to claim 4 is characterized in that, wherein above-mentioned the 4th passive component is an electric capacity.
7. filter circuit according to claim 1 is characterized in that, wherein above-mentioned the 3rd passive component group comprises:
One the 5th passive component; And
One the 6th passive component, the one end is coupled to the positive signal end of the above-mentioned second I/O side by above-mentioned the 5th passive component, and the other end of above-mentioned the 6th passive component then is coupled to the negative signal end of the above-mentioned second I/O side.
8. filter circuit according to claim 7 is characterized in that, wherein above-mentioned the 5th passive component is a resistance, an inductance or a Tao Tie magnetic bead.
9. filter circuit according to claim 7 is characterized in that, wherein above-mentioned the 6th passive component is an electric capacity.
10. filter circuit according to claim 1 is characterized in that, wherein above-mentioned first I/O side or the above-mentioned second I/O side are in order to receive a differential wave.
11. filter circuit according to claim 10, it is characterized in that wherein above-mentioned differential wave is a digital video interface signal (DVI), a LAN signal, a universal serial bus signal, an IEEE 1394 signals or a Low Voltage Differential Signal.
12. a filter circuit is characterized in that, comprising:
One first passive component;
One second passive component;
One the 3rd passive component;
One the 4th passive component;
One first electric capacity, one end couple first end of above-mentioned first passive component, and the other end then is coupled to first end of above-mentioned second passive component by above-mentioned the 3rd passive component; And
One second electric capacity, one end couple second end of above-mentioned first passive component, and the other end then is coupled to second end of above-mentioned second passive component by above-mentioned the 4th passive component.
13. filter circuit according to claim 12 is characterized in that, wherein above-mentioned first passive component and above-mentioned second passive component are choking-winding, inductance, resistance or Tao Tie magnetic bead.
14. filter circuit according to claim 12 is characterized in that, first termination of wherein above-mentioned first passive component and above-mentioned second passive component is received a differential wave.
15. filter circuit according to claim 12 is characterized in that, second termination of wherein above-mentioned first passive component and above-mentioned second passive component is received a differential wave.
16. filter circuit according to claim 12 is characterized in that, wherein above-mentioned the 3rd passive component and above-mentioned the 4th passive component are resistance.
17. filter circuit according to claim 16 is characterized in that, wherein the Standard resistance range of above-mentioned these resistance is between 1-330 ohm.
18. filter circuit according to claim 12 is characterized in that, wherein above-mentioned the 3rd passive component and above-mentioned the 4th passive component are the Tao Tie magnetic bead.
19. filter circuit according to claim 18 is characterized in that, the Standard resistance range of wherein above-mentioned these Tao Tie magnetic beads is between 10-330 ohm.
20. filter circuit according to claim 12 is characterized in that, wherein above-mentioned the 3rd passive component and above-mentioned the 4th passive component are inductance.
21. filter circuit according to claim 12 is characterized in that, the capacitance of wherein above-mentioned first electric capacity and above-mentioned second electric capacity is between the 3-330 pico farad.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710002530XA CN101232274A (en) | 2007-01-25 | 2007-01-25 | Filter circuit for reducing differential signal electromagnetic interference |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNA200710002530XA CN101232274A (en) | 2007-01-25 | 2007-01-25 | Filter circuit for reducing differential signal electromagnetic interference |
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| Publication Number | Publication Date |
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| CN101232274A true CN101232274A (en) | 2008-07-30 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNA200710002530XA Pending CN101232274A (en) | 2007-01-25 | 2007-01-25 | Filter circuit for reducing differential signal electromagnetic interference |
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| CN (1) | CN101232274A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101847988B (en) * | 2009-03-25 | 2011-12-28 | 承景科技股份有限公司 | Signal converter |
| CN103503313A (en) * | 2011-07-27 | 2014-01-08 | 松下电器产业株式会社 | Power distribution circuit |
| CN103503313B (en) * | 2011-07-27 | 2016-11-30 | 松下知识产权经营株式会社 | Power distributing circuit |
| CN106533576A (en) * | 2015-09-09 | 2017-03-22 | 瑞昱半导体股份有限公司 | Common mode noise suppression apparatuses applicable to Ethernet |
| CN108134170A (en) * | 2016-12-01 | 2018-06-08 | 国基电子（上海）有限公司 | A kind of balun |
-
2007
- 2007-01-25 CN CNA200710002530XA patent/CN101232274A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101847988B (en) * | 2009-03-25 | 2011-12-28 | 承景科技股份有限公司 | Signal converter |
| CN103503313A (en) * | 2011-07-27 | 2014-01-08 | 松下电器产业株式会社 | Power distribution circuit |
| CN103503313B (en) * | 2011-07-27 | 2016-11-30 | 松下知识产权经营株式会社 | Power distributing circuit |
| CN106533576A (en) * | 2015-09-09 | 2017-03-22 | 瑞昱半导体股份有限公司 | Common mode noise suppression apparatuses applicable to Ethernet |
| CN106533576B (en) * | 2015-09-09 | 2019-11-15 | 瑞昱半导体股份有限公司 | It can be used for the common mode noise rejection device of Ethernet |
| CN108134170A (en) * | 2016-12-01 | 2018-06-08 | 国基电子（上海）有限公司 | A kind of balun |
| CN108134170B (en) * | 2016-12-01 | 2021-02-19 | 国基电子（上海）有限公司 | Balance-unbalance converter |
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Open date: 20080730 |