CN100454759C - Wave filtering method and apparatus - Google Patents
Wave filtering method and apparatus Download PDFInfo
- Publication number
- CN100454759C CN100454759C CNB2003101132014A CN200310113201A CN100454759C CN 100454759 C CN100454759 C CN 100454759C CN B2003101132014 A CNB2003101132014 A CN B2003101132014A CN 200310113201 A CN200310113201 A CN 200310113201A CN 100454759 C CN100454759 C CN 100454759C
- Authority
- CN
- China
- Prior art keywords
- filtering
- serial ports
- circuit
- filter circuit
- serial
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Shielding Devices Or Components To Electric Or Magnetic Fields (AREA)
Abstract
The present invention discloses a filtering method and a device thereof, which can be applied to serial ports. The method comprises the following steps: a), a filtering circuit is arranged in a serial port circuit, is arranged in a serial port receiving/sending circuit and is used for filtering and removing noise in serial ports; b), a printing circuit board of the serial port circuit is provided with a silence place, and the filtering circuit is connected with a reference place GND through the silence place for isolating noise in the reference place GND. The filtering device comprises the filtering circuit and the silence place, wherein the filtering circuit is connected with the reference place GND through the silence place. Because the silence place can isolate high frequency noise in the reference place GND, the present invention can reach a good filtering effect and can further reduce production cost.
Description
Technical field
The present invention relates to electric technical field, refer to be applied to a kind of filtering method and the device of serial line interface (abbreviation serial ports) especially.
Background technology
Electromagnetic interference is the problem that often runs in the communication, and electromagnetic noise can be inhibited by effective electromagnetic protection, and this is even more important in the production of communication products.In addition, in order to make the product of producing qualified, also comprise the test link usually in process of producing product, EMC (Electro Magnetic Compatibility) test is exactly wherein to be used for detecting a kind of the test whether product of producing meets the EMC standard.
Serial ports is the transfer of data mouth that often uses in the communication, and the electromagnetic interference in its production test procedure also is the problem that must avoid, often occurs in the product test process because the serial ports radiated emission exceeds standard and makes the product can not be by the problem of EMC test.In order to make the serial ports radiation be lower than the EMC standard of regulation, adopt usually the signal filtering transmitted in the serial ports to reduce the serial ports radiation.Therefore, the filtering of serial ports is very important.The circuit of existing techniques in realizing serial ports filtering as shown in Figure 1, in the transmission of serial ports and receiving circuit, all be connected to filter circuit, described filter circuit is made up of the LC filter circuit, C1, C2 form filter circuit with L1, L2 respectively as shown in Figure 1, and described filter circuit is used for the noise of filtering serial ports.
There is following problem in above-mentioned prior art scheme:
Because filter circuit directly links to each other with reference ground GND, and very unclean usually with reference to ground GND, has very strong high-frequency noise, because the existence of described high-frequency noise, the serial ports radiation often exceeds standard, and this makes that the filter effect of described filter circuit is also bad.In addition, in production test procedure, the serial interface cable radiation usually surpasses the prescribed limits of EMC standard, for guaranteeing that the serial ports radiation does not exceed standard, have to adopt expensive shielded type cable, can not test by EMC when serious even with shielded type cable, this improves production cost.And be connected in reference to the rs 232 serial interface signal backflow ground wire of ground GND and can directly will take equipment out of with reference to the high-frequency noise on the ground GND, influence other equipment then.
Summary of the invention
There is high-frequency noise in order to solve in the existing serial ports filtering method because reference ground GND, so that influences the problem of filter effect, the invention provides a kind of filtering method and device.
According to filtering method provided by the invention, this method may further comprise the steps:
A) filter circuit is set in serial port circuit, described filter circuit is arranged in the serial ports reception/transtation mission circuit, is used for the noise of filtering serial ports;
B) a quiet ground is set on the printed circuit board (PCB) under the described serial port circuit, and makes described filter circuit be used for isolating described noise with reference to ground GND by described linking to each other with reference ground GND via magnetic bead quietly.
Concrete, described filter circuit is the LC filter circuit that magnetic bead, electric capacity are formed.
Wherein, described serial ports is RS232 interface or interface V.24.
Correspondingly, filter provided by the invention comprises:
Filter circuit and quiet ground, described filter circuit is arranged in the serial ports reception/transtation mission circuit, and by link to each other with reference ground GND via magnetic bead quietly, is used for the noise of filtering serial ports.
Concrete, described filter circuit is the LC filter circuit that magnetic bead, electric capacity are formed.
Compared with prior art, the present invention has the following advantages:
1, the present invention can eliminate with reference to the high-frequency noise on the ground GND owing to by a quiet ground is set on the PCB under the serial port circuit (printed circuit board (PCB)), filter circuit is separated with reference ground GND by described quietly, effectively improves the effect of serial ports filtering;
2, owing to isolated the high-frequency noise of reference ground GND quietly, therefore, the rs 232 serial interface signal backflow ground wire that connects quiet ground can will not taken equipment out of with reference to the high-frequency noise among the ground GND, can eliminate the ground beta radiation, and the serial interface cable radiation is lower;
3, further the present invention is owing to the raising of serial ports filter effect and the minimizing of serial ports radiation, and serial interface cable can adopt common cable and not need to adopt shielded type cable can reach the EMC testing standard again, can further save cost.
Description of drawings
Fig. 1 is the circuit diagram of existing techniques in realizing serial ports filtering;
Fig. 2 is the flow chart of filtering method specific embodiment of the present invention;
Fig. 3 is the circuit diagram of filter specific embodiment of the present invention.
Embodiment
The objective of the invention is to reduce of the influence of the high-frequency noise of reference ground GND existence in the serial ports,, improve filter effect to reduce production costs to filter circuit filtering.In this specific embodiment be with the serial ports RS232 interface or V.24 interface describe, used magnetic bead is an electromagnetic interface bead, as ferrite bean etc.
Fig. 2 is the flow chart of filtering method specific embodiment of the present invention.
With reference to figure 2, filtering method of the present invention specifically may further comprise the steps:
Concrete, in sub-frame or rack I/O (I/O) signal outward, often mixing has unnecessary interfering noise signal, therefore, needs to be provided with described filter circuit and be used for filtering in serial ports transmission/receiving circuit by cable transmission.In order to reach better filter effect, the LC filter circuit that described filter circuit preferably adopts magnetic bead and electric capacity to form;
The invention described above serial ports filtering method, the setting by quiet ground can effectively reduce with reference to the influence of the high-frequency noise among the ground GND to filtering, and the serial ports filter effect is better than prior art.
Fig. 3 is a filter specific embodiment circuit diagram of the present invention.
As shown in Figure 3, serial ports is the RS232 interface among the figure, described RS232 interface comprises GND with sending pin TX, reception pin RX and reference, the rs 232 serial interface signal that transmits from serial port connector receives by receiving pin RX, pass in the equipment through serial port chip, and the rs 232 serial interface signal that spreads out of in the equipment sends by sending pin TX through serial port chip.
In order to realize filtering, in the serial ports transtation mission circuit, be connected to a LC filter circuit, a described LC filter circuit is made up of magnetic bead L1 and capacitor C 1, wherein said magnetic bead L1 one end links to each other with serial port chip, the other end links to each other with serial port connector by sending pin TX, and the described magnetic bead L1 of the described capacitor C 1 one terminations other end, the quiet ground of another termination, rs 232 serial interface signal in the equipment sends out through magnetic bead L1, send through serial port connector by sending pin TX, the rs 232 serial interface signal that described magnetic bead L1 and capacitor C 1 are used for equipment is spread out of carries out filtering, with the incoherent noise signal of filtering.
Similarly, in the serial ports receiving circuit, be connected to the 2nd LC filter circuit, described the 2nd LC filter circuit is made up of magnetic bead L2 and capacitor C 2.Wherein said magnetic bead L2 one end links to each other with serial port chip, the other end receives pin RX with serial port connector and links to each other, capacitor C 2 one ends link to each other with the magnetic bead L2 other end, the quiet ground of another termination, outside next rs 232 serial interface signal receives by receiving pin RX through serial port connector, is sent to serial port chip through magnetic bead L2 again, is sent in the equipment by serial port chip, described magnetic bead L2 and capacitor C 2 are used for the rs 232 serial interface signal that imports equipment into is carried out filtering, with the incoherent noise signal of filtering.
In the above-mentioned serial ports filter circuit, described is an isolated ground of cutting apart on pcb board quietly, and area can not be too big, and zone, quiet ground does not allow power supply and other any holding wire cabling except that rs 232 serial interface signal.Concrete, described quiet ground can link to each other with reference ground GND by a ferrite bean L3, and described ferrite bean L3 also plays the effect of rs 232 serial interface signal current return circuit except isolating the HF noise signal with reference to ground GND.Described quiet ground also is connected to the metal shell of equipment by serial port connector shell pin.Intercepted the high-frequency noise that exists with reference among the ground GND owing to being provided with of described quiet ground is effective, therefore, the filter effect of serial ports filter circuit improves greatly.
The above only is a possible embodiments of the present invention, and is non-so promptly limit to interest field of the present invention, and the equivalence that all utilizations specification of the present invention and accompanying drawing content are done changes, and all reason is with being contained in the claim scope of the present invention.
Claims (8)
1, a kind of filtering method is used for the filtering of serial ports, it is characterized in that, said method comprising the steps of:
A) filter circuit is set in serial port circuit, described filter circuit is arranged in the serial ports reception/transtation mission circuit, is used for the noise of filtering serial ports;
B) a quiet ground is set on the printed circuit board (PCB) under the described serial port circuit, and described filter circuit is linked to each other with reference ground GND via magnetic bead by described quietly, be used for isolating described noise with reference to ground GND.
According to the described filtering method of claim 1, it is characterized in that 2, described filter circuit is the LC filter circuit that magnetic bead, electric capacity are formed.
According to claim 1 or 2 described filtering methods, it is characterized in that 3, described serial ports is the RS232 interface.
According to claim 1 or 2 described filtering methods, it is characterized in that 4, described serial ports is interface V.24.
5, a kind of filter is used for the filtering of serial ports, it is characterized in that, described device comprises:
Filter circuit and quiet ground, described filter circuit is arranged in the serial ports reception/transtation mission circuit, and by link to each other with reference ground GND via magnetic bead quietly, is used for the noise of filtering serial ports.
According to the described filter of claim 5, it is characterized in that 6, described filter circuit is the LC filter circuit that magnetic bead, electric capacity are formed.
According to claim 5 or 6 described filters, it is characterized in that 7, described serial ports is the RS232 interface.
According to claim 5 or 6 described filters, it is characterized in that 8, described serial ports is interface V.24.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101132014A CN100454759C (en) | 2003-11-05 | 2003-11-05 | Wave filtering method and apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB2003101132014A CN100454759C (en) | 2003-11-05 | 2003-11-05 | Wave filtering method and apparatus |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1614885A CN1614885A (en) | 2005-05-11 |
| CN100454759C true CN100454759C (en) | 2009-01-21 |
Family
ID=34759852
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB2003101132014A Expired - Fee Related CN100454759C (en) | 2003-11-05 | 2003-11-05 | Wave filtering method and apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN100454759C (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104094292B (en) * | 2012-04-25 | 2017-03-08 | 株式会社村田制作所 | Wireless ic device and wireless communication terminal |
| CN107861899A (en) * | 2017-11-21 | 2018-03-30 | 盛科网络（苏州）有限公司 | A kind of serial line interface |
| CN111510094A (en) * | 2020-04-14 | 2020-08-07 | 华东计算技术研究所（中国电子科技集团公司第三十二研究所） | Suppression method and system based on anti-serial port electromagnetic leakage |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319260A (en) * | 1991-07-23 | 1994-06-07 | Standard Microsystems Corporation | Apparatus and method to prevent the disturbance of a quiescent output buffer caused by ground bounce or by power bounce induced by neighboring active output buffers |
| US5495358A (en) * | 1992-11-23 | 1996-02-27 | Hewlett-Packard Company | Optical transceiver with improved range and data communication rate |
| CN1185692A (en) * | 1996-09-06 | 1998-06-24 | 东光株式会社 | Interface mould block |
| US5781456A (en) * | 1997-07-11 | 1998-07-14 | Space Systems/Loral, Inc. | Software select and test |
| CN2384370Y (en) * | 1999-06-01 | 2000-06-21 | 四川泰通智能电器有限公司 | House power line high-frequency signal isolator |
| CN2413407Y (en) * | 1999-12-08 | 2001-01-03 | 杨继深 | Noninductive isolated interference filter connector |
| CN1304070A (en) * | 1999-12-14 | 2001-07-18 | 英群企业股份有限公司 | Additional circuit for computer output/input interface |
| CN2488102Y (en) * | 2001-07-09 | 2002-04-24 | 倚天资讯股份有限公司 | High-frequency interference resisting apparatus for person digital aid |
| CN2520081Y (en) * | 2001-12-28 | 2002-11-06 | 联想(北京)有限公司 | Power source for coordinate circuit of data interface of external modem |
-
2003
- 2003-11-05 CN CNB2003101132014A patent/CN100454759C/en not_active Expired - Fee Related
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5319260A (en) * | 1991-07-23 | 1994-06-07 | Standard Microsystems Corporation | Apparatus and method to prevent the disturbance of a quiescent output buffer caused by ground bounce or by power bounce induced by neighboring active output buffers |
| US5495358A (en) * | 1992-11-23 | 1996-02-27 | Hewlett-Packard Company | Optical transceiver with improved range and data communication rate |
| CN1185692A (en) * | 1996-09-06 | 1998-06-24 | 东光株式会社 | Interface mould block |
| US5781456A (en) * | 1997-07-11 | 1998-07-14 | Space Systems/Loral, Inc. | Software select and test |
| CN2384370Y (en) * | 1999-06-01 | 2000-06-21 | 四川泰通智能电器有限公司 | House power line high-frequency signal isolator |
| CN2413407Y (en) * | 1999-12-08 | 2001-01-03 | 杨继深 | Noninductive isolated interference filter connector |
| CN1304070A (en) * | 1999-12-14 | 2001-07-18 | 英群企业股份有限公司 | Additional circuit for computer output/input interface |
| CN2488102Y (en) * | 2001-07-09 | 2002-04-24 | 倚天资讯股份有限公司 | High-frequency interference resisting apparatus for person digital aid |
| CN2520081Y (en) * | 2001-12-28 | 2002-11-06 | 联想(北京)有限公司 | Power source for coordinate circuit of data interface of external modem |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1614885A (en) | 2005-05-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5346410A (en) | Filtered connector/adaptor for unshielded twisted pair wiring | |
| WO2002030003A3 (en) | Power line networking apparatus and method | |
| EP1263136A3 (en) | Filter structures for integrated circuit interfaces | |
| KR20120011430A (en) | Usb connector for wireless communication device | |
| CN100454759C (en) | Wave filtering method and apparatus | |
| US5642416A (en) | AM broadcast band interference filter for line-powered telephone | |
| CN114204240A (en) | Vertical transition structure of broadband in multilayer microwave board | |
| US20140009243A1 (en) | Network signal coupling and emi protection circuit | |
| CN110018408B (en) | Adjusting method for failure of home gateway type communication terminal to pass conducted disturbance test | |
| CN203166879U (en) | Spurious suppression circuit of radio frequency transmitter and mobile terminal | |
| CN113169921A (en) | Isolation circuit and device for controller area network communication | |
| JPH0879190A (en) | Electromagnetic hazard preventing device for balanced transmission line | |
| US20140009238A1 (en) | Network Signal Coupling and EMI Protection Circuit | |
| CN201138709Y (en) | Interference resisting filtering connector | |
| CN212543737U (en) | EMI filtering device | |
| CN201260173Y (en) | Concentrated E1 interface electromagnetic interference inhibition apparatus for communication device | |
| US11211679B2 (en) | Common-mode in-line radio frequency filter isolator | |
| CN208369469U (en) | A kind of power-supply filter | |
| CA2188843A1 (en) | Connecting arrangement for reducing induced noise | |
| EP1384320B1 (en) | Method and apparatus for reducing electromagnetic radiation | |
| CN217935576U (en) | Filter | |
| CN218730929U (en) | QFN (quad Flat No lead) packaging structure, radio frequency transceiving module structure and electronic equipment | |
| CN213906902U (en) | Audio power amplifier filtering device and system, audio power amplifier filtering line and adapter | |
| CN103166589B (en) | Communication equipment E1 interface line terminal electromagnetic radiation suppression circuit | |
| CN207038856U (en) | Electric connector |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| C10 | Entry into substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20090121 Termination date: 20141105 |
|
| EXPY | Termination of patent right or utility model |