CN208548912U - Communication system - Google Patents

Abstract

This disclosure relates to communication system.It describes using CMC, transformer, auto-transformer, the various technologies of the combined termination differential pair of differential mode choke coil (DMC) and AC coupling capacitor.These technologies improve exchange Common Mode insertion loss in the case where not weakening differential data signals, while simplifying the requirement of CMC.In one example, there is the first winding, the second winding is connected with centre tapped auto-transformer across PHY, and wherein centre cap provides Low ESR over the ground with attenuation common-mode noise.CMC is coupled on auto-transformer and a pair of conducting wire for carrying differential data, and CMC has greatly decayed common-mode noise.Due to auto-transformer, the requirement of CMC decreases.

Description

Communication system

Cross reference to related applications

The application based on and require the U.S. Provisional Application sequence submitted by Andrew J. Gardner on March 1st, 2017 Number 62/465,737, submitted on March 1st, 2017 62/465,745 and submitted on March 3rd, 2017 62/467, 036 priority, all applications are incorporated herein by reference.

Technical field

The utility model relates to use the communication system of differential data on the twisted-pair, and in particular to improve common mode insertion damage Consume the technology of characteristic.

Background technique

Common mode choke (CMC) can eliminate the common-mode noise in differential pair, and the degree of filtering common mode noise is claimed For Common Mode insertion loss.In the data transmission applications using unshielded twisted pair (UTP) cable, in the presence of common-mode noise Under, the Common Mode insertion loss for the CMC that the data physical channels layer equipment (PHY) at the every end of cable uses is for keeping data communication chain The integrality on road is most important.

Common Mode insertion loss is limited by constraints several on CMC, such as occupied area, interwinding capacity, leakage inductance, winding DCR and iron loss etc..In addition, CMC must have low insertion loss and high return loss, this is the differential data transmitted between PHY Required.Need to realize in noisy environment the application of the UTP cable of very low error rate for using, traditional CMC may It cannot achieve required Common Mode insertion loss.Solve this deadlock usually require with relatively expensive shielded cable and connector come Substitute UTP cable and connector.

Superior technique is needed to eliminate the common-mode noise for the line centering for carrying differential data.

Utility model content

It describes using CMC, transformer, auto-transformer, the combination of differential mode choke coil (DMC) and AC coupling capacitor The various technologies of terminating differential line pair.These technologies improve exchange common mode in the case where not significant attenuated differential data-signal Insertion loss, while simplifying the requirement of CMC.

One aspect according to the present utility model discloses a kind of communication system, for a pair from carrying differential data AC common-mode signal is filtered in conducting wire, comprising: physical link layer equipment PHY, the PHY including the transceiver for differential mode data With first terminal and Second terminal；Auto-transformer has the first winding, the second winding and is located at the first winding and the Centre cap between two windings, auto-transformer have the third terminal for the first terminal for being coupled to PHY and are coupled to PHY Second terminal forth terminal, wherein centre cap pass through Low ESR be grounded；With common mode choke CMC, has and be coupled to 5th terminal of the third terminal of auto-transformer and be coupled to auto-transformer forth terminal the 6th terminal, CMC is also The 8th of the 7th terminal with the first conducting wire being coupled in the conducting wire and the second conducting wire being coupled in the conducting wire Terminal, the biography of the common-mode noise between the pair of conducting wire and the PHY wherein the CMC and auto-transformer are significantly decayed It is defeated, while the transmission for the differential mode data signals that do not decay significantly between the pair of conducting wire and the PHY.

In some implementations, the CMC is ac-coupled to described one by first capacitor device and the second capacitor To conducting wire, the first capacitor device be coupled in the CMC the 7th terminal and the conducting wire in first conducting wire it Between, second capacitor is coupled between second conducting wire in the 8th terminal and the conducting wire of the CMC.

In some implementations, the centre cap DC of the auto-transformer is coupled to ground.

In some implementations, the centre cap AC of the auto-transformer is coupled to ground.

In some implementations, the communication system further includes the centre cap for being coupled to the auto-transformer Voltage source, for into Power over Ethernet (PoE) network the pair of conducting wire provide DC current potential.

In some implementations, the third terminal of the auto-transformer is coupled to institute via first capacitor device AC The first terminal of PHY is stated, and the forth terminal of the auto-transformer is coupled to institute via the second capacitor AC State the Second terminal of PHY.

In some implementations, the communication system further includes being coupled to the termination circuit of the pair of conducting wire, described Termination circuit includes first resistor device-capacitor circuit that the first conducting wire in the conducting wire is coupled to ground, and will be described The second conducting wire in conducting wire is coupled to the second resistor-capacitor circuit on ground.

In some implementations, the PHY is coupled to the pair of by first capacitor device and the second capacitor AC Conducting wire, the first capacitor device is coupled in series between first conducting wire in the first terminal and the conducting wire, described Second capacitor is coupled between second conducting wire in the Second terminal and the conducting wire.

One aspect according to the present utility model discloses a kind of communication system, for from carrying differential data signals AC common-mode signal is filtered in couple of conductor, comprising: first port has be coupled to the transceiver for receiving differential data signals two A first terminal；Second port has two Second terminals for being coupled to the pair of conducting wire；With being connected to AC termination circuit Two third terminals third port；The common mode choke CMC being coupled between the second port and the first port, The CMC includes that there are two the first transformers of the identical winding of polarity for tool；And it is coupled between first port and third port Differential mode choke coil DMC, DMC include tool there are two opposite polarity winding the second transformer, wherein the CMC decaying described in AC common-mode signal in couple of conductor and substantially pass through the differential data signals, wherein the DMC substantially make from The pair of conducting wire passes through by the AC common-mode signal of the CMC and the AC common-mode signal is applied to the termination Circuit is in the AC common-mode signal that decays that takes a step forward of the transceiver reception AC common-mode signal.

In some implementations, the CMC is First CMC, the system also includes with the First CMC series coupled And the second CMC of the First CMC is connected at first node, wherein the DMC is coupled in the first node and Between three ports.

In some implementations, the AC termination circuit includes one be coupled in the third terminal and reference electricity First capacitor device between pressure, and be coupled in the third terminal another between the reference voltage second electricity Container.

In some implementations, the AC termination circuit include be coupled in described two third terminals and reference voltage it Between first capacitor device.

In some implementations, the AC termination circuit includes being connected to described two third terminals of reference voltage.

In some implementations, the communication system further includes being coupled to the pair of conducting wire via DC coupling circuit DC voltage source, wherein the DC voltage source also serves as the AC termination circuit.

In some implementations, the DC coupling circuit include one or more inductors.

In some implementations, the DC coupling circuit include the DMC, and the D/C voltage is coupled to institute State third port.

In some implementations, the transceiver includes the PHY for being coupled to the first port via AC coupling circuit.

In some implementations, the AC coupling circuit include concatenated with described two first terminals and the PHY Capacitor.

One aspect according to the present utility model discloses a kind of communication system, for a pair from carrying differential data AC common-mode signal is filtered in conducting wire, comprising: the physical link layer equipment PHY including the transceiver for differential mode data signals, institute PHY is stated with first terminal and Second terminal；Transformer, with what is coupled across the first terminal and the Second terminal Armature winding, the transformer also have secondary first winding, secondary second winding and secondary first winding and secondary second Centre cap between winding, wherein the centre cap is grounded by Low ESR；With common mode choke CMC, there is coupling To the third terminal of secondary first winding, and there is the forth terminal for being coupled to secondary second winding, the CMC Also there is the of the 5th terminal of the first conducting wire being coupled in the conducting wire and the second conducting wire being coupled in the conducting wire Six terminals, the transmission of the common-mode noise between the pair of conducting wire and the PHY wherein the CMC and transformer are significantly decayed, The transmission for the differential mode data signals indistinctively decayed between the pair of conducting wire and the PHY simultaneously.

In some implementations, the communication system further includes the centre tapped electricity for being coupled to the transformer Potential source provides DC current potential for the pair of conducting wire into Power over Ethernet (PoE) network.

One aspect according to the present utility model discloses a kind of communication system, comprising: including being used for differential mode data signals Transceiver physical link layer equipment PHY, the PHY has first terminal and Second terminal；Transformer type balun has coupling The third terminal of the first terminal is closed, and there is the forth terminal for being coupled to the Second terminal, the balun also has There is the 5th terminal for being coupled to reference voltage, and there is the 6th terminal；It is coupled to the DC blocking equipment of the 6th terminal； DC voltage source；The DC voltage source is coupled to the AC blocking equipment of the DC blocking equipment；And coaxial cable, with coupling The shielded conductor of reference voltage is closed, and there is the center conductor for being coupled to AC blocking equipment.

In some implementations, the DC blocking equipment includes capacitor.

In some implementations, the AC blocking equipment includes inductor.

Detailed description of the invention

Fig. 1 shows a kind of communication link between two PHY using UTP cable.

Fig. 2 shows the circuits for combining AC coupling PHY with shunting differential mode choke coil (DMC) and CMC.

Fig. 3 is shown coupled to another circuit for shunting DMC, with terminated wires and eliminates AC common-mode signal.

Fig. 4 shows the combination of AC coupling PHY with two connect CMC and shunting DMC that " T shape " configures.

Fig. 5 shows a type of termination of Differential data communication system, and wherein PHY prevents balance double by CMC Common-mode signal in strand cable application, and the AC coupling resistance in parallel on MDI is relied on to terminate common-mode signal.

Fig. 6 shows one embodiment of the utility model, use autotransformer with center tap as shunt DMC, Wherein centre cap is ac-coupled to ground.

Fig. 7 shows another embodiment of the utility model, and wherein the centre cap of auto-transformer is straight by voltage source Stream is coupled to ground.

Fig. 8 shows an alternate embodiment of the utility model, and wherein autotransformer with center tap is replaced by change Depressor, and the side the MDI winding of transformer is grounded by centre cap and by voltage source DC.

Fig. 9 shows another embodiment of the utility model, wherein compared with embodiment shown in Fig. 8, CMC and DC resistance The position of plug capacitor is exchanged.

Figure 10 shows the modification of the embodiment in Fig. 9, wherein increasing DC coupling inductance at the PHY side terminal of CMC Device, so that the D/C voltage generated by voltage source to be multiplexed on two conductors of balancing twisted-pair line cable.

Figure 11 shows the alternate embodiment of Figure 10, and wherein centre-tapped transformer is replaced by centre cap self coupling transformation Device, and wherein the centre cap of auto-transformer is grounded through capacitor AC.

Figure 12 illustrates the embodiments of the present invention for two couples of PHY.Common-mode DC voltage is applied to auto-transformer Centre cap on, to provide common-mode voltage on two conductors of each balancing twisted-pair line cable.

Figure 13 shows an alternate embodiment, and wherein the auto-transformer of Figure 12 is replaced by transformer, and PHY terminal It is galvanically isolated with MDI.

Figure 14 illustrates a circuit, wherein a line with data line power supply (PoDL) is to Ethernet and balancing twisted-pair Line cable is used together.

Figure 15 shows the power coupling circuit for single line to ethernet PHY, and it is poor to allow to transmit by coaxial cable Both divided data and DC power.

Identical or equivalent element indicates identical element number.

Specific embodiment

Show the multiple technologies for reducing the common-mode noise in Differential data communication system.

Common mode choke and differential mode choke coil combination for being carried out data transmission by twisted pair

Fig. 1 shows the communication link between two PHY 10 and 12 using UTP cable 14.CMC 16 and 18 is for filtering Except common-mode noise.AC coupling capacitor C1-C4 filters out DC, so that PHY 10 and 12 only receives the differential data of AC coupling.PHY 10 and 12 can also send the differential data of AC coupling.PHY 10 and 12 includes transceiver and circuit for signal conditioning, and parameter is logical Often provided by ieee standard.

CMC includes two coupling windings and is connected in series with twisted pair.As shown in the point on CMC winding, winding is to common mode Signal polarity having the same, so being substantially cancelled by the magnetic field that difference mode signal generates.Therefore, CMC is to differential-mode current Inductance or impedance very little.However, common mode current due to winding the coupling inductance not being cancelled and see high impedance.

CMC is ideally eliminated or greatly attenuation common-mode RF noise, while providing the loss of very little for differential mode voltage signal. But CMC has the constraint for limiting the ability that it prevents common-mode signal.This constraint includes interwinding capacity, the direct current of winding Resistance (DCR) and iron loss.CMC must also provide low insertion loss and high return loss to differential mode data.

This paper presents the combinations of differential mode choke coil (DMC) and one or more CMC, substantially improve common mode insertion Loss, while remaining required differential mode return loss and insertion loss.In following figure, for the sake of simplicity, one is only shown A PHY, and the both ends that circuit can be online pair are symmetrical.

Fig. 2 shows the circuits that AC coupling PHY 10 is combined with DMC 20 and series connection CMC 22 is shunted.CMC 22 and DMC 20 this configuration so that the AC common-mode signal between Media Dependent Interface (MDI) 24 and PHY 10 is substantially prevented, and The transmission of difference mode signal is substantially unobstructed, and the commonly connected common-mode signal between ground of CMC 22 and DMC 20 Transmission is substantially unobstructed, and the transmission of AC difference mode signal is substantially prevented.The shunting connection on DMC 20 to ground passes through electricity The AC coupled of container 26 and 27.

In this way, the requirement of CMC 22 substantially reduces, because any AC common-mode noise by CMC 22 passes through coupling The AC coupling capacitor 26 and 27 closed to ground is shunted via DMC 20.

Another circuit for being coupled to DMC 20 with terminated wires and eliminating AC common-mode signal is shown in Fig. 3.In Fig. 3, A terminal of DMC 20 is coupled to ground via AC coupling capacitor 27, and the Second terminal of DMC20 is connected to and capacitor The capacitor 30 of 27 connections.The embodiment is substantially identical to Fig. 2.

Fig. 4 show AC coupling PHY 10 with " T shape " configures two connect CMC's 22 and 32 and shunting DMC 20 Combination.The configuration so that both PHY10 and CMC22/32 and DMC20 it is commonly connected between common-mode signal transmission base It is prevented from this, and the transmission of difference mode signal is substantially unobstructed.In the points of common connection of CMC 22/32 and DMC 20 to ground Between common-mode signal transmission it is substantially unobstructed, and difference mode signal to ground transmission be substantially prevented.Substantially hinder Stop the transmission for the common-mode signal of CMC 22/32 and DMC 20 being commonly connected between MDI 24, and MDI 24 and public company The transmission of difference mode signal between connecing is substantially unobstructed.The shunting connection on DMC 20 to ground is AC coupled.It can set Think that the other embodiments that DMC is coupled to ground will be shunted.Increased CMC 32 further reduced at AC coupling capacitor C1 and C2 AC common-mode noise, while alleviating the demand of DMC 20 and CMC 22, because exchanging common mode to the input signal on 14 for line Noise is decayed before reaching DMC 20 by CMC 22, and the AC common-mode noise generated in 10 side PHY (in the output signal) Decayed before reaching DMC 20 by CMC 32.Therefore, because CMC 32, PHY 10 can see high AC common code impedance.By There is symmetrical CMC 22/32 in its input terminal in DMC 20, so the public noise reduction of AC sends and receives PHY 10 It is symmetrically, this can mitigate the demand of DMC 20 and CMC 22/32.

For enhancing the circuit engineering of the common mode choke performance of balancing twisted-pair line cable PHY

In the data transmission applications for relying on balancing twisted-pair line cable, there are common-mode noise, the every end of cable The performance of common mode choke (CMC) that uses of data physical channels layer equipment (PHY) for keeping the complete of data link Whole property is most important.

Fig. 5 shows the termination of Differential data communication system, and wherein PHY 10 prevents balancing twisted-pair line electricity by CMC 60 Common-mode signal in cable application.AC coupling capacitor 62 and 63 allows difference AC data to pass through.Including resistor 66 and 68 and The RC circuit of capacitor 70 and 72 provides AC coupled impedance matching for common-mode signal.

Common Mode insertion loss is limited by constraint conditions many on CMC, such as occupied area, interwinding capacity, the DCR of winding With iron loss etc..In addition, CMC must have low insertion loss and high return loss required by transmission differential mode data.For needing The application of the balancing twisted-pair line cable of very low error rate is realized in noisy environment, traditional CMC may cannot achieve required Common Mode insertion loss.The solution of this deadlock may be needed using relatively expensive shielded cable and connector, to mitigate Requirement to CMC or completely without CMC.

This paper presents autotransformer with center tap or the group of the transformer with center-tapped secondary winding and CMC It closes, substantially improves Common Mode insertion loss using simple CMC in the PHY application using balancing twisted-pair line cable.

Fig. 6 shows one embodiment of the utility model using autotransformer with center tap 74.Auto-transformer It is transformer only with a winding.In auto-transformer, a part of same winding as transformer primary side and Secondary side.Their polarity can be made to be added by the way that inductance is together in series, configure two identical coupling inductances to Heart tap auto-transformer.On the contrary, common transformer has the independent primary and secondary winding being galvanically isolated.

PHY 10 is coupled to MDI 24 by CMC 76 and DC block-condenser 78 and 80.Autotransformer with center tap 74 Connection is shunted between two terminals of PHY 10.The centre cap of auto-transformer 74 is ac-coupled to by capacitor 82 Common mode.Two 24 bonder terminals of MDI have via the RC circuit being made of resistor 66/68 and capacitor 70/72 To the AC coupling common-mode noise termination on common mode ground.Common mode termination minimizes the reflection of incident common-mode signal at MDI 24.

CMC 76 is essentially prevented AC common-mode signal, but does not prevent difference mode signal substantially.Due to indicated winding Polarity is applied to the common-mode signal at two terminals common with 10 terminal of PHY of auto-transformer 74 and sees common mode ground Low impedance path, and the difference mode signal of PHY 10 sees relatively high AC impedance.Therefore, AC difference mode signal is existed with low-loss It is transmitted between MDI 24 and PHY 10, and the loss of AC common-mode signal transmission is much larger than and is matched using simple series connection CMC shown in fig. 5 Set achievable loss.Compared with the configuration of Fig. 5, auto-transformer 74 is used together with CMC 76 reduces wanting for CMC 76 It asks, and improves common mode noise rejection, and to differential mode data almost without adverse effect.

Another CMC can be inserted between auto-transformer 74 and PHY 10, so that PHY 10 sees high common mode resistance It is anti-.Additional CMC can further decrease the transmission of common-mode noise, more than the feasible situation in single CMC.

All autotransformer with center taps as shown in FIG. 6 can also replace the DMC 20 in Fig. 4.

Fig. 7 shows an alternate embodiment of the utility model, wherein using voltage source 86 in auto-transformer 74 Centre cap applies DC voltage.It is assumed that voltage source 86 has Low ESR, it is diverted to ground for common-mode noise will to be exchanged.Fig. 7's One purposes of embodiment is online to providing D/C voltage (relative to systematically) on 14 with to being set what the other end connected by electricity Standby (PD) powers.

Fig. 8 shows an alternate embodiment of the utility model, and wherein autotransformer with center tap is by transformer 87 Instead of, and the side the MDI winding of transformer 87 is by centre cap and with being connected to common mode.The embodiment is using some efficiency as cost Additional isolation to PHY 10 is provided.

Fig. 9 shows another embodiment of the utility model, wherein compared with embodiment shown in fig. 8, CMC76 and The position of DC block-condenser 88 and 90 is exchanged.

Figure 10 shows the modification of the embodiment in Fig. 9, wherein increasing DC coupling electricity at the PHY side terminal of CMC 76 Sensor 92 and 94, so as to the two of the twisted-pair cable 14 of the D/C voltage duplex (diplex) that will be generated by voltage source 96 to balance On a conductor.DC voltage is used for the load supplying in data line power supply (PoDL) network for 14 other end of conducting wire.

Figure 11 shows the alternate embodiment of Figure 10, and wherein centre-tapped transformer is replaced by centre cap self coupling transformation Device 74, and wherein the centre cap of auto-transformer 74 is grounded by capacitor 98AC.Use is explained previously with reference to Fig. 6 The benefit of auto-transformer.

Figure 12 shows one embodiment of the utility model for two couples of PHY 100.It is total to by what voltage source 102 generated The centre cap of mould D/C voltage across auto-transformer 104 and 106 applies, so as in each balancing twisted-pair line cable 14A and 14B Two conductors on common-mode voltage is provided.Blocking capacitor 108-112 is by the terminal of PHY100 and balancing twisted-pair line cable 14A With the conductor of 14B present on D/C voltage isolation.Due to the terminal of cable 14A and 14B be it is identical, so corresponding component To being marked as A and B.

This is configured to Power over Ethernet system, and one of line is to the one DC potential (positive electricity of voltage source 102 of conduction Pressure), another line is to another DC potential (negative voltage of voltage source 102) of conduction, and potential difference is used for as line to the other end Load supplying.

Figure 13 shows alternate embodiment, and wherein the auto-transformer of Figure 12 is replaced by transformer 116 and 118, and 100 terminal of PHY is galvanically isolated with MDI 24A and 24B.Centre cap across transformer 116 and 118 applies by voltage source 102 The D/C voltage of generation, to provide common-mode voltage on two conductors of each balancing twisted-pair line cable 14A and 14B.

In embodiment as shown in figs. 6-13, the common-mode signal that can reduce the integrality of PHY differential signal passes through CMC The low common code impedance of centre-tapped transformer or auto-transformer of the side PHY be diverted to ground.PHY can be directly connected to, and be passed through Blocking capacitor connection, is connected, or pass through the series connection group of transformer interface and blocking capacitor by transformer interface Close the terminal for being connected to CMC.The terminal towards MDI of CMC can be connected to MDI directly or by partiting dc capacitor.MDI is upper can There can be common mode termination, to prevent from occurring at MDI undesirable common-mode signal reflection.The coupling electricity of a pair of of PHY can be used DC voltage is applied to leading for balancing twisted-pair line cable by the centre cap of the transformer or auto-transformer of sensor or PHY Body, wherein PHY carries out the transmission of data dependent on two or more line cables.

The single pair Ethernet of coaxial cable with data line power supply (PoDL)

A line with data line power supply (PoDL) is usually used together Ethernet with balancing twisted-pair line cable 120, As shown in figure 14.In Figure 14, DC voltage source 122 is coupled to the input of CMC 22 by dc-couple inductance L1 and L2.Inductance L1 and L2 hinders difference AC signal.Since DC voltage is not common mode AC signal, so CMC 22 will not hinder DC voltage.

However, in some cases (such as in very noisy environment), being sent by coaxial cable using direct current A pair of of line may be very useful to Ethernet data.

The power coupling circuit of ethernet PHY is allowed to lead to for the single line with PoDL below with reference to Figure 15 description Cross coaxial cable transmission both differential data and DC power.Figure 15 is similar in the U.S. Publication for transferring Broadcom company The circuit of Fig. 3 in 20160308683, in addition to blocking capacitor 124 is added in circuit.If without capacitor 124, Broadcom circuits will be unable to work, therefore Broadcom disclosure and the not enabled circuit.

The balanced differential interface of PHY 10 is transformed to the single-ended of coaxial cable 128 using balun 126 by the circuit of this Figure 15 Interface.The external shield ground connection of coaxial cable 128 thinks that center line shields external noise.Blocking capacitor 124 is by balun 126 Existing D/C voltage is isolated between the side MDI winding and two conductors of cable 128.Inductor L1 is used for DC power supply 130 or bears In two conductors for carrying (other end for being coupled to cable 128) insertion cable 128.It is contemplated that for by the side MDI of balun 126 The additional aspects that D/C voltage between winding and two conductors of cable 128 is isolated.

While there has been shown and described that the specific embodiment of the utility model, but to those skilled in the art It is readily apparent that can be changed and modified without departing substantially from the broader aspect of the utility model, and because This appended claims is included within all these in the true spirit and range of the utility model in the range of them Change and modifies.

Claims (23)

1. a kind of communication system, for filtering AC common-mode signal from the couple of conductor for carrying differential data, comprising:

Physical link layer equipment PHY, the PHY including the transceiver for differential mode data have first terminal and second end Son；

Auto-transformer is taken out with the first winding, the second winding and the center between the first winding and the second winding Head, auto-transformer have the third terminal for the first terminal for being coupled to PHY and are coupled to the 4th end of the Second terminal of PHY Son, wherein centre cap is grounded by Low ESR；With

Common mode choke CMC has the 5th terminal of the third terminal for being coupled to auto-transformer and is coupled to self coupling change 6th terminal of the forth terminal of depressor, CMC also have the 7th terminal and coupling for the first conducting wire being coupled in the conducting wire The 8th terminal of the second conducting wire in the conducting wire is closed,

Wherein the CMC and auto-transformer are significantly decayed the transmission of the common-mode noise between the pair of conducting wire and the PHY, The transmission for the differential mode data signals that do not decay significantly between the pair of conducting wire and the PHY simultaneously.

2. system according to claim 1, wherein the CMC passes through first capacitor device and the second capacitor AC coupled To the pair of conducting wire, the first capacitor device be coupled in the 7th terminal of the CMC and in the conducting wire described the Between one conducting wire, what second capacitor was coupled in the 8th terminal and the conducting wire of the CMC described second is led Between line.

3. system according to claim 1, wherein the centre cap DC of the auto-transformer is coupled to ground.

4. system according to claim 1, wherein the centre cap AC of the auto-transformer is coupled to ground.

5. system according to claim 1 further includes the centre tapped voltage for being coupled to the auto-transformer Source provides DC current potential for the pair of conducting wire into Power over Ethernet (PoE) network.

6. system according to claim 1, wherein the third terminal of the auto-transformer is via first capacitor device AC is coupled to the first terminal of the PHY, and the forth terminal of the auto-transformer is via the second capacitor AC is coupled to the Second terminal of the PHY.

7. system according to claim 1 further includes the termination circuit for being coupled to the pair of conducting wire, the termination circuit First resistor device-capacitor circuit including the first conducting wire in the conducting wire to be coupled to ground, and will be in the conducting wire Second conducting wire is coupled to the second resistor-capacitor circuit on ground.

8. system according to claim 1, wherein the PHY is coupled to by first capacitor device and the second capacitor AC The pair of conducting wire, the first capacitor device be coupled in series in first conducting wire in the first terminal and the conducting wire it Between, second capacitor is coupled between second conducting wire in the Second terminal and the conducting wire.

9. a kind of communication system, for filtering AC common-mode signal from the couple of conductor for carrying differential data signals, comprising:

First port has two first terminals for being coupled to the transceiver for receiving differential data signals；

Second port has two Second terminals for being coupled to the pair of conducting wire；

Third port with two third terminals for being connected to AC termination circuit；

The common mode choke CMC, the CMC being coupled between the second port and the first port include that there are two poles for tool First transformer of the identical winding of property；With

The differential mode choke coil DMC, DMC being coupled between first port and third port include that there are two opposite polarity windings for tool The second transformer,

Wherein the CMC, which decays, the AC common-mode signal on the pair of conducting wire and substantially makes the differential data signals logical It crosses, and

Wherein the DMC substantially makes to pass through from the pair of conducting wire by the AC common-mode signal of the CMC and by institute It states AC common-mode signal and is applied to the termination circuit to receive the decaying that takes a step forward of the AC common-mode signal in the transceiver The AC common-mode signal.

10. system according to claim 9, wherein the CMC is First CMC, the system also includes with described first CMC series coupled and the second CMC that the First CMC is connected at first node, wherein the DMC is coupled in described Between one node and third port.

11. system according to claim 9, wherein the AC termination circuit includes one be coupled in the third terminal A first capacitor device between reference voltage, and another and the reference voltage that are coupled in the third terminal it Between the second capacitor.

12. system according to claim 9, wherein the AC termination circuit include be coupled in described two third terminals and First capacitor device between reference voltage.

13. system according to claim 9, wherein the AC termination circuit includes be connected to reference voltage described two Third terminal.

14. system according to claim 9 further includes the D/C voltage for being coupled to the pair of conducting wire via DC coupling circuit Source, wherein the DC voltage source also serves as the AC termination circuit.

15. system according to claim 14, wherein the DC coupling circuit include one or more inductors.

16. system according to claim 14, wherein the DC coupling circuit include the DMC, and the D/C voltage It is coupled to the third port.

17. system according to claim 9, wherein the transceiver includes being coupled to described first via AC coupling circuit The PHY of port.

18. system according to claim 17, wherein the AC coupling circuit include and described two first terminals and institute State the concatenated capacitor of PHY.

19. a kind of communication system, for filtering AC common-mode signal from the couple of conductor for carrying differential data, comprising:

Physical link layer equipment PHY, the PHY including the transceiver for differential mode data signals have first terminal and second Terminal；

Transformer, has the armature winding coupled across the first terminal and the Second terminal, and the transformer also has There is the centre cap between the second winding of secondary first winding, secondary second winding and secondary first winding and secondary, wherein The centre cap is grounded by Low ESR；With

Common mode choke CMC has the third terminal for being coupled to secondary first winding, and has and be coupled to described time The forth terminal of the second winding of grade, the CMC also have the 5th terminal and coupling for the first conducting wire being coupled in the conducting wire The 6th terminal of the second conducting wire in the conducting wire is closed,

Wherein the CMC and transformer are significantly decayed the transmission of the common-mode noise between the pair of conducting wire and the PHY, simultaneously The transmission for the differential mode data signals indistinctively decayed between the pair of conducting wire and the PHY.

20. system according to claim 19 further includes the centre tapped voltage source for being coupled to the transformer, DC current potential is provided for the pair of conducting wire into Power over Ethernet (PoE) network.

21. a kind of communication system, comprising:

Physical link layer equipment PHY, the PHY including the transceiver for differential mode data signals have first terminal and second Terminal；

Transformer type balun has the third terminal for being coupled to the first terminal, and has and be coupled to the Second terminal Forth terminal, the balun also has the 5th terminal for being coupled to reference voltage, and has the 6th terminal；

It is coupled to the DC blocking equipment of the 6th terminal；

DC voltage source；

The DC voltage source is coupled to the AC blocking equipment of the DC blocking equipment；With

Coaxial cable has the shielded conductor for being coupled to reference voltage, and there is the center for being coupled to AC blocking equipment to lead Body.

22. system according to claim 21, wherein the DC blocking equipment includes capacitor.

23. system according to claim 21, wherein the AC blocking equipment includes inductor.