(12) United States Patent
`De Nic0l0
`
`US006295356B1
`(10) Patent N0.2
`US 6,295,356 B1
`(45) Date of Patent:
`Sep. 25, 2001
`
`(54) POWER FEED FOR NETWORK DEVICES
`
`(75) Inventor: Maurilio Tazio De Nic0l0; Saratoga;
`CA (Us)
`
`'
`.
`-
`(73) Asslgnee' (35560 Technology’ Inc" San Jose’ CA
`(
`)
`.
`.
`.
`.
`SubJect' to any disclaimer, the term of this
`Pawnt 1S mended 0r adlllsted under 35
`
`.
`( * ) Notice:
`
`U.S.C. 154(b) by 0 days'
`
`(21) APPL NO; 09/562 920
`’
`May 2, 2000
`
`(22) Filed:
`
`5,541,957
`5,574,748
`5,655,077
`5,659,542
`5,671,354
`5,684,950
`5,796,185
`5,799,040
`5,802,042
`578157665
`5,918,016
`
`5,944,824
`5,994,998
`6,011,910
`6,021,496
`6,047,376
`6,092,196
`
`7/1996 Lau .................................... .. 375/258
`11/1996 Vander Mey et al.
`375/204
`8/1997 Jones et a1~ -------- --
`395/187-01
`8/1997 Bell et al. .
`370/496
`9/1997 Ito et al.
`395/187.01
`11/1997 Dare et al.
`395/187.01
`8/1998 Takata e161. .
`307/140
`8/1998 Lau ................ ..
`.. 375/258
`9/1998 Natarajan et al.
`370/255
`9/1998 Teper et aL
`39500059
`6/1999 Brewer et al.
`.. 395/2005
`
`8/1999 He . . . . . . . . . . . . . . . .
`11/1999 Fisher et al. ..
`1/2000 Chau et al.
`2/2000 Dutcher et al
`4/2000 Hosoe ........ ..
`7/2000 Reiche .... ..
`
`. . . . .. 713/201
`340/31001
`395/20059
`713/202
`713/201
`713/200
`
`
`
`.. .... .. 713/300
`
`Related U-SI Application Data
`
`6,134,666
`
`
`
`De NlCOlO 10/2000 De Nicolo
`
`
`
`Continuation of application I\IO~ 26, 1998, now Pat. NO. 6,115,468.
`
`on Mar‘
`
`
`
`
`
`FlSllef et a1. .................. .. * FOREIGN PATENT DOCUMENTS
`
`(51) Int. Cl.7 . . . . .
`
`. . . . . . . . . . . . . . . . . . . . . . . . . . .. H04M 1/00
`
`(52) US. Cl. ........................ .. 379/413; 379/412; 379/324;
`375/257; 375/258; 375/285; 333/177
`(58) Field of Search ......................... ........ .. 379/413, 412,
`379/400’_324’ 90'01’ 3_75/257’_258’ 285’
`370/352’ 356’ 333/177’ 32’ 363/17’ 323/247’
`270
`
`10 1999 WO ........................... .. G06F 15 16
`99 53408
`~
`/
`(
`)
`/
`/
`/
`'
`* clted by exarnlner
`Primary Examiner_w?ham Korzuch
`Assistant Examiner—Vijay B ChaWa
`(74) Attorney, Agent, or Firm—David B. Ritchie; Thelen
`Reid & Priest LLP
`
`(56)
`
`References Cited
`
`(57)
`
`ABSTRACT
`
`U.S. PATENT DOCUMENTS
`370/105
`4/1992 Howson
`Re 33 900
`12/1978 Weinstein """"""""""""""" "'179/1702
`4'131’767
`7/1979 Parikh et
`................... .. 340/147
`471617719
`11/1980 BOatWright et a1_
`__ 179/18
`4:232j199
`8/1983 Howson ,,,,,,,,,,, ,,
`370/105
`4,397,020
`7/1985 Flores et al. ......................... .. 370/85
`4,532,626
`2/1988 Jones et al. .......................... .. 379/93
`4,723,267
`47875223 * 10/1989 Cums ~~~~~~~ ~~
`375/258
`1;;
`gfinc‘lirle et a1‘ '
`"
`10/1991 Kanare et a1. ....................... .. 379/33
`5,056,131
`3/1993 Wilson
`375/1O4
`5 199 049
`572237806 * 6/1993 Curtis all iiii ii
`__ 333/12
`5,285,477
`2/1994 Leonowich ........................... .. 375/36
`5,311,518
`5/1994 Takato et al. ................... .. 370/110.1
`5,321,372 * 6/1994 Smith ..................................... .. 333/1
`
`,
`
`,
`
`in e s ................................ ..
`
`An Ethernet device power transmission system includes an
`input transformer; an output transformer and a pair of
`tWisted pair conductors. The input transformer includes a
`Pair of Primaries for Connection to a Source of Ethernet dam
`The input transformer also includes a pair of secondaries;
`each having a center-tap. A ?rst tWisted pair conductor is
`connected across the ?rst secondary; a second tWisted pair
`conductor is connected across the second secondary and a
`DC-bias is provided betWeen the respective center taps of
`the ?rst and second secondaries. At the local end; the output
`transformer mcludes a ?rst and Second Center tapped pm
`mary and a ?rst and second secondary for connection to the
`load device. The ?rst and second primary center taps are
`Connected to a Power Processor for “traction of DC Power
`
`_
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`U.S. Patent
`
`Sep. 25,2001
`
`Sheet 2 of3
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`US 6,295,356 B1
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`US 6,295,356 B1
`
`1
`POWER FEED FOR NETWORK DEVICES
`
`This application is a continuation of Ser. No. 09/048,922
`?led Mar. 26, 1998 US. Pat. No. 6,115,468.
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention is directed to a method and appa
`ratus Which provide electrical poWer to ethernet-based tele
`phones over an ethernet Wire link.
`2. The Background Art
`Telephones require electrical poWer in order to operate.
`The poWer can be delivered over the telephone lines or via
`a separate poWer connection, typically through a poWer
`transformer connected to the electrical poWer grid. Tele
`phones poWered in the latter fashion Will be inoperable
`during a poWer failure unless provision is made both locally
`at the telephone and at the PBX or local telephone sWitch for
`emergency poWer to be supplied. While it is normal to
`provide an uninterruptible poWer supply to an of?ce’s PBX
`or telephone sWitch, it is not desirable for cost and other
`reasons to provide electrical poWer back up systems to each
`telephone location. In the past, the poWer problem Was
`frequently solved by using an 8-Wire telephone connection
`to the telephone sWitch. With 8 Wires there is more than
`enough capability for analog audio digital and poWer con
`nections to the telephone sWitch.
`The groWth of the Internet and similar local and Wide area
`netWorks based on Ethernet technology has created a poten
`tial market for telephone systems Which Would connect
`directly to existing Ethernet connections. The Ethernet
`protocol, hoWever, does not provide a mechanism for poW
`ering such telephones. A typical Ethernet connection to an
`of?ce location Would include a pair of unshielded tWisted
`pair (UTP) lines for a total of four conductors—one pair for
`transmit, one for receive. The transmit pair is dedicated to
`send packets of data over the Ethernet connection; the
`receive pair receives packets of data over the Ethernet
`connection. Simply placing a DC bias on tWo or more of
`these conductors and using the bias to poWer a local Ethernet
`telephone is risky because the bias is not part of the Ethernet
`protocol and might damage Ethernet compliant equipment
`not designed to handle such a bias.
`Turning to FIGS. 1 and 2, a prior art scheme for providing
`poWer over a single tWisted pair connection is shoWn. In the
`prior art, system 10 and poWer supply 11 provides DC poWer
`over lines 12 (positive lead) and 14 (negative lead) to a
`series of ports on the netWork. Filter capacitor 16 and ?lter
`inductors 18 and 20 are preferably provided to insure a clean
`source of DC poWer and to avoid AC cross-talk betWeen the
`netWork and the poWer supply. Each port 22, 24 and 26 of
`the netWork is coupled to a tWisted pair link 28, 30 and 32,
`respectively, via a transformer, 34, 36, and 38, respectively.
`Transformer 34, for example, operates as folloWs: Data on
`port 1 (22) is applied to the primary 40 of transformer 34 and
`coupled to a pair of secondary Winding 42, 44 of transformer
`34 through transformer core 46 in a conventional manner.
`One end 48 of secondary Winding 42 is connected to tWisted
`pair 28 and the other end 50 of secondary Winding 42 is
`connected to the positive lead 12 of poWer supply 11. One
`end 52 of secondary Winding 44 is connected to tWisted pair
`link 28 and the other end 54 of secondary Winding 44 is
`connected to the negative lead 14 of poWer supply 11. Leads
`50 and 54 are AC-coupled to one another With capacitor 56
`as shoWn. This blocks DC current from ?oWing and alloWs
`a DC bias to be established over the tWo conductors of
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`tWisted pair link 28 While simultaneously alloWing the How
`of data over the link.
`At the telephone end of the tWisted-pair link 28, a
`similarly structured transformer 58 receives the data signal
`as Well as the DC bias. First primary 60 and second primary
`62 are AC-coupled With capacitor 64 so as to be able to
`couple data signals from tWisted-pair link 28 With trans
`former 58 While holding off a DC bias. The DC bias of
`tWisted-pair link 28 is applied to a poWer processor 66 and
`from there provides to local equipment to be poWered by the
`tWisted pair system. A typical embodiment of a poWer
`processor 66 is shoWn in FIG. 2. It comprises a ?lter 68, a
`recti?er 70, a ?lter capacitor 72 and a DC-DC converter 74.
`While ?t for its intended purpose, the above-described
`system has some draWbacks Which make it a less than ideal
`choice for an Ethernet environment. For example, each
`secondary 42 and 44 of transformer 34 and each primary 60
`and 62 of transformer 58 Will experience a net current ?oW
`equal to the total amount of current draWn by the load at the
`distal end of the tWisted-pair link. This current Will affect the
`choice of transformer core siZe at each end of the link and
`Will affect the choice of Wire gauge used for the link.
`It Would be desirable to provide an improved method and
`apparatus for poWering Ethernet telephones over a 4-Wire
`link. Such a system Would be able to take advantage of
`existing Wiring Without the need to reWire the premises to
`install such devices. Furthermore, by providing poWer over
`the Ethernet connection, poWer transformers are not
`required at the device location, and a central uninterruptible
`poWer supply is made possible to provide poWer to the entire
`telephone system in case of a poWer failure.
`
`SUMMARY OF THE INVENTION
`
`An Ethernet device poWer transmission system provides
`electrical poWer to devices such as Ethernet telephones and
`related equipment over a 4-Wire Ethernet connection Without
`any need for reWiring premises having an existing 4-Wire
`Ethernet system. The system eliminates any requirement for
`local poWer such as transformers to poWer such equipment
`as all poWer can be provided over the existing Ethernet
`Wiring. A central uninterruptible poWer supply (UPS) is
`thereby made possible to provide back-up poWer to all such
`equipment. The system includes an input transformer, an
`output transformer and a pair of tWisted pair conductors. The
`input transformer includes a pair of primaries for connection
`to a source of Ethernet data. The input transformer also
`includes a pair of secondaries, each having a center-tap. A
`?rst tWisted pair conductor is connected across the ?rst
`secondary, a second tWisted pair conductor is connected
`across the second secondary and a DC-bias is provided
`betWeen the respective center taps of the ?rst and second
`secondaries. At the local end, the output transformer
`includes a ?rst and second center-tapped primary and a ?rst
`and second secondary for connection to the load device. The
`?rst and second primary center taps are connected to a poWer
`processor for extraction of DC poWer.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an electrical schematic diagram of a prior art
`telephone poWer distribution system for use over a tWo-Wire
`tWisted pair system.
`FIG. 2 is an electrical schematic diagram of a prior art
`telephone poWer extraction system or poWer processor.
`FIG. 3 is an electrical schematic diagram of an Ethernet
`telephone poWer distribution system according to a presently
`preferred embodiment of the present invention.
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`US 6,295,356 B1
`
`3
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`Those of ordinary skill in the art Will realize that the
`following description of the present invention is illustrative
`only and is not intended to be in any Way limiting. Other
`embodiments of the invention Will readily suggest them
`selves to is such skilled persons from an examination of the
`Within disclosure.
`Turning noW to FIG. 3, in accordance With a presently
`preferred embodiment of the present invention, a system
`including a plurality of data ports 80, 82, 84 is provided to
`transmit data on lines 86, 88, 90, 92, 94, 96 to and from load
`devices 1 (98), 2 (100) and 3 (102). Load devices 98, 100
`and 102 may be Ethernet telephones and/or other Ethernet
`devices requiring poWer to be transmitted to them in addi
`tion to data over Ethernet tWisted pair lines.
`Turning to Port 1 (80) as an example, data on lines 88 and
`86 is provided to transmitter 104 and from receiver 106,
`respectively. Transmitter 104 drives tWisted pair 108.
`Receiver 106 receives from tWisted pair 110. First trans
`former 112 includes a ?rst primary 114 and a second primary
`116. First primary 114 is connected to tWisted pair 108 and
`second primary 116 is connected to tWisted pair 110.
`At load 98 a similar arrangement exists. Second trans
`former 118 includes a ?rst secondary 120 and a second
`secondary 122. These are respectively connected to tWisted
`pairs 124 and 126 Which are, in turn, connected through
`receiver 125 and transmitter 127 to load device 98.
`Ethernet link 128 couples ?rst and second secondaries
`130, 132 of ?rst transformer 112 to ?rst and second prima
`ries 134, 136 of second transformer 118. Ethernet link 128
`preferably comprises a pair of tWisted pair conductors 128a
`and 128b Wherein tWisted pair 128a connects ?rst secondary
`130 to ?rst primary 134 of the tWisted pair 128b connects
`second secondary B2 to several primary 136.
`PoWer coupling is provided as folloWs. Secondaries 130
`and 132 of ?rst transformer 112 each include a center tap,
`138, 140 respectively. Center tap 138 is connected to the
`positive lead 142 of a poWer supply 144 and center tap 140
`is connected to the negative lead 146 of poWer supply 144
`Which may preferably be an uninterruptible poWer supply
`(UPS). DC ?ltering components 148a, 148b, 148c may be
`provided as Well knoWn to those of ordinary skill in the art.
`NoW the entire loop of tWisted pair 128a is at the potential
`of positive lead 142 While the entire loop of tWisted pair
`128b is at the potential of negative lead 146. A poWer
`processor 149, as in FIG. 2, may preferably be attached to
`center taps 150, 152, respectively, of ?rst and second pri
`maries 134 and 136 of second transformer 118 so as to
`provide a DC poWer source to poWer processor 149. PoWer
`processor 149 performs any DC-DC poWer conversion and
`?ltering required and provides poWer over leads 154, 156 to
`load 98 Which may be an Ethernet telephone or other device.
`The present invention provides a number of advantages
`over the prior art. First, poWer delivered to the load device
`is split equally over four Wires rather than tWo reducing the
`current carrying requirements of all four Wires over a tWo
`Wire system delivering the same amount of poWer. Second,
`because the transmitted poWer is applied at and removed at
`center taps, there is no net current ?oW due to the DC bias
`through either primary or secondary of each respective
`tWisted pair 128a, 128b. This reduces the siZe requirements
`for the transformer 112, 118 core over a system With a net
`current, as in the system of FIG. 1. This permits off-the-shelf
`transformers for Ethernet applications to be used maintain
`ing compatibility With Ethernet systems not having this
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`poWer delivery requirement. Note that if the prior art system
`of FIG. 1 Were used With a load device lacking decoupling
`betWeen the tWo primaries on the netWork side of the
`transformer, the poWer supply Would be effectively shorted.
`In the system according to FIG. 3, as long as the separate
`data channels are not shorted (Which Would not normally
`occur), any interface can be used on the load side of the
`netWork—Whether it makes use of the poWer available there
`or not.
`Alternative Embodiments
`Although illustrative presently preferred embodiments
`and applications of this invention are shoWn and described
`herein, many variations and modi?cations are possible
`Which remain Within the concept, scope, and spirit of the
`invention, and these variations Would become clear to those
`of skill in the art after perusal of this application. In
`particular, the use of the term primary and secondary in
`referring to transformer Windings herein is for explanation
`only. As the links are bi-directional, the terms primary and
`secondary may be interchanged as Would be knoWn to those
`of ordinary skill in the art. The invention, therefore, is not to
`be limited except in the spirit of the appended claims.
`What is claimed is:
`1. An Ethernet telephone adapted to be supplied With
`electrical poWer over an Ethernet connection from a remote
`source of poWer, said Ethernet telephone comprising:
`a transformer including a ?rst primary With a ?rst center
`tap, a second primary With a second center-tap, a ?rst
`secondary and a second secondary, said ?rst and second
`secondaries for coupling data to an Ethernet telephone,
`said ?rst and second primaries for coupling data to an
`Ethernet telephone, said ?rst and second primaries for
`coupling, respectively, to ?rst and second pairs of
`conductors of the Ethernet connection;
`a ?rst potential input of the Ethernet telephone coupled to
`said ?rst center-tap of said transformer; and
`a second potential input of the Ethernet telephone coupled
`to said second center-tap of said transformer.
`2. An Ethernet telephone according to claim 1, Wherein
`said ?rst pair of conductors is a tWisted pair.
`3. An Ethernet telephone according to claim 2, Wherein
`said second pair of conductors is a tWisted pair.
`4. A remote device supplied With DC electrical poWer
`over a connection from a source of poWer, said device
`comprising:
`a transformer including a ?rst primary With a ?rst center
`tap, a second primary With a second center-tap, a ?rst
`secondary and a second secondary, said ?rst and second
`secondaries for coupling to the remote device, said ?rst
`and second primaries for coupling, respectively, to ?rst
`and second pairs of conductors of the connection;
`a ?rst potential input of the remote device coupled to said
`?rst center-tap of said transformer; and
`a second potential input of the remote device coupled to
`said second center-tap of said transformer.
`5. A device according to claim 4, Wherein said ?rst pair of
`conductors is a tWisted pair.
`6. Adevice according to claim 5, Wherein said second pair
`of conductors is a tWisted pair.
`7. A device for transceiving data and a DC signal simul
`taneously over a connection from a remote source of poWer,
`said device comprising:
`a transformer including a ?rst primary With a ?rst center
`tap, a second primary With a second center-tap, a ?rst
`secondary and a second secondary, said ?rst secondary
`for coupling to a ?rst pair of conductors over Which a
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`US 6,295,356 B1
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`5
`?rst data signal is to be communicated With the device,
`and said second secondary for coupling to a second pair
`of conductors over Which a second data signal is to be
`communicated With the device;
`a ?rst potential input of the device coupled to said ?rst
`center-tap of said transformer; and
`a second potential input of the device coupled to said
`second center-tap of said transformer.
`8. A method for supplying a DC poWer connection and a
`bi-directional data connection to a device, said bi-directional
`data connection including a ?rst data signal and a second
`data signal, said method comprising:
`transmitting the ?rst data signal to a ?rst primary Winding
`of a transformer;
`transmitting the second data signal from a second primary
`Winding of said transformer;
`transmitting the ?rst data signal to the device over a ?rst
`secondary Winding of said transformer;
`receiving the second data signal from the device over a
`second secondary Winding of said transformer;
`extracting a DC signal from a center-tap of said ?rst
`primary Winding of said transformer and a center-tap of
`said second primary Winding of said transformer; and
`applying said extracted DC signal to the device.
`9. A poWer feed system for supplying poWer to Ethernet
`telephones, said system comprising:
`a ?rst and a second center-tapped Winding disposed in a
`transformer, each said Winding having a ?rst conductor,
`a second conductor and a center-tap conductor, said
`?rst and second conductors adopted for connection to
`an Ethernet telecommunications link;
`a third and fourth Winding disposed in said transformer,
`each said Winding having a ?rst conductor and a second
`conductor, said ?rst and second conductors adapted to
`couple a data signal to the Ethernet telephone; and
`means for extracting a poWer signal from said ?rst center
`tap conductor and said second center-tap conductor of
`said transformer and for applying said extracted poWer
`signal to the Ethernet telephone.
`10. Asystem for supplying DC poWer to a remote device,
`said system comprising:
`a ?rst and second center-tapped Winding disposed in a
`transformer, each said Winding having a ?rst conductor,
`a second conductor and a center-tap conductor;
`a third and fourth Winding disposed in said transformer,
`each said Winding having a ?rst conductor and a second
`conductor;
`?rst coupling means for coupling ?rst and second pairs of
`conductors, respectively, of the remote device to said
`third and fourth Windings of said transformer;
`means for extracting a poWer signal from said ?rst center
`tap conductor and said second center-tap conductor of
`said transformer and for applying said extracted poWer
`signal to the remote device.
`11. A method for supplying DC poWer to a remote device
`over an Ethernet connection having a ?rst tWisted pair of
`conductors for transmission of data packets from said
`remote device and a second tWisted pair of conductors for
`reception of data packets at said remote device, the method
`comprising:
`extracting a ?rst level of the DC poWer from a center tap
`of a ?rst transformer Winding coupled across a proxi
`mal end of the ?rst tWisted pair of conductors; and
`extracting a second level of the DC poWer from a center
`tap of a second transformer Winding coupled across a
`proximal end of the second tWisted pair of conductors.
`
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`12. A system for supplying DC poWer to a remote device
`over an Ethernet connection having a ?rst tWisted pair of
`conductors for transmission of data packets from said
`remote device and a second tWisted pair of conductors for
`5 reception of data packets at said remote device, the system
`comprising:
`means for extracting a ?rst DC poWer level from a
`center-tap of a ?rst transformer Winding coupled across
`a proximal end of the ?rst tWisted pair of conductors;
`and
`means for extracting a second DC poWer level from a
`center tap of a second transformer Winding coupled
`across a proximal end of the second tWisted pair of
`conductors.
`13. A system according to claim 12 further comprising an
`uninterruptible poWer supply for sourcing the DC poWer.
`14. A poWer feed system for Ethernet telephones, said
`system comprising:
`a ?rst transformer including a ?rst primary, a second
`primary, a ?rst secondary With a ?rst center-tap and a
`second secondary With a second center-tap, said ?rst
`primary for coupling to a ?rst pair of conductors, said
`second primary for coupling to a second pair of con
`ductors; and
`a direct current poWer supply having a ?rst output poten
`tial on a ?rst line and a second output potential different
`from said ?rst output potential on a second line, said
`?rst line coupled to said ?rst center-tap of said ?rst
`transformer and said second line coupled to said second
`center-tap of said ?rst transformer.
`15. A poWer feed system for Ethernet telephones accord
`ing to claim 14, Wherein said ?rst pair of conductors is a
`tWisted pair.
`16. A poWer feed system for Ethernet telephones accord
`ing to claim 15, Wherein said second pair of conductors is a
`tWisted pair.
`17. A system for supplying DC poWer to a remote device,
`said system comprising:
`a ?rst transformer including a ?rst primary, a second
`primary, a ?rst secondary With a ?rst center-tap and a
`second secondary With a second center-tap, said ?rst
`primary for coupling to a ?rst pair of conductors, said
`second primary for coupling to a second pair of con
`ductors; and
`a direct current poWer supply having a ?rst output poten
`tial on a ?rst line and a second output potential different
`from said ?rst output potential on a second line, said
`?rst line coupled to said ?rst center-tap of said ?rst
`transformer and said second line coupled to said second
`center tap of said ?rst transformer.
`18. A system according to claim 17, Wherein said ?rst pair
`of conductors is a tWisted pair.
`19. A system according to claim 18, Wherein said second
`pair of conductors is a tWisted pair.
`20. A system for transmitting data and a DC signal
`simultaneously from a ?rst device, said system comprising:
`a ?rst transformer including a ?rst primary, a second
`primary, a ?rst secondary With a ?rst center-tap and a
`second secondary With a second center-tap, said ?rst
`primary for coupling to a ?rst pair of conductors over
`Which a ?rst data signal is to be communicated With the
`?rst device, said second primary for coupling to a
`second pair of conductors over Which a second data
`signal is to be communicated With the ?rst device; and
`a direct current poWer supply associated With the ?rst
`device having a ?rst output potential on a ?rst line and
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`a second output potential different from said ?rst output
`potential on a second line, said ?rst line coupled to said
`?rst center-tap of said ?rst transformer and said second
`line coupled to said second center-tap of said ?rst
`transformer.
`21. A method for supplying a DC poWer connection and
`a bi-directional data connection to a remote device, said
`bi-directional data connection including a ?rst data signal
`and a second data signal, said method comprising:
`transmitting the ?rst data signal to a ?rst primary Winding
`of a ?rst transformer;
`receiving the second data signal from a second primary
`Winding of said ?rst transformer;
`transmitting the ?rst data signal from a ?rst secondary
`Winding of said ?rst transformer to a ?rst terminal;
`receiving the second data signal from a second terminal;
`and
`applying a DC signal betWeen a center-tap of said ?rst
`secondary Winding of said ?rst transformer and a
`center-tap of said second secondary Winding of said
`?rst transformer.
`22. A poWer feed system for Ethernet telephones, said
`system comprising:
`?rst coupling means for coupling a ?rst conductor of a
`?rst pair of conductors to a ?rst Winding of a ?rst
`transformer;
`second coupling means for coupling a second conductor
`of said ?rst pair of conductors to a second Winding of
`said ?rst transformer;
`a ?rst and second center-tapped Winding disposed in said
`?rst transformer, each said Winding having a ?rst
`conductor, a second conductor and a center-tap con
`ductor; and
`means for applying a poWer signal to said ?rst center tap
`conductor and said second center-tap conductor of said
`?rst transformer.
`23. Asystem for supplying DC poWer to a remote device,
`said system comprising:
`?rst coupling means for coupling a ?rst conductor of a
`?rst pair of conductors to a ?rst Winding of a ?rst
`transformer;
`second coupling means for coupling a second conductor
`of said ?rst pair of conductors to a second Winding of
`said ?rst transformer;
`a ?rst and second center-tapped Winding disposed in said
`?rst transformer, each said Winding having a ?rst
`conductor, a second conductor and a center-tap con
`ductor; and
`means for applying a poWer signal to said ?rst center
`tapped conductor and said second center-tapped con
`ductor of said ?rst transformer.
`24. Amethod for supplying DC poWer to a remote device
`over an Ethernet connection having a ?rst tWisted pair of
`conductors for transmission of data packets from said
`remote device and a second tWisted pair of conductors for
`reception of data packets at said remote device, the method
`comprising:
`applying a ?rst voltage level of the DC poWer to a center
`tap of a ?rst transformer Winding connected across a
`distal end of the ?rst tWisted pair of conductors;
`applying a second voltage level of the DC poWer to a
`center tap of a second transformer Winding connected
`across a distal end of the second tWisted pair of
`conductors, said record voltage level being different
`from said ?rst voltage level;
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`extracting said ?rst voltage level from a center tap of a
`third transformer Winding coupled across a proximal
`end of the ?rst tWisted pair of conductors; and
`extracting said second voltage level from a center tap of
`a fourth transformer Winding coupled across a proximal
`end of the second tWisted pair of conductors.
`25. A system for supplying DC poWer to a remote device
`over an Ethernet connection having a ?rst tWisted pair of
`conductors for transmission of data packets from said
`remote device and a second tWisted pair of conductors for
`receptions of data packets at said remote device, the system
`comprising:
`means for applying a ?rst voltage level of the DC poWer
`to a center tap of a ?rst transformer Winding connected
`across a distal end of the ?rst tWisted pair of conduc
`tors;
`means for applying a second voltage level of the DC
`poWer to a center tap of a second transformer Winding
`connected across a distal end of the second tWisted pair
`of conductors, said second voltage level being different
`from said ?rst voltage level;
`means for extracting said ?rst voltage level from a center
`tap of a third transformer Winding coupled across a
`proximal end of the ?rst tWisted pair of conductors; and
`means for extracting said second voltage level from a
`center tap of a fourth transformer Winding coupled
`across a proximal end of the second tWisted pair of
`conductors.
`26. A system according to claim 25 further comprising an
`uninterruptible poWer supply for sourcing the DC poWer.
`27. Amethod for supplying DC poWer to a remote device
`over an Ehernet connection having a ?rst tWisted pair of
`conductors for transmission of data packets from said
`remote device and a second tWisted pair of conductors for
`reception of data packets at said remote device, the method
`comprising:
`applying a ?rst voltage level of the DC poWer to a center
`tap of a ?rst transformer Winding coupled across a
`distal end of the ?rst tWisted pair of conductors;
`applying a second voltage level of the DC poWer to a
`center tap of a second transformer Winding coupled
`across a distal end of the second tWisted pair of
`conductors, said record voltage level being different
`from said ?rst voltage level.
`28. A system for supplying DC poWer to a remote device
`over an Ethernet connection having a ?rst tWisted pair of
`conductors for transmission of data packets from said
`remote device and a second tWisted pair of conductors for
`reception of data packets at a said remote device, the system
`comprising:
`means for applying a ?rst voltage level of the DC poWer
`to a center tap of a ?rst transformer Winding coupled
`across a distal end of the ?rst tWisted pair of conduc
`tors; and
`means for applying a second voltage level of the DC
`poWer to a center tap of a second transformer Winding
`coupled across a distal end of the second tWisted pair of
`conductors, said second voltage level being different
`from said ?rst voltage level.
`29. A system according to claim 28 further comprising an
`uninterruptible poWer supply for sourcing the DC poWer.
`30. ApoWer feed system for netWork devices, said system
`comprising:
`a ?rst primary transformer Winding, a second primary
`transformer Winding, a ?rst secondary transformer
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`IPR2016-01397
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`US 6,295,356 B1
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`Winding With a ?rst center-tap and a second secondary
`transformer Winding With a second center-tap, said ?rst
`primary transformer Winding for coupling to a ?rst pair
`of conductors, said second primary transformer Wind
`ing for coupling to a second pair of conductors;
`a third primary transform