Apparatus for transmitting and/or receiving data at different data transfer rates especially in applications such as dual-rate ethernet local-area networks

• US 5,541,957 A
• Filed: 06/15/1994
• Issued: 07/30/1996
• Est. Priority Date: 06/15/1994
• Status: Expired due to Term

• Current Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Original Assignee: National Semiconductor Corporation (Texas Instruments, Inc.)
• Inventors: Lau, Hung-Wah A.
• Primary Examiner(s): Chin, Stephen
• Assistant Examiner(s): GHEBRETINSAE, TEMESGHEN
• Application Number:
  US08/260,150
• Time in Patent Office: 776 Days
• Field of Search: 375/258, 375/257, 370/84, 370/85.3, 333/100, 333/119, 333/126, 333/131
• US Class Current: 375/258
• CPC Class Codes: H04L 12/40136 Nodes adapting their rate to the physical link properties LAN switches H04L49/351
• CPC Class Codes: H04L 12/44 Star or tree networks
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A data-transmitting apparatus contains first and second transmitters, a transmit transformer, and a connecting unit for coupling the transformer to an outgoing twisted-pair cable. The first transmitter filters data to produce outgoing data transmitted to the transformer at a first data rate. The second transmitter transmits outgoing data to the transformer at a different, typically greater, second data rate. A data-receiving apparatus contains first and second receivers, a receive transformer, and a connecting unit for coupling an incoming twisted-pair cable to the receive transformer. The first and second receivers receive incoming data from the secondary winding respectively at the first and second data rates. Incoming data is typically provided along data transfer paths that extend from the receive transformer in a daisy chain manner to the receivers. Data moving at either data rate can be transmitted and received without the need for hot switching in the data paths. Optical cables, including an optical transceiver, can be used with, or in place of, the twisted-pair cables.

Claims

1. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate, the first transmitter containing a digital waveshaper that at least partially provides the low-pass filtering in the first transmitter; and

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate greater than the first data rate.

2. Apparatus as in claim 1 further including a transmit filter that low-pass filters outgoing data from the second transmitter at a frequency bandwidth greater than that of the first transmitter.

3. Apparatus as in claim 2 wherein the transformer is electronically coupled through the transmit filter to the connecting unit.

4. Apparatus as in claim 1 wherein:

outgoing data at the first data rate has a first characteristic data rate frequency; and

outgoing data at the second data rate has a second characteristic data rate frequency greater than the first characteristic data rate frequency.

5. Apparatus as in claim 4 wherein:

the first transmitter has a low-pass cut-off frequency in the range extending between the characteristic data rate frequencies; and

the apparatus includes a transmit filter that low-pass filters outgoing data from the second transmitter, the transmit filter having a low-pass cut-off frequency greater than or equal to the second characteristic data rate frequency.

6. Apparatus as in claim 1 further including a pair of first impedance elements, outgoing data from the first transmitter being transmitted differentially through the first impedance elements respectively to a pair of first electrical conductors coupled to the primary winding.

7. Apparatus as in claim 6 further including a pair of second impedance elements, outgoing data from the second transmitter being transmitted differentially on a pair of second electrical conductors coupled to the primary winding, each second impedance element coupled between a source of a common reference voltage and a corresponding one of the second electrical conductors.

8. Apparatus as in claim 7 wherein each impedance element comprises a resistor.

9. Apparatus as in claim 7 further including rate circuitry that determines whether outgoing data is to be transmitted at the first data rate or at the second data rate and generates a corresponding data rate signal.

10. Apparatus as in claim 9 further including a pair of switches respectively corresponding to the second impedance elements, each switch coupled in series with the corresponding second impedance element between the source of the common reference voltage and the corresponding second electrical conductor, the switches opening when the data rate signal indicates that outgoing data is to be transmitted at the first data rate and closing when the data rate signal indicates that outgoing data is to be transmitted at the second data rate.

11. Apparatus as in claim 1 further including a common-mode choke through which the secondary winding is electronically coupled to the connecting unit.

12. Apparatus as in claim 1 further including:

a first transmit state machine that performs state functions on digital data to produce data supplied at the first data rate to the first transmitter;

a second transmit state machine that performs state functions on digital data to produce data supplied at the second data rate to the second transmitter; and

selection circuitry that selectively passes digital data either to the first state machine or to the second state machine.

13. Apparatus as in claim 1 further including:

a further isolation transformer having a further primary winding and a further secondary winding, the connecting unit being electronically coupled to the further primary winding and connectable to a pair of lines of a further twisted-pair cable so as to electronically couple the further twisted-pair cable to the further primary winding;

a first receiver that differentially receives incoming data from the further secondary winding largely at the first data rate; and

a second receiver that differentially receives incoming data from the further secondary winding largely at the second data rate.

14. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the primary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the primary winding;

a first receiver that differentially receives incoming data from the secondary winding largely at a first data transfer rate; and

a second receiver that differentially receives incoming data from the secondary winding largely at a second data transfer rate greater than the first data rate, incoming data from the secondary winding being provided along data transfer paths that extend from the secondary winding through where one of the receivers physically receives incoming data to where the other of the receivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation, incoming data from the secondary winding being provided differentially during normal apparatus operation on a pair of electrical conductors non-interruptibly coupled to both receivers and to the secondary winding.

15. Apparatus as in claim 14 further including a terminating network at which the electrical conductors are terminated and through which incoming data from the secondary winding is supplied to a specified one of the receivers.

16. Apparatus as in claim 15 wherein the terminating network comprises:

a pair of first impedance elements, each coupled between (a) a corresponding one of the electrical conductors and (b) a corresponding one of a pair of nodes coupled to the specified receiver; and

a pair of second impedance elements, each coupled between (a) a corresponding one of the nodes and (b) a source of a common reference voltage so that the second impedance elements respectively form a pair of voltage dividers with the first impedance elements.

17. Apparatus as in claim 16 wherein each impedance element comprises a resistor.

18. Apparatus in claim 15 wherein the electrical conductors are capacitively coupled to the remaining one of the receivers.

19. Apparatus as in claim 18 wherein the specified and remaining receivers respectively are the second and first receivers.

20. Apparatus as in claim 14 further including at least one of a receive filter and a common-mode choke through which the secondary winding is non-interruptibly coupled to the pair of electrical conductors.

21. Apparatus as in claim 14 further including:

a first receive state machine that performs state functions on data received from the first receiver at the first data rate to produce further data;

a second receive state machine that performs state functions on data received from the second receiver at the second data rate to produce further data; and

selection circuitry that selectively passes further data either from the first state machine or from the second state machine.

22. Apparatus as in claim 14 further including:

a further isolation transformer having a further primary winding and a further secondary winding, the connecting unit being electronically coupled to the further secondary winding and connectable to a pair of lines of a further twisted-pair cable so as to electronically couple the further twisted-pair cable to the further secondary winding;

a first transmitter that differentially transmits outgoing data to the further primary winding largely at the first data rate; and

a second transmitter that differentially transmits outgoing data to the further primary winding largely at the second data rate.

23. Electronic apparatus comprising:

a transmit isolation transformer having a primary winding and a secondary winding;

a receive isolation transformer having a primary winding and a secondary winding;

a connecting unit (a) electronically coupled to the secondary winding of the transmit transformer and connectable to a pair of lines of an outgoing twisted-pair cable so as to electronically couple the outgoing cable to the transmit transformer and (b) electronically coupled to the primary winding of the receive transformer and connectable to a pair of lines of an incoming twisted-pair cable so as to electronically couple the incoming cable to the receive transformer;

a first transceiver that (a) low-pass filters digital data to produce outgoing data which the first transceiver differentially transmits to the primary winding of the transmit transformer largely at a first data transfer rate and (b) differentially receives incoming data from the secondary winding of the receive transformer largely at the first data rate; and

a second transceiver that (a) differentially transmits outgoing data to the primary winding of the transmit transformer largely at a second data transfer rate different from the first data rate and (b) differentially receives incoming data from the secondary winding of the receive transformer largely at the second data rate, incoming data from the secondary winding of the receive transformer being provided along data transfer paths that extend from the secondary winding of the receive transformer through where one of the transceivers physically receives incoming data to where the other of the transceivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation.

24. Apparatus as in claim 23 wherein the second data rate is greater than the first data rate.

25. Apparatus as in claim 24 further including a transmit filter that low-pass filters outgoing data from the second transceiver at a frequency bandwidth greater than that of the first transceiver.

26. Apparatus as in claim 25 wherein the transmit transformer is electronically coupled through the transmit filter to the connecting unit.

27. Apparatus as in claim 24 further including:

a pair of first impedance elements, output data from the first transceiver being transmitted differentially through the first impedance elements respectively to a pair of first electrical conductors coupled to the primary winding of the transmit transformer; and

a pair of second impedance elements, output data from the second transceiver being transmitted differentially on a pair of second electrical conductors coupled to the primary winding of the transmit transformer, each second impedance element coupled between a source of a common reference voltage and a corresponding one of the second electrical conductors.

28. Apparatus as in claim 27 further including rate circuitry that determines whether outgoing or incoming data is to be transferred at the first data rate or at the second data rate and generates a corresponding data rate signal.

29. Apparatus as in claim 28 further including a pair of switches respectively corresponding to the second impedance elements, each switch coupled in series with the corresponding second impedance element between the source of the common reference voltage and the corresponding second electrical conductor, the switches opening when the data rate signal indicates that output data is to be transferred at the first data rate and closing when the data rate signal indicates that output data is to be transferred at the second data rate.

30. Apparatus as in claim 27 wherein incoming data from the secondary winding of the receive transformer is provided differentially during normal apparatus operation on a pair of third electrical conductors non-interruptibly coupled to both transceivers and to the secondary winding of the receive transformer.

31. Apparatus as in claim 23 further including:

a first state machine coupled to the first transceiver;

a second state machine coupled to the second transceiver; and

a multiplexer coupled to the state machines.

32. Apparatus as in claim 23 further including an optical transceiver coupled to the twisted-pair cables and to at least one optical cable.

33. Apparatus as in claim 23 wherein the apparatus meets the standards of IEEE Specification 802.3.

34. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding substantially in accordance with the 10 Base-T protocol, the first transmitter containing a digital waveshaper that at least partially provides the low-pass filtering in the first transmitter; and

a second transmitter that differentially transmits outgoing data to the primary winding substantially in accordance with the 100 Base-TX protocol.

35. Apparatus as in claim 34 further including a transmit filter that low-pass filters outgoing data from the second transmitter at a frequency bandwidth greater than that of the first transmitter.

36. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the primary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the primary winding;

a first receiver that differentially receives incoming data from the secondary winding substantially in accordance with the 10 Base-T protocol; and

a second receiver that differentially receives incoming data from the secondary winding substantially in accordance with the 100 Base-TX protocol, incoming data from the secondary winding being provided during normal apparatus operation along data transfer paths that extend from the secondary winding through where one of the receivers physically receives incoming data to where the other of the receivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation, incoming data from the secondary winding being provided differentially during normal apparatus operation on a pair of electrical conductors non-interruptibly coupled to both receivers and to the secondary winding.

37. Apparatus as in claim 36 further including a terminating network at which the electrical conductors are terminated and through which incoming data from the secondary winding is supplied to a specified one of the receivers.

38. Electronic apparatus comprising:

a transmit isolation transformer having a primary winding and a secondary winding;

a receive isolation transformer having a primary winding and a secondary winding;

a connecting unit (a) electronically coupled to the secondary winding at the transmit transformer and connectable to a pair of lines of an outgoing twisted-pair cable so as to electronically couple the outgoing cable to the transmit transformer and (b) electronically coupled to the primary winding of the receive transformer and connectable to a pair of lines of an incoming twisted-pair cable so as to electronically couple the incoming cable to the receive transformer;

a first transceiver that (a) low-pass filters digital data to produce outgoing data which the first transceiver differentially transmits to the primary winding of the transmit transformer substantially in accordance with the 10 Base-T protocol and (b) differentially receives incoming data from the secondary winding of the receive transformer substantially in accordance with the 10 Base-T protocol; and

a second transceiver that (a) differentially transmits outgoing data to the primary winding of the transmit transformer substantially in accordance with the 100 Base-TX protocol and (b) differentially receives incoming data from the secondary winding of the receive transformer substantially in accordance with the 100 Base-TX protocols, incoming data from the secondary winding of the receiving transformer being provided along data transfer paths that extend from the secondary winding of the receive transformer through where one of the transceivers physically receives incoming data to where the other of the transceivers physically receives incoming data.

39. Apparatus as in claim 38 further including a transmit filter that low-pass filters outgoing data from the second transceiver at a frequency bandwidth greater than that of the first transceiver.

40. Electronic apparatus comprising:

a transmit isolation transformer having a primary winding and a secondary winding;

a receive isolation transformer having a primary winding and a secondary winding;

a first transceiver that (a) low-pass filters digital data to produce outgoing data which the first transceiver differentially transmits to the primary winding of the transmit transformer largely at a first data transfer rate and (b) differentially receives incoming data from the secondary winding of the receive transformer largely at the first data rate;

a second transceiver that (a) differentially transmits outgoing data to the primary winding of the transmit transformer largely at a second data transfer rate different from the first data rate and (b) differentially receives incoming data from the secondary winding of the receive transformer largely at the second data rate, incoming data from the secondary winding of the receive transformer being provided along data transfer paths that extend from the secondary winding of the receive transformer through where one of the transceivers physically receives incoming data to where the other of the transceivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation; and

an optical transceiver connectable to at least one optical cable and electronically coupled to (a) the secondary winding of the transmit transformer and (b) the primary winding of the receive transformer.

41. Apparatus as in claim 40 wherein the second data rate is greater than the first data rate.

42. Electronic apparatus comprising:

a transmit isolation transformer having a primary winding and a secondary winding;

a receive isolation transformer having a primary winding and a secondary winding;

means for (a) providing outgoing data from the secondary winding of the transmit transformer to cable means and (b) for providing incoming data from the cable means to the primary winding of the receive transformer;

a first transceiver that (a) low-pass filters digital data to produce outgoing data which the first transceiver differentially transmits to the primary winding of the transmit transformer largely at a first data transfer rate and (b) differentially receives incoming data from the secondary winding of the receive transformer largely at the first data rate; and

a second transceiver that (a) differentially transmits outgoing data to the primary winding of the transmit transformer largely at a second data transfer rate different from the first data rate and (b) differentially receives incoming data from the secondary winding of the receive transformer largely at the second data rate, incoming data from the secondary winding of the receive transformer being provided along data transfer paths that extend from the secondary winding of the receive transformer through where one of the transceivers physically receives incoming data to where the other of the transceivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation.

43. Apparatus as in claim 42 wherein the second data rate is greater than the first data rate.

44. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate;

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate grater than the first data rate; and

a transmit filter that low-pass filters outgoing data from the second transmitter at a frequency bandwidth greater than that of the first transmitter, the transformer being electronically coupled through the transmit filter to the connecting unit.

45. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate;

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate greater than the first data rate; and

a transmit filter that low-pass filters outgoing data from the second transmitter, where (a) outgoing data at the first data rate has a first characteristic data rate frequency, (b) outgoing data at the second data rate has a second characteristic data rate frequency greater than the first characteristic data rate frequency, (c) the first transmitter has a low-pass cut-off frequency in the range extending between the first and second characteristic data rate frequencies, and (d) the transmit filter has a low-pass cut-off frequency greater than or equal to the second characteristic data rate frequency.

46. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate;

a pair of first impedance elements, outgoing data from the first transmitter being transmitted differentially through the first impedance elements respectively to a pair of first electrical conductors coupled to the primary winding; and

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate greater than the first data rate.

47. Apparatus as in claim 46 further including a pair of second impedance elements, outgoing data from the second transmitter being transmitted differentially on a pair of second electrical conductors coupled to the primary winding, each second impedance element coupled between a source of a common reference voltage and a corresponding one of the second electrical conductors.

48. Apparatus as in claim 47 wherein each impedance element comprises a resistor.

49. Apparatus as in claim 48 further including rate circuitry that determines whether outgoing data is to be transmitted at the first data rate or at the second data rate and generates a corresponding data rate signal.

50. Apparatus as in claim 49 further including a pair of switches respectively corresponding to the second impedance elements, each switch coupled in series with the corresponding second impedance element between the source of the common reference voltage and the corresponding second electrical conductor, the switches opening when the data rate signal indicates that outgoing data is to be transmitted at the first data rate and closing when the data rate signal indicates that outgoing data is to be transmitted at the second data rate.

51. Apparatus as in claim 46 further including a transmit filter that low-pass filters outgoing data from the second transmitter at a frequency bandwidth greater than that of the first transmitter.

52. Apparatus as in claim 51 wherein the transformer is electronically coupled through the transmit filter to the connecting unit.

53. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a common-mode choke through which the secondary winding is electronically coupled to the connecting unit;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate; and

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate greater than the first data rate.

54. Apparatus as in claim 53 further including a transmit filter that low-pass filters outgoing data from the second transmitter at a frequency bandwidth greater than that of the first transmitter.

55. Apparatus as in claim 54 wherein the transformer is electronically coupled through the transmit filter to the connecting unit.

56. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate;

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate greater than the first data rate;

a first transmit state machine that performs state functions on digital data to produce data supplied at the first data rate to the first transmitter;

a second transmit state machine that performs state functions on digital data to produce data supplied at the second data rate to the second transmitter; and

selection circuitry that selectively passes digital data either to the first state machine or to the second state machine.

57. Apparatus as in claim 56 further including a transmit filter that low-pass filters outgoing data from the second transmitter at a frequency bandwidth greater than that of the first transmitter.

58. Apparatus as in claim 57 wherein the transformer is electronically coupled through the transmit filter to the connecting unit.

59. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the secondary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the secondary winding;

a first transmitter that low-pass filters digital data to produce outgoing data which the first transmitter differentially transmits to the primary winding largely at a first data transfer rate;

a second transmitter that differentially transmits outgoing data to the primary winding largely at a second data transfer rate greater than the first data rate;

a further isolation transformer having a further primary winding and a further secondary winding, the connecting unit being electronically coupled to the further primary winding and connectable to a pair of lines of a further twisted-pair cable so as to electronically couple the further twisted-pair cable to the further primary winding;

a first receiver that differentially receives incoming data from the further secondary winding largely at the first data rate; and

a second receiver that differentially receives incoming data from the further secondary winding largely at the second data rate.

60. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the primary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the primary winding;

a first receiver that differentially receives incoming data from the secondary winding largely at a first data transfer rate;

a second receiver that differentially receives incoming data from the secondary winding largely at a second data transfer rate greater than the first data rate, incoming data from the secondary winding being provided along data transfer paths that extend from the secondary winding through where one of the receivers physically receives incoming data to where the other of the receivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation;

a first receive state machine that performs state functions on data received from the first receiver at the first data rate to produce further data;

a second receive state machine that performs state functions on data received from the second receiver at the second data rate to produce further data; and

selection circuitry that selectively passes further data either from the first state machine or from the second state machine.

61. Electronic apparatus comprising:

an isolation transformer having a primary winding and a secondary winding;

a connecting unit electronically coupled to the primary winding and connectable to a pair of lines of a twisted-pair cable so as to electronically couple the twisted-pair cable to the primary winding;

a first receiver that differentially receives incoming data from the secondary winding largely at a first data transfer rate;

a second receiver that differentially receives incoming data from the secondary winding largely at a second data transfer rate greater than the first data rate, incoming data from the secondary winding being provided along data transfer paths that extend from the secondary winding through where one of the receivers physically receives incoming data to where the other of the receivers physically receives incoming data, the data transfer paths having a characteristic impedance that is largely constant during normal apparatus operation;

a further isolation transformer having a further primary winding and a further secondary winding, the connecting unit being electronically coupled to the further secondary winding and connectable to a pair of lines of a further twisted-pair cable so as to electronically couple the further twisted-pair cable to the further secondary winding;

a first transmitter that differentially transmits outgoing data to the further primary winding largely at the first data rate; and

a second transmitter that differentially transmits outgoing data to the further primary winding largely at the second data rate.