Direct digital access arrangement circuitry and method for connecting to phone lines

• US 7,283,584 B2
• Filed: 02/17/2004
• Issued: 10/16/2007
• Est. Priority Date: 04/22/1997
• Status: Expired due to Fees

• Current Assignee: Silicon Laboratories Incorporated
• Original Assignee: Silicon Laboratories Incorporated
• Inventors: Scott, Jeffrey W., Welland, David R., Sooch, Navdeep S.
• Primary Examiner(s): PHU, PHUONG M
• Application Number:
  US10/780,142
• Publication Number:
  US 20040161023A1
• Time in Patent Office: 1,337 Days
• Field of Search: 375/220, 375/222, 375/285, 375/219, 375/257, 375/259, 375/359, 379/399.02, 379/412, 379/413
• US Class Current: 375/220
• CPC Class Codes: H04L 25/0266 Arrangements for providing Galvanic isolation, e.g. by means of magnetic or capacitive coupling
• CPC Class Codes: H04L 25/06 Dc level restoring means; Bias distortion correction ; Decision circuits providing symbol by symbol detection
• CPC Class Codes: H04L 7/033 using the transitions of the received signal to control the phase of the synchronising-signal-generating means, e.g. using a phase-locked loop
• CPC Class Codes: H04M 1/573 Line monitoring circuits for detecting caller identification
• CPC Class Codes: H04M 1/76 Compensating for differences in line impedance
• CPC Class Codes: H04M 11/06 Simultaneous speech and data transmission, e.g. telegraphic transmission over the same conductors
• CPC Class Codes: H04M 19/001 Current supply source at the exchanger providing current to substations
• CPC Class Codes: H04M 19/02 providing ringing current or supervisory tones, e.g. dialling tone or busy tone
• CPC Class Codes: H04M 3/007 Access interface units for simultaneous transmission of speech and data, e.g. digital subscriber line [DSL] access interface units DSL access multiplexers H04Q11/0478, and H04L12/2856

Abstract

An isolation system is provided that is suitable for use in telephony, medical instrumentation, industrial process control and other applications. Preferred embodiments of the invention comprise a capacitive isolation barrier across which a digital signal is communicated. The system provides a means of communication across the isolation barrier that is highly immune to amplitude and phase noise interference. Clock recovery circuitry may be employed on one side of the isolation barrier to extract timing information from the digital signal communicated across the barrier, and to filter the effects of phase noise introduced at the barrier. Delta-sigma converters may be disposed on both sides of the isolation barrier to convert signals between analog and digital domains. An isolated power supply may also be provided on the isolated side of the barrier, whereby direct current is generated in response to the digital data received across the isolation barrier. Finally, a bidirectional isolation system is provided whereby bidirectional communication of digital signals is accomplished using a single pair of isolation capacitors. In preferred embodiments, the digital data communicated across the barrier consists of digital delta-sigma data signals multiplexed in time with other digital control, signaling and framing information.

Claims

1. Powered side circuitry for digital direct access arrangement circuitry for terminating a phone line connection at a user end of a phone line, comprising:

a communication interface capable of being coupled to an external user end device;

an isolation interface capable of communicating digitally with user end phone line side circuitry through a user end isolation barrier that comprises a plurality of isolation elements; and

encode circuitry within said isolation interface to generate an encoded digital differential signal from a digital data stream for transmission across at least two of the isolation elements of said isolation barrier, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, and the isolation interface being capable of communicating bi-directionally across said first and second isolation capacitors of said isolation barrier;

wherein said encoded digital differential signal comprises control data added to said digital data stream and wherein said encoded digital differential signal comprises framing data added to said digital data stream for data synchronization within said phone line side circuitry;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements; and

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards.

2. The powered side circuitry of claim 1, wherein the powered side circuitry is further configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor.

3. The powered side circuitry of claim 1, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

4. The powered side circuitry of claim 1, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

5. Powered side circuitry for digital direct access arrangement circuitry for terminating a phone line connection at a user end of a phone line, comprising:

a communication interface capable of being coupled to an external user end device;

an isolation interface capable of communicating digitally with user end phone line side circuitry through a user end isolation barrier that comprises a plurality of isolation elements; and

encode circuitry within said isolation interface to generate an encoded digital differential signal from a digital data stream for transmission across at least two of the isolation elements of said isolation barrier, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, and the isolation interface being capable of communicating bi-directionally across said first and second isolation capacitors of said isolation barrier;

wherein said encoded digital differential signal comprises control data added to said digital data stream and wherein said encoded digital differential signal comprises framing data added to said digital data stream for data synchronization within said phone line side circuitry;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor;

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry to generate at least one power supply within the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards; and

wherein the encoded digital differential signal includes both data information and control information.

6. The powered side circuitry of claim 5, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

7. The powered side circuitry of claim 5, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

8. Digital direct access arrangement circuitry for terminating a phone line connection, comprising:

powered side circuitry operable to communicate digitally with phone line side circuitry across an isolation barrier that comprises a plurality of isolation elements, said digital communication comprising a first digital data stream transmitted as a first digital differential signal across at least two of the isolation elements of said isolation barrier through a first set of hi-directional connections, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor; and

phone line side circuitry operable to communicate digitally with said powered side circuitry by a second digital differential signal transmitted across the same first and second isolation capacitors of said isolation barrier through a second set of bi-directional connections so that the first and second isolation capacitors bidirectionally transfer the first and second digital differential signals;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements; and

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards.

9. The digital direct access arrangement circuitry of claim 8, further comprising said isolation barrier coupled between said powered side circuitry and said phone line side circuitry.

10. The digital direct access arrangement circuitry of claim 8, wherein said first digital differential signal comprises an first encoded digital differential signal;

and wherein said powered side circuitry includes encode circuitry coupled to said digital data stream to generate said first encoded digital differential signal for transmission across said first and second isolation capacitors of said isolation barrier; and

wherein said phone line circuitry includes first decode circuitry to generate a first decoded digital signal from said first encoded digital differential signal.

11. The digital direct access arrangement circuitry of claim 10, wherein said first encoded digital differential signal comprises control data added to said digital data stream.

12. The digital direct access arrangement circuitry of claim 10, wherein said first encoded digital differential signal comprises framing data added to said digital data stream for data synchronization within said phone line side circuitry.

13. The digital direct access arrangement circuitry of claim 8, wherein said second digital differential signal comprises a second encoded digital differential signal;

and wherein said phone line side circuitry includes second encode circuitry coupled to said digital data stream to generate said second encoded digital differential signal for transmission across said isolation barrier; and

wherein said powered circuitry includes second decode circuitry to generate a second decoded digital signal from said second encoded digital differential signal.

14. The digital direct access arrangement circuitry of claim 13, wherein said encoded digital differential signal comprises control data added to said digital data stream.

15. The digital direct access arrangement circuitry of claim 14, wherein said control data comprises phone line status information.

16. The digital direct access arrangement circuitry of claim 8, wherein at least one of the first digital differential signal and the second digital differential signal includes both data information and control information.

17. The digital direct access arrangement circuitry of claim 8, wherein the powered side circuitry is further configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor.

18. The digital direct access arrangement circuitry of claim 8, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

19. The digital direct access arrangement circuitry of claim 8, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

20. Digital direct access arrangement circuitry for terminating a phone line connection, comprising:

powered side circuitry operable to communicate digitally with phone line side circuitry across an isolation barrier that comprises a plurality of isolation elements, said digital communication comprising a digital data stream transmitted as a first digital differential signal across at least two of the isolation elements of said isolation barrier through a first set of bi-directional connections, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor; and

phone line side circuitry operable to communicate digitally with said powered side circuitry by a second digital differential signal transmitted across the same first and second isolation capacitors of said isolation barrier through a second set of bi-directional connections so that the first and second isolation capacitors bidirectinoally transfer the first and second digital differential signals'"'"';

wherein the powered side circuitry is further configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor;

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry to generate at least one power supply within the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards; and

wherein at least one of the first digital differential signal and the second digital differential signal includes both data information and control information.

21. The digital direct access arrangement circuitry of claim 20, further comprising said isolation barrier coupled between said powered side circuitry and said phone line side circuitry.

22. The digital direct access arrangement circuitry of claim 20, wherein said first digital differential signal comprises an encoded digital differential signal;

and wherein said powered side circuitry includes encode circuitry coupled to said digital data stream to generate said encoded digital differential signal for transmission across said first and second isolation capacitors of said isolation barrier; and

wherein said phone line circuitry includes decode circuitry to generate a decoded digital signal from said encoded digital differential signal.

23. The digital direct access arrangement circuitry of claim 22, wherein said encoded digital differential signal comprises control data added to said digital data stream.

24. The digital direct access arrangement circuitry of claim 22, wherein said encoded digital differential signal comprises framing data added to said digital data stream for data synchronization within said phone line side circuitry.

25. The digital direct access arrangement circuitry of claim 20, wherein said second digital differential signal comprises an encoded digital differential signal;

and wherein said phone line side circuitry includes encode circuitry coupled to said digital data to generate said encoded digital differential signal for transmission across said isolation barrier; and

wherein said powered circuitry includes decode circuitry to generate a decoded digital signal from said encoded digital differential signal.

26. The digital direct access arrangement circuitry of claim 25, wherein said encoded digital differential signal comprises control data added to said digital data stream.

27. The digital direct access arrangement circuitry of claim 26, wherein said control data comprises phone line status information.

28. The digital direct access arrangement circuitry of claim 20, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

29. The digital direct access arrangement circuitry of claim 20, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

30. Powered side circuitry for digital direct access arrangement circuitry for terminating a phone line connection at a user end of a phone line, comprising:

a communication interface capable of being coupled to an external user end device;

an isolation interface capable of communicating digitally with user end phone line side circuitry through a user end isolation barrier that comprises a plurality of isolation elements; and

encode circuitry within said isolation interface to generate an encoded digital differential signal from a digital data stream for transmission across at least two of the isolation elements of said isolation barrier, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, and the isolation interface being capable of communicating hi-directionally across said first and second isolation capacitors of said isolation barrier;

wherein said encoded digital differential signal comprises control data added to said digital data stream;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements; and

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards.

31. The powered side circuitry of claim 30, wherein signals communicated through said communication interface comprise digital data signals, control signals and phone line status signals.

32. The powered side circuitry of claim 31, wherein said communication interface comprises a digital serial port interface.

33. The powered side circuitry of claim 30, wherein the encoded digital differential signal includes both data information and control information.

34. The powered side circuitry of claim 30, wherein the powered side circuitry is further configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor.

35. The powered side circuitry of claim 30, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

36. The powered side circuitry of claim 30, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

37. Powered side circuitry for digital direct access arrangement circuitry for terminating a phone line connection at a user end of a phone line, comprising:

a communication interface capable of being coupled to an external user end device;

an isolation interface capable of communicating digitally with user end phone line side circuitry through a user end isolation barrier that comprises a plurality of isolation elements; and

encode circuitry within said isolation interface to generate an encoded digital differential signal from a digital data stream for transmission across at least two of the isolation elements of said isolation barrier, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor, and the isolation interface being capable of communicating bi-directionally across said first and second isolation capacitors of said isolation barrier;

wherein said encoded digital differential signal comprises control data added to said digital data stream;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor;

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry to generate at least one power supply within the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards; and

wherein the encoded digital differential signal includes both data information and control information.

38. The powered side circuitry of claim 37, wherein signals communicated through said communication interface comprise digital data signals, control signals and phone line status signals.

39. The powered side circuitry of claim 38, wherein said communication interface comprises a digital serial port interface.

40. The powered side circuitry of claim 37, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

41. The powered side circuitry of claim 37, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

42. Digital direct access arrangement circuitry for terminating a phone line connection, comprising:

powered side circuitry operable to communicate digitally with phone line side circuitry, said digital communication comprising a digital data stream transmitted across an isolation barrier that comprises a plurality of isolation elements;

phone line side circuitry operable to communicate digitally with powered side circuitry across said isolation barrier that comprises a plurality of isolation elements; and

encode and decode circuitry coupled to said digital data stream to generate an encoded digital differential signal for transmission and receipt across at least two of the isolation elements of said isolation barrier, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor;

wherein said encoded digital differential signal comprises control data added to said digital data stream;

wherein communication across said isolation barrier is bi-directional across said first and second isolation capacitors of said isolation barrier;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements; and

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards.

43. The digital direct access arrangement circuitry of claim 42, further comprising said isolation barrier coupled between said powered side circuitry and said phone line side circuitry.

44. The digital direct access arrangement circuitry of claim 42, wherein said powered side circuitry includes encode circuitry coupled to said digital data stream to generate an encoded digital differential signal for transmission across said at least two isolation elements of said isolation barrier and wherein said phone line circuitry includes decode circuitry to generate a decoded digital signal from said encoded digital differential signal.

45. The digital direct access arrangement circuitry of claim 42, wherein said phone line side circuitry includes encode circuitry coupled to said digital data to generate an encoded digital differential signal for transmission across said at least two isolation elements of said isolation barrier and said powered circuitry includes decode circuitry to generate a decoded digital signal from said encoded digital differential signal.

46. The digital direct access arrangement circuitry of claim 45, wherein said control data comprises phone line status information.

47. The digital direct access arrangement circuitry of claim 42, wherein said phone line side circuitry has analog output signals that is capable of being coupled to phone lines through hook-switch circuitry and diode bridge circuitry.

48. The digital direct access arrangement circuitry of claim 42, wherein the encoded digital differential signal includes both data information and control information.

49. The digital direct access arrangement circuitry of claim 42, wherein the powered side circuitry is further configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor.

50. The digital direct access arrangement circuitry of claim 42, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

51. The digital direct access arrangement circuitry of claim 42, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.

52. Digital direct access arrangement circuitry for terminating a phone line connection, comprising:

powered side circuitry operable to communicate digitally with phone line side circuitry, said digital communication comprising a digital data stream transmitted across an isolation barrier that comprises a plurality of isolation elements;

phone line side circuitry operable to communicate digitally with powered side circuitry across said isolation barrier that comprises a plurality of isolation elements; and

encode and decode circuitry coupled to said digital data stream to generate an encoded digital differential signal for transmission and receipt across at least two of the isolation elements of said isolation barrier, the at least two isolation elements comprising at least a first isolation capacitor and a second isolation capacitor;

wherein said encoded digital differential signal comprises control data added to said digital data stream;

wherein communication across said isolation barrier is bi-directional across said first and second isolation capacitors of said isolation barrier;

wherein the powered side circuitry is configured to provide a clock signal to the phone line side circuitry through at least one of the plurality of isolation elements that is separate from the first isolation capacitor and the second isolation capacitor;

wherein the powered side circuitry is configured so that power is capable of being provided from the powered side circuitry to the phone line side circuitry to generate at least one power supply within the phone line side circuitry while still maintaining the isolation required by the phone line isolation regulatory standards; and

wherein the encoded digital differential signal includes both data information and control information.

53. The digital direct access arrangement circuitry of claim 52, further comprising said isolation barrier coupled between said powered side circuitry and said phone line side circuitry.

54. The digital direct access arrangement circuitry of claim 52, wherein said powered side circuitry includes encode circuitry coupled to said digital data stream to generate an encoded digital differential signal for transmission across said at least two isolation elements of said isolation baffler and wherein said phone line circuitry includes decode circuitry to generate a decoded digital signal from said encoded digital differential signal.

55. The digital direct access arrangement circuitry of claim 52, wherein said phone line side circuitry includes encode circuitry coupled to said digital data to generate an encoded digital differential signal for transmission across said at least two isolation elements of said isolation barrier and said powered circuitry includes decode circuitry to generate a decoded digital signal from said encoded digital differential signal.

56. The digital direct access arrangement circuitry of claim 55, wherein said control data comprises phone line status information.

57. The digital direct access arrangement circuitry of claim 52, wherein said phone line side circuitry has analog output signals that is capable of being coupled to phone lines through hook-switch circuitry and diode bridge circuitry.

58. The digital direct access arrangement circuitry of claim 52, wherein each of said plurality of isolation elements of said isolation barrier comprises a capacitor.

59. The digital direct access arrangement circuitry of claim 52, wherein at least a portion of said plurality of isolation elements of said isolation barrier each comprises a capacitor.