Voltage limiter for coaxial cable carrying RF signals and voltage

• US 20050047051A1
• Filed: 08/13/2004
• Published: 03/03/2005
• Est. Priority Date: 08/26/2003
• Status: Active Grant

• Current Assignee: Eagle Comtronics Incorporated
• Original Assignee: Eagle Comtronics Incorporated
• Inventors: Marland, Dale W.
• Granted Patent: US 7,345,864 B2
• Time in Patent Office: Days
• US Class Current: 361/119
• CPC Class Codes: H02H 9/005 avoiding undesired transient conditions
• CPC Class Codes: H04H 20/78 CATV [Community Antenna Television] systems

Abstract

A voltage limiter for a coaxial cable line that carries an RF signal and an AC powering voltage signal is provided, including a signal input carrying a first AC voltage signal and an RF signal, a signal output arranged in series with the input and carrying the RF signal and a second AC voltage signal that is lower than the first AC voltage signal, and a voltage limiting mechanism arranged between the input and the output. The voltage limiting mechanism reduces the first AC voltage signal to the second AC voltage signal without substantially affecting the integrity of the RF signal.

Claims

1. A voltage limiter for a coaxial line that carries an RF signal and an AC powering voltage signal, said voltage limiter comprising:

a signal input carrying a first AC voltage signal and an RF signal;

a signal output arranged in series with said input and carrying said RF signal and a second AC voltage signal that is lower than said first AC voltage signal; and

a voltage limiting mechanism arranged between said input and said output, wherein said voltage limiting mechanism reduces said first AC voltage signal to said second AC voltage signal without substantially affecting the integrity of said RF signal.

2. The voltage limiter of claim 1, wherein the total voltage of said first AC voltage signal comprises an AC powering waveform having a positive region and a negative region, and said voltage limiting mechanism comprises a plurality of diodes arranged to reduce the total amplitude of said first AC voltage signal down to said second AC voltage signal.

3. The voltage limiter of claim 2, wherein said plurality of diodes comprises a pair of diodes arranged in series cathode to cathode.

4. The voltage limiter of claim 3, wherein said pair of diodes comprises a first Zener diode having a predetermined avalanche voltage and a second Zener diode having a predetermined avalanche voltage.

5. The voltage limiter of claim 4, wherein said predetermined avalanche voltage of each of said first and said second Zener diodes is substantially the same.

6. The voltage limiter of claim 5, wherein said predetermined avalanche voltage is 30 volts.

7. The voltage limiter of claim 5, wherein said predetermined avalanche voltage is 15 volts.

8. The voltage limiter of claim 2, wherein said plurality of diodes comprises a first diode pair configured to pass said positive region of said AC powering waveform of said first AC voltage signal and a second diode pair configured to pass said negative region of said AC powering waveform of said first AC voltage signal.

9. The voltage limiter of claim 8, wherein said first diode pair comprises a steering diode and a Zener diode having a predetermined avalanche voltage arranged in series cathode to cathode.

10. The voltage limiter of claim 8, wherein said second diode pair comprises a steering diode and a Zener diode having a predetermined avalanche voltage arranged in series cathode to cathode.

11. The voltage limiter of claim 8, wherein said first diode pair is arranged in parallel with said second diode pair.

12. The voltage limiter of claim 9, wherein said first diode pair is arranged in parallel with said second diode pair.

13. The voltage limiter of claim 10, wherein said first diode pair is arranged in parallel with said second diode pair.

14. The voltage limiter of claim 9, wherein said predetermined avalanche voltage is 30 volts.

15. The voltage limiter of claim 9, wherein said predetermined avalanche voltage is 15 volts.

16. The voltage limiter of claim 10, wherein said predetermined avalanche voltage is 30 volts.

17. The voltage limiter of claim 10, wherein said predetermined avalanche voltage is 15 volts.

18. The voltage limiter of claim 1, further comprising a first capacitor arranged between said input and said output, said first capacitor having a sufficiently high impedance to effectively block said first AC voltage signal while allowing said RF signal to pass without any substantial signal degradation.

19. The voltage limiter of claim 18, further comprising an RF choke arranged between said input and said voltage limiting mechanism, said RF choke having a sufficiently high impedance to effectively block said RF signal while allowing said first AC voltage signal to pass without any substantial signal degradation.

20. The voltage limiter of claim 19, further comprising a second capacitor arranged between said RF choke and ground, said second capacitor having a value that is selected to provide a low-pass filter for any portion of said RF signal that leaks past said RF choke, and to shunt said leaked portion of said RF signal to ground.

21. The voltage limiter of claim 19, further comprising a second RF choke arranged between said voltage limiting mechanism and said output, said second RF choke having a sufficiently high impedance to effectively block said RF signal while allowing said second AC voltage signal to pass without any substantial signal degradation.

22. The voltage limiter of claim 21, further comprising a third capacitor arranged between said second RF choke and ground, said third capacitor having a value that is selected to provide a low-pass filter for any portion of said RF signal that leaks past said second RF choke, and to shunt said leaked portion of said RF signal to ground.

23. The voltage limiter of claim 19, wherein said RF choke comprises an inductor.

24. The voltage limiter of claim 21, wherein said second RF choke comprises an inductor.

25. The voltage limiter of claim 1, further comprising surge protection means arranged between said input and said output.

26. The voltage limiter of claim 18, further comprising surge protection means arranged between said input and said output.

27. The voltage limiter of claim 26, wherein said surge protection means comprises a first surge protection device arranged between said input and said first capacitor.

28. The voltage limiter of claim 27, wherein said surge protection means comprises a second surge protection device arranged between said first capacitor and said output.

29. The voltage limiter of claim 27, wherein said first surge protection device comprises a gas tube.

30. The voltage limiter of claim 28, wherein said second surge protection device comprises a gas tube.

31. The voltage limiter of claim 26, wherein surge protection means comprises a spark gap.

32. The voltage limiter of claim 20, further comprising a fourth capacitor arranged between said first RF choke and ground, wherein said fourth capacitor is electrically common to said second capacitor and wherein said fourth capacitor comprises a different material than said second capacitor.

33. The voltage limiter of claim 22, further comprising a fifth capacitor arranged between said second RF choke and ground, wherein said fifth capacitor is electrically common to said third capacitor, and wherein said fifth capacitor comprises a different material than said third capacitor.

34. The voltage limiter of claim 1, further comprising a fuse mechanism arranged between said voltage limiting mechanism and said output.

35. The voltage limiter of claim 34, wherein said fuse mechanism comprises a self resettable fuse device.

36. The voltage limiter of claim 3, further comprising at least one capacitor arranged between said pair of diodes and ground.

37. The voltage limiter of claim 36, wherein said at least one capacitor comprises one capacitor arranged between said first Zener diode and ground and another capacitor arranged between said second Zener diode and ground.

38. A voltage limiter for a coaxial line that carries an RF signal and an AC powering voltage signal, said voltage limiter comprising:

a signal input carrying a first AC voltage signal and an RF signal;

a signal output carrying said RF signal and a second AC voltage signal that is lower than said first AC voltage signal;

a first branch connecting said input to said output, said first branch being configured to pass said RF signal while blocking transmission of said first AC voltage signal; and

a second branch arranged in parallel with said first branch, said second branch being configured to pass said first AC voltage signal while blocking transmission of said RF signal, said second branch further comprising a voltage limiting mechanism that reduces said first AC voltage signal to said second AC voltage signal without substantially affecting the integrity of said RF signal.

39. The voltage limiter of claim 38, wherein the total voltage of said first AC voltage signal comprises an AC powering waveform having a positive region and a negative region, and said voltage limiting mechanism comprises a plurality of diodes arranged to reduce the total amplitude of said first AC voltage signal down to said second AC voltage signal.

40. The voltage limiter of claim 39, wherein said plurality of diodes comprises a pair of diodes arranged in series cathode to cathode on said second branch.

41. The voltage limiter of claim 40, wherein said pair of diodes comprises a first Zener diode having a predetermined avalanche voltage and a second Zener diode having a predetermined avalanche voltage.

42. The voltage limiter of claim 41, wherein said predetermined avalanche voltage of each of said first and said second Zener diodes is substantially the same.

43. The voltage limiter of claim 42, wherein said predetermined avalanche voltage is 30 volts.

44. The voltage limiter of claim 42, wherein said predetermined avalanche voltage is 15 volts.

45. The voltage limiter of claim 39, wherein said second branch comprises a first sub-branch and a second sub-branch arranged in parallel to said first sub-branch.

46. The voltage limiter of claim 45, wherein said plurality of diodes comprises a first diode pair arranged on said first sub-branch, said first diode pair being configured to pass said positive region of said AC powering waveform of said first AC voltage signal;

and

a second diode pair arranged on said second sub-branch, said second diode pair being configured to pass said negative region of said AC powering waveform of said first AC voltage signal.

47. The voltage limiter of claim 46, wherein said first diode pair comprises a steering diode and a Zener diode having a predetermined avalanche voltage.

48. The voltage limiter of claim 46, wherein said second diode pair comprises a steering diode and a Zener diode having a predetermined avalanche voltage.

49. The voltage limiter of claim 47, wherein said predetermined avalanche voltage is 30 volts.

50. The voltage limiter of claim 47, wherein said predetermined avalanche voltage is 15 volts.

51. The voltage limiter of claim 48, wherein said predetermined avalanche voltage is 30 volts.

52. The voltage limiter of claim 48, wherein said predetermined avalanche voltage is 15 volts.

53. The voltage limiter of claim 38, further comprising a first capacitor arranged on said first branch between said input and said output, said first capacitor having a sufficiently high impedance to effectively block said first AC voltage signal while allowing said RF signal to pass without any substantial signal degradation.

54. The voltage limiter of claim 53, further comprising an RF choke arranged between said input and said voltage limiting mechanism on said second branch, said RF choke having a sufficiently high impedance to effectively block said RF signal while allowing said first AC voltage signal to pass without any substantial signal degradation.

55. The voltage limiter of claim 54, further comprising a second capacitor arranged on said first branch between said RF choke and ground, said second capacitor having a value that is selected to provide a low-pass filter for any portion of said RF signal that leaks past said RF choke, and to shunt said leaked portion of said RF signal to ground.

56. The voltage limiter of claim 55, further comprising second RF choke arranged on said second branch between said voltage limiting mechanism and said output, said second RF choke having a sufficiently high impedance to effectively block said RF signal while allowing said second AC voltage signal to pass without any substantial signal degradation.

57. The voltage limiter of claim 56, further comprising a third capacitor arranged between said second RF choke and ground, said third capacitor having a value that is selected to provide a low-pass filter for any portion of said RF signal that leaks past said second RF choke, and to shunt said leaked portion of said RF signal to ground.

58. The voltage limiter of claim 54, wherein said RF choke comprises an inductor.

59. The voltage limiter of claim 56, wherein said second RF choke comprises an inductor.

60. The voltage limiter of claim 38, further comprising surge protection means arranged on said first branch between said input and said output.

61. The voltage limiter of claim 53, further comprising surge protection means arranged on said first branch between said input and said output.

62. The voltage limiter of claim 61, wherein said surge protection means comprises a first surge protection device arranged on said first branch between said input and said first capacitor.

63. The voltage limiter of claim 61, wherein said surge protection means comprises a second surge protection device arranged on said first branch between said first capacitor and said output.

64. The voltage limiter of claim 62, wherein said first surge protection device comprises a gas tube.

65. The voltage limiter of claim 63, wherein said second surge protection device comprises a gas tube.

66. The voltage limiter of claim 60, wherein surge protection means comprises a spark gap.

67. The voltage limiter of claim 55, further comprising a fourth capacitor arranged between said first RF choke and ground, wherein said fourth capacitor is electrically common to said second capacitor and wherein said fourth capacitor comprises a different material than said second capacitor.

68. The voltage limiter of claim 57, further comprising a fifth capacitor arranged between said second RF choke and ground, wherein said fifth capacitor is electrically common to said third capacitor, and wherein said fifth capacitor comprises a different material than said third capacitor.

69. The voltage limiter of claim 38, further comprising a fuse mechanism arranged on said second branch between said voltage limiting mechanism and said output.

70. The voltage limiter of claim 69, wherein said fuse mechanism comprises a self resettable fuse device.

71. The voltage limiter of claim 41, further comprising at least one capacitor arranged on said second branch between said pair of diodes and ground.

72. The voltage limiter of claim 71, wherein said at least one capacitor comprises one capacitor arranged between said first Zener diode and ground and another capacitor arranged between said second Zener diode and ground.

73. A voltage limiter for a coaxial cable line carrying an RF signal and an AC powering voltage signal, said voltage limiter comprising:

a signal input carrying a first AC voltage signal and an RF signal;

a signal output carrying said RF signal and a second AC voltage signal;

a first branch connecting said input to said output, said first branch comprising means for passing said RF signal while blocking transmission of said first AC voltage signal; and

a second branch arranged in parallel with said first branch, said second branch comprising means for passing said first AC voltage signal while blocking transmission of said RF signal, said second branch further comprising voltage limiting means for reducing said first AC voltage signal to said second AC voltage signal without substantially affecting the integrity of said RF signal.

74. A CATV distribution system device, comprising:

a housing having an input port configured to communicate with a first coaxial line carrying an RF signal and a first AC voltage signal, and an output port configured to communicate with a second coaxial line carrying said RF signal and a second AC voltage signal, said second AC voltage signal being lower than said first AC voltage signal; and

a voltage limiting mechanism positioned with said housing to reduce said first AC voltage signal to said second AC voltage signal without substantially affecting the integrity of said RF signal.

75. The device of claim 74, wherein said first coaxial line comprises a CATV main line cable and said second coaxial line comprises a drop cable.