Data access arrangement using a high frequency transformer for electrical isolation

• US 7,277,491 B2
• Filed: 05/14/2002
• Issued: 10/02/2007
• Est. Priority Date: 05/14/2002
• Status: Expired due to Fees

• Current Assignee: ESS Technology Incorporated (Semiconductor Holding Corp.)
• Original Assignee: ESS Technology Incorporated (Semiconductor Holding Corp.)
• Inventors: Cookman, Jordan C., Dong, Ping
• Primary Examiner(s): Ghayour; M.
• Assistant Examiner(s): GHULAMALI, QUTBUDDIN
• Application Number:
  US10/146,200
• Publication Number:
  US 20030215020A1
• Time in Patent Office: 1,967 Days
• Field of Search: 375/220, 375/222, 375/257, 375/258, 375/295, 375/259, 375/367, 375/256, 375/239, 375/221, 375/252, 375/247, 370/509, 370/441, 370/320, 370/342, 370/515, 370/506, 370/337, 455/76, 455/102, 455/427, 455/504, 455/506, 455/522, 342/27, 342/21, 342/22, 714/776, 327/103
• US Class Current: 375/258
• CPC Class Codes: H01F 2019/085 Transformer for galvanic isolation
• CPC Class Codes: H04L 25/0268 with modulation and subsequent demodulation

Abstract

An electrical isolation barrier for use in a Data Access Arrangement uses a high frequency (HF) transformer 24 to provide isolation. An input signal, which may be analog or digital, is connected to a modulator. The analog output of the modulator is connected to the input of the HF transformer. The output of the HF transformer is connected to the input of a demodulator. Simple amplitude modulation can be used in the modulator to modulate the input signal to the frequency range of operation of the HF transformer. A simple low pass filter may be incorporated in the demodulator to remove harmonic distortion caused by the HF transformer. The output signal of the demodulator is substantially the same as input signal.

Claims

1. An electrical isolation barrier for use in a data access arrangement for providing electrical isolation between a system side circuit and a line side circuit, comprising, in combination:

an HF transformer having a desired frequency range of operation, and having a first port and a second port;

a first modulator coupled to first port of said HF transformer, said first modulator modulating a first 1-bit digital signal to a first analog pass band signal within said desired frequency range and transmitting the modulated signal to said HF transformer;

a first demodulator coupled to said first second port of said HF transformer, said demodulator demodulating said first analog pass band signal to recover said first 1-bit digital signal for transmission to said line side circuit;

wherein said first modulator is coupled to said HF transformer through a first HF hybrid circuit and said HF transformer is coupled to said first demodulator through a second HF hybrid circuit;

a second modulator coupled to said second port of said HF transformer through said second HF hybrid circuit, said second modulator modulating a second 1-bit digital signal to a second analog pass band signal within said desired frequency range and transmitting it to said HF transformer;

a second demodulator coupled to said first port of said HF transformer through said first HF hybrid circuit, said second demodulator demodulating said second analog pass band signal to recover said second 1-bit digital signal for transmission to said system side circuit; and

wherein the line side circuit includes an analog portion of a sigma-delta codec, said analog portion converting an analog receive signal to a third 1-bit digital signal; and

wherein the line side circuit includes a second multiplexor connected to said second modulator, receiving digital status signals and said third 1-bit digital signal, said multiplexor combining said digital status signals and said third 1-bit digital signal to form said second 1-bit digital signal.

2. The electrical isolation barrier of claim 1 wherein the second multiplexor includes a second frame generation circuit to align the digital status signals.

3. The electrical isolation barrier of claim 1 wherein the system side circuit includes (1) a second demultiplexor connected to a second demodulator, said second demultiplexor recovering said digital status signals and said fourth 1-bit digital signal from the recovered third 1-bit digital signal, and (2) a digital portion of a sigma-delta codec to convert said fourth 1-bit digital signal to digital modem signals.

4. The electrical isolation barrier of claim 3 wherein the second demultiplexor includes a second frame detection circuit to detect the alignment of the digital status signals.

5. An electrical isolation barrier for use in a data access arrangement for providing electrical isolation between a system side circuit and a line side circuit, comprising, in combination:

an HF transformer having a desired frequency range of operation, and having a first port and a second port;

a first modulator coupled to first port of said transformer through a first HF hybrid circuit, said first modulator modulating a first 1-bit digital signal to a first analog pass band signal within said desired frequency range and transmitting the modulated signal to said transformer;

a first demodulator coupled to said second port of said transformer through a second HF hybrid circuit, said demodulator demodulating said first pass band signal to recover said first 1-bit digital signal for transmission to said line side circuit;

a second modulator coupled to said second port of said transformer through said second HF hybrid circuit, said second modulator modulating a third 1-bit digital signal to a second analog pass band signal within said desired frequency range and transmitting it to said transformer;

a second demodulator coupled to said first port of said transformer through said first HF hybrid circuit, said second demodulator demodulating said second pass band signal to recover said third 1-bit digital signal for transmission to said system side circuit;

a digital portion of a sigma-delta codec included in said system side circuit for converting digital modem signals to a second 1-bit digital signal and converting a fourth 1-bit digital signal to digital modem signals;

a first multiplexor included in the system side circuit and connected to said first modulator, said first multiplexor receiving digital control signals and said second 1-bit digital signal and multiplexing them to form said first 1-bit digital signal;

a first demultiplexor included in the line side circuit and connected to the first demodulator, said first demultiplexor separating the digital control signals and second 1-bit digital signal from the recovered first 1-bit digital signal;

an analog portion of a sigma-delta codec included in the line side circuit, said analog portion converting an analog receive signal to a fourth 1-bit digital signal and converting a second 1-bit digital signal to an analog transmit signal;

a second multiplexor included in the line side circuit and connected to said second modulator, said second multiplexor receiving digital status signals and said fourth 1-bit digital signal and combining them to form said third 1-bit digital signal;

a second demultiplexor included in the system side circuit and connected to the second demodulator, said second demultiplexor recovering said digital status signals and said fourth 1-bit digital signal from the recovered third 1-bit digital signal.

6. The electrical isolation barrier of claim 5 wherein

the first multiplexor includes a first frame generation circuit to align the digital control signals;

the first demultiplexor includes a first frame detection circuit to detect the alignment of the digital control signals;

the second multiplexor includes a second frame generation circuit to align the digital status signals; and

the second demultiplexor includes a second frame detection circuit to detect the alignment of the digital status signals.

7. An electrical isolation barrier for use in a data access arrangement, comprising, in combination:

an input circuit and an output circuit;

an HF transformer for providing electrical isolation between the input circuit and the output circuit and having a frequency range of desired operation, said transformer having two ports;

a modulator and high frequency circuit combination capable of bidirectional operation and having an input and an output,

said modulator input capable of being connected to the input circuit, said modulator shifting an input signal to a bandpass signal within the frequency range of the transformer, such that integer multiples of two or greater of frequencies of the shifted input signal fall outside of the frequency range of the transformer;

said modulator output coupled to the first port of the transformer to supply said shifted signals to the transformer;

a demodulator and high frequency circuit combination capable of bidirectional operation having an input and an output,

said demodulator input coupled to the second port of the transformer, said demodulator shifting said bandpass signals from the frequency range of the transformer to an output signal for use by the output circuit.

8. The electrical isolation barrier of claim 7 wherein:

the modulator includes a multiplier, said multiplier being connected to a clock for multiplying the input signal by a clock signal;

the demodulator includes a multiplier, said multiplier connected to a clock for multiplying the output of the transformer by said clock signal; and

the demodulator includes a low pass filter to remove distortion from the output signal.

9. The electrical isolation barrier of claim 7 wherein:

the input signal to the modulator is a first 1-bit digital signal;

the modulator converts said first 1-bit digital signal to an input signal having frequencies in the frequency range of the transformer;

the demodulator converts signals having frequencies in the frequency range of the transformer to recover the first 1-bit digital signal.

10. The electrical isolation barrier of claim 9 wherein at least some portion of the first 1-bit digital signal is generated using sigma-delta techniques.

11. The electrical isolation barrier of claim 9 wherein the input circuit includes a multiplexor to multiplex digital status or control signals with a second 1-bit digital signal to form the first 1-bit digital signal.

12. The electrical isolation barrier of claim 11 wherein the output circuit includes a demultiplexor to extract digital status or control signals and the second 1-bit digital signal from the first 1-bit digital signal.

13. The electrical isolation barrier of claim 12 wherein the second 1-bit digital signal is generated using sigma-delta techniques.

14. The electrical isolation barrier of claim 12 wherein the multiplexor includes a frame generation circuit to align the digital status or control signals.

15. The electrical isolation barrier of claim 12 wherein the demultiplexor includes a frame detection circuit to detect the alignment of the digital status or control signals.

16. The electrical isolation barrier of claim 7 further including a multiplexor to multiplex status or control signals with line signals for transmission over the electrical isolation barrier.

17. The electrical isolation barrier of claim 16 wherein the signal output from the demodulator includes status or control information.

18. The electrical isolation barrier of claim 16 wherein said status signals are of different frequencies from said control signals.

19. The method of providing an electrical isolation barrier in a modem system comprising the steps of:

providing a single high frequency transformer in the data access arrangement section of the modem, which transformer has a predetermined frequency operation range and an input port and an output port, and is capable of duplex operation;

shifting an input signal to a passband within the frequency operation range of the transformer such that integer multiples of two or greater of frequencies of the shifted signal fall outside of the frequency range of the transformer, and providing the shifted signal to the transformer input port;

obtaining from the output port of the transformer an output signal; and

shifting the output signal to recover the input signal.

20. The method of claim 19 wherein the input signal is a 1-bit digital signal;

and

the step of modulating the input signal includes multiplying a clock signal with the 1-bit digital signal to form a high-frequency signal; and

the step of demodulating the output signal to recover the input signal includes demodulating the high frequency signal by clock multiplication.

21. The method of claim 20 wherein at least some of the bits in the 1-bit digital signal are obtained using sigma-delta techniques.

22. The method of claim 19 further including providing a half-wave rectifier circuit to derive power from said modulated first signal.

23. An electrical isolation barrier for use in a data access arrangement for providing electrical isolation between a line side circuit and a system side circuit, comprising, in combination:

a first pair of input and output circuits for a TX signal and a second pair of input and output circuits for an RX signal, wherein the first input circuit and the second output circuit are located in the line side circuit, and the second input circuit and the first output circuit are located in the system side circuit;

a first HF transformer for providing electrical isolation between the first pair of input and output circuits and having a frequency range of desired operation, said first transformer having two ports;

a first modulator having an input and an output,

said first modulator input capable of being connected to the input circuit of the first pair of input and output circuits and modulating an input signal to frequencies within the frequency range of the first transformer such that integer multiples of two or greater of frequencies of the shifted signal fall outside of the frequency range of the transformer;

said first modulator output connected to the first port of the first transformer to supply the modulated signals to the first transformer;

a first demodulator having an input and an output,

said first demodulator input connected to the second port of the first transformer for demodulating signals from the frequency range of the first transformer to an output signal for use by the output circuit of the first pair of input and output circuits;

a second HF transformer for providing electrical isolation between the second pair of input and output circuits and having a frequency range of desired operation, said second transformer having two ports;

a second modulator having an input and an output,

said second modulator input capable of being connected to the input circuit of the second pair of input and output circuits and modulating the input signal to frequencies within the frequency range of the second transformer;

said second modulator output connected to the first port of the second transformer to supply the modulated signals to the second transformer;

a second demodulator having an input and an output,

said second demodulator input connected to the second port of the second transformer for demodulating signals from the frequency range of the second transformer to an output signal for use by the output circuit of the second pair of input and output circuits.

24. An electrical isolation barrier for use in a data access arrangement for providing electrical isolation between a system side circuit and a line side circuit, comprising, in combination:

an HF transformer having a desired frequency range of operation, and having a first port and a second port;

a first modulator coupled to the first port of said transformer through a first HF circuit, said first modulator modulating a first base band signal to a first pass band signal within said desired frequency range such that integer multiples of two or greater of frequencies of the first pass band signal fall outside of the disired frequency range of the HF transformer, and transmitting the first pass band signal to said HF transformer;

a first demodulator coupled to said second port of said transformer through a second HF circuit, said demodulator demodulating said first pass band signal to recover said first base band signal for transmission to said line side circuit.

25. The electrical isolation barrier of claim 24 wherein said first modulator is coupled to said transformer through a first HF circuit and said transformer is coupled to said first demodulator through a second HF circuit.

26. The electrical isolation barrier of claim 24, wherein the system side circuit includes (1) a codec for converting digital modem signals to a transmit signal, and (2) a first multiplexor connected to said first modulator, said first multiplexor receiving control signals and said transmit signal and multiplexing said control signals and said transmit signal to form said first base band signal.

27. The electrical isolation barrier of claim 26 wherein the line side circuit includes a first demultiplexor connected to first demodulator, said demodulator shifting the frequency of said first pass band signal back to the original base band and said first demultiplexor separating the said control signals from the said transmit signal.

28. The electrical isolation barrier of claim 24 including a clock recovery circuit connected to said second HF circuit for locking the frequency of said first demodulator to that of said first modulator.

29. The electrical isolation barrier of claim 24 wherein the line side circuit includes a LF circuit coupled to a communications line for receiving receive signals and transmitting transmit signals.

30. The electrical isolation barrier of claim 24 including

a second modulator coupled to said second port of said transformer through said second HF circuit, said second modulator modulating a second base band signal to a second pass band signal within said desired frequency range and transmitting it to said transformer;

a second demodulator coupled to said first port of said transformer through said first HF circuit, said second demodulator demodulating said second pass band signal to recover said second base band signal for transmission to said system side circuit.

31. The electrical isolation barrier of claim 30, wherein the line side circuit includes a second multiplexor connected to said second modulator, receiving status signals and a receive signal, said multiplexor combining said status signals and said receive signal to form said second base band signal.

32. The electrical isolation barrier of claim 31 wherein the system side circuit includes (1) a codec for converting a receive signal to digital modem signals and (2) a second demultiplexor connected to second demodulator, said demodulator shifting the frequency of said second pass band signal back to the original base band and said second demultiplexor separating said status signals from said receive signal.

33. An electrical isolation barrier for use in a data access arrangement for providing electrical isolation between a system side circuit and a line side circuit, comprising, in combination:

an HF transformer having a desired frequency range of operation, and having a first port and a second port;

a first modulator coupled to first port of said transformer, said first modulator modulating a first 1-bit digital signal to a first pass band signal within said desired frequency range such that integer multiples of two or greater of frequencies of the shifted signal fall outside of the frequency range of the transformer, and transmitting the modulated first pass band signal to said HF transformer;

a first demodulator coupled to said second port of said transformer, said demodulator demodulating said first pass band signal to recover said first 1-bit digital signal for transmission to said line side circuit.

34. The electrical isolation barrier of claim 33 wherein said first modulator is coupled to said transformer through a first HF circuit and said transformer is coupled to said first demodulator through a second HF circuit.

35. The electrical isolation barrier of claim 34 including a clock recovery circuit connected to said second HF circuit for locking the frequency of said first demodulator to that of said first modulator.

36. The electrical isolation barrier of claim 34 including

a second modulator coupled to said second port of said transformer through said second HF circuit, said second modulator modulating a third 1-bit digital signal to a second pass band signal within said desired frequency range and transmitting it to said transformer;

a second demodulator coupled to said first port of said transformer through said first HF circuit, said second demodulator demodulating said second pass band signal to recover said third 1-bit digital signal for transmission to said system side circuit.

37. The electrical isolation barrier of claim 36, wherein the line side circuit includes a portion of a sigma-delta codec, said portion converting a receive signal to a fourth 1-bit digital signal.

38. The electrical isolation barrier of claim 37, wherein the line side circuit includes a second multiplexor connected to said second modulator, receiving digital status signals and said fourth 1-bit digital signal, said multiplexor combining said digital status signals and said fourth 1-bit digital signal to form said third 1-bit digital signal.

39. The electrical isolation barrier of claim 38 wherein the second multiplexor includes a second frame generation circuit to align the digital status signals.

40. The electrical isolation barrier of claim 38 wherein the system side circuit includes (1) a second demultiplexor connected to a second demodulator, said second demultiplexor recovering said digital status signals and said fourth 1-bit digital signal from the recovered third 1-bit digital signal, and (2) a digital portion of a sigma-delta codec to convert said fourth 1-bit digital signal to digital modem signals.

41. The electrical isolation barrier of claim 40 wherein the second demultiplexor includes a second frame detection circuit to detect the alignment of the digital status signals.

42. The electrical isolation barrier of claim 33, wherein the system side circuit includes (1) a digital portion of a sigma-delta codec for converting digital modem signals to a second 1-bit digital signal, and (2) a first multiplexor connected to said first modulator, said first multiplexor receiving digital control signals and said second 1-bit digital signal and multiplexing said digital control signals and second 1-bit digital signal to form said first 1-bit digital signal.

43. The electrical isolation barrier of claim 42 wherein the first multiplexor includes a first frame generation circuit to align the digital control signals.

44. The electrical isolation barrier of claim 42 wherein the lineside circuit includes a first demultiplexor connected to the first demodulator, said first demultiplexor separating the digital control signals and second 1-bit digital signal from the recovered first 1-bit digital signal.

45. The electrical isolation barrier of claim 44 wherein the first demultiplexor includes a frame detection circuit to detect the alignment of the digital control signals.

46. The electrical isolation barrier of claim 44, wherein the line side circuit includes a portion of a sigma-delta codec coupled to said first demodulator, said portion of sigma-delta codec converting the recovered second 1-bit digital signal into a transmit signal.

47. The electrical isolation barrier of claim 44 wherein the separation in the first multiplexor is accomplished using filter banks.

48. The electrical isolation barrier of claim 33 wherein the line side circuit includes a LF circuit coupled to a communications line for receiving receive signals and transmitting transmit signals.

49. The electrical isolation barrier of claim 33 further wherein said line side circuit includes a half-wave rectifier circuit to derive power from said pass band signal.

50. An electrical isolation barrier for use in a data access arrangement for providing electrical isolation between a system side circuit and a line side circuit, comprising, in combination:

an HF isolation element having a desired frequency range of operation, and having a first port and a second port;

a first modulator coupled to the first port of said isolation element through a first HF circuit, said first modulator modulating a first base band signal to a first pass band signal within said desired frequency range such that integer multiples of two or greater of frequencies of the first pass band signal fall outside of the frequency range, and transmitting the modulated signal to said isolation element;

a first demodulator coupled to said second port of said isolation element through a second HF circuit, said demodulator demodulating said first pass band signal to recover said first base band signal for transmission to said line side circuit;

a second modulator coupled to said second port of said isolation element through said second HF circuit, said second modulator modulating a second base band signal to a second pass band signal within said desired frequency range such that integer multiples of two or greater of frequencies of the shifted signal fall outside of the frequency range, and transmitting it to said isolation element;

a second demodulator coupled to said first port of said isolation element through said first HF circuit, said second demodulator demodulating said second pass band signal to recover said second base band signal for transmission to said system side circuit.

51. An electrical isolation barrier for use in a data access arrangement, comprising, in combination:

an HF transformer for providing electrical isolation between an input circuit and an output circuit and having a frequency range of desired operation, said transformer having a first port and a second port ports;

a modulator and high frequency circuit combination capable of bidirectional operation and having an input and an output,

said modulator input capable of being connected to the input circuit, said modulator modulating the input signal to frequencies within the frequency range of the transformer such that integer multiples of two or greater of frequencies of the modulated input signal fall outside of the frequency range of the transformer;

said modulator output coupled to the first port of the transformer to supply the modulated signals to the transformer;

a demodulator and high frequency circuit combination capable of bidirectional operation having an input and an output,

said demodulator input coupled to the second port of the transformer, said demodulator demodulating signals from the frequency range of the transformer to an output signal for use by the output circuit.

52. The electrical isolation barrier of claim 51 wherein:

the modulator includes a multiplier, said multiplier being connected to a clock for multiplying the input signal by a clock signal;

the demodulator includes a multiplier, said multiplier connected to a clock for multiplying the output of the transformer by said clock signal; and

the demodulator includes a low pass filter to remove distortion from the output signal.

53. The method of providing an electrical isolation barrier in a modem system comprising the steps of:

providing a single high frequency transformer in the data access arrangement section of the modem, which transformer has a predetermined frequency operation range and an input port and an output port, and delivers both signal and power;

providing a power deriving circuit to derive power from a modulated signal;

shifting an input signal to a bandpass signal within the frequency operation range of the transformer such that integer multiples of two or greater of frequencies of the shifted signal fall outside of the frequency range of the transformer, and providing the shifted first signal to the transformer input port;

obtaining from the output port of the transformer an output signal;

utilizing said power deriving circuit to derive power from said first modulated shifted signal; and

shifting the frequency of the output signal to recover the input signal.