Systems and methods for analog to digital conversion

• US 7,091,894 B2
• Filed: 06/12/2004
• Issued: 08/15/2006
• Est. Priority Date: 06/12/2004
• Status: Expired due to Fees

• Current Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Original Assignee: L-3 Communications Integrated Systems LP (L3Harris Technologies, Inc.)
• Inventors: McClain, Ross A. Jr., Fudge, Gerald L.
• Primary Examiner(s): Jeanglaude, Jean Bruner
• Application Number:
  US10/866,532
• Publication Number:
  US 20050275576A1
• Time in Patent Office: 794 Days
• Field of Search: 341/118, 341/143, 341/161, 342/162, 708/3
• US Class Current: 341/155
• CPC Class Codes: H03M 1/0626 by filtering
• CPC Class Codes: H03M 1/12 Analogue/digital converters H03M1/001 – H03M1/10 take precedence

Abstract

Systems and methods for analog to digital conversion that may be implemented using a digital to analog converter (DAC) to provide negative feedback to at least Partially cancel one or more signals (e.g., one or more interfering signals present with one or more desired signals, one or more strong desired signals, etc.) at the analog input of an analog to digital converter (ADC), and that may be used to extend the effective dynamic range of an ADC. The effective dynamic range of an ADC may be extended by detecting and isolating signals and using digital adaptive digital filtering along with a digital to analog converter (DAC) to provide negative feedback to cancel the signal/s at the input of the ADC.

Claims

1. An analog to digital conversion system having an analog input and a digital output, said system comprising:

a signal analog to digital conversion (ADC) component having an analog signal input coupled to said analog input of said system and a digital signal output coupled to said digital output of said system;

a signal cancellation digital to analog conversion (DAC) component having a digital signal input and an analog signal output, said analog signal output being coupled between said input of said analog to digital conversion system and said analog input of said signal ADC component; and

digital feedback circuitry having a digital signal input coupled to said digital signal output of said signal ADC component, and having a digital signal output coupled to said cancellation DAC component;

wherein said analog input of said system is configured to receive a system analog input signal that is of sufficient strength to at least partially saturate said signal ADC component;

wherein said signal cancellation DAC is configured to provide an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal that does not saturate said signal ADC components;

wherein said analog to digital conversion system comprises an interference cancellation system;

wherein said system analog input signal comprises at least one desired signal in the presence of at least one interfering signal, and wherein said analog to digital conversion system is configured to provide a digital output signal based at least in part on said desired signal present in said system analog input signal;

wherein said signal cancellation DAC component is configured to provide said analog cancellation signal based on a digital feedback signal received from said digital feedback circuitry, said analog cancellation signal being effective to at least partially cancel said at least one interfering signal in said system analog input signal when combined with said system analog input signal so as to produce said modified analog input signal;

wherein said signal ADC component is configured to produce a digital output signal based on said modified analog input signal, and to provide said digital output signal to said digital signal input of said digital feedback circuitry and to said digital output of said system; and

wherein said digital feedback circuitry is configured to produce said digital feedback signal based at least in part on said digital output signal produced by said signal ADC component.

3. The system of claim 1, wherein said at least one interfering signal of said system analog input signal has a signal strength sufficient to at least partially saturate said signal ADC component;

and wherein a strength of said at least one interfering signal in said modified analog input signal is not sufficient to saturate said signal ADC component.

4. The system of claim 1, wherein said digital feedback circuitry further comprises at least one analog signal input coupled to receive said system analog input signal or said modified analog input signal;

and wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said system analog input signal, said modified analog input signal received by said at least one analog signal input of said digital feedback circuitry, or a combination thereof.

5. The system of claim 1, wherein said digital feedback circuitry further comprises a cancellation ADC component coupled to receive said modified analog input signal;

and wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said modified analog input signal received by said cancellation ADC component of said digital feedback circuitry.

6. The system of claim 1, wherein said digital feedback circuitry further comprises a cancellation ADC component coupled to receive said system analog input signal;

and wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said system analog input signal received by said cancellation ADC component of said digital feedback circuitry.

7. The system of claim 6, further comprising a time delay component coupled to delay said system analog input signal prior to combination with said analog cancellation signal, said time delay component configured to delay said system analog input signal for a period of time that is sufficient to allow said analog cancellation signal to be provided and combined with said system analog input signal to produce said modified analog input signal that is provided to said signal ADC component.

8. The system of claim 1, wherein said analog to digital conversion system comprises an interference cancellation system;

and wherein said digital feed back circuitry comprises at least one signal cancellation component configured to produce said digital feedback signal, and at least one signal cancellation control component coupled to said digital signal input of said digital feedback circuitry and configured to control said signal cancellation component to produce said digital feedback signal based at least in part on said digital output signal received from said signal ADC component.

9. The system of claim 8, wherein said signal cancellation component comprises an adaptive filter;

and wherein said signal cancellation control component comprises a filter adaptation algorithm.

10. The system of claim 1, wherein said system analog input signal comprises a radio frequency (RF) signal.

11. The system of claim 1, wherein a dynamic range capability of said analog to digital conversion system is greater than a dynamic range capability of said signal ADC component alone.

2. A method for analog to digital conversion of a signal, comprising:

combining an analog input signal with an analog cancellation signal to form a modified analog input signal;

converting said modified analog input signal to a digital output signal in a first analog to digital conversion (ADC) component;

producing a digital feedback signal based at least in part on said digital output signal;

producing said digital feedback signal based at least in part on said analog input signal, said modified analog input signal, or a combination thereof, and

converting said digital feedback signal to said analog cancellation signal;

wherein said analog input signal has a signal strength sufficient to at least partially saturate said first ADC component, and

wherein said modified analog input signal has a signal strength that is not sufficient to saturate said first ADC component.

12. An analog to digital conversion system having a system analog input for receiving a system analog input signal and a system digital output for providing a system digital output signal, said system comprising:

a signal analog to digital conversion (ADC) component having an analog signal input coupled to said system analog input and a digital signal output coupled to said system digital output;

a signal cancellation digital to analog conversion (DAC) component having a digital signal input and an analog signal output, said analog signal output being coupled between said system analog input and said analog input of said signal ADC component; and

digital feedback circuitry comprising a cancellation ADC component coupled to said system analog input, said digital feedback circuitry having a digital signal input coupled to said digital signal output of said signal ADC component, and a digital signal output coupled to said cancellation DAC component.

13. The system of claim 12, wherein said system analog input is configured to receive a system analog input signal;

wherein said signal cancellation DAC is configured to provide an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal, said analog cancellation signal being based on a digital feedback signal received from said digital feedback circuitry;

wherein said digital signal input of said digital feedback circuitry is coupled to receive said system digital output signal from as signal ADC component;

wherein said at least one analog signal input of said digital feedback circuitry is coupled to receive at least one of said system analog input signal, said modified analog input signal, or a combination thereof; and

wherein said digital feedback circuitry is configured to produce said digital feedback signal based at least in part on said digital output signal produced by said signal ADC component, and based on at least one of said system analog input signal, said modified analog input signal, or a combination thereof.

14. The system of claim 13, wherein said system analog input is configured to receive a system analog input signal that is of sufficient strength to at least partially saturate said signal ADC component;

and wherein said digital feedback circuitry is configured to provide a digital feedback signal to said signal cancellation DAC to produce an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal that does not saturate said signal ADC component.

15. The system of claim 12, wherein said analog to digital conversion system comprises an interference cancellation system;

wherein said system analog input signal comprises at least one desired signal in the presence of at least one interfering signal, and wherein said system digital output signal is based at least in part on said desired signal present in said system analog input signal;

wherein said signal cancellation DAC component is configured to provide said analog cancellation signal based on a digital feedback signal received from said digital feedback circuitry, said analog cancellation signal being effective to at least partially cancel said at least one interfering signal in said system analog input signal when combined with said system analog input signal so as to produce a modified analog input signal;

wherein said signal ADC component is configured to produce a digital output signal based on said modified analog input signal, and to provide said digital output signal to said digital signal input of said digital feedback circuitry and to said system digital output; and

wherein said digital feedback circuitry is configured to produce said digital feedback signal based at least in part on said digital output signal produced by said signal ADC component and on at least one analog signal received by said analog input of said digital feedback circuitry coupled to said system analog input, said at least one analog signal received by said analog input of said digital feedback circuitry comprising said system analog input signal or said modified analog input signal.

16. The system of claim 15, wherein said at least one interfering signal of said system analog input signal has a signal strength sufficient to at least partially saturate said signal ADC component;

and wherein a strength of said at least one interfering signal in said modified analog input signal is not sufficient to saturate said signal ADC component.

17. The system of claim 13, wherein said analog signal input of said digital feedback circuitry is coupled to receive said modified analog input signal;

and wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said modified analog input signal received by said at least one analog signal input of said digital feedback circuitry.

18. The system of claim 13, wherein said analog signal input of said digital feedback circuitry is coupled to receive said system analog input signal;

and wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said system analog input signal received by said at least one analog signal input of said digital feedback circuitry.

19. The system of claim 18, further comprising a time delay component coupled to delay said system analog input signal prior to combination with said analog cancellation signal, said time delay component configured to delay said system analog input signal for a period of time that is sufficient to allow said analog cancellation signal to be provided and combined with said system analog input signal to produce said modified analog input signal that is provided to said signal ADC component.

20. The system of claim 12, wherein said analog to digital conversion system comprises an interference cancellation system;

wherein said digital feedback circuitry comprises at least one signal cancellation component configured to produce said digital feedback signal based at least in part on at least one analog signal received by said analog signal input of said digital feedback circuitry coupled to said system analog input.

21. The system of claim 20, further comprising at least one signal cancellation control component coupled to said at least one signal cancellation component;

and wherein said at least one signal cancellation control component is configured to control said at least one signal cancellation component to produce said digital feedback signal based at least in part on said digital signal output received by said digital signal input of said digital feedback circuitry from said signal ADC component.

22. The system of claim 20, wherein said at least one signal cancellation component comprises a cancellation ADC component coupled to an adaptive filter.

23. The system of claim 22, further comprising an interference adaptation algorithm coupled to control said cancellation ADC component based at least in part on said digital signal output received by said digital signal input of said digital feedback circuitry from said signal ADC component;

and a filter adaptation algorithm coupled to control said adaptive filter based at least in part on said digital signal output received by said digital signal input of said digital feedback circuitry from said signal ADC component.

24. The system of claim 12, wherein said system analog input signal comprises a radio frequency (RF) signal.

25. The system of claim 12, wherein said cancellation ADC component of said digital feedback circuitry is configured to be selectably enabled.

26. The system of claim 12, wherein a dynamic range capability of said analog to digital conversion system is greater than a dynamic range capability of said signal ADC component alone.

27. A method for analog to digital conversion of a signal, comprising:

combining an analog input signal with an analog cancellation signal to form a modified analog input signal;

converting said modified analog input signal to a digital output signal in a first analog to digital conversion (ADC) component;

producing a digital feedback signal based at least in part on said digital output signal; and

converting said digital feedback signal to said analog cancellation signal;

wherein said analog input signal has a signal strength sufficient to at least partially saturate said first ADC component, and wherein said modified analog input signal has a signal strength that is not sufficient to saturate said first ADC component;

wherein said analog input signal comprises at least one desired signal in the presence of at least one interfering signal, and wherein said digital output signal is based at least in part on said desired signal present in said analog input signal; and

wherein said analog cancellation signal is effective to at least partially cancel said at least one interfering signal in said analog input signal to produce said modified analog input signal.

28. The method of claim 27, wherein said at least one interfering signal of said analog input signal has a signal strength sufficient to at least partially saturate said first ADC component;

and wherein a strength of said at least one interfering signal in said modified analog input signal is not sufficient to saturate said ADC component.

30. The method of claim 27, further comprising producing said digital feedback signal based at least in part on said analog input signal, said modified analog input signal, or a combination thereof.

31. The method of claim 27, further comprising producing said digital feedback signal using a second ADC component and based at least in part on said modified analog input signal.

32. The method of claim 27, further comprising producing said digital feedback signal using a second ADC component and based at least in part on said analog input signal.

33. The method of claim 32, further comprising delaying said analog input signal prior to combining said analog input signal with said analog cancellation signal so that said analog input signal is delayed for a period of time that is sufficient to allow said analog cancellation signal to be produced and combined with said analog input signal to form said modified analog input signal prior to converting said modified analog input signal to said digital output signal.

34. The method of claim 27, further comprising producing said digital feedback signal using digital feed back circuitry, said digital feedback circuitry comprising at least one signal cancellation component configured to produce said digital feedback signal, and at least one signal cancellation control component configured to control said signal cancellation component to produce said digital feedback signal based at least in part on said digital output signal received from said ADC component.

35. The method of claim 34, wherein said signal cancellation component comprises an adaptive filter;

and wherein said signal cancellation control component comprises a filter adaptation algorithm.

36. The method of claim 27, wherein said analog input signal comprises a radio frequency (RF) signal.

37. The method of claim 27, wherein said method is implemented to achieve a dynamic range of analog to digital conversion that is greater than a dynamic range capability of said first ADC component alone.

29. A method for analog to digital conversion of a signal, comprising:

combining an analog input signal with an analog cancellation signal to form a modified analog input signal;

converting said modified analog input signal to a digital output signal in a first analog to digital conversion (ADC) component;

producing a digital feedback signal based at least in part on said digital output signal;

producing said digital feedback signal using a second ADC component and based at least in part on said modified analog input signal; and

converting said digital feedback signal to said analog cancellation signal;

wherein said analog input signal has a signal strength sufficient to at least partially saturate said first ADC component, and

wherein said modified analog input signal has a signal strength that is not sufficient to saturate said first ADC component.

38. A method for analog to digital conversion of a signal, comprising:

combining an analog input signal with an analog cancellation signal to form a modified analog input signal;

converting said modified analog input signal to a digital output signal;

producing a digital feedback signal based at least in part on said digital output signal and on at least one analog signal that is based at least in part on said analog input signal; and

converting said digital feedback signal to said analog cancellation signal.

39. The method of claim 38, further comprising producing said digital feedback signal based at least in part on said digital output signal and on at least one of said system analog input signal, said modified analog input signal, or a combination thereof.

40. The method of claim 39, further comprising converting said modified analog input signal to a digital output signal in a first ADC component;

wherein said analog input signal is of sufficient strength to at least partially saturate said first ADC component; and

wherein said modified analog input signal does not saturate said first ADC component.

41. The method of claim 38, wherein said analog input signal comprises at least one desired signal in the presence of at least one interfering signal, and wherein said digital output signal is based at least in part on said desired signal present in said system analog input signal;

wherein said analog cancellation signal is effective to at least partially cancel said at least one interfering signal in said analog input signal when combined with said analog input signal to produce said modified analog input signal; and

wherein said method further comprises producing said digital feedback signal based at least in part on said digital output signal and on at least one of said system analog input signal, said modified analog input signal, or a combination thereof.

42. The method of claim 41, further comprising converting said modified analog input signal to a digital output signal in a first ADC component;

wherein said at least one interfering signal of said system analog input signal has a signal strength sufficient to at least partially saturate said first ADC component; and

wherein a strength of said at least one interfering signal in said modified analog input signal is not sufficient to saturate said first ADC component.

43. The method of claim 39, further comprising producing said digital feedback signal based at least in part on said digital output signal and on said modified analog input signal.

44. The method of claim 39, further comprising producing said digital feedback signal based at least in part on said digital output signal and on said analog input signal.

45. The method of claim 44, further comprising delaying said analog input signal prior to combining said analog input signal with said analog cancellation signal so that said analog input signal is delayed for a period of time that is sufficient to allow said analog cancellation signal to be produced and combined with said analog input signal to form said modified analog input signal prior to converting said modified analog input signal to said digital output signal.

46. The method of claim 38, further comprising converting said modified analog input signal to a digital output signal in a first ADC component, and producing said digital feedback signal using digital feed back circuitry, said digital feedback circuitry comprising at least one signal cancellation component configured to produce said digital feedback signal, and at least one signal cancellation control component configured to control said signal cancellation component to produce said digital feedback signal based at least in part on said digital output signal.

47. The method of claim 46, wherein said signal cancellation component comprises an adaptive filter;

and wherein said signal cancellation control component comprises a filter adaptation algorithm.

48. The method of claim 46, wherein said at least one signal cancellation component comprises a second ADC coupled to an adaptive filter.

49. The method of claim 48, further comprising using an interference adaptation algorithm to control said second ADC based at least in part on said digital output signal;

and using a filter adaptation algorithm to control said adaptive filter based at least in part on said digital output signal.

50. The method of claim 38, wherein said analog input signal comprises a radio frequency (RF) signal.

51. The method of claim 38, wherein said method is implemented to increase the dynamic range capability for analog to digital conversion of said analog input signal to said digital output signal.

52. An analog to digital conversion system having an analog input and a digital output, said system comprising:

a signal analog to digital conversion (ADC) component having an analog signal input coupled to said analog input of said system and a digital signal output coupled to said digital output of said system;

a signal cancellation digital to analog conversion (DAC) component having a digital signal input and an analog signal output, said analog signal output being coupled between said input of said analog to digital conversion system and said analog input of said signal ADC component; and

digital feedback circuitry having a digital signal input coupled to said digital signal output of said signal ADC component, and having a digital signal output coupled to said cancellation DAC component;

wherein said analog input of said system is configured to receive a system analog input signal that is of sufficient strength to at least partially saturate said signal ADC component;

wherein said signal cancellation DAC is configured to provide an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal that does not saturate said signal ADC component; and

wherein said digital feedback circuitry further comprises at least one analog signal input coupled to receive said system analog input signal or said modified analog input signal; and

wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said system analog input signal, said modified analog input signal received by said at least one analog signal input of said digital feedback circuitry, or a combination thereof.

53. An analog to digital conversion system having an analog input and a digital output, said system comprising:

a signal analog to digital conversion (ADC) component having an analog signal input coupled to said analog input of said system and a digital signal output coupled to said digital output of said system;

a signal cancellation digital to analog conversion (DAC) component having a digital signal input and an analog signal output, said analog signal output being coupled between said input of said analog to digital conversion system and said analog input of said signal ADC component; and

digital feedback circuitry having a digital signal input coupled to said digital signal output of said signal ADC component, and having a digital signal output coupled to said cancellation DAC component;

wherein said analog input of said system is configured to receive a system analog input signal that is of sufficient strength to at least partially saturate said signal ADC component;

wherein said signal cancellation DAC is configured to provide an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal that does not saturate said signal ADC component; and

wherein said digital feedback circuitry further comprises a cancellation ADC component coupled to receive said modified analog input signal; and

wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said modified analog input signal received by said cancellation ADC component of said digital feedback circuitry.

54. An analog to digital conversion system having an analog input and a digital output, said system comprising:

a signal analog to digital conversion (ADC) component having an analog signal input coupled to said analog input of said system and a digital signal output coupled to said digital output of said system;

a signal cancellation digital to analog conversion (DAC) component having a digital signal input and an analog signal output, said analog signal output being coupled between said input of said analog to digital conversion system and said analog input of said signal ADC component; and

digital feedback circuitry having a digital signal input coupled to said digital signal output of said signal ADC component, and having a digital signal output coupled to said cancellation DAC component;

wherein said analog input of said system is configured to receive a system analog input signal that is of sufficient strength to at least partially saturate said signal ADC component;

wherein said signal cancellation DAC is configured to provide an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal that does not saturate said signal ADC component; and

wherein said digital feedback circuitry further comprises a cancellation ADC component coupled to receive said system analog input signal; and

wherein said digital feedback circuitry is further configured to produce said digital feedback signal based at least in part on said system analog input signal received by said cancellation ADC component of said digital feedback circuitry.

55. The system of claim 54, further comprising a time delay component coupled to delay said system analog input signal prior to combination with said analog cancellation signal, said time delay component configured to delay said system analog input signal for a period of time that is sufficient to allow said analog cancellation signal to be provided and combined with said system analog input signal to produce said modified analog input signal that is provided to said signal ADC component.

56. An analog to digital conversion system having an analog input and a digital output, said system comprising:

a signal analog to digital conversion (ADC) component having an analog signal input coupled to said analog input of said system and a digital signal output coupled to said digital output of said system;

a signal cancellation digital to analog conversion (DAC) component having a digital signal input and an analog signal output, said analog signal output being coupled between said input of said analog to digital conversion system and said analog input of said signal ADC component; and

digital feedback circuitry having a digital signal input coupled to said digital signal output of said signal ADC component, and having a digital signal output coupled to said cancellation DAC component;

wherein said analog input of said system is configured to receive a system analog input signal that is of sufficient strength to at least partially saturate said signal ADC component;

wherein said signal cancellation DAC is configured to provide an analog cancellation signal for combination with said system analog input signal to produce a modified analog input signal that does not saturate said signal ADC component; and

wherein said analog to digital conversion system comprises an interference cancellation system; and

wherein said digital feed back circuitry comprises at least one signal cancellation component configured to produce said digital feedback signal, and at least one signal cancellation control component coupled to said digital signal input of said digital feedback circuitry and configured to control said signal cancellation component to produce said digital feedback signal based at least in part on said digital output signal received from said signal ADC component.

57. The system of claim 56, wherein said signal cancellation component comprises an adaptive filter;

and wherein said signal cancellation control component comprises a filter adaptation algorithm.

58. A method for analog to digital conversion of a signal, comprising:

combining an analog input signal with an analog cancellation signal to form a modified analog input signal;

converting said modified analog input signal to a digital output signal in a first analog to digital conversion (ADC) component;

producing a digital feedback signal based at least in part on said digital output signal;

producing said digital feedback signal using a second ADC component and based at least in part on said analog input signal; and

converting said digital feedback signal to said analog cancellation signal;

wherein said analog input signal has a signal strength sufficient to at least partially saturate said first ADC component, and

wherein said modified analog input signal has a signal strength that is not sufficient to saturate said first ADC component.

59. The method of claim 58, further comprising delaying said analog input signal prior to combining said analog input signal with said analog cancellation signal so that said analog input signal is delayed for a period of time that is sufficient to allow said analog cancellation signal to be produced and combined with said analog input signal to form said modified analog input signal prior to converting said modified analog input signal to said digital output signal.

60. A method for analog to digital conversion of a signal, comprising:

combining an analog input signal with an analog cancellation signal to form a modified analog input signal;

converting said modified analog input signal to a digital output signal in a first analog to digital conversion (ADC) component;

producing a digital feedback signal based at least in part on said digital output signal;

producing said digital feedback signal using digital feed back circuitry, said digital feedback circuitry comprising at least one signal cancellation component configured to produce said digital feedback signal, and at least one signal cancellation control component configured to control said signal cancellation component to produce said digital feedback signal based at least in part on said digital output signal received from said ADC component;

converting said digital feedback signal to said analog cancellation signal; and

wherein said analog input signal has a signal strength sufficient to at least partially saturate said first ADC component, and

wherein said modified analog input signal has a signal strength that is not sufficient to saturate said first ADC component.

61. The method of claim 60, wherein said signal cancellation component comprises an adaptive filter;

and wherein said signal cancellation control component comprises a filter adaptation algorithm.