Transmission apparatus for a wireless device using delta-sigma modulation

• US 9,178,731 B2
• Filed: 09/22/2014
• Issued: 11/03/2015
• Est. Priority Date: 07/11/2012
• Status: Active Grant

• Current Assignee: DRNC Holdings, Inc. (InterDigital, Inc.)
• Original Assignee: Tag-Comm Inc.
• Inventors: Manku, Tajinder
• Primary Examiner(s): PANWALKAR, VINEETA S
• Application Number:
  US14/493,262
• Publication Number:
  US 20150009018A1
• Time in Patent Office: 407 Days
• Field of Search: 340/13.26, 340/12.51, 375/315, 375/295, 343/700.R, 343/749, 343/750
• US Class Current: 1/1
• CPC Class Codes: G01S 13/756 using a signal generator for modifying the reflectivity of the reflector G01S13/758 takes precedence
• CPC Class Codes: G01S 13/758 using a signal generator powered by the interrogation signal
• CPC Class Codes: G01S 13/825 with exchange of information between interrogator and responder
• CPC Class Codes: G06K 19/0723 the record carrier comprising an arrangement for non-contact communication, e.g. wireless communication circuits on transponder cards, non-contact smart cards or RFIDs
• CPC Class Codes: G06K 19/07749 the record carrier being capable of non-contact communication, e.g. constructional details of the antenna of a non-contact smart card
• CPC Class Codes: H04B 5/45 Transponders
• CPC Class Codes: H04L 27/0008 arrangements for allowing a transmitter or receiver to use more than one type of modulation negotiating modulation type for two-way transmission paths H04L5/1453
• CPC Class Codes: H04L 27/04 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/20 Modulator circuits; Transmitter circuits
• CPC Class Codes: H04L 27/2626 Arrangements specific to the transmitter only
• CPC Class Codes: H04L 27/36 Modulator circuits; Transmitter circuits

Abstract

A transmission apparatus for a wireless device, comprising: an antenna for receiving an original signal and for backscattering a modulated signal containing information from the wireless device; a variable impedance coupled to the antenna, the variable impedance having an impedance value; a delta-sigma modulator coupled to the variable impedance for modulating the impedance value, and thereby a backscattering coefficient for the antenna, in accordance with the information to generate the modulated signal; and, a decoder coupled to the delta-sigma modulator for generating the impedance value from the information.

Claims

1. A transmission apparatus for a wireless device, comprising:

an antenna for receiving an original signal and for backscattering a modulated signal containing information from the wireless device;

a variable impedance coupled to the antenna, the variable impedance having an impedance value;

a delta-sigma modulator coupled to the variable impedance for modulating the impedance value, and thereby a backscattering coefficient for the antenna, in accordance with the information to generate the modulated signal; and

,

a decoder coupled to the delta-sigma modulator for generating the impedance value from the information.

2. The transmission apparatus of claim 1 wherein the variable impedance is coupled in series with the antenna.

3. The transmission apparatus of claim 1 wherein the wireless device is powered by energy from the original signal.

4. The transmission apparatus of claim 1 wherein the variable impedance includes an array of impedances and respective switches.

5. The transmission apparatus of claim 1 wherein the decoder includes a backscattering coefficient to impedance value decoder.

6. The transmission apparatus of claim 1 wherein the information is an N-bit digital waveform.

7. The transmission apparatus of claim 6 wherein the N-bit digital waveform is applied to the decoder and then to the delta-sigma modulator to produce a control signal for the variable impedance that is related to the N-bit digital waveform.

8. The transmission apparatus of claim 7 wherein a change in the impedance value backscatters the original signal to produce the modulated signal, the modulated signal being a frequency offset form of the N-bit digital waveform.

9. The transmission apparatus of claim 7 wherein the control signal for the variable impedance switches an array of impedances within the variable impedance which changes the impedance value and thereby changes characteristics of the backscattering coefficient of the antenna.

10. The transmission apparatus of claim 1 wherein the information is a complex modulation signal.

11. The transmission apparatus of claim 10 wherein the complex modulation signal is offset in frequency from the original signal.

12. The transmission apparatus of claim 10 wherein the complex modulation signal is one of a GMSK signal, a nPSK signal, a 8PSK signal, a nQAM signal, and an OFDM signal.

13. The transmission apparatus of claim 10 wherein the complex modulation signal is represented by I+jQ, where I is an in-phase component, Q is a quadrature component, and j is a square root of −

1.

14. The transmission apparatus of claim 10 wherein the complex modulation signal alternates between an in-phase signal and a quadrature signal via a control signal.

15. The transmission apparatus of claim 14 wherein the variable impedance switches between backscattering coefficients that are 90 degrees offset from each other depending on whether the complex modulation signal is the in-phase signal or the quadrature signal.

16. The transmission apparatus of claim 14 wherein the control signal is a clock signal.

17. The transmission apparatus of claim 14 and further comprising a digital signal generator.

18. The transmission apparatus of claim 17 wherein the digital signal generator applies a constant value signal to the in-phase signal and the quadrature signal.

19. The transmission apparatus of claim 17 wherein the digital signal generator applies sine and cosine wave signals to the in-phase signal and the quadrature signal, respectively.

20. The transmission apparatus of claim 10 wherein the complex modulation signal is a sum of an in-phase signal and a quadrature signal.

21. The transmission apparatus of claim 20 and further comprising a digital signal generator.

22. The transmission apparatus of claim 21 wherein the digital signal generator applies a constant value signal to the in-phase signal and the quadrature signal.

23. The transmission apparatus of claim 21 wherein the digital signal generator applies sine and cosine wave signals to the in-phase signal and the quadrature signal, respectively.

24. The transmission apparatus of claim 6 wherein the N-bit digital waveform is adjusted to compensate for errors in at least one of the decoder, the delta-sigma modulator, and the variable impedance.

25. The transmission apparatus of claim 1 wherein the variable impedance includes a filter for filtering noise generated by at least one of the decoder and the delta-sigma modulator.

26. The transmission apparatus of claim 1 wherein the modulated signal is an arbitrary signal.

27. The transmission apparatus of claim 1 wherein the wireless device is a radio frequency identification (“

RFID”

) tag.

28. The transmission apparatus of claim 1 wherein the original signal is received from a RFID reader.

29. The transmission apparatus of claim 28 wherein the RFID reader is configured to correct for errors in at least one of the decoder, the delta-sigma modulator, and the variable impedance.

30. The transmission apparatus of claim 1 and further comprising a processor for controlling the transmission apparatus and memory for storing the information.

60. The transmission apparatus of claim 1 wherein the delta-sigma modulator is one of a low-pass delta-sigma modulator and a band-pass delta-sigma modulator.

61. The transmission apparatus of claim 1 wherein the delta-sigma modulator is a single bit delta-sigma modulator.

62. The transmission apparatus of claim 1 wherein the delta-sigma modulator switches the impedance value between at least two states.

31. A transmission apparatus for a wireless device, comprising:

an inductor for receiving an original signal and for transmitting by mutual inductance a modulated signal containing information from the wireless device;

a variable impedance coupled to the inductor, the variable impedance having an impedance value;

a delta-sigma modulator coupled to the variable impedance for modulating the impedance value, and thereby a value of the mutual inductance, in accordance with the information to generate the modulated signal; and

,

a decoder coupled to the delta-sigma modulator for generating the impedance value from the information.

32. The transmission apparatus of claim 31 wherein the variable impedance is coupled in parallel with the inductor.

33. The transmission apparatus of claim 31 wherein the wireless device is powered by energy from the original signal.

34. The transmission apparatus of claim 31 wherein the variable impedance includes an array of impedances and respective switches.

35. The transmission apparatus of claim 31 wherein the information is an N-bit digital waveform.

36. The transmission apparatus of claim 35 wherein the N-bit digital waveform is applied to the decoder and then to the delta-sigma modulator to produce a control signal for the variable impedance that is related to the N-bit digital waveform.

37. The transmission apparatus of claim 36 wherein the modulated signal is a frequency offset form of the N-bit digital waveform.

38. The transmission apparatus of claim 36 wherein the control signal for the variable impedance switches an array of impedances within the variable impedance which changes the impedance value.

39. The transmission apparatus of claim 31 wherein the information is a complex modulation signal.

40. The transmission apparatus of claim 39 wherein the complex modulation signal is offset in frequency from the original signal.

41. The transmission apparatus of claim 39 wherein the complex modulation signal is one of a GMSK signal, a nPSK signal, a 8PSK signal, a nQAM signal, and an OFDM signal.

42. The transmission apparatus of claim 39 wherein the complex modulation signal is represented by I+jQ, where I is an in-phase component, Q is a quadrature component, and j is a square root of −

1.

43. The transmission apparatus of claim 39 wherein the complex modulation signal alternates between an in-phase signal and a quadrature signal via a control signal.

44. The transmission apparatus of claim 43 wherein the variable impedance switches between impedance values that are 90 degrees offset from each other depending on whether the complex modulation signal is the in-phase signal or the quadrature signal.

45. The transmission apparatus of claim 43 wherein the control signal is a clock signal.

46. The transmission apparatus of claim 43 and further comprising a digital signal generator.

47. The transmission apparatus of claim 46 wherein the digital signal generator applies a constant value signal to the in-phase signal and the quadrature signal.

48. The transmission apparatus of claim 46 wherein the digital signal generator applies sine and cosine wave signals to the in-phase signal and the quadrature signal, respectively.

49. The transmission apparatus of claim 39 wherein the complex modulation signal is a sum of an in-phase signal and a quadrature signal.

50. The transmission apparatus of claim 49 and further comprising a digital signal generator.

51. The transmission apparatus of claim 50 wherein the digital signal generator applies a constant value signal to the in-phase signal and the quadrature signal.

52. The transmission apparatus of claim 50 wherein the digital signal generator applies sine and cosine wave signals to the in-phase signal and the quadrature signal, respectively.

53. The transmission apparatus of claim 35 wherein the N-bit digital waveform is adjusted to compensate for errors in at least one of the decoder, the delta-sigma modulator, and the variable impedance.

54. The transmission apparatus of claim 31 wherein the variable impedance includes a filter for filtering noise generated by at least one of the decoder and the delta-sigma modulator.

55. The transmission apparatus of claim 31 wherein the modulated signal is an arbitrary signal.

56. The transmission apparatus of claim 31 wherein the wireless device is a radio frequency identification (“

RFID”

) tag.

57. The transmission apparatus of claim 31 wherein the original signal is received from a RFID reader.

58. The transmission apparatus of claim 57 wherein the RFID reader is configured to correct for errors in at least one of the decoder, the delta-sigma modulator, and the variable impedance.

59. The transmission apparatus of claim 31 and further comprising a processor for controlling the transmission apparatus and memory for storing the information.

63. The transmission apparatus of claim 31 wherein the delta-sigma modulator is one of a low-pass delta-sigma modulator and a band-pass delta-sigma modulator.

64. The transmission apparatus of claim 31 wherein the delta-sigma modulator is a single bit delta-sigma modulator.

65. The transmission apparatus of claim 31 wherein the delta-sigma modulator switches the impedance value between at least two states.