Carrier and clock recovery using universal frequency translation

• US 7,027,786 B1
• Filed: 05/10/2000
• Issued: 04/11/2006
• Est. Priority Date: 10/21/1998
• Status: Expired due to Fees

• Current Assignee: ParkerVision, Inc.
• Original Assignee: ParkerVision, Inc.
• Inventors: Cook, Robert W., Rawlins, Gregory S., Bultman, Michael J., Sorrells, David F., Short, Robert T., Moses, Charley D. Jr., Looke, Richard C., Rawlins, Michael W., Smith, Francis J.
• Primary Examiner(s): Trinh, Sonny
• Application Number:
  US09/567,978
• Time in Patent Office: 2,162 Days
• Field of Search: 455112-113, 455130-131, 455/138, 455/139, 455/141, 455/147, 455/118, 375/325, 375/322, 375/324, 375/329, 375/373, 375/375
• US Class Current: 455/139
• CPC Class Codes: H03D 7/00 Transference of modulation from one carrier to another, e.g. frequency-changing H03D9/00, H03D11/00 take precedence; dielectric amplifiers, magnetic amplifiers, parametric amplifiers used as a frequency-changers H03F

Abstract

Coherent detection of a received EM signal using universal frequency translation (UFT) is described herein. The received EM signal is sampled according to a sub-harmonic LO signal, where the LO signal is in frequency and phase coherence with the received EM signal. The coherent receiver includes a down-converter/demodulator and a synthesizer/loop filter that are both implemented using UFT technology. The down-converter/demodulator samples the EM input signal using a UFT module according to the coherent sub-harmonic LO signal that is generated by the synthesizer/loop filter. The synthesizer/loop filter generates the coherent LO signal using a phase detector, a loop filter, and an up-converter. The phase detector and up-converter are implemented using UFT modules.

Claims

1. A method of coherent down-conversion, comprising:

receiving an electromagnetic (EM) input signal;

generating a sub-harmonic local oscillator (LO) signal that is at least one of frequency coherent and phase coherent with the EM input signal; and

down-converting the EM input signal using said sub-harmonic LO signal;

wherein said step of generating comprises,

dividing the EM input signal into a direct signal and a coupled signal;

comparing the coupled signal with a harmonic of said sub-harmonic LO signal, and generating an error signal representative of a difference between said coupled signal and said harmonic of said sub-harmonic LO signal;

up-converting said error signal according to a reference LO signal, resulting in an up-converted signal having harmonics that repeat at multiples of a frequency of said reference LO signal;

selecting said sub-harmonic LO signal from said up-converted signal for said down-converting step; and

selecting a harmonic of said sub-harmonic LO signal for said comparing step.

2. The method of claim 1, further comprising the steps of:

detecting variations in the frequency and phase of the EM input signal, and adjusting said sub-harmonic LO signal to compensate for said variations.

3. The method of claim 1, wherein the step of comparing comprises the step of comparing at least one of a phase and a frequency of said coupled signal with a phase and a frequency of said harmonic of said sub-harmonic LO signal.

4. The method of claim 1, wherein said error signal represents a phase error between said coupled signal and said harmonic of said sub-harmonic LO signal.

5. The method of claim 1, wherein said error signal represents a frequency error between said coupled signal and said harmonic of said sub-harmonic signal.

6. The method of claim 1, further comprising the step of low-pass filtering the error signal, thereby reducing a noise level of said low-passed error signal.

7. The method of claim 1, wherein said step of selecting said sub-harmonic LO signal comprises the step of bandpass filtering said up-converted signal at a frequency of said sub-harmonic LO signal.

8. The method of claim 1, wherein said step of selecting a harmonic of said sub-harmonic LO signal comprises the step of bandpass filtering said sub-harmonic LO signal at a harmonic of said sub-harmonic LO signal.

9. The method of claim 1, wherein said step of up-converting comprises the step of sampling said error signal according to said reference LO signal.

10. The method of claim 9, wherein said step of sampling comprises the step of transferring energy to a desired harmonic.

11. The method of claim 10, wherein said desired harmonic is said sub-harmonic LO.

12. The method of claim 1, wherein said step of selecting comprises the step of bandpass filtering said harmonic of said sub-harmonic LO signal.

13. The method of claim 1, wherein said step of comparing comprises the step of sampling the coupled signal according to said harmonic of said sub-harmonic signal, to generate said error signal.

14. The method of claim 13, wherein said step of sampling comprises the step of transferring energy from said coupled signal to said error signal.

15. The method of claim 1, wherein said step of down-converting comprises the step of sampling said EM signal according to said sub-harmonic LO signal.

16. The method of claim 15, wherein said step of sampling comprises the step of transferring energy from said EM signal to said down-converted signal.

17. A coherent receiver, for coherently down-converting an electromagnetic (EM) input signal, comprising:

a down-converter that samples said EM input signal according to a coherent sub-harmonic local oscillator (LO) signal that is at least one of frequency and phase coherent with said EM input signal; and

a synthesizer/loop filter that generates said coherent sub-harmonic LO signal, comprising;

a phase detector that generates an error signal representative of a phase or frequency difference between said EM input signal and said coherent sub-harmonic LO signal; and

an up-converter that up-converts said error signal according to a reference LO signal, wherein said up-converter generates said sub-harmonic LO signal.

18. The coherent receiver of claim 17, further comprising a loop filter coupled between said phase detector and said up-converter.

19. The coherent receiver of claim 18, wherein said loop filter removes unwanted noise from said error signal.

20. The coherent receiver of claim 18, further comprising a bandpass filter coupled to an output of said up-converter, wherein said bandpass filter has a passband that is centered on a characteristic frequency f₂ of said reference LO signal.

21. The coherent receiver of claim 20, further comprising a second bandpass filter coupled between said output of said up-converter and said phase detector, wherein said second bandpass filter has a passband that is centered at nf₂.

22. The coherent receiver of claim 21, wherein said phase detector, said loop filter, said up-converter, and said second bandpass filter form a loop that corrects for variations between said received EM signal and said sub-harmonic LO signal.

23. The coherent receiver of claim 17, wherein said down-converter comprises a controlled switch that is controlled by said coherent sub-harmonic LO signal.

24. The coherent receiver of claim 23, wherein said controlled switch transfers energy from said EM input signal to a down-converted signal according to said coherent sub-harmonic LO signal.

25. A coherent receiver for coherently down-converting an electromagnetic (EM) input signal, comprising:

a down-converter comprising a first controlled switch, wherein said first controlled switch samples said EM input signal according to a sub-harmonic local oscillator (LO) signal that is coherent with said EM input signal;

a synthesizer/loop filter that generates said sub-harmonic LO signal, comprising;

a phase detector that generates an error signal at a frequency f₁ representative of a phase or frequency difference between said EM input signal and said sub-harmonic LO signal,

a loop filter for filtering said error signal,

an up-converter comprising a second controlled switch that samples said filtered error signal according to a reference LO to generate said sub-harmonic LO signal at a frequency of f₂ and a harmonic of said sub-harmonic LO signal at a frequency of nf₂, and

a bandpass filter coupled between an output of said up-converter and an input of said phase detector, wherein said bandpass filter has passband that is centered at said harmonic (nf₂) of said sub-harmonic LO signal; and

a second bandpass filter that is coupled between said output of said up-converter and said down-converter, wherein said second bandpass filter has a second passband that is centered at said frequency f₂ of said sub-harmonic LO signal.

26. The coherent receiver of claim 25, wherein said controlled switch transfers energy from said EM signal to a down-converted signal according to said sub-harmonic LO signal.

27. The coherent receiver of claim 25, wherein said sub-harmonic LO signal is phase coherent with said EM input signal.

28. The coherent receiver of claim 25, wherein said sub-harmonic LO signal is frequency coherent with said EM input signal.

29. The coherent receiver of claim 25, wherein said sub-harmonic LO signal is frequency coherent and phase coherent with said EM input signal.

30. The coherent receiver of claim 25, wherein said sub-harmonic LO signal is approximately a sub-harmonic of said EM signal.

31. The coherent receiver of claim 25, wherein said first controlled switch is a field effect transistor (FET) having a gate controlled by said sub-harmonic LO signal.

32. The coherent receiver of claim 25, wherein said second controlled switch is a FET having a gate controlled by said reference LO.

33. The coherent receiver of claim 25, wherein said first controlled switch transfers energy from said EM signal to a down-converted signal.

34. The coherent receiver of claim 25, wherein said second controlled switch transfers energy from said filtered error signal to said sub-harmonic LO signal.

35. The coherent receiver of claim 25, wherein said second controlled switch transfers energy from said filtered error to said frequency of f₂.

36. A coherent receiver for coherently down-converting an electromagnetic (EM) input signal, comprising:

a first field effect transistor (FET), wherein a gate of said first FET is controlled by a sub-harmonic local oscillator (LO) signal that is coherent with said EM input signal;

a synthesizer/loop filter that generates said sub-harmonic LO signal, comprising;

a phase detector that generates an error signal at a frequency f₁ representative of a phase difference between said EM input signal and said sub-harmonic LO signal,

a loop filter for filtering said error signal,

a second FET, wherein a gate of said second FET is controlled by a reference LO to generate said sub-harmonic LO signal at a frequency of f₂ and a harmonic of said sub-harmonic LO signal at a frequency of nf₂, and

a bandpass filter coupled between an output of said up-converter and an input of said phase detector, wherein said bandpass filter has passband that is centered at said harmonic (nf₂) of said sub-harmonic LO signal; and

a second bandpass filter that is coupled between said output of said up-converter and said down-converter, wherein said second bandpass filter has a second passband that is centered at said frequency f₂ of said sub-harmonic LO signal.

37. The coherent receiver of claim 36, wherein said first FET samples said EM signal according to said sub-harmonic LO signal.

38. The coherent receiver of claim 36, wherein said first FET transfers energy from said EM signal to a down-converted signal.

39. The coherent receiver of claim 36, wherein said second FET samples said filtered error signal according to said reference LO signal.

40. The coherent receiver of claim 39, wherein said second FET transfers energy from said filtered error signal according to said reference LO to said sub-harmonic LO signal.

41. The coherent receiver of claim 36, wherein said sub-harmonic LO is one of frequency coherent and phase coherent with said EM input signal.

42. A method of coherent down-conversion, comprising:

receiving an electromagnetic (EM) input signal;

generating a sub-harmonic local oscillator (LO) signal that is at least one of frequency coherent and phase coherent with the EM input signal, said step of generating including up-converting an error signal, said error signal representative of phase or frequency coherence between said sub-harmonic LO signal and said EM input signal; and

down-converting the EM input signal according to said sub-harmonic LO signal.