DC offset, re-radiation, and I/Q solutions using universal frequency translation technology

• US 6,879,817 B1
• Filed: 03/14/2000
• Issued: 04/12/2005
• Est. Priority Date: 04/16/1999
• Status: Expired due to Term

• Current Assignee: ParkerVision, Inc.
• Original Assignee: ParkerVision, Inc.
• Inventors: Young, Jamison L, 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., Johnson, Martin R., Jensen, Jonathan S.
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US09/526,041
• Time in Patent Office: 1,855 Days
• Field of Search: 455/70, 455/118, 455/207, 455/209, 455/296, 455/307, 455313-314, 455/323, 455333-334, 455337-339, 327113-116, 329/315, 329/345, 329/347, 375/324, 375/328, 375/340
• US Class Current: 455/296
• CPC Class Codes: H03C 3/40 using two signal paths the outputs of which have a predetermined phase difference and at least one output being amplitude-modulated
• CPC Class Codes: H03D 3/006 by sampling the oscillations and further processing the samples, e.g. by computing techniques H03D3/007 takes precedence
• 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
• CPC Class Codes: H04B 1/12 Neutralising, balancing, or compensation arrangements
• CPC Class Codes: H04B 1/123 using adaptive balancing or compensation means adaptive filter circuits and algorithms H03H
• CPC Class Codes: H04B 1/28 the receiver comprising at least one semiconductor device having three or more electrodes
• CPC Class Codes: H04B 1/30 for homodyne or synchrodyne receivers demodulator circuits H03D1/22

Abstract

Methods, systems, and apparatuses for down-converting an electromagnetic (EM) signal by aliasing the EM signal, and applications thereof are described herein. Reducing or eliminating DC offset voltages and re-radiation generated when down-converting an electromagnetic (EM) signal is also described herein. Down-converting a signal and improving receiver dynamic range is also described herein.

Claims

1. An apparatus for down-converting an electromagnetic signal, comprising:

a first frequency down-conversion module that receives an input signal, wherein said first frequency down-conversion module down-converts said input signal according to a first control signal and outputs a first down-converted signal;

a second frequency down-conversion module that receives said input signal, wherein said second frequency down-conversion module down-converts said input signal according to a second control signal and outputs a second down-converted signal;

a first subtractor module that subtracts said second down-converted signal from said first down-converted signal and outputs a channel down-converted signal;

a third frequency down-conversion module that receives said input signal, wherein said third frequency down-conversion module down-converts said input signal according to a third control signal and outputs a third down-converted signal;

a fourth frequency down-conversion module that receives said input signal, wherein said fourth frequency down-conversion module down-converts said input signal according to a fourth control signal and outputs a fourth down-converted signal; and

a second subtractor module that subtracts said fourth down-converted signal from said third down-converted signal and outputs a second channel down-converted signal;

wherein said input signal comprises an I/Q modulated signal;

wherein said first channel down-converted signal comprises an I-phase information signal portion of said I/Q modulated signal, and wherein said second channel down-converted signal comprises a Q-phase information signal portion of said I/Q modulated signal; and

wherein said first universal frequency down-conversion module under-samples said input signal according to said first control signal, and said second universal frequency down-conversion module under-samples said input signal according to said second control signal.

2. The apparatus of claim 1, wherein said input signal is a RF carrier signal that is AM, FM, or PM modulated with an information signal.

3. The apparatus of claim 2, wherein said channel down-converted signal is a baseband signal.

4. The apparatus of claim 2, wherein said channel down-converted signal is an intermediate frequency signal.

5. The apparatus of claim 1, wherein said first control signal comprises a first control pulse and said second control signal comprises a second control pulse, wherein said second control signal pulse is delayed relative to said first control signal pulse by 0.5+n cycles of said input signal, wherein n is an integer.

6. The apparatus of claim 1, wherein said first subtractor comprises a differential amplifier.

7. The apparatus of claim 1, wherein said first subtractor and said second subtractor each comprise a differential amplifier.

8. The apparatus of claim 1, further comprising:

a first filter that filters said first down-converted signal;

a second filter that filters said second down-converted signal;

a third filter that filters said third down-converted signal; and

a fourth filter that filters said fourth down-converted signal.

9. The apparatus of claim 8, wherein said first, second, third, and fourth filters each comprise a low-pass filter.

10. The apparatus of claim 9, wherein said low-pass filter comprises a resistor and a capacitor.

11. The apparatus of claim 1, further comprising a low-noise amplifier that amplifies said input signal.

12. The apparatus of claim 1, wherein said first control signal comprises a first control signal pulse, said second control signal comprises a second control signal pulse, said third control signal comprises a third control signal pulse, and said fourth control signal comprises a fourth control signal pulse;

wherein a potentially re-radiated signal comprises attenuated components of said first, second, third, and fourth control signal pulses to form a cumulative frequency; and

wherein said cumulative frequency of said potentially re-radiated signal is chosen to be greater than a frequency of said input signal.

13. The apparatus of claim 1, wherein a first DC offset voltage in said first down-converted signal due to said first frequency down-conversion module and a second DC offset voltage in said second down-converted signal due to said second frequency down-conversion module are substantially cancelled from said first channel output signal in said first subtractor;

and

wherein a third DC offset voltage in said third down-converted signal due to said third frequency down-conversion module and a fourth DC offset voltage in said fourth down-converted signal due to said fourth frequency down-conversion module are substantially cancelled from said second channel output signal in said second subtractor.

14. The apparatus of claim 1, further comprising at least one control signal generator that outputs said first, said second, said third, and said fourth control signal.

15. An apparatus for down-converting an electromagnetic signal, comprising:

a first frequency down-conversion module that receives an input signal, wherein said first frequency down-conversion module down-converts said input signal according to a first control signal and outputs a first down-converted signal;

a second frequency down-conversion module that receives said input signal, wherein said second frequency down-conversion module down-converts said input signal according to a second control signal and outputs a second down-converted signal;

a subtractor module that subtracts said second down-converted signal from said first down-converted signal and outputs a channel down-converted signal;

a third frequency down-conversion module that receives said input signal, wherein said third frequency down-conversion module down-converts said input signal according to a third control signal and outputs a third down-converted signal;

a fourth frequency down-conversion module that receives said input signal, wherein said fourth frequency down-conversion module down-converts said input signal according to a fourth control signal and outputs a fourth down-converted signal; and

a second subtractor module that subtracts said fourth down-converted signal from said third down-converted signal and outputs a second channel down-converted signal;

wherein said input signal comprises an I/Q modulated signal;

wherein said first channel down-converted signal comprises an I-phase information signal portion of said I/Q modulated signal, and wherein said second channel down-converted signal comprises a Q-phase information signal portion of said I/Q modulated signal; and

wherein said first and said second frequency down-conversion modules each comprise a switch and a storage element, wherein a first node of said switch is coupled to anode of said storage element, and a second node of said switch is coupled to a reference potential.

16. The apparatus of claim 15, wherein said storage element comprises a capacitor in series with said input signal, wherein said capacitor reduces a DC offset voltage.

17. An apparatus for down-converting an electromagnetic signal, comprising:

a first frequency down-conversion module that receives an input signal, wherein said first frequency down-conversion module down-converts said input signal according to a first control signal and outputs a first down-converted signal;

a second frequency down-conversion module that receives said input signal, wherein said second frequency down-conversion module down-converts said input signal according to a second control signal and outputs a second down-converted signal;

a subtractor module that subtracts said second down-converted signal from said first down-converted signal and outputs a channel down-converted signal;

a third frequency down-conversion module that receives said input signal, wherein said third frequency down-conversion module down-converts said input signal according to a third control signal and outputs a third down-converted signal;

a fourth frequency down-conversion module that receives said input signal, wherein said fourth frequency down-conversion module down-converts said input signal according to a fourth control signal and outputs a fourth down-converted signal; and

a second subtractor module that subtracts said fourth down-converted signal from said third down-converted signal and outputs a second channel down-converted signal;

wherein said input signal comprises an I/Q modulated signal;

wherein said first channel down-converted signal comprises an I-phase information signal portion of said I/Q modulated signal, and wherein said second channel down-converted signal comprises a Q-phase information signal portion of said I/Q modulated signal; and

wherein a second control signal pulse of said second control signal occurs 1.5 cycles of a frequency of said input signal after the occurrence of a first control signal pulse of said first control signal;

wherein a fourth control signal pulse of said fourth control signal occurs 1.5 cycles of said frequency of said input signal after the occurrence of a third control signal pulse of said fourth control signal; and

wherein said third control signal pulse occurs 0.75 cycles of said frequency of said input signal after the occurrence of said first control signal pulse.

18. The apparatus of claim 17, wherein a re-radiated signal comprises attenuated components of said first, second, third, and fourth control signal pulses to form a cumulative frequency, wherein a ratio of said cumulative frequency of said re-radiated signal to said frequency of said input signal is substantially 4:

3.

19. An apparatus for down-converting an electromagnetic signal, comprising:

a first frequency down-conversion module that receives an input signal, wherein said first frequency down-conversion module down-converts said input signal according to a first control signal and outputs a first down-converted signal;

a second frequency down-conversion module that receives said input signal, wherein said second frequency down-conversion module down-converts said input signal according to a second control signal and outputs a second down-converted signal;

a subtractor module that subtracts said second down-converted signal from said first down-converted signal and outputs a channel down-converted signal;

a third frequency down-conversion module that receives said input signal, wherein said third frequency down-conversion module down-converts said input signal according to a third control signal and outputs a third down-converted signal;

a fourth frequency down-conversion module that receives said input signal, wherein said fourth frequency down-conversion module down-converts said input signal according to a fourth control signal and outputs a fourth down-converted signal; and

a second subtractor module that subtracts said fourth down-converted signal from said third down-converted signal and outputs a second channel down-converted signal;

wherein said first frequency down-conversion module samples said input signal according to said first control signal, said second frequency down-conversion module samples said input signal according to said second control signal, said third frequency down-conversion module samples said input signal according to said third control signal, and said fourth frequency down-conversion module samples said input signal according to said fourth control signal.

20. The apparatus of claim 19, wherein said input signal comprises an I/Q modulated signal.

21. The apparatus of claim 19, wherein said first, said second, said third, and said fourth frequency down-conversion modules each comprise a switch and a storage element, wherein a first node of said switch is coupled to a node of said storage element, and a second node of said switch is coupled to a reference potential.

22. The apparatus of claim 21, wherein said storage element comprises a capacitor.

23. The apparatus of claim 22, wherein said capacitor reduces a DC offset voltage at least due to charge injection effects.

24. The apparatus of claim 22, wherein said capacitor is coupled in series with said input signal.

25. The apparatus of claim 19, wherein said first, said second, said third, and said fourth frequency down-conversion modules each comprise a switch and a storage element, wherein a first node of said storage element is coupled to a node of said switch, and a second node of said storage element is coupled to a reference potential.

26. An apparatus for down-converting an electromagnetic signal, comprising:

a first frequency down-conversion module that receives an input signal, wherein said first frequency down-conversion module down-converts said input signal according to a first control signal and outputs a first down-converted signal;

a second frequency down-conversion module that receives said input signal, wherein said second frequency down-conversion module down-converts said input signal according to a second control signal and outputs a second down-converted signal;

a subtractor module that subtracts said second down-converted signal from said first down-converted signal and outputs a channel down-converted signal;

a third frequency down-conversion module that receives said input signal, wherein said third frequency down-conversion module down-converts said input signal according to a third control signal and outputs a third down-converted signal;

a fourth frequency down-conversion module that receives said input signal, wherein said fourth frequency down-conversion module down-converts said input signal according to a fourth control signal and outputs a fourth down-converted signal; and

a second subtractor module that subtracts said fourth down-converted signal from said third down-converted signal and outputs a second channel down-converted signal;

wherein said input signal comprises an I/Q modulated signal;

wherein said first channel down-converted signal comprises an I-phase information signal portion of said I/Q modulated signal, and wherein said second channel down-converted signal comprises a Q-phase information signal portion of said I/Q modulated signal; and

wherein said first, said second, said third, and said fourth frequency down-conversion modules each comprise a switch and a storage element, wherein a first node of said switch is coupled to anode of said storage element, and a second node of said switch is coupled to a reference potential.

27. The apparatus of claim 26, wherein said storage element comprises a capacitor.

28. The apparatus of claim 27, wherein said capacitor reduces a DC offset voltage at least due to charge injection effects.

29. The apparatus of claim 27, wherein said capacitor is coupled in series with said input signal.

30. An apparatus for down-converting an electromagnetic signal, comprising:

a first frequency down-conversion module that receives an input signal, wherein said first frequency down-conversion module down-converts said input signal according to a first control signal and outputs a first down-converted signal;

a second frequency down-conversion module that receives said input signal, wherein said second frequency down-conversion module down-converts said input signal according to a second control signal and outputs a second down-converted signal;

a subtractor module that subtracts said second down-converted signal from said first down-converted signal and outputs a channel down-converted signal;

a third frequency down-conversion module that receives said input signal, wherein said third frequency down-conversion module down-converts said input signal according to a third control signal and outputs a third down-converted signal;

a fourth frequency down-conversion module that receives said input signal, wherein said fourth frequency down-conversion module down-converts said input signal according to a fourth control signal and outputs a fourth down-converted signal;

a second subtractor module that subtracts said fourth down-converted signal from said third down-converted signal and outputs a second channel down-converted signal; and

a control signal generator, wherein said control signal generator comprises;

a local oscillator;

a 180 degree phase shifter coupled to an output of said local oscillator;

a first divide-by-two module coupled to said output of said local oscillator;

a second divide-by-two module coupled to an output of said 180 degree phase shifter;

a first pulse generator coupled to an output of said first divide-by-two module, wherein said first pulse generator outputs said first control signal;

a second pulse generator coupled to an inverting output of said first divide-by-two module, wherein said second pulse generator outputs said second control signal;

a third pulse generator coupled to an output of said second divide-by-two module, wherein said third pulse generator outputs said third control signal; and

a fourth pulse generator coupled to an inverting output of said second divide-by-two module, wherein said fourth pulse generator outputs said fourth control signal.

31. A method of down-converting an electromagnetic signal, comprising the steps of:

(1) receiving an input signal;

(2) frequency down-converting the input signal with a first frequency down-conversion module to a first down-converted signal;

(3) frequency down-converting the input signal with a second frequency down-conversion module to a second down-converted signal; and

(4) subtracting the second down-converted signal from the first down-converted signal to form an output signal;

wherein step (2) comprises the step of;

sampling the input signal according to a first control signal; and

wherein step (3) comprises the step of;

sampling the input signal according to a second control signal;

wherein the first control signal comprises a first pulse, and wherein the second control signal comprises a second pulse; and

wherein the second pulse is delayed relative to the first pulse by 0.5+n cycles of the input signal, wherein n is an integer.

32. The method of claim 31, further comprising the step of:

(5) amplifying the output signal.

33. The method of claim 32, further comprising the step of:

(6) differentially amplifying the first and second down-converted signals, wherein step (6) comprises steps (4) and (5).

34. The method of claim 31, further comprising the step of:

(5) filtering the first down-converted signal and the second down-converted signal.

35. The method of claim 31, further comprising

(5) frequency down-converting the input signal with a third universal frequency down-conversion module to a third down-converted signal;

(6) frequency down-converting the input signal with a fourth universal frequency down-conversion module to a fourth down-converted signal; and

(7) subtracting the fourth down-converted signal from the third down-converted signal to form a second output signal.

36. The method of claim 31, wherein the first and second frequency down-conversion modules each comprise a capacitor in series with the input signal,

wherein step (2) further comprises the step of:

(B) reducing a first DC offset voltage in the first down-converted signal using the capacitor of the first frequency down-conversion module;

wherein step (3) further comprises the step of;

(B) reducing a second DC offset voltage in the second down-converted signal using the capacitor of the second frequency down-conversion module;

wherein the first and second DC offset voltages are due at least to charge injection effects in the first and second frequency down-conversion modules, respectively, from interaction with the first and second control signals, respectively.

37. A method of down-converting an electromagnetic signal, comprising the steps of:

(1) receiving an input signal;

(2) frequency down-converting the input signal with a first frequency down-conversion module to a first down-converted signal;

(3) frequency down-converting the input signal with a second frequency down-conversion module to a second down-converted signal;

(4) subtracting the second down-converted signal from the first down-converted signal to form an output signal;

(5) frequency down-converting the input signal with a third frequency down-conversion module to a third down-converted signal;

(6) frequency down-converting the input signal with a fourth frequency down-conversion module to a fourth down-converted signal; and

(7) subtracting the fourth down-converted signal from the third down-converted signal to form a second output signal;

wherein step (2) comprises the step of;

(A) sampling the input signal according to a first control signal;

wherein step (3) comprises the step of;

(A) sampling the input signal according to a second control signal;

wherein step (5) comprises the step of;

(A) sampling the input signal according to a third control signal; and

wherein step (6) comprises the step of;

(A) sampling the input signal according to a fourth control signal.

38. The method of claim 37,

wherein step (2)(A) comprises the step of:

(i) generating the first control signal;

wherein step (3)(A) comprises the step of;

(i) generating the second control signal, wherein the second control signal is a phase-shifted version of the first control signal;

wherein step (5)(A) comprises the step of;

(i) generating the third control signal, wherein the third control signal is a phase-shifted version of the first control signal; and

wherein step (6)(A) comprises the step of;

(i) generating the fourth control signal, wherein the fourth control signal is a phase-shifted version of the first control signal.

39. The method of claim 37, wherein the first control signal comprises a first control signal pulse, the second control signal comprises a second control signal pulse, the third control signal comprises a third control signal pulse, and the fourth control signal comprises a fourth control signal pulse, and wherein the method comprises further comprises the step of:

(8) re-radiating a signal that comprises attenuated components of the first, second, third, and fourth control signal pulses, wherein the attenuated components of the first, second, third, and fourth control signal pulses form a cumulative frequency; and

(9) configuring the first, second, third, and fourth control signal pulses such that the cumulative frequency is greater than a frequency of the input signal.

40. The method of claim 37,

wherein step (4) comprises the step of:

(A) canceling a first DC offset voltage in the first down-converted signal and a second DC offset voltage in the second down-converted signal; and

wherein step (7) comprises the step of;

(A) canceling a third DC offset voltage in the third down-converted signal and a fourth DC offset voltage in the fourth down-converted signal.

41. The method of claim 40, wherein the first, second, third, and fourth DC offset voltages are at least generated by the first, second, third, and fourth frequency down-conversion modules, respectively.

42. The method of claim 37, wherein the first, second, third, and fourth frequency down-conversion modules each comprise a capacitor in series with the input signal,

wherein step (2) further comprises the step of:

(B) reducing a first DC offset voltage in the first down-converted signal with the capacitor of first frequency down-conversion module;

wherein step (3) further comprises the step of;

(B) reducing a second DC offset voltage in the second down-converted signal with the capacitor of second frequency down-conversion module;

wherein step (5) further comprises the step of;

(B) reducing a third DC offset voltage in the third down-converted signal with the capacitor of third frequency down-conversion module; and

wherein step (6) further comprises the step of;

(B) reducing a fourth DC offset voltage in the fourth down-converted signal with the capacitor of fourth frequency down-conversion module;

wherein the first, second, third, and fourth DC offset voltages are at least due to charge injection effects in the first, second, third, and fourth frequency down-conversion modules, respectively, from interaction with the first, second, third, and fourth control signals, respectively.

43. A method of down-converting an electromagnetic signal, comprising the steps of:

(1) receiving an input signal;

(2) frequency down-converting the input signal with a first frequency down-conversion module to a first down-converted signal;

(3) frequency down-converting the input signal with a second frequency down-conversion module to a second down-converted signal;

(4) subtracting the second down-converted signal from the first down-converted signal to form an output signal;

(5) frequency down-converting the input signal with a third frequency down-conversion module to a third down-converted signal;

(6) frequency down-converting the input signal with a fourth frequency down-conversion module to a fourth down-converted signal; and

(7) subtracting the fourth down-converted signal from the third down-converted signal to form a second output signal;

wherein the input signal comprises an I/Q modulated signal, and

wherein step (2) comprises the step of;

(A) frequency down-converting the input signal to a non-inverted I-phase signal portion of the I/Q modulated signal;

wherein step (3) comprises the step of;

(A) frequency down-converting the input signal to an inverted Q-phase signal portion of the I/Q modulated signal.

wherein step (5) comprises the step of;

(A) frequency down-converting the input signal to a non-inverted Q-phase signal portion of the I/Q modulated signal; and

wherein step (6) comprises the step of;

(A) frequency down-converting the input signal to an inverted I-phase signal portion of the I/Q modulated signal.

44. The method of claim 43,

wherein step (2)(A) comprises the step of:

(i) under-sampling a first phase of the in-phase signal portion of the I/Q modulated signal;

wherein step (3)(A) comprises the step of;

(i) under-sampling a second phase of the in-phase signal portion of the I/Q modulated signal, wherein the second phase of the in-phase signal portion is of an opposite phase to the first phase of the in-phase signal portion;

wherein step (5)(A) comprises the step of;

(i) under-sampling a third phase of the quadrature-phase signal portion of the I/Q modulated signal; and

wherein step (6)(A) comprises the step of;

(i) under-sampling a fourth phase of the quadrature-phase signal portion of the I/Q modulated signal, wherein the fourth phase of the quadrature-phase signal portion is of an opposite phase to the third phase of the quadrature-phase signal portion.

45. The method of claim 44,

wherein step (3)(A)(i) comprises the step of:

(a) under-sampling the I/Q modulated signal 1.5 cycles of a frequency of the I/Q modulated signal after under-sampling the I/Q modulated signal in step (2)(A)(i);

wherein step (5)(A)(i) comprises the step of;

(a) under-sampling the I/Q modulated signal 0.75 cycles of the frequency of the I/Q modulated signal after under-sampling of the I/Q modulated signal occurs in step (2)(A)(i); and

wherein step (6)(A)(i) comprises the step of;

(a) under-sampling the I/Q modulated signal 1.5 cycles of the frequency of the I/Q modulated signal after under-sampling of the I/Q modulated signal occurs in step (5)(A)(i).

46. The method of claim 45, wherein step (2)(A) further comprises the step of:

(ii) under-sampling the I/Q modulated signal 3.0 cycles of the frequency of the I/Q modulated signal after a previous under-sample of the I/Q modulated signal.

47. The method of claim 43, wherein the first, second, third, and fourth frequency down-conversion modules each comprise a capacitor in series with the input signal,

wherein step (2) further comprises the step of:

(B) reducing a first DC offset voltage in the first down-converted signal using the capacitor of the first frequency down-conversion module;

wherein step (3) further comprises the step of;

(B) reducing a second DC offset voltage in the second down-converted signal using the capacitor of the second frequency down-conversion module;

wherein step (5) further comprises the step of;

(B) reducing a third DC offset voltage in the third down-converted signal using the capacitor of the third frequency down-conversion module; and

wherein step (6) further comprises the step of;

(B) reducing a fourth DC offset voltage in the fourth down-converted signal using the capacitor of the fourth frequency down-conversion module;

wherein the first, second, third, and fourth DC offset voltages are due to at least charge injection effects in the first, second, third, and fourth frequency down-conversion modules, respectively, from interaction with the first, second, third, and fourth control signals, respectively.