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

• US 20050143042A1
• Filed: 02/17/2005
• Published: 06/30/2005
• Est. Priority Date: 04/16/1999
• Status: Active Grant

• 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., Young, Jamison L., Rawlins, Michael W., Johnson, Martin R., Jensen, Jonathan S.
• Granted Patent: US 7,539,474 B2
• Time in Patent Office: Days
• US Class Current: 455/313
• 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. (canceled)

2. An apparatus for down-converting an input signal, comprising:

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

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

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

wherein the first frequency down-conversion module comprises a first switch and a first storage element, wherein the first switch is coupled to the first storage element at a first node and coupled to a first reference potential; and

wherein the second frequency down-conversion module comprises a second switch and a second storage element, wherein the second switch is coupled to the second storage element at a second node and coupled to a second reference potential;

3. The apparatus of claim 2, wherein:

the first switch is coupled in parallel to the input signal; and

the second switch is coupled in parallel to the input signal.

4. The apparatus of claim 2, wherein:

the first storage element is coupled in series between the input signal and the first node; and

the second storage element is coupled in series between the input signal and the second node.

5. The apparatus of claim 4, wherein:

the first storage element comprises a first capacitor; and

the second storage element comprises a second capacitor.

6. The apparatus of claim 5, wherein:

the first capacitor reduces a first DC offset voltage in the first down-converted signal; and

the second capacitor reduces a second DC offset voltage in the second down-converted signal;

wherein the first DC offset voltage is at least due to charge injection effects in the first down-conversion module; and

wherein the second DC offset voltage is at least due to charge injection effects in the second down-conversion module.

7. The apparatus of claim 2, wherein:

the first switch under-samples the input signal according to the first control signal; and

the second switch under-samples the input signal according to the second control signal.

8. The apparatus of claim 2, wherein:

the first control signal comprises a first pulse; and

the second control signal comprises a second pulse;

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

9. The apparatus of claim 2, further comprising:

a first amplifier coupled between the input signal and the first frequency down-conversion module; and

a second amplifier coupled between the input signal and the second frequency down-conversion module.

10. The apparatus of claim 2, wherein:

the first reference potential is a first ground potential; and

the second reference potential is a second ground potential.

11. The apparatus of claim 2, further comprising:

a first filter coupled between the first node and a non-inverting input of the subtractor module;

a second filter coupled between the second node and an inverting input of the subtractor module.

12. The apparatus of claim 11, wherein:

the first filter comprises a first low pass filter; and

the second filter comprises a second low pass filter.

13. 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 a first 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 in-phase/quadrature-phase (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 I-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 Q-phase signal portion of the I/Q modulated signal.

14. The method of claim 13,

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.

15. The method of claim 14,

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).

16. The method of claim 15, 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.

17. The method of claim 13, 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.

18. A method of down-converting an input signal, comprising:

(1) receiving a radio-frequency (RF) I/Q input signal;

(2) down-converting the RF I/Q input signal with a first down-conversion module according to a first energy transfer signal to form a first down-converted signal; and

(3) down-converting the RF I/Q input signal with a second down-conversion module according to a second energy transfer signal to form a second down-converted signal;

wherein the second energy transfer signal is phase-shifted by 90+m·

180 degrees of a frequency of the RF I/Q input signal relative to the first energy transfer signal, wherein m is any integer greater than or equal to 1;

wherein the first down-converted signal comprises an in-phase information signal; and

wherein the second down-converted signal comprises a quadrature-phase information signal.

19. The method of claim 18,

wherein step (2) comprises the step of:

(A) under-sampling the RF I/Q input signal according to the first energy transfer signal; and

wherein step (3) comprises the step of;

(A) under-sampling the RF I/Q input signal according to the second energy transfer signal.

20. The method of claim 19,

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

(i) generating the first energy transfer signal; and

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

(i) generating the second energy transfer signal.

21. The method of claim 20,

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

(a) generating a first train of pulses; and

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

(a) generating a second train of pulses;

wherein the first and the second train of pulses have non-negligible apertures that tend away from zero time in duration, thereby lowering impedances of the first and the second down-conversion modules, respectively.

22. The method of claim 21, wherein steps (2)(A)(i)(a) and (3)(A)(i)(a) each comprise generating the first and the second train of pulses to have apertures approximately equal to 180+360·

n degrees of a frequency of the RF I/Q input signal, wherein n is any integer greater than or equal to 0.

23. The method of claim 22, wherein steps (2)(A)(i)(a) and (3)(A)(i)(a) each comprise generating the first and the second train of pulses to have non-overlapping pulses with respect to each other.

24. The method of claim 20,

wherein step (2)(A) and (3)(A) each comprise the step of:

(ii) transferring non-negligible amounts of energy from the RF I/Q input signal, at a rate that is substantially equal to a harmonic of the RF I/Q input signal, to form the first and the second down-converted signals, respectively.

25. The method of claim 20,

wherein step (2)(A) and (3)(A) each comprise the step of:

(ii) transferring non-negligible amounts of energy from the RF I/Q input signal, at a rate that is substantially equal to a sub-harmonic of the RF I/Q input signal, to form the first and the second down-converted signals, respectively.