Coherent adaptive calibration system and method

• US 6,842,489 B2
• Filed: 03/17/2003
• Issued: 01/11/2005
• Est. Priority Date: 06/03/1999
• Status: Expired due to Fees

• Current Assignee: Axiom Microdevices Incorporated (Skyworks Solutions Incorporated)
• Original Assignee: Ditrans IP, Inc.
• Inventors: Masenten, Wesley K.
• Primary Examiner(s): Ha, Dac V.
• Application Number:
  US10/391,038
• Publication Number:
  US 20030179836A1
• Time in Patent Office: 666 Days
• Field of Search: 375/261, 375/316, 375/317, 375/324, 375/340, 375/345, 375/349, 455/63, 455/67.3, 455/138, 455/232.1, 455/234.1, 455/239.1, 455/340.1, 455/245.1, 455/247.1, 455/250.1, 455/326, 455/240.1, 329/308, 329/363
• US Class Current: 375/261
• CPC Class Codes: H03D 3/008 Compensating DC offsets
• CPC Class Codes: H03D 3/009 Compensating quadrature phase or amplitude imbalances
• CPC Class Codes: H04L 2027/0016 Stabilisation of local oscillators
• CPC Class Codes: H04L 27/0014 Carrier regulation of chaotic carriers H04L27/001; for multicarrier receivers H04L27/2657

Abstract

A receiver is adaptively calibrated by using a coherent reference signal. The reference signal is selected to be offset from a center frequency of the calibration signal such that the resultant product is offset from baseband by some small amount. The resultant product is used to determine a next value of the calibration parameters.

Claims

1. A coherent adaptive calibration method for a receiver, comprising:

removing at least a portion of a DC offset from a series of first channel signal samples to produce a series of corrected first channel samples;

computing a linear combination of said series of corrected first channel samples and a series of second channel signal samples to produce a series of corrected second channel samples, wherein parameters for said linear combination are computed at least in part from a gain imbalance correction parameter and a phase correction parameter;

down-converting said series of corrected first channel samples to produce a first in-phase down-converted signal;

down-converting said series of corrected second channel samples to produce a quadrature down-converted signal; and

determining a next value of said gain imbalance correction parameter based upon at least said first in-phase down-converted signal and said quadrature down-converted signal.

2. The method of claim 1, wherein said linear combination of said series of corrected first channel samples an series of second channel signal samples comprises multiplying said series of first channel signal samples by said phase correction parameter.

3. The method of claim 1 wherein said linear combination of said series of corrected first channel samples and said series of second channel signal samples comprises adding an offset to remove at least a portion of a DC offset of said series of second channel signal samples.

4. The method of claim 1, wherein said linear combination of said series of corrected first channel samples and said series of second channel signal samples comprises adding an offset to remove at least a portion of a DC offset of said series of second channel signal samples to produce offset samples, multiplying said offset samples by said gain imbalance correction parameter, and multiplying said series of corrected first channel samples by said phase correction parameter.

5. The method of claim 1, wherein said determining a next value of said gain imbalance correction parameter comprises a ratio corresponding to said first in-phase down-converted signal and said quadrature down-converted signal.

6. The method of claim 1 wherein the series of channel signal samples comprises a received calibration signal.

7. The method of claim 1, wherein the series of channel signal samples comprises energy received over the air and a calibration signal from an internal source.

8. The method of claim 1, wherein said determining a next value of said gain imbalance correction parameter comprises using a stochastic gradient equation.

9. The method of claim 1, wherein said down-converting said series of corrected second channel samples produce a quadrature down-converted signal comprises multiplying said series of corrected second channel samples by a sine wave signal.

10. The method of claim 1, further comprising:

down-converting said series of corrected second channel samples to produce a second in-phase down-converted signal;

filtering said second in-phase down-converted signal to determine a phase error measurement; and

determining a next value of said phase correction parameter based upon said gain imbalance corrector parameter and said phase error measurement.

11. The method of claim 1, wherein said phase correction parameter is obtained using an adaptive correction algorithm.

12. The method of claim 1, wherein said gain imbalance correction parameter is obtained using an adaptive correction algorithm.

13. A receiver, comprising:

a first correction module to remove at least a portion of a DC offset from a series of first channel signal samples to produce a series of corrected first channel samples;

a linear combiner to combine said series of corrected first channel samples and a series of corrected second channel signal samples to produce a series of corrected second channel samples, wherein parameters for said linear combiner are computed at least in part from a gain imbalance correction parameter and a phase correction parameter;

a first down-converter to down-convert said series of corrected first channel samples to produce a first in-phase down-converted signal;

a second down-converter to down-convert said series of corrected second channel samples to produce a quadrature down-converted signal; and

an adaptive correction module to compute a next value of said gain imbalance correction parameter based upon at least said first in-phase down-converted signal and said quadrature down-converted signal.

14. The receiver of claim 13, wherein said linear combiner is configured to multiply said series of first channel signal samples by said phase correction parameter.

15. The receiver of claim 13, wherein said linear combiner is configured at least in part to add an offset to remove at least a portion of a DC offset of said series of corrected second channel signal samples.

16. The receiver of claim 13, wherein said linear combiner is configured at least in part to add an offset to remove at least a portion of a DC offset of said series of second channel signal samples to produce offset samples, multiply said offset samples by said gain imbalance correction parameter, and multiplying said corrected first channel samples by said phase correction parameter.

17. The receiver of claim 13, wherein said adaptive correction module is configured to compute a ratio corresponding to said first in-phase down-converted signal and said quadrature down-converted signal.

18. The receiver of claim 13, wherein the series of channel signal samples comprises a calibration signal.

19. The receiver of claim 13, wherein the series of channel signal samples comprises a signal from an external source and a calibration signal from an internal source.

20. The receiver of claim 13, wherein said adaptive correction module comprises a stochastic gradient equation.

21. The receiver of claim 13, wherein said adaptive correction module is configured to determine a next value of said phase correction parameter based upon a gain imbalance measurement and a phase error measurement.

22. The receiver of claim 13, wherein said phase correction parameter is obtained using an adaptive correction algorithm.

23. The receiver of claim 13, wherein said adaptive correction module comprises an adaptive phase correction algorithm.

24. The receiver of claim 13, wherein said adaptive correction module comprises an adaptive gain correction algorithm.

25. The receiver of claim 13, wherein said first down-converter is configured to operate on digital data.

26. The receiver of claim 13, wherein said adaptive correction module is configured to operate on digital data.

27. A receiver, comprising:

a first correction module to remove at least a portion of a DC offset from a series of first channel signal samples to produce a series of corrected first channel samples;

a linear combiner to combine said series of corrected first channel samples and a series of corrected second channel signal samples to produce a series of corrected second channel samples, wherein parameters for said linear combiner are computed at least in part from a gain imbalance correction parameter and a phase correction parameter;

a first down-converter to down-convert said series of corrected first channel samples to produce an in-phase down-converted signal;

a second down-converter to down-convert said series of corrected second channel samples to produce a quadrature down-converted signal; and

means for computing said gain imbalance correction parameter and said phase correction parameter using at least said in-phase and quadrature down-converted signals.