WIDEBAND QUADRATURE ERROR DETECTION AND CORRECTION

• US 20150030103A1
• Filed: 07/24/2014
• Published: 01/29/2015
• Est. Priority Date: 05/20/2013
• Status: Active Grant

• Current Assignee: Analog Devices, Inc.
• Original Assignee: Analog Devices, Inc.
• Inventors: Hormis, Raju, Bal, Steven R., Montalvo, Antonio, McLaurin, David J., McCormick, Martin
• Granted Patent: US 11,012,201 B2
• Time in Patent Office: Days
• US Class Current: 375/296
• CPC Class Codes: H04L 1/243 at the transmitter, using a loop-back
• CPC Class Codes: H04L 27/364 Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels

Abstract

A transmission module is provided that includes a transmitter, a loopback receiver, and a QEC controller. The QEC controller identifies quadrature imbalance in the transmitter based at least one a comparison of the data signals at the output of the loopback receiver with data signals at the input of the transmitter. Based on the comparison, the QEC controller can adjust one or more characteristics of the transmitter to correct quadrature errors in the transmitter.

Claims

1. An apparatus, comprising:

a transmitter;

a loopback receiver;

a controller configured to;

receive a first data signal from the loopback receiver,

identify an in-phase/quadrature-phase imbalance in the transmitter based at least on a comparison of the first data signal received from the loopback receiver with a buffered data signal that corresponds to a data signal received by the transmitter as an input, and

correct the in-phase/quadrature-phase imbalance present in the transmitter based at least in part on the comparison of the first data signal received from the loopback receiver with the buffered data signal.

2. The apparatus of claim 1, wherein the controller is configured to identify the in-phase/quadrature-phase based on a cross-covariance of the first data signal received from the loopback receiver and the buffered data signal that corresponds to a data signal received by the transmitter.

3. The apparatus of claim 1, wherein the controller is configured to estimate low-rank signals using singular value decomposition.

4. The apparatus of claim 1, wherein the controller is further configured to generate a precoder matrix configured to correct the I/Q imbalances.

5. The apparatus of claim 4, wherein the controller configured to generate the precoder matrix based on a cross-covariance of the data signal received from the loopback receiver and the buffered data signal that corresponds to a data signal received by the transmitter.

6. The apparatus of claim 1, wherein the controller is further configured to generate at least one of a gain correction, phase correction, or group delay correction parameter.

7. The apparatus of claim 6, wherein the controller is configured to generate at least one of the gain correction, phase correction, or group delay correction parameter based on a minimum mean square error (MMSE) channel estimate.

8. The apparatus of claim 6, wherein the controller is configured to generate at least one of the gain correction, phase correction, or group delay correction parameter based on a minimum mean square error (MMSE) channel estimate.

9. The apparatus of claim 6, wherein the controller is configured to generate at least one of the gain correction, phase correction, or group delay correction parameter based on a parameterized linear transformation.

10. An electronically-implemented method of quadrature error correction comprising:

receiving a first data signal from a loopback receiver,

identifying an in-phase/quadrature-phase imbalance in the transmitter based at least on a comparison of the first data signal received from the loopback receiver with a buffered data signal that corresponds to a data signal received by the transmitter, and

correcting the in-phase/quadrature-phase imbalance present in the transmitter based at least in part on the comparison of the first data signal received from the loopback receiver with the buffered data signal.

11. The method of claim 10, further comprising identifying the in-phase/quadrature-phase based on a cross-covariance of the first data signal received from the loopback receiver and the buffered data signal that corresponds to a data signal received by the transmitter.

12. The method of claim 10, further comprising estimating low-rank signals using singular value decomposition.

13. The method of claim 10, further comprising generating a precoder matrix configured to correct the I/Q imbalances.

14. The method of claim 13, further comprising generating the precoder matrix based on a cross-covariance of the data signal received from the loopback receiver and the buffered data signal that corresponds to a data signal received by the transmitter.

15. The method of claim 10, further comprising generating at least one of a gain correction, phase correction, or group delay correction parameter.

16. The method of claim 15, further comprising generating at least one of the gain correction, phase correction, or group delay correction parameter based on a minimum mean square error (MMSE) channel estimate.

17. The method of claim 15, further comprising generating at least one of the gain correction, phase correction, or group delay correction parameter based on a minimum mean square error (MMSE) channel estimate.

18. The method of claim 15, further comprising generating at least one of the gain correction, phase correction, or group delay correction parameter based on a parameterized linear transformation.

19. An apparatus comprising:

a transmitter;

a loopback receiver;

a means for quadrature error correction comprising;

a means for receiving a first data signal from the loopback receiver that corresponds to a second data signal generated by the transmitter as an output,

a means for identifying an in-phase/quadrature-phase imbalance in the transmitter based at least on a comparison of the first data signal received from the loopback receiver with a buffered data signal that corresponds to a data signal received by the transmitter, and

a means for correcting the in-phase/quadrature-phase imbalance present in the transmitter based at least in part on the comparison of the first data signal received from the loopback receiver with the buffered data signal.

20. A non-transitory computer-readable medium comprising code that, when executed, causes an apparatus to:

receive a first data signal from a loopback receiver,

identify an in-phase/quadrature-phase imbalance in the transmitter based at least on a comparison of the first data signal received from the loopback receiver with a buffered data signal that corresponds to a data signal received by the transmitter, and

correct the in-phase/quadrature-phase imbalance present in the transmitter based at least in part on the comparison of the first data signal received from the loopback receiver with the buffered data signal.