Method and apparatus for low-complexity frequency dependent IQ imbalance compensation

Patent metadata

Field	Value
Publication number	US-9712369-B2
Application number	US-201614987022-A
Country	US
Kind code	B2
Filing date	Jan 4, 2016
Priority date	Nov 3, 2015
Publication date	Jul 18, 2017
Grant date	Jul 18, 2017

Abstract

Methods and apparatuses are provided in which a processor of a transceiver selects one of a real component of a complex signal and an imaginary component of the complex signal. The complex signal has IQ imbalance. An adaptive filter of the transceiver performs a real multiplication operation using an adaptive filter coefficient and the one of the real component and the imaginary component of the complex signal to generate a complex compensation signal. An adder of the transceiver sums the complex signal and the complex compensation signal to generate a compensated signal in which the IQ imbalance is corrected. The compensated signal is output for digital processing.

First claim

What is claimed is:

1. A method, comprising:
selecting, by a processor of a transceiver, one of a real component of a complex signal and an imaginary component of the complex signal;
performing, by an adaptive filter of the transceiver, a real multiplication operation using an adaptive filter coefficient and the one of the real component and the imaginary component of the complex signal to generate a complex compensation signal; and
generating a compensated signal based on summing, by an adder of the transceiver, the complex signal and the complex compensation signal,
wherein a filter adaptation module adapts the adaptive filter coefficient in subsequent iterations using the compensated signal.

2. The method of claim 1 , wherein the adaptive filter coefficient and the one of the real component and the imaginary component are real multiplier values.

3. The method of claim 1 , wherein the complex signal is a received radio frequency signal having been down-converted through two filters with a 90 degree phase offset for quadrature reception with resulting components having been passed through low-pass filters.

4. The method of claim 1 , wherein the real component is an in-phase (I) component of the complex signal and the imaginary component is a quadrature (Q) component of the complex signal.

5. The method of claim 4 , wherein the adaptive filter is a finite impulse response (FIR) filter.

6. The method of claim 1 , wherein the complex signal has IQ imbalance, and the complex compensated signal corrects the IQ imbalance of the complex signal.

7. The method of claim 1 , wherein summing the complex signal and the complex compensation signal cancels an image term of the complex signal using a scalable term in the complex compensation signal.

8. The method of claim 1 , wherein the compensated signal is used in transmission or reception IQ imbalance compensation.

9. The method of claim 1 , wherein the complex compensation signal is expressed as:

w
⁢

⁢
2
⁢

(
t
)

*

(

z
*

⁡

(
t
)

+

z
⁡

(
t
)

)

2

=

1
2

⁢
w
⁢

⁢
2
⁢

(
t
)

*

(

g
2
*

⁡

(
t
)

+

g
1

⁡

(
t
)

)

*

s
⁡

(
t
)

+

1
2

⁢
w
⁢

⁢
2
⁢

(
t
)

*

(

g
1
*

⁡

(
t
)

+

g
2

⁡

(
t
)

)

*

s
*

⁡

(
t
)

where z(t) is the complex signal, z*(t) is a conjugate of z(t), s(t) is a real passband signal, s*(t) is a conjugate of s(t), g(t) is a gain, g*(t) is a conjugate of g(t), and w2(t) is a weight coefficient.

10. An apparatus comprising:
a processor configured to select one of a real component of a complex signal and an imaginary component of the complex signal;
an adaptive filter configured to perform a real multiplication operation using an adaptive filter coefficient and the one of the real component and the imaginary component of the complex signal to generate a complex compensation signal;
an adder configured to sum the complex signal and the complex compensation signal to generate a compensated signal; and
a filter adaptation module configured to adapt the adaptive filter coefficient in subsequent iterations using the compensated signal.

11. The apparatus of claim 10 , wherein the adaptive filter coefficient and the one of the real component and the imaginary component are real multiplier values.

12. The apparatus of claim 10 , wherein the complex signal is a received radio frequency signal having been down-converted through two filters with a 90 degree phase offset for quadrature reception with resulting components having been passed through low-pass filters.

13. The apparatus of claim 10 , wherein the real

Assignees

• Samsung Electronics Co Ltd
• Samsung Electronics Co Ltd

Inventors

• Kim Jaeyoung
• Feygin Gennady
• Dayal Pranav
• Lee Jungwon

Classifications

• H04L27/364 Primary

  Arrangements for overcoming imperfections in the modulator, e.g. quadrature error or unbalanced I and Q levels · CPC title

• H04L27/3863 Primary

  Compensation for quadrature error in the received signal · CPC title

• H04L27/368

  adaptive predistortion · CPC title

• H04L27/2089

  with unbalanced quadrature channels · CPC title

• H04L27/361 Primary

  Modulation using a single or unspecified number of carriers, e.g. with separate stages of phase and amplitude modulation · CPC title