Method and apparatus for in-phase and quadrature imbalance correction in a frequency domain

Patent metadata

Field	Value
Publication number	US-2022200838-A1
Application number	US-202017131823-A
Country	US
Kind code	A1
Filing date	Dec 23, 2020
Priority date	Dec 23, 2020
Publication date	Jun 23, 2022
Grant date	—

Abstract

An apparatus and method for in-phase/quadrature (I/Q) imbalance correction in a transceiver. The apparatus includes an I/Q imbalance correction circuit and a correction coefficient generation circuit. The I/Q imbalance correction circuit is configured to modify I/Q data in a frequency domain using correction coefficients to generate corrected I/Q data. The correction coefficient generation circuit is configured to generate the correction coefficients for the I/Q imbalance correction circuit based on the I/Q data and reference data.

First claim

What is claimed is:

1 . An apparatus for in-phase/quadrature (I/Q) imbalance correction in a transceiver, comprising:
an analog mixer circuit configured to down-convert a received signal to a non-zero intermediate frequency; an analog-to-digital converter (ADC) configured convert the down-converted received signal to I/Q data in a digital domain; a first down-conversion circuit configured to down-convert the I/Q data to baseband for a signal of interest; a second down-conversion circuit configured to down-convert the I/Q data to baseband for a mirror image of the signal of interest; an I/Q imbalance correction circuit configured to modify the baseband I/Q data of the signal of interest in a frequency domain using correction coefficients to generate corrected I/Q data, wherein the I/Q imbalance correction circuit is configured to generate the corrected I/Q data based on the baseband I/Q data of the signal of interest and a complex conjugate of the baseband I/Q data of the mirror image of the signal of interest in a frequency domain; and a correction coefficient generation circuit configured to generate the correction coefficients for the I/Q imbalance correction circuit based on the baseband I/Q data of the signal of interest and reference data.

2 . The apparatus of claim 1 , wherein the ADC is a radio frequency (RF) ADC configured to digitize the down-converted received signal over a frequency of the signal of interest and a frequency of the mirror image of the signal of interest.

3 . The apparatus of claim 1 , wherein the received signal is an orthogonal frequency division multiplex (OFDM) modulated signal and a cyclic prefix attached to an OFDM symbol is longer than an impulse response length of an I/Q imbalance channel.

4 . The apparatus of claim 1 , wherein the I/Q imbalance correction circuit is further configured to perform RF equalization.

5 . The apparatus of claim 1 , wherein the reference data is obtained from a pilot signal, a reference symbol, or a training sequence included in the received signal.

6 . An apparatus for in-phase/quadrature (I/Q) imbalance correction in a transceiver, comprising:
an I/Q imbalance correction circuit configured to modify I/Q data for transmission using correction coefficients to generate corrected I/Q data, wherein the I/Q imbalance correction circuit is configured to generate the corrected I/Q data based on the I/Q data and a complex conjugate of the I/Q data at a mirror image frequency; a correction coefficient generation circuit configured to generate the correction coefficients for the I/Q imbalance correction circuit based on the I/Q data and reference data; a digital-to-analog converter (DAC) configured to convert the corrected I/Q data to an analog transmit signal; a first mixer circuit for up-converting the analog transmit signal using a first local oscillator signal; and an observation receiver configured to receive the up-converted analog transmit signal as a feedback signal and generate the reference data based on the feedback signal, wherein the observation receiver includes a second mixer circuit configured to down-convert the feedback signal using a second local oscillator signal to a zero intermediate frequency, wherein the observation receiver is configured to generate the reference data by down-converting the feedback signal using the second local oscillator signal with different phase shifts at different time instants.

7 . The apparatus of claim 6 , wherein the phase shifts are any combination of two out of 0°, 45°, 60°, or 90°.

8 . The apparatus of claim 6 , wherein the I/Q data is an orthogonal frequency division multiplex (OFDM) modulated data and a cyclic prefix attached to an OFDM symbol is longer than an impulse response length of an I/Q imbalance channel.

9 . The apparatus of claim 6 , wherein the I/Q imbalance correction circuit is further configured to perform RF equalization.

10 . A method for in-phase/quadrature (I/Q) imbalance correction in a transceiver, comprising:
down-converting a received signal to a non-zero intermediate frequency; converting, by an analog-to-digital converter (ADC), the down-converted received signal to I/Q data in a digital domain; down-converting the I/Q data to baseband for a signal of interest; down-converting the I/Q data to baseband for a mirror image of the signal of interest; generating correction coefficients based on the baseband I/Q data of the signal of interest and reference data; and modifying the baseband I/Q data of the signal of interest in a frequency domain using the correction coefficients to generate corrected I/Q data, wherein the corrected I/Q data is generated based on the baseband I/Q data of the signal of interest and a complex conjugate of the baseband I/Q data of the mirror image of the signal of interest in a frequency domain.

11 . The method of claim 10 , wherein the ADC is a radio frequency (RF) ADC configured to digitize the down-converted received signal over a frequency of the signal of interest and a frequency of the mirror image of the signal of interest.

12 . The method of claim 10 , wherein the received signal is an orthogonal frequency division multiplex (OFDM) modulated signal and a cyclic prefix attached to an OFDM symbol is longer than an impulse response length of an I/Q imbalance channel.

13 . The method of claim 10 , further comprising performing RF equalization.

14 . The method of claim 10 , wherein the reference data is obtained from a pilot signal, a reference symbol, or a training sequence included in the received signal.

15 . A method for in-phase/quadrature (I/Q) imbalance correction in a transceiver, comprising:
generating correction coefficients for I/Q imbalance correction based on I/Q data and reference data; modifying the I/Q data for transmission using the correction coefficients to generate corrected I/Q data, wherein the corrected I/Q data is generated based on the I/Q data and a complex conjugate of the I/Q data at a mirror image frequency; converting the corrected I/Q data to an analog transmit signal; up-converting the analog transmit signal using a first local oscillator signal; receiving the up-converted analog transmit signal as a feedback signal; and generating the reference data based on the feedback signal, wherein the feedback signal is down-converted using a second local oscillator signal to a zero intermediate frequency, and the reference data is generated by down-converting the feedback signal using the second local oscillator signal with different phase shifts at different time instants.

16 . The method of claim 15 , wherein the phase shifts are any combination of two out of 0°, 45°, 60°, or 90°.

17 . The method of claim 15 , wherein the I/Q data is an orthogonal frequency division multiplex (OFDM) modulated data and a cyclic prefix attached to an OFDM symbol is longer than an impulse response length of an I/Q imbalance channel.

18 . The method of claim 15 , further comprising performing RF equalization.

Assignees

• Intel Corp

Inventors

• Azadet Kameran
• Tiebout Marc Jan Georges

Classifications

• H04B1/0475

  with means for limiting noise, interference or distortion (H04B1/0483 takes precedence) · CPC title

• H04L27/364

  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

• H03D3/009

  Compensating quadrature phase or amplitude imbalances · CPC title