Real-time I/Q imbalance correction for wide-band RF receiver

Patent metadata

Field	Value
Publication number	US-10050744-B2
Application number	US-201313764076-A
Country	US
Kind code	B2
Filing date	Feb 11, 2013
Priority date	Mar 16, 2012
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

A receiver apparatus models and corrects the frequency-dependent and the frequency-independent mismatches between I and Q paths jointly by polynomial estimations. The receiver apparatus may sample digitized I and Q path signals. The sampled data point may be modeled in equations with real and imaginary components. The sampled discrete time-domain data may be converted to frequency-domain data. Multiple statistics values based on the frequency-domain data may be computed. Coefficients for the polynomial equations may be estimated based on the computed statistic values. The channel mismatches may be estimated from the polynomial equations and used to compensate the mismatch either on the I path or the Q path.

First claim

We claim:

1. A signal receiver apparatus that processes an electromagnetic signal that is received by an antenna and amplified by an amplifier, comprising:
a down converter receiving the amplified electromagnetic signal to generate an I signal and a Q signal orthogonal in phase relative to the I signal; and
a signal processor correcting quadrature errors in the I signal and the Q signal orthogonal in phase relative to the I signal, by generating, based on frequency-independent mismatch errors and frequency-dependent mismatch errors in the I signal and the Q signal orthogonal in phase relative to the I signal, a plurality of finite impulse response (FIR) coefficients and a plurality of phase compensation factors, and applying the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors to the I signal and the Q signal.

2. The signal receiver apparatus in claim 1 , wherein the signal processor comprises: a quadrature error corrector correcting the quadrature errors in the I signal and the Q signal, by generating, based on the frequency-independent mismatch errors and the frequency-dependent mismatch errors in the I signal and the Q signal, the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors, and applying the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors to the I signal and the Q signal.

3. The signal receiver apparatus in claim 2 , wherein the quadrature error corrector generates a discrete-time signal model based on a real-time signal model of the I signal and the Q signal, to estimate the frequency-independent mismatch errors and the frequency-dependent mismatch errors in the I signal and the Q signal, wherein the discrete-time signal model is in frequency domain.

4. The signal receiver apparatus in claim 3 , wherein the quadrature error corrector comprises:
an I/Q imbalance estimator estimating the frequency-independent mismatch errors and the frequency-dependent mismatch errors in the I signal and the Q signal, to generate the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors; and
a corrector applying the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors to the I signal and the Q signal.

5. The signal receiver apparatus in claim 4 , wherein the corrector comprises:
a finite impulse response (FIR) filter correcting frequency-dependent mismatch in the I signal and the Q signal based on the plurality of the finite impulse response (FIR) coefficients;
a plurality of registers storing the plurality of the phase compensation factors;
a plurality of multipliers; and
an adder, wherein the plurality of the multipliers and the adder correct frequency-independent phase mismatch in the I signal and the Q signal based on the plurality of the phase compensation factors.

6. The signal receiver apparatus in claim 4 , wherein the I/Q imbalance estimator comprises:
a windowing circuit generating a window of samples from the I signal and the Q signal, wherein the windowing circuit multiplies each corresponding sampled I signal and each corresponding sampled Q signal to a corresponding window coefficient to generate the window of samples of the I signal and the Q signal;
a fast-fourier transformer generating frequency-domain signals from the window of samples of the I signal and the Q signal;
a statistics generator generating statistics of the frequency-domain signals; and
an estimator generating, based on the statistics of the frequency-domain signals, the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors,
wherein the estimator estimates, based on the statistics of the frequency-domain signals, a model equation of a magnitude mismatch profile and a model equation of a phase mismatch profile for each frequency of the frequency-domain signals and for the frequency-independent mismatch errors, to generate the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors,
wherein the estimator is a polynomial estimator that uses polynomial equations to model the magnitude mismatch profile and the phase mismatch profile,
wherein the polynomial estimator calculates, based on the polynomial equation of the magnitude mismatch profile and the polynomial equation of the phase mismatch profile for each frequency of the frequency-domain signals and for the frequency-independent mismatch errors, a plurality of time-domain mismatch values, to generate the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors.

7. The signal receiver apparatus in claim 6 , wherein the statistics generator comprises a plurality of statistics value generators generating a plurality of statistics values for each of each point of the frequency-domain signals;
each of the plurality of the statistics value generators comprises:
a statistics value multiplier;
a statistics value accumulator generating, based on an output of the statistics value multiplier, an accumulated statistics value; and
a history factor generating, based on an output of the statistics value accumulator, an historical statistics value,
wherein the statistics value multiplier multiplies each point of the frequency-domain signals with a conjugate of the each point of the frequency-domain signals, multiplies the each point of the frequency-domain signals with the each point of the frequency-domain signals, or multiplies the each point of the frequency-domain signals with a corresponding paired point of the frequency-domain signals.

8. A method of processing an electromagnetic signal that is received by an antenna and amplified by an amplifier, by a signal receiver apparatus, comprising:
receiving, by a down converter, the amplified electromagnetic signal to generate an I signal and a Q signal orthogonal in phase relative to the I signal; and
correcting, by a signal processor, quadrature errors in the I signal and the Q signal orthogonal in phase relative to the I signal, by generating, based on frequency-independent mismatch errors and frequency-dependent mismatch errors in the I signal and the Q signal orthogonal in phase relative to the I signal, a plurality of finite impulse response (FIR) coefficients and a plurality of phase compensation factors, and applying the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors to the I signal and the Q signal.

9. The method in claim 8 , wherein the signal processor comprises: a quadrature error corrector correcting the quadrature errors in the I signal and the Q signal, by generating, based on the frequency-independent mismatch errors and the frequency-dependent mismatch errors in the I signal and the Q signal, the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors, and applying the plurality of the finite impulse response (FIR) coefficients and the plurality of the phase compensation factors to the I signal and the Q signal.

10. The method in claim 9 , further comprising generating, by the quadrature error corrector, a discrete-time signal model based on a real-time signal model of the I signal and the Q signal, to estimate the frequency-independent mismatch errors and the frequency-dependent mismatch errors in the I signal and the Q signal, wherein the discrete-time signal model is in frequency domain.

11. The method in claim 10 , furth

Assignees

• Analog Devices Inc

Inventors

• An Wei
• Reggiannini Brian
• Schubert Richard P

Classifications

• H03D2200/0062

  Computation of input samples, e.g. successive samples · CPC title

• H03D3/009 Primary

  Compensating quadrature phase or amplitude imbalances · CPC title

• H04L1/02 Primary

  by diversity reception · CPC title