APPARATUS AND METHOD FOR ADAPTIVE I/Q IMBALANCE COMPENSATION
First Claim
1. An apparatus comprising:
- a finite impulse response (FIR) filter configured to filter a version of a digital signal to generate a compensation signal, wherein the FIR filter has filter coefficients, wherein the digital signal comprises a digital representation of a demodulated in-phase and quadrature phase component of a radio frequency (RF) signal;
an adder configured to sum another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal; and
an adaptation step size adaptor for providing two or more different adaptation step sizes for updating the filter coefficients,wherein one of the versions of the digital signal or the version of the compensation signal is a complex conjugate of the digital signal or a complex conjugate of the compensation signal, respectively, and the others are not the complex conjugates, wherein the FIR filter and the adder comprise electronic hardware.
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Abstract
An I/Q imbalance compensation block of a RF receiver for compensating an imbalance between an in-phase component and a quadrature component of an RF signal is disclosed. The compensation block includes a conjugation block; an adaptive finite impulse response (FIR) filter; and an adder. The filter use filter coefficients iteratively updated at least partly in response to a compensated digital signal. The filter can have a complex number for at least one, but not all of filter taps, and real numbers for other filter taps. The filter can be provided with adaptation step sizes different from filter tap to filter tap. The filter can also be provided with an adaptation step size(s) varying over time. The filter can also be provided with an adaptation step size(s) divided by the square norm of the compensated signal.
6 Citations
20 Claims
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1. An apparatus comprising:
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a finite impulse response (FIR) filter configured to filter a version of a digital signal to generate a compensation signal, wherein the FIR filter has filter coefficients, wherein the digital signal comprises a digital representation of a demodulated in-phase and quadrature phase component of a radio frequency (RF) signal; an adder configured to sum another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal; and an adaptation step size adaptor for providing two or more different adaptation step sizes for updating the filter coefficients, wherein one of the versions of the digital signal or the version of the compensation signal is a complex conjugate of the digital signal or a complex conjugate of the compensation signal, respectively, and the others are not the complex conjugates, wherein the FIR filter and the adder comprise electronic hardware. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An apparatus comprising:
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a finite impulse response (FIR) filter configured to filter a version of a digital signal to generate a compensation signal, wherein the FIR filter has filter coefficients, wherein the digital signal comprises a digital representation of a demodulated in-phase and quadrature phase component of a radio frequency (RF) signal; an adder configured to sum another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal; and an adaptation step size adaptor for providing adaptation step sizes for updating the filter coefficients, wherein the adaptation step size adaptor is configured to vary adaptation step sizes for one or more of the filter coefficients over time, wherein one of the versions of the digital signal or the version of the compensation signal is a complex conjugate of the digital signal or a complex conjugate of the compensation signal, respectively, and the others are not the complex conjugates, wherein the FIR filter and the adder comprise electronic hardware. - View Dependent Claims (11, 12, 13)
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14. An apparatus comprising:
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a finite impulse response (FIR) filter configured to filter a version of a digital signal to generate a compensation signal, wherein the FIR filter has filter coefficients, wherein the digital signal comprises a digital representation of a demodulated in-phase and quadrature phase component of a radio frequency (RF) signal; an adder configured to sum another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal; and an adaptation step size adaptor for providing adaptation step sizes for updating the filter coefficients, wherein the adaptation step size adaptor is configured to divide adaptation step sizes for one or more of the filter coefficients by the square norm of the balanced digital signal, wherein one of the versions of the digital signal or the version of the compensation signal is a complex conjugate of the digital signal or a complex conjugate of the compensation signal, respectively, and the others are not, the complex conjugates, wherein the FIR filter and the adder comprise electronic hardware.
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15. A method of improving an image rejection ratio of a digital signal having demodulated in-phase and quadrature-phase components of a radio frequency signal, the method comprising:
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filtering a version of the digital signal with a finite impulse response (FIR) filter having filter coefficients to generate a compensation signal, wherein filtering is implemented by hardware or by instructions implemented by a processor; generating a complex conjugate of the digital signal or the compensation signal; summing another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal, wherein one of the versions of the digital signal and the version of the compensation signal corresponds to a complex conjugate of the digital signal or the compensation signal, respectively, and the others are not the complex conjugates; generating a feedback signal by multiplying the correlation of the balanced digital signal with two or more different adaptation step sizes for the filter coefficients; and determining the filter coefficients, using the feedback signal. - View Dependent Claims (16, 17)
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18. A method of improving an image rejection ratio of a digital signal having demodulated in-phase and quadrature-phase components of a radio frequency signal, the method comprising:
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filtering a version of the digital signal with a finite impulse response (FIR) filter having filter coefficients to generate a compensation signal, wherein filtering is implemented by hardware or by instructions implemented by a processor; generating a complex conjugate of the digital signal or the compensation signal; summing another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal, wherein one of the versions of the digital signal and the version of the compensation signal corresponds to a complex conjugate of the digital signal or the compensation signal, respectively, and the others are not the complex conjugates; generating a feedback signal by multiplying the correlation of the balanced digital signal with one or more adaptation step sizes for the filter coefficients, wherein at least one of the adaptation step sizes is varied over time; and determining the filter coefficients, using the feedback signal. - View Dependent Claims (19)
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20. A method of improving an image rejection ratio of a digital signal having demodulated in-phase and quadrature-phase components of a radio frequency signal, the method comprising:
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filtering a version of the digital signal with a finite impulse response (FIR) filter having filter coefficients to generate a compensation signal, wherein filtering is implemented by hardware or by instructions implemented by a processor; generating a complex conjugate of the digital signal or the compensation signal; summing another version of the digital signal and a version of the compensation signal to generate a balanced digital signal that has an improved image rejection ratio versus the digital signal, wherein one of the versions of the digital signal and the version of the compensation signal corresponds to a complex conjugate of the digital signal or the compensation signal, respectively, and the others are not the complex conjugates; generating a feedback signal by multiplying the correlation of the balanced digital signal with one or more adaptation step sizes for the filter coefficients, wherein the one or more of the adaptation step sizes is divided by the square norm of the balanced digital signal; and determining the filter coefficients, using the feedback signal.
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Specification