All digital transmitter noise correction
First Claim
1. A circuit comprising:
- an estimator circuit modeling nonlinear signal distortion from a transmitter at a receiver based on an analysis of an outgoing digital signal converted to an analog signal and transmitted at the transmitter;
a mixer mixing an output of the estimator circuit with a frequency offset signal and shifting the estimator circuit output to an intermediate frequency offset representing a difference between frequencies of the transmitter and the receiver; and
a subtractor coupled to the mixer and subtracting the frequency shifted estimator circuit output from a digitized incoming signal received at the receiver;
a delay unit delaying the estimator circuit output until the estimator circuit output is synchronized with a corresponding portion of the incoming signal at the subtractor; and
a decimator downsampling the mixed estimator circuit output to a frequency of the incoming signal before the subtractor subtracts the downsampled estimator output from the incoming signal.
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Accused Products
Abstract
An all digital model of nonlinear transmitter signal distortion in signals received at a receiver of a transmitter-receiver may be used to estimate distortion. The estimated distortion may then be cancelled from the received signals to improve signal quality of the received signal. The digital nonlinear model may be part of an estimator circuit that estimates nonlinear distortion terms by applying a formula or transformation to a digitized version of the signals transmitter at a transmitter of the transmitter-receiver. A mixer may be used to shift a frequency of the estimated nonlinear terms away from a transmitter frequency so that the nonlinear terms can later be subtracted from the incoming signal received at the receiver at a receiver frequency. Circuits and methods are provided.
16 Citations
20 Claims
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1. A circuit comprising:
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an estimator circuit modeling nonlinear signal distortion from a transmitter at a receiver based on an analysis of an outgoing digital signal converted to an analog signal and transmitted at the transmitter; a mixer mixing an output of the estimator circuit with a frequency offset signal and shifting the estimator circuit output to an intermediate frequency offset representing a difference between frequencies of the transmitter and the receiver; and a subtractor coupled to the mixer and subtracting the frequency shifted estimator circuit output from a digitized incoming signal received at the receiver; a delay unit delaying the estimator circuit output until the estimator circuit output is synchronized with a corresponding portion of the incoming signal at the subtractor; and a decimator downsampling the mixed estimator circuit output to a frequency of the incoming signal before the subtractor subtracts the downsampled estimator output from the incoming signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A noise cancellation circuit comprising:
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a plurality of receivers, each coupled to a respective analog-digital converter (ADC); a plurality of transmitters, each coupled to a respective ADC; and a plurality of digital noise correcting circuits, each noise correcting circuit including an estimator circuit coupled to a mixer coupled to a subtractor and including a delay circuit and a decimator, with at least one noise correcting circuit coupled between each of the transmitters and the receiver ADCs, wherein; each estimator circuit models nonlinear signal distortion between a respective transmitter and a respective receiver based on a digitized version of an outgoing signal transmitted at the respective transmitter, each mixer mixes an output of the respective estimator circuit with a respective frequency offset signal, each subtractor subtracts the mixed estimator circuit output from the respective estimator circuit from an incoming signal digitized at the respective receiver ADC, each delay unit delays the estimator circuit output until the estimator circuit output is synchronized with a corresponding portion of an incoming signal, and each decimator downsamples the mixed estimator circuit output to a frequency of an incoming signal. - View Dependent Claims (14)
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15. A method comprising:
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digitizing incoming radio frequency (RF) signals received at a receiver and outgoing signals for transmission at a RF transmitter; channelizing the digitized incoming and outgoing signals;
modeling nonlinear signal distortion between the transmitter and the receiver on at least one channel based on an analysis of at least one of the channelized outgoing signals;mixing the modeled distortion on at least one channel with an offset signal offsetting the modeled distortion based on a difference in angular frequencies of the at least one channel of the transmitter and the receiver; delaying offsetted modeled nonlinear distortion until the offsetted modeled nonlinear distortion is time aligned with a corresponding section of the channelized incoming RF signal; decimating the delayed modeled nonlinear distortion; and subtracting the decimated modeled distortion from the at least one channel of the channelized incoming RF signal. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification