Strong signal tolerant OFDM receiver and receiving methods
First Claim
1. A receiver circuit, comprising:
- a downconverter unit configured to downconvert a received radio frequency signal, comprising a desired signal and one or more interfering signals, to a processing frequency, to obtain a processing frequency signal;
a distortion waveform generator configured to generate an estimated distortion waveform from the one or more interfering signals, the estimated distortion waveform comprising one or more intermodulation products of the interfering signals;
first and second filters configured to filter the processing frequency signal and the estimated distortion waveform, respectively;
first and second sampling units configured to sample the filtered processing frequency signal and the filtered estimated distortion waveform to obtain a sampled signal of interest and a sampled distortion signal, respectively;
first and second transform units to divide the sampled signal of interest and the sampled distortion signal, respectively, into a plurality of frequency channels; and
an interference subtracting unit configured to combine the sampled distortion signal for each of a selected number of frequency channels with the corresponding sampled signal of interest for each of the same frequency channels to obtain interference-reduced signal samples for each of the selected number of frequency channels.
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Abstract
Circuits and methods are disclosed for compensating for received signal distortion caused by non-linearities in wideband receivers. An exemplary receiver includes a distortion waveform generator configured to approximate non-linear response characteristics of a downconverter circuit used to downconvert the received radio frequency signal. The resulting estimated distortion waveform is filtered, using filter(s) substantially similar to those used for filtering an intermediate frequency signal that includes the desired signal and non-linear distortion products caused by strong interfering signals. The filtered estimated distortion waveform and intermediate frequency signal are sampled, to obtain a sampled distortion signal and a sampled signal of interest. The sampled distortion signal and the sampled signal of interest are divided into a plurality of frequency channels. For a selected number of frequency channels, the sampled distortion signal for a frequency channel is scaled, and subtracted from the corresponding sampled signal of interest for the same frequency channel to obtain reduced-interference signal samples for the frequency channel.
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Citations
22 Claims
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1. A receiver circuit, comprising:
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a downconverter unit configured to downconvert a received radio frequency signal, comprising a desired signal and one or more interfering signals, to a processing frequency, to obtain a processing frequency signal; a distortion waveform generator configured to generate an estimated distortion waveform from the one or more interfering signals, the estimated distortion waveform comprising one or more intermodulation products of the interfering signals; first and second filters configured to filter the processing frequency signal and the estimated distortion waveform, respectively; first and second sampling units configured to sample the filtered processing frequency signal and the filtered estimated distortion waveform to obtain a sampled signal of interest and a sampled distortion signal, respectively; first and second transform units to divide the sampled signal of interest and the sampled distortion signal, respectively, into a plurality of frequency channels; and an interference subtracting unit configured to combine the sampled distortion signal for each of a selected number of frequency channels with the corresponding sampled signal of interest for each of the same frequency channels to obtain interference-reduced signal samples for each of the selected number of frequency channels. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method for reducing interference from intermodulation distortion in a receiver, the method comprising:
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downconverting a received radio frequency signal comprising a desired signal and one or more interfering signals to obtain a processing frequency signal; generating an estimated distortion waveform from the one or more interfering signals, the estimated distortion waveform comprising one or more intermodulation products of the interfering signals; filtering the processing frequency signal and the estimated distortion waveform with first and second filters, respectively; sampling the filtered processing frequency signal and the filtered estimated distortion waveform to obtain a sampled signal of interest and a sampled distortion signal, respectively; dividing each of the sampled signal of interest and the sampled distortion signal into a plurality of frequency channels; and combining the sampled distortion signal for each of a selected number of frequency channels with the corresponding sampled signal of interest for each of the same frequency channels to obtain interference-reduced signal samples for each of the selected number of frequency channels. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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Specification