Cancellation of spurious responses from local oscillator cross-coupling
First Claim
1. A method, in a radio transceiver configured to transmit a radio-frequency transmit signal at a transmit frequency and having two or more local oscillators operative to simultaneously generate local oscillator signals, at corresponding local oscillator frequencies, for simultaneously down-converting two or more corresponding received radio-frequency signals, the method comprising:
- identifying one or more self-interfering frequencies, based on the local oscillator frequencies and the transmit frequency;
generating a baseband cancellation signal by weighting and frequency-shifting a baseband representation of the transmit signal, based on the identified self-interfering frequencies; and
combining the baseband cancellation signal with a down-converted received signal, to obtain an interference-reduced baseband signal;
wherein identifying the one or more self-interfering frequencies comprises;
determining a set of spurious frequencies corresponding to nonlinear products of the local oscillator signals;
comparing each of the spurious frequencies with the transmit frequency; and
identifying as self-interfering frequencies those of the spurious frequencies that fall within a predetermined range of the transmit frequency.
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Accused Products
Abstract
Interference cancellation techniques may be implemented in a radio transceiver configured to transmit a radio-frequency transmit signal at a transmit frequency and having two or more local oscillators operative to simultaneously generate local oscillator signals, at corresponding local oscillator frequencies, for simultaneously down-converting two or more corresponding received radio-frequency signals. An example method begins with identifying one or more self-interfering frequencies, based on the local oscillator frequencies and the transmit frequency. A baseband cancellation signal is then generated by weighting and frequency-shifting a baseband representation of the transmit signal, based on the identified self-interfering frequencies. The baseband cancellation signal is then combined with a down-converted received signal, to obtain an interference-reduced baseband signal.
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Citations
18 Claims
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1. A method, in a radio transceiver configured to transmit a radio-frequency transmit signal at a transmit frequency and having two or more local oscillators operative to simultaneously generate local oscillator signals, at corresponding local oscillator frequencies, for simultaneously down-converting two or more corresponding received radio-frequency signals, the method comprising:
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identifying one or more self-interfering frequencies, based on the local oscillator frequencies and the transmit frequency; generating a baseband cancellation signal by weighting and frequency-shifting a baseband representation of the transmit signal, based on the identified self-interfering frequencies; and combining the baseband cancellation signal with a down-converted received signal, to obtain an interference-reduced baseband signal; wherein identifying the one or more self-interfering frequencies comprises; determining a set of spurious frequencies corresponding to nonlinear products of the local oscillator signals; comparing each of the spurious frequencies with the transmit frequency; and identifying as self-interfering frequencies those of the spurious frequencies that fall within a predetermined range of the transmit frequency. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A radio transceiver comprising:
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a transmitter circuit configured to transmit a radio-frequency transmit signal at a transmit frequency; two or more local oscillators configured to simultaneously generate local oscillator signals, at corresponding local oscillator frequencies; and a receiver circuit configured to simultaneously down-convert two or more received radio-frequency signals, using corresponding ones of the two or more local oscillators; and a baseband processing circuit configured to identify one or more self-interfering frequencies, based on the local oscillator frequencies and the transmit frequency; generate a baseband cancellation signal by weighting and frequency-shifting a baseband representation of the transmit signal; and combine the baseband cancellation signal with a down-converted received signal, to obtain an interference-reduced baseband signal; wherein the baseband processing circuit is configured to identify the one or more self-interfering frequencies by; determining a set of spurious frequencies corresponding to nonlinear products of the local oscillator signals; comparing each of the spurious frequencies with the transmit frequency; and identifying as self-interfering frequencies those of the spurious frequencies that fall within a predetermined range of the transmit frequency. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. A wireless device comprising a radio transceiver, the radio transceiver comprising
a transmitter circuit configured to transmit a radio-frequency transmit signal at a transmit frequency; -
two or more local oscillators configured to simultaneously generate local oscillator signals, at corresponding local oscillator frequencies; and a receiver circuit configured to simultaneously down-convert two or more received radio-frequency signals, using corresponding ones of the two or more local oscillators; and a baseband processing circuit configured to identify one or more self-interfering frequencies, based on the local oscillator frequencies and the transmit frequency; generate a baseband cancellation signal by weighting and frequency-shifting a baseband representation of the transmit signal; and combine the baseband cancellation signal with a down-converted received signal, to obtain an interference-reduced baseband signal; wherein the baseband processing circuit is configured to identify the one or more self-interfering frequencies by; determining a set of spurious frequencies corresponding to nonlinear products of the local oscillator signals; comparing each of the spurious frequencies with the transmit frequency; and identifying as self-interfering frequencies those of the spurious frequencies that fall within a predetermined range of the transmit frequency. - View Dependent Claims (17, 18)
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Specification