Rejection of transmit signal leakage in wireless communication device
First Claim
1. A filter circuit for a radio frequency (RF) receiver, the filter circuit comprising:
- a summer that receives an RF receive (RX) input signal having a transmit (TX) leakage signal, and subtracts a TX leakage signal estimate from the RX input signal to produce an RX output signal; and
an estimator that generates the TX leakage signal estimate exclusive of a TX signal and based on the RX output signal and an unmodulated reference signal at a carrier frequency of the TX leakage signal.
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Accused Products
Abstract
This disclosure describes techniques for reducing adverse effects of transmit signal leakage in a full-duplex, wireless communication system. The disclosure describes techniques for reducing adverse effects of second order distortion and cross-modulation distortion of transmit signal leakage from a transmitter via a duplexer. The techniques may be effective in rejecting at least a portion of a transmit leakage signal, thereby reducing or eliminating distortion. The adaptive filter may include an estimator circuit that generates a transmit leakage signal estimate. A summer subtracts the estimate from the received signal to cancel transmit leakage and produce an output signal. The estimator circuit generates the transmit leakage signal estimate based on a reference signal and feedback from the output signal. The reference signal approximates the carrier signal used to generate the transmit signal in the transmitter. The reference signal may be provided by the same oscillator used to produce the transmit carrier signal.
38 Citations
47 Claims
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1. A filter circuit for a radio frequency (RF) receiver, the filter circuit comprising:
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a summer that receives an RF receive (RX) input signal having a transmit (TX) leakage signal, and subtracts a TX leakage signal estimate from the RX input signal to produce an RX output signal; and an estimator that generates the TX leakage signal estimate exclusive of a TX signal and based on the RX output signal and an unmodulated reference signal at a carrier frequency of the TX leakage signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A method for filtering a transmit (TX) leakage signal from a received input signal in a radio frequency (RF) receiver, the method comprising:
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receiving an RF receive (RX) input signal having a TX leakage signal; subtracting a TX leakage signal estimate from the input signal to produce an output signal; and generating the TX leakage signal estimate exclusive of a TX signal and based on the output signal and an unmodulated reference signal at a carrier frequency of the TX leakage signal. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
filtering the first in-phase signal to generate a second in-phase signal; multiplying the second in-phase signal with the in-phase component of the reference signal to generate a third in-phase signal; multiplying the output signal with a quadrature component of the reference signal to generate a first quadrature signal; filtering the first quadrature signal to generate a second quadrature signal; multiplying the second quadrature signal with the quadrature component of the reference signal to generate a third quadrature signal; and summing the third in-phase signal and the third quadrature signal to generate the TX leakage signal estimate.
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17. The method of claim 16, further comprising filtering the first in-phase signal with a first low-pass filter, and filtering the first quadrature signal with a second low-pass filter, wherein the first and second low pass filters are cross-coupled.
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18. The method of claim 16, further comprising filtering the first in-phase signal with a first low-pass filter, and filtering the first quadrature signal with a second low-pass filter, wherein each of the first and second low pass filters is coupled to receive both the first in-phase signal and the first quadrature signal.
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19. The method of claim 13, wherein generating the TX leakage signal estimate comprises multiplying the output signal by the reference signal to down-convert the TX leakage signal in the output signal to a TX baseband, and multiplying the down-converted TX leakage signal by the reference signal to up-convert the down-converted TX leakage signal to the carrier frequency.
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20. The method of claim 13, further comprising subtracting the TX leakage signal estimate from the input signal at an input to an amplifier.
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21. The method of claim 13, further comprising subtracting the TX leakage signal estimate from the input signal at an output of an amplifier.
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22. The method of claim 13, further comprising subtracting the TX leakage signal estimate from the input signal at a node in a receive chain prior to a down-conversion mixer.
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23. The method of claim 13, further comprising amplifying the input signal to produce the output signal.
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24. The method of claim 13, further comprising providing the output signal to a mixer that down-converts the output signal to a receive baseband.
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25. A filter circuit for a radio frequency (RF) receiver, the filter circuit comprising:
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means for receiving an RF receive (RX) input signal having a transmit (TX) leakage signal; means for subtracting a TX leakage signal estimate from the input signal to produce an output signal; and means for generating the TX leakage signal estimate exclusive of a TX signal and based on the output signal and an unmodulated reference signal at a carrier frequency of the TX leakage signal. - View Dependent Claims (26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36)
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37. A radio frequency (RF) receiver, the receiver comprising:
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an antenna that receives a receive (RX) input signal; an amplifier that amplifies the RX input signal; a duplexer that couples the RX input signal from the antenna to the amplifier, and passes a transmit (TX) leakage signal to the amplifier as part of the RX input signal; a summer that subtracts a TX leakage signal estimate from the RX input signal to produce an RX output signal; an estimator that generates the TX leakage signal estimate exclusive of a TX signal and based on the RX output signal and an unmodulated reference signal at a carrier frequency of the TX leakage signal; and a mixer that downconverts the RX output signal to a baseband. - View Dependent Claims (38, 39, 40, 41, 42, 43, 44, 45, 46, 47)
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Specification