SIMPLIFIED ADAPTIVE FILTER ALGORITHM FOR THE CANCELLATION OF TX-INDUCED EVEN ORDER INTERMODULATION PRODUCTS
First Claim
1. A transmitter induced even-order intermodulation noise cancellation circuit, comprising:
- a first real valued adaptive filter configured to receive an adaptive filter input signal based upon a transmission signal, to operate a real valued adaptive algorithm on the input signal to estimate a first component of an intermodulation noise, and to cancel the first component in a desired signal; and
a second real valued adaptive filter configured to receive the adaptive filter input signal, and to operate a real valued adaptive algorithm on the input signal to estimate a second component of the intermodulation noise, and to cancel the second component in the desired signal.
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Abstract
One embodiment of the present invention relates to an adaptive filtering apparatus comprising first and second real valued adaptive filters, respectively configured to receive an adaptive filter input signal based upon a transmission signal in a transmission path. The first real valued adaptive filter is configured to operate a real valued adaptive filter algorithm on the input signal to estimate a first intermodulation noise component (e.g., an in-phase component) in a desired signal and to cancel the estimated noise. The second real valued adaptive filter is configured to operate a real valued adaptive filter algorithm on the input signal to estimate a second intermodulation noise component (e.g., a quadrature phase component) in the desired signal and to cancel the estimated noise. Accordingly, each filter operates a real valued adaptive algorithm to cancel a noise component, thereby removing complex cross terms between the components from the adaptive filtering process.
117 Citations
20 Claims
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1. A transmitter induced even-order intermodulation noise cancellation circuit, comprising:
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a first real valued adaptive filter configured to receive an adaptive filter input signal based upon a transmission signal, to operate a real valued adaptive algorithm on the input signal to estimate a first component of an intermodulation noise, and to cancel the first component in a desired signal; and a second real valued adaptive filter configured to receive the adaptive filter input signal, and to operate a real valued adaptive algorithm on the input signal to estimate a second component of the intermodulation noise, and to cancel the second component in the desired signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A second order intermodulation noise (IM2) cancellation circuit, comprising:
an adaptive filtering system comprising a plurality of real valued adaptive filters configured to generate a plurality of adaptive filter output signals, respectively comprising a receiver signal corrected for a transmitter induced even-ordered intermodulation noise component, wherein each adaptive filter output signal is generated by a real valued adaptive filter configured to estimate the intermodulation noise component by operating a real valued adaptive filtering algorithm that is independent from the real valued adaptive filtering algorithms operated by a remainder of the plurality of real valued adaptive filters. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for transmitter induced even ordered intermodulation noise cancellation, comprising:
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generating an adaptive filter input signal from a transmission signal; applying a first real valued adaptive filter algorithm to the adaptive filter input signal to estimate a first component of a transmitter induced even-order intermodulation noise; applying a second real valued adaptive filter algorithm to the adaptive filter input signal to estimate a second component of the intermodulation noise; and cancelling the first component and the second component of the intermodulation noise from a desired signal; wherein the first and second real valued adaptive filter algorithms are independent from each other. - View Dependent Claims (19, 20)
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Specification