Patent ID: 8050201

Claim:
A transceiver for modulating transmit data signals to generate transmit signals and for demodulating receive signals to generate received data signals, comprising: a first circuit including a baseband processing chain for receiving the receive signals and generating the received data signals at an output of the baseband processing chain from the receive signals; an estimator circuit including a second processing chain for separately receiving in-phase and quadrature phase components of the transmit data signal and generating an estimate of second-order intermodulation present in the receive signals as a result of undesired coupling of the transmit signal in the receive signals in the transceiver, the estimate of second-order intermodulation provided at an output of the second processing chain and the transmit signal induced second-order intermodulation is at least partially removed from the received data signals; and a canceller including a delay estimator and a signal adjuster, the delay estimator including an N-tap digital filter, each tap delaying the estimate of second-order intermodulation by a delay plus the delay of any prior taps, each tap combining its respective delayed estimate of second-order intermodulation with the received data signals, each tap determining a peak magnitude of its respective combined tap signal, the delay estimator further including a maximum detector for determining the maximum of the peak magnitudes, the delay estimator further including a selector element for identifying the delayed estimate of second-order intermodulation associated with the maximum peak magnitude, and the signal adjuster including an adaptive filter for filtering the identified delayed estimate, the signal adjuster further including a combiner for subtracting the filtered estimate from the received data signals to generate a modified received data signal, the signal adjuster further including a least mean squares element for receiving the modified received data signal and the identified delayed estimate and generating filter coefficients of the adaptive filter by adaptively minimizing the difference between the received data signals and the identified delayed estimate.