Patent ID: 8855029
Filing Date: 2014-10-07
Classification: H04B,H04L

Abstract:
1. A portable handset, comprising: an antenna; a front-end module coupled to the antenna, leakage associated with a transmit signal coupling with a receive signal within the front-end module to introduce second-order intermodulation (IM2) into the receive signal; and a digital transmit-signal (IM2) canceller that operates in a full-duplex mode, the digital transmit-signal IM2 canceller including a delay estimator configured to receive the receive signal and an estimate of the IM2 introduced in the receive signal, the delay estimator including an N-tap digital filter configured to generate a delayed estimate of the IM2 for each tap, each of the delayed estimates corresponding to respective delay paths having differing amounts of delay, the delay estimator further configured to combine the receive signal with each delayed estimate, determine a peak magnitude of each combined signal, and, during power up or factory calibration of the portable handset, identify the tap associated with a maximum peak magnitude and select the delayed estimate associated with the identified tap for use during operation of the portable handset, the selected delayed estimate and corresponding amount of delay being fixed during operation of the portable handset, the IM2 canceller further including a digital signal adjuster configured to generate a modified signal by combining the receive signal with a filtered output of the identified tap.