Patents Assigned to Globespan Virata Corporation
  • Patent number: 6813311
    Abstract: The present invention, generally speaking, provides for cancellation of non-linear distortions within the echo path of a communications system by characterizing the nonlinearity, performing digital processing of a data signal to cause substantially the same nonlinearity to be applied to the data signal, and inputting a resulting data signal to a non-linear echo-cancellation path. In an exemplary embodiment, the non-linear echo-cancellation path includes as a nonlinear echo canceller a transversal filter or the like. A separate linear echo cancellation path is also provided. Training of the nonlinear echo canceller follows training of the linear echo canceller. This technique is particularly applicable to cancelling the effects of DAC nonlinearity, which can be readily characterized. Using this technique, cancellation improvement of about 3dB can readily be obtained. Alternatively, instead of achieving a lower residual echo floor, the linearity requirements for the transmit DAC can be relaxed.
    Type: Grant
    Filed: March 14, 2000
    Date of Patent: November 2, 2004
    Assignee: Globespan Virata Corporation
    Inventors: Debajyoti Pal, Chung-Li Lu, Sujai Chari