Patent ID: 7139342
Filing Date: 2006-11-21
Classification: H04B

Abstract:
1. For use in a full duplex transceiver comprising a line driver capable of sending analog transmit signals through a cable and a line receiver capable of receiving analog receive signals from said cable, a system for cancelling echoes of said analog transmit signals that are present in said analog receive signals, wherein said system comprises: an echo canceller impedance model circuit coupled to the output of said line driver and coupled to the input of said line receiver, wherein said echo canceller impedance model circuit generates an echo canceller current that is substantially equal in magnitude and substantially opposite in phase to a current that represents said signal echoes; and wherein said echo canceller impedance model circuit generates said echo canceller current by iteratively generating control signals to vary a value of a variable impedance of said echo canceller model circuit until a generated value of said echo canceller current substantially cancels said signal echoes; and wherein said echo canceller impedance model circuit comprises at least one digital to analog converter that provides at least one control signal that varies a value of said variable impedance of said echo canceller impedance model circuit.