Method and apparatus for combining voice line card and xdsl line card functions

Abstract

An integrated line card for providing an analog termination for both POTS and xDSL signals that present the appropriate impedances at xDSL frequencies for the xDSL signals and appropriate impedances at POTS frequencies for POTS signals. The line card comprises a front end for coupling combined POTS and xDSL transceiver circuits to a telephone line at a single termination and an impedance generator responsive to the frequency range of the POTS and the xDSL circuits for generating the appropriate impedances on the line at xDSL frequencies for xDSL signals and the appropriate impedances at POTS frequencies for POTS signals, such that the signals are coupled to the card without the use of a splitter. Preferably, the xDSL circuits and the POTS circuits share a common driver for driving signals onto the loop. An advantage of this arrangement is that the two circuits may be designed together thus ensuring out-of-band noise generated by either source does not interfere with the other. In a further embodiment the generation of the frequency dependent impedance is implemented by using a feedback circuit that feeds a signal representing current sensed on the loop back into the transmit driver.