Broadband XDSL transceiver
Broadband xDSL transceiver for transmitting and receiving signals in a predetermined broadband frequency range (ΔF) via a signal line which has a complex line impedance (Z L ), wherein the xDSL transceiver ( 1 ) comprises a line driver ( 3 ) for driving a transmission signal applied to a signal input ( 4 a, 4 b ) of said line driver ( 3 ) via said signal line; a receiver ( 8 ) for evaluating a reception signal received via said signal line and applied to a signal input of said receiver ( 8 ); an echo canceling bridge ( 10 ) for canceling the transmission signal at the signal input ( 9 a, 9 b ) of said receiver ( 8 ); a sense impedance ( 11 ) connected to the signal line; a feedback resistor network ( 15 a, 15 b ) provided between the sense impedance ( 11 ) and the signal input ( 4 a, 4 b ) of said line driver ( 3 ) performing a synthesized termination impedance (Z T ) of the xDSL transceiver ( 1 ) as a product of the sense impedance and an impedance synthesis factor (G); wherein the sense impedance ( 11 ) is a complex impedance (Z S ) so that the synthesized termination impedance (Z T ) matches the line impedance (Z L ) over the predetermined broadband frequency range (ΔF).
1 - 7 . (canceled)
8 . A broadband xDSL transceiver for transmitting and receiving signals in a predetermined broadband frequency range via a signal line which has a complex line impedance, the xDSL transceiver comprising:
(a) a line driver having a signal input and configured to drive a transmission signal received at the signal input, the line driver operably coupled to provide the transmission signal to the signal line;
(b) a receiver having a receiver signal input and configured to process a reception signal received at the receiver signal input via said signal line;
(c) an echo canceling bridge configured to cancel the transmission signal at the receiver signal input, the echo canceling bridge coupled to a control device via at least a first control line, the echo canceling circuit having an aspect that is programmable via at least the first control line;
(d) a sense impedance connected to the signal line;
(e) a feedback resistor network provided between the sense impedance and the signal input, the feedback resistor network operable to form a synthesized termination impedance of the xDSL transceiver as a product of the sense impedance and an impedance synthesis factor, the feedback resistor network configured to be controllably varied by the control device such that controllable variation of the feedback resistor network adjusts the impedance synthesis factor such that sysnthesized termination impedance matches the line impedance of said signal line;
wherein the sense impedance is a complex impedance and is configured such that the synthesized termination impedance substantially matches the line impedance over the predetermined broadband frequency range.
9 . The broadband xDSL transceiver according to claim 8 wherein the line driver, the receiver, the feedback resistor network and the echo canceling bridge are integrated into an integrated circuit chip.
10 . The broadband xDSL transceiver according to claim 8 wherein the line driver has a fully differential signal input.
11 . The broadband xDSL transceiver according to claim 8 wherein the line driver comprises a signal output which is connected via a transformer to the signal line.
12 . The broadband xDSL transceiver according to claim 11 wherein the echo canceling bridge comprises a resistor network.
13 . The broadband xDSL transceiver according to claim 12 , wherein the resistor network comprises two resistors having resistances R 1 and R 2 respectively, and wherein a gain GRX of the reception signal received by said receiver is given by:
GRX =(1/ G )*( G+A );
wherein A=(1−G)/(1+R 2 /R 1 ) and G is the impedance synthesis factor.
14 . The broadband xDSL transceiver according to claim 13 , wherein the feedback resistor network is programmed such that the synthesis factor is sufficiently high to have an acceptable gain GRX of the reception signal and sufficiently low to achieve a low power dissipation.
15 . An arrangement for transmitting and receiving xDSL signals in a broadband frequency range via a signal line which has a complex line impedance, the arrangement comprising:
(a) a line driver having a signal input and configured to drive a transmission signal received at the signal input, the line driver operably coupled to provide the transmission signal to the signal line;
(b) a receiver having a receiver signal input and configured to process a reception signal received at the receiver signal input via said signal line;
(c) an echo canceling circuit configured to attenuate the transmission signal at the receiver signal input, the echo canceling circuit having an aspect that is programmable via at least a first control line;
(d) a sense impedance connected to the signal line, the sense impedance having a complex impedance;
(e) a variable feedback resistor network provided between the sense impedance and the signal input, the feedback resistor network operable to form a synthesized termination impedance of the arrangement as a function of the sense impedance and an impedance synthesis factor.
16 . The arrangement according to claim 15 wherein the line driver, the receiver, the feedback resistor network and the echo canceling circuit are integrated into an integrated circuit chip.
17 . The arrangement according to claim 15 wherein the line driver has a fully differential signal input.
18 . The arrangement according to claim 15 wherein the echo canceling circuit includes devices that are substantially only resistive.
19 . The arrangement according to claim 15 wherein the echo canceling circuit comprises a resistor bridge network.
20 . The arrangement according to claim 15 , wherein the echo canceling circuit includes at least one switchably connectable resistor.
21 . The arrangement according to claim 18 , wherein the echo canceling circuit includes at least one switchably connectable resistor.
22 . An arrangement for transmitting and receiving xDSL signals in a broadband frequency range via a signal line which has a complex line impedance, the arrangement comprising:
(a) a line driver having a signal input and configured to drive a transmission signal received at the signal input, the line driver operably coupled to provide the transmission signal to the signal line;
(b) a receiver having a receiver signal input and configured to process a reception signal received at the receiver signal input via said signal line;
(c) an echo canceling circuit configured to attenuate the transmission signal at the receiver signal input, the echo canceling circuit having an aspect that is programmable via at least a first control line;
(d) a sense impedance connected to the signal line;
(e) a variable feedback resistor network provided between the sense impedance and the signal input, the feedback resistor network operable to form a synthesized termination impedance of the arrangement as a function of the sense impedance and an impedance synthesis factor.
23 . The arrangement according to claim 22 wherein the line driver, the receiver, the feedback resistor network and the echo canceling circuit are integrated into an integrated circuit chip.
24 . The arrangement according to claim 22 wherein the line driver has a fully differential signal input and is operable to drive a differential transmission signal.
25 . The arrangement according to claim 23 wherein the echo canceling circuit includes devices that are substantially only resistive.
27 . The arrangement according to claim 23 wherein the echo canceling circuit comprises a resistor bridge network.
28 . The arrangement according to claim 23 , wherein the echo canceling circuit includes at least one switchably connectable resistor.