ECHO CANCELLING ARRANGEMENT

摘要

In a line driver/receiver circuit where the line driver (3) is connected with its output terminals to a load (ZL) for supplying a transmit signal thereto and where the receiver (2) is connected with its input terminals to the load (ZL) for simultaneously receiving a receive signal therefrom, the transmit signal on the input terminals of the receiver (2) is cancelled by connecting the output terminals of the line driver (3) to the load (ZL) via equal complex sense impedances (ZS) of an impedance value that is much smaller than the impedance value of the load impedance (ZL) to match the load impedance (ZL), connecting the input terminals of the receiver (2) to the load (ZL) via equal first resistors (R1) and to respective output terminal of the line driver (3) via equal second resistors (R2), and providing transconductance amplifiers to sense the voltage across the sense impedances (ZS) and supply corresponding currents to respective input terminal of the line driver (3).