Active Output Impedance for ADSL Line Drivers

Signal termination is very common in bidirectional communication systems. Termination allows for receiving signals while transmitting different signals at the same time. With the increasing popularity of asymmetrical digital subscriber lines (ADSL), the requirement for a low power line driver amplifier combined with line termination becomes a very difficult goal. This application note examines the line driver amplifier requirements of an ADSL system and how to utilize active impedance to obtain low power dissipation. Actual lab measurements with a THS6032 line driver are discussed. Additionally, the receiver amplifier circuit requirements and the system?s noise requirements are discussed with a THS6062 low-noise amplifier used as an example.