| 摘要 |
An improved line interface device (300) and an improved xDSL modem (305) for use in connecting data communications equipment to a xDSL line (312) is disclosed. The line interface device (300) provides the required isolation between the xDSL line and the communication equipment (310) using optical isolation or capacitive techniques, as well as provides the power necessary to produce the transmit signal levels required by the communication service by utilizing a switching power supply (360) deriving its power from a source isolated from the line, and including a transformer (364) for isolating the source from the xDSL line (312). By switching at high frequencies the size of the transformer (364) can be sufficiently small so that the interface device (300) and supply can be provided in accordance with small form factor requirements.
|
