An analog front end for communicating discrete multitone modulated signals on
a subscriber line includes a transmit block, a receive block, and a hybrid packaged
within a same integrated circuit. Upstream data to be transmitted to the subscriber
line is pre-processed to eliminate even images. A power spectral density shaping
filter subsequently substantially eliminates undesired energy in the upstream data
signal. A high pass filter further rejects upstream data from the downstream data
signal. The power spectral density filter and the high pass filter enable the use
of a first order hybrid network for extracting the downstream data. The analog
front end may include an additional analog channel to enable voiceband (e.g., v.90)
communication concurrent with non-voiceband (e.g., xDSL) operation. Sample rate
conversion is utilized to avoid the use of multiple independent clocks for otherwise
incompatible clocking requirements.
