Datasheet

NRND
TP3404
www.ti.com SNOS703 –DECEMBER 2004
LINE RECEIVE SECTIONS
The input of each receive section, Li0–Li3, consists of a continuous anti-alias filter followed by a switched-
capacitor low-pass filter designed to limit the noise bandwidth with minimum intersymbol interference. To correct
pulse attenuation and distortion caused by the transmission line an AGC circuit and first-order equalizer adapt to
the received pulse shape, thus restoring a “flat” channel response with maximum received eye opening over a
wide spread of cable attenuation characteristics.
From the equalized output a DPLL (Digital Phase-Locked Loop) recovers a low-jitter clock for optimum sampling
of the received symbols. The MCLK input provides the reference clock for the DPLL at 4.096 MHz.
Following detection of the recovered symbols, the received data is de-scrambled by the same X
9
+ X
5
+ 1
polynomial and presented to the digital system interface circuit.
When a transmission line is de-activated, a Line-Signal Detect Circuit is enabled to detect the presence of
incoming bursts if the far-end starts to activate the loop.
Figure 3. Typical AMI Waveform at Lo
Figure 4. Typical AMI Transmit Spectrum Measured at LO Output (With RGB = 100 Hz)
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