2.0 Functional Description
CX28331/CX28332/CX28333
2.2 Transmitter
Single/Dual/Triple E3/DS3/STS-1 Line Interface Unit
For DS3/STS-1 rates, a pulse-shaper block is used to shape the transmit
waveform and reduce its high-frequency energy content. This ensures that the
transmit pulse template is met at the cross-connect block, which follows 0–450
feet of transmit-side coaxial cable.
2.2.3 Line Driver
The differential line driver takes the filtered transmit waveform, increases it to the
proper level, and drives it into the transmit magnetics. The two external discrete
back-matching resistors (36 Ω) aid in line matching. The driver is presented with
an approximately 150 Ω differential load. Driver gain accounts for the 6 dB gain
loss in the back-matching resistors.
Figure 2-3 illustrates the Pulse/Power template measurement points for the
various data rates.
Figure 2-3. Pulse Measurement Points
Pulse/Power Template for DS3/STS-1
0–450 ft COAX
(type 734/728)
0–450 ft COAX
(type 734/728)
RX
DSX
TX
Pulse/Power Template for E3
0–450 ft COAX
(type 734/728)
0–450 ft COAX
(type 734/728)
DSX
TX
RX
100604_013
2-4
Conexant
100985A
CONEXANT [ CONEXANT SYSTEMS, INC ]
