CX28331 datasheet(36/68 Pages) CONEXANT

36 / 68 page

2.0 Functional Description

CX28331/CX28332/CX28333

2.2 Transmitter

Single/Dual/Triple E3/DS3/STS-1 Line Interface Unit

2-4

Conexant

100985A

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

0–450 ft COAX

(type 734/728)

DSX

0–450 ft COAX

Pulse/Power Template for E3

Pulse/Power Template for DS3/STS-1

(type 734/728)

DSX

0–450 ft COAX

(type 734/728)

0–450 ft COAX

(type 734/728)

100604_013

CX28331 데이터시트(PDF) 36 Page - Synaptics Incorporated.