XRT73LC04A_08 Datasheet, PDF (39/64 Pages) Exar Corporation – 4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT

XRT73LC04A
REV. 1.0.2
4 CHANNEL DS3/E3/STS-1 LINE INTERFACE UNIT
3.0 THE RECEIVE SECTION
Figure 13 indicates the Receive Section consists of
the following blocks:
• AGC/Equalizer
• Peak Detector
• Slicer
• Clock Recovery PLL
• Data Recovery
• HDB3/B3ZS Decoder
The purpose of the Receive Section is to take an in-
coming attenuated/distorted bipolar signal from the
line and encode it back into the TTL/CMOS format
where it can be received and processed by the Termi-
nal Equipment.
3.1 INTERFACING THE RECEIVE SECTIONS OF THE
XRT73LC04A TO THE LINE
The design of the Receive Circuitry should be trans-
former-coupled to the Receive Section to the line.
The specification documents for E3, DS3, and STS-1
all specify 75 Ohm termination loads when transmit-
ting over coaxial cable. The recommended method to
interface the Receive Section to the line in a manner
is shown in Figure 22.
FIGURE 22. RECOMMENDED SCHEMATIC FOR INTERFACING THE RECEIVE SECTION OF THE
XRT73LC04A TO THE LINE (TRANSFORMER-COUPLING)
RxPOS_(n)
RxNEG_(n)
RxClk_(n)
RTIP_(n)
Channel (n)
RPOS_(n)
RNEG_(n)
RxClk_(n)
R1
37.4Ω
R2
37.4Ω
RRing_(n)
Only One Channel Shown
C1
0.01uf
J1
T1
BNC
1:1
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