XRT73L06 Datasheet, PDF (20/63 Pages) Exar Corporation – SIX CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT

XRT73L06
REV. 1.0.2
SIX CHANNEL E3/DS3/STS-1 LINE INTERFACE UNIT
2.0 THE RECEIVER SECTION
The receiver is designed so that the LIU can recover clock and data from an attenuated line signal caused by
cable loss or flat loss according to industry specifications. Once data is recovered, it is processed and
presented at the receiver outputs according to the format chosen to interface with a Framer/Mapper or ASIC.
This section describes the detailed operation of various blocks within the receive path. A simplified block
diagram of the receive path is shown in Figure 5.
FIGURE 5. RECEIVE PATH BLOCK DIAGRAM
RTIP_n
RRing_n
Peak Detector
AGC/
Equalizer
Slicer
Clock & Data
Recovery
LOS
Detector
HDB3/
MUX
B3ZS
Decoder
Channel n
RxClk_n
RxPOS_n
RxNEG/LCV_n
RLOS_n
2.1 Receive Line Interface
Physical Layer devices are AC coupled to a line interface through a 1:1 transformer. The transformer provides
isolation and a level shift by blocking the DC offset of the incoming data stream. The typical medium for the
line interface is a 75Ω coxial cable. Whether using E3, DS-3 or STS-1, the LIU requires the same bill of
materials, see Figure 6.
FIGURE 6. RECEIVE LINE INTERFACECONNECTION
1:1
Receiver
DS-3/E3/STS-1
37.5Ω
37.5Ω
RLOS_n
0.01µF
RTIP_n
75Ω
RRing_n
17