Fiber Optics V23816-N1018-C/L352, 3.3V, 4-Line LVDS Parallel 2.7GBd Trp OC-48 OTU1 FEC SONET/SDH SR, 2km
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DESCRIPTION
The Infine on single mode SONET/SDH t ransponder is compli-
ant with the Bellcore GR-253, ITU-T G.957, and ITU-T G.958
specifications. The transmitter section consists of a multiplexer
(Mux), laser driver , F abry Perot (FP) laser diode and pigtail single
mode fiber with LC/PC or SC/PC 0 ° termination. The receiver
section consists of a multimode fiber pigtail with LC/PC or SC/
PC termination, a packaged PIN photodiode and preamplifier,
postamplifier, clock and data recovery (CDR), and a demulti-
plexer (Demux). The Mux and Demux functions are integrated
together onto a single Transceiver IC. The 666.51 MHz parallel
data int er f ace fre es t he us er fr om the c onc erns of pc b la y ou t at
2.7 Gb/s. The pluggable connector blind mates easily to the
customer pcb, and all ows the trans ponder to be removed prior
to any solder reflow or washing of the users pcb.
The transponder operates from a single +3.3 V power supply.
The electrical interface is via a 60 pin pluggable connec tor. The
transmit and receive electrical signals each consist of 4 parallel
differential LVDS data, and a differential LVDS clo ck. The trans-
mit input data and clock lines, and the receive output data and
clock lines, are al l intern al l y bi a sed and te rminate d. Al l li nes are
DC coupled to the interface connector.
The transponder is designed to transmit and receive O T U1 FEC
Rate serial OC-48 (2666.057 Mb/s) data over standard non-dis-
persion-s hifted single mode fiber at a wavelength of 1310 nm.
T h e OTU1 FEC Ra t e ba n d w id t h expa ns io n is 7.14%, and sup-
ports a (255,239) Reed-Solomon code, with error correction
capability of 8 bytes per 255-Byte block, per ITU-T G.709.
Transmitter (Mux Section)
Please refer to the transponder block diagram.
The transmitter accepts a 4 bit wide parallel input data word,
TXD A T AP/N[3:0], at a 666.51 Mb/s data rate. The TX input clock,
TXCLKP/N, is synchronous with the incoming data, at a fre-
quency of 666.51 MHz. This clock is used to load the data into a
4-bit latch. Th e data is read in on the rising edge of the positive
input clock. (See TX Input Timing Diagram).
A reference input clock, REFCLKP/N, at 166.6285 MHz, is sup-
plied as a referenc e input to the high speed Clock Synthesizer.
The high speed output of the clock synthesizer will clock the
Timing Generator and the Parallel-to-Serial Converter. The Paral-
lel-to-Serial Conv erter will output the retimed data as a serial bit
stream, TSDP/N, at 2666.057 Mb/s data rate. Bit 3 of the
TXDATAP/N parallel input word is the MSB, and is transmitted
first in the data stream. Bit 0, the LSB, is transmitted last.
The output of the high speed Clock Synthesizer, which is inter-
nally set to 2666.057 MHz, is tapped off the Timing Generator,
and is divided to 666.51 MHz. This output (PCLKP/N) is
intended to be used as a reference clock for TX upstream logic.
The TX Clock Synthesizer section provides a lock alarm output
signa l , TXLOCK, whi ch ind ic a tes if th e c lo ck synth es izer i s prop-
erly phase locked.
Transmitter (Electro-Optical Section)
T h e s eri a l d a ta ou t put , TSD P/N , of t he Transcei ver IC is in p ut to
a las er d riv er IC. The lase r driver provid es b ot h bia s an d mod ula -
tion to a laser diode. The laser bias current is controlled by a
closed-loop circuit, which regula tes the output average power
of the lase r o v er co ndit ions of t emp era t ur e an d ag in g. The Mon -
itor PIN diode, which is mechanically built into the laser, pro-
vides a feedback signal to the laser driver, and prevents the
lase r power from exceeding the factory preset operat ing limits.
The laser driver includes an eye saf ety feat ure that will automat-
ically shut off power to the laser if a fault condition occurs
which causes excessively high laser bias current or excessively
high average output pow er. Such a fault will be indicated on the
TX_FAULT output. The fault can be cleared by cycling DC
power, or by strobing the RESET_L input.
The M ux and Laser Driver can be r eset with the RESE T_L input.
During the time that RESET_L is held active, there will be no
optical output from the transmitter. The RESET_L input will
clear any fault indication that has occu rred on the T X_FAULT
output.
The laser can be switched off at any time with the
LASER_DISABLE input.
The TX_BIASALM output is provided as an alarm to indicate if
the laser bias current is outside of the normal operating range.
This output can be use d to monitor the aging of the laser.
The laser diode is a Fabry-Perot type, which, due to the cavity
nature of its design, will emit li ght at several longitudinal wave-
lengths, or modes centered about 1310 nm. This type of laser is
suitable f or the short reach tr ansmission ov er single-mode fiber
that this transponder is intended for. The laser has a single-
mode f iber pi gtail, whic h is t erminat ed in a n LC/PC o r SC/PC 0 °
optical connector.
Receiver (Electro-Optical Section)
Th e input light to the RX is coupled from the transmission fiber
into a PIN/Preamp assembly on the transponder. The PIN/
P rea mp c ontai ns a mu lti-mo de f ib er pi gtai l, wh ic h i s t ermin at ed
in an LC/PC or SC/PC 0 ° optical connector. The multi-mode
fiber pigtail has a larger core diameter (50 µ m) than the single-
mode transmission fiber (9 µm). Th eref ore, all the light from the
single-mode fiber is coupled into the larger diameter core of the
multi-mode pigtail.
The PIN/Preamp contains a PIN photodiode, trans-impedance
amplifier and non-limiting post-amplifier in one package. The
PIN diode produces a current output, which is directly propor-
tional to the intensity of the incoming light. The trans-imped-
ance amplifier performs current-to-voltage conversion, and the
non-limiting post-amplifier quantizes the signal into a digital out-
put.
The receiver contains a RX power monitor ou tput, which is a
voltage output directly prop ortional t o the average optical input
power.
The Limiting Post-Amplifier provides additional voltage amplifi-
cation, and also provides a Loss Of Signal (RX_LOS) indicator.
LOS wil l oc c ur a t a RX in pu t p ow er le vel l e ss t ha n t he s pe c ified
RX Sensitivity, and is an indication that the RX is taking bit
errors.