5
Application Information
The Applications Engineering group in the Avago
Technologies Fiber Optics Communication Division is
available to assist you with the technical understanding
and design trade-os associated with these transceivers.
You can contact them through your Avago Technologies
sales representative.
The following information is provided to answer some
of the most common questions about the use of these
parts.
Transceiver Optical Power Budget versus Link Length
Optical Power Budget (OPB) is the available optical
power for a ber optic link to accommodate ber cable
losses plus losses due to in-line connectors, splices,
optical switches, and to provide margin for link aging
and unplanned losses due to cable plant reconguration
or repair.
Figure 4 illustrates the predicted OPB associated with
the transceiver series specied in this data sheet at the
Beginning of Life (BOL). These curves represent the at-
tenuation and chromatic plus modal dispersion losses
associated with the 62.5/125 µm and 50/125 µm ber
cables only. The area under the curves represents the
remaining OPB at any link length, which is available for
overcoming non-ber cable related losses.
Avago Technologies LED technology has produced
1300 nm LED devices with lower aging characteristics
than normally associated with these technologies in the
industry. The industry convention is 1.5 dB aging for 1300
nm LEDs. The Avago Technologies 1300 nm LEDs will
experience less than 1 dB of aging over normal commer-
cial equipment mission life periods. Contact your Avago
Technologies sales representative for additional details.
Figure 4 was generated with a Avago Technologies ber
optic link model containing the current industry conven-
tions for ber cable specications and the FDDI PMD
and LCF-PMD optical parameters. These parameters are
reected in the guaranteed performance of the trans-
ceiver specications in this data sheet. This same model
has been used extensively in the ANSI and IEEE commit-
tees, including the ANSI X3T9.5 committee, to establish
the optical performance requirements for various ber
optic interface standards. The cable parameters used
come from the ISO/IEC JTC1/SC 25/WG3 Generic Cabling
for Customer Premises per DIS 11801 document and the
EIA/TIA-568-A Commercial Building Telecommunications
Cabling Standard per SP-2840.
Transceiver Signaling Operating Rate Range and BER Perfor-
mance
For purposes of denition, the symbol (Baud) rate, also
called signaling rate, is the reciprocal of the shortest
symbol time. Data rate (bits/sec) is the symbol rate
divided by the encoding factor used to encode the data
(symbols/bit).
When used in Fast Ethernet, FDDI and ATM 100 Mb/s
applications the performance of the 1300 nm transceiv-
ers is guaranteed over the signaling rate of 10 MBd to
125 MBd to the full conditions listed in individual product
specication tables.
TRANSCEIVER RELATIVE OPTICAL POWER BUDGET
AT CONSTANT BER (dB)
0 200
0
SIGNAL RATE (MBd)
25 75 100 125
2.5
2.0
1.5
1.0
175
0.5
50 150
CONDITIONS:
1. PRBS 2
7
-1
2. DATA SAMPLED AT
CENTER OF DATA SYMBOL.
3. BER = 10
-6
4. T
A
= +25˚ C
5. V
CC
= 3.3 V to 5 V dc
6. INPUT OPTICAL RISE/
FALL TIMES = 1.0/2.1 ns.
0.5
OPTICAL POWER BUDGET (dB)
0
FIBER OPTIC CABLE LENGTH (km)
0.5 1.5 2.0 2.5
12
10
8
6
4
2
1.
00.3
AFBR-5803, 62.5/125 µm
AFBR-5803
50/125 µm
Figure 4. Optical Power Budget at BOL versus Fiber Optic Cable Length.
Figure 5. Transceiver Relative Optical Power Budget at Constant BER vs.
Signaling Rate.
The transceivers may be used for other applications at
signaling rates outside of the 10 MBd to 125 MBd range
with some penalty in the link optical power budget
primarily caused by a reduction of receiver sensitivity.
Figure 5 gives an indication of the typical performance
of these 1300 nm products at dierent rates.
These transceivers can also be used for applications
which require dierent Bit Error Rate (BER) performance.
Figure 6 illustrates the typical trade-o between link BER
and the receivers input optical power level.
