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Design Summary:
Design for low-cost, high-volume manufacturing
Avago’s parallel optics solution combines twelve 2.5
Gb/s channels into discrete transmitter and receiver
modules providing a maximum aggregate data rate of
30 Gb/s. Moreover, these modules employ a heat sink for
thermal management when used on high-density cards,
have excellent EMI performance, and interface with the
industry standard MTP®/MPO connector systems. They
provide the most cost-eective high- density (Gb/s per
inch) solutions for high-data capacity applications. See
Figure 1 for the transmitter and Figure 2 for the receiver
block diagrams.
The AFBR-732BWZ transmitter and the AFBR-742BZ
receiver modules provide very closely spaced, high-speed
parallel data channels. Within these modules there will be
some level of cross talk between channels. The cross talk
within the modules will be exhibited as additional data
jitter or sensitivity reduction compared to single-channel
performance. Avago Technologies’ jitter and sensitiv-
ity specications include cross talk penalties and thus
represent real, achievable module performance.
Functional Description, Transmitter Section
The transmitter section, Figure 1, uses a 12-channel 850
nm VCSEL array as the optical source and a diractive
optical lens array to launch the beam of light into the
ber. The package and connector system are designed to
allow repeatable coupling into standard 12-ber ribbon
cable. In addition, this module has been designed to be
compliant with IEC 60825 Class 1M eye safety require-
ments.
The optical output is controlled by a custom IC, which
provides proper laser drive parameters and monitors
drive current to ensure eye safety. An EEPROM and state
machine are programmed to provide both ac and dc
current drive to the laser to ensure correct modulation,
eye diagram over variations of temperature and power
supply voltages.
Functional Description, Receiver Section
The receiver section, Figure 2, contains a 12-channel
AlGaAs/ GaAs photodetector array, transimpedance
preamplier, lter, gain stages to amplify and buer the
signal, and a quantizer to shape the signal.
The Signal Detect function is designed to sense the
proper optical output signal on each of the 12 channels.
If loss of signal is detected on an individual channel, that
channel output is squelched.
Packaging
The exible electronic subassembly was designed to
allow high-volume assembly and test of the VCSEL, PIN
photo diode and supporting electronics prior to nal
assembly.
Regulatory Compliance
The overall equipment design into which the parallel
optics module is mounted will determine the certica-
tion level. The module performance is oered as a gure
of merit to assist the designer in considering their use in
the equipment design.
Organization Recognition
See the Regulatory Compliance Table for a listing of the
standards, standards associations and testing laboratories
applicable to this product.
Electrostatic Discharge (ESD)
There are two design cases in which immunity to ESD
damage is important.
The rst case is during handling of the module prior
to mounting it on the circuit board. It is important to
use normal ESD handling precautions for ESD sensitive
devices. These precautions include using grounded wrist
straps, work benches, and oor mats in ESD controlled
areas.
The second case to consider is static discharges to the
exterior of the equipment chassis containing the module
parts. To the extent that the MTP® (MPO) connector recep-
tacle is exposed to the outside of the equipment chassis
it may be subject to system level ESD test criteria that the
equipment is intended to meet.
See the Regulatory Compliance Table for further details.
