Design Summary:
Design for low-cost, high-volume manufacturing
Avago Technologies’ parallel optics solution
combines twelve 2.7 Gbd channels into discrete
transmitter and receiver modules providing a
maximum aggregate data rate of 32 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-effective high- density (Gbd per inch)
solutions for high-data capacity applications.
See Figure 1 for the transmitter and Figure 2
for the receiver block diagrams.
The HFBR-779BZ transmitter and the HFBR-
789BZ receiver modules provide very closely
spaced, highspeed 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 sensitivity specifications 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 diffractive optical lens array to
launch the beam of light into the fiber. The
package and connector system are designed to
allow repeatable coupling into standard 12-fiber
ribbon cable. In addition, this module has been
designed to be compliant with IEC 60825 Class
1 eye safety requirements. 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 and
extinction ratio 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,
transimpedence preamplifier, filter, gain stages
to amplify and buffer 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 flexible electronic subassembly was designed
to allow high-volume assembly and test of the
VCSEL, PIN photo diode and supporting
electronics prior to final assembly.
Regulatory Compliance
The overall equipment design into which the
parallel optics module is mounted will determine
the certification level. The module performance
is offered as a figure 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 first 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 floor 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® (MTO) connector receptacle 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.
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AVAGO [ AVAGO TECHNOLOGIES LIMITED ]
