Optical Gigabit Ethernet Group 4 Presentation 3 February 10, 2005 David Larado.
Optical Gigabit Ethernet
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Transcript of Optical Gigabit Ethernet
Optical Gigabit Ethernet
Group 4February 3, 2005
Ronen Adato
Progress Overview
Tested Evaluation board Continued part research Created an Optical Link Budget Began contacting part vendors
Evaluation Board Testing
Setup for BER testing; the clock was fed into the BER tester, thus the oscilloscope signal was triggered on itself
Setup for viewing eye diagrams; the clock was used to trigger the oscilloscope signal, producing a better eye
Evaluation Board Testing
Self triggered setup, signal PRBS 7 with 40 db attenuation
Clock triggered setup, signal PRBS 7 with 40 db attenuation
Evaluation Board Testing
Signal quality decreased with attenuation in general
BER remained constant 0 db was too little
attenuation
BERs for signal PRBS 7
Attenuation BER
0 db 1.2x10-1
10-70 db 10-9
Signal PRBS 7, 0 db attenuation
VCSEL and PD Selection
6 possible VCSEL vendors Advanced Optical Components,
Lasermate, Roithner Lasertechnik, Appointech, Oepic Inc. and TERAdian Inc.
6 possible PD vendors Optoway Inc., OSI Fibercomm,
Appointech, Luxnet, Hamamatsu and OECA
VCSEL and PD Selection
VCSEL and PD Selection
VCSEL and PD Selection
Equations I = (P/η) + Ith Imax = (Pmax/η) + Ith Imin = (Pmin/η) + Ith Ibias = (Imax + Imin)/2 Imod = Imax - Imin
VCSEL and PD Selection
VCSEL and PD Selection
Equations Pat PD = (Pfrom VCSEL)(10-(fiber loss/10)) Iout = R x Pat PD
VCSEL and PD Selection Optical Link Budget
The Limiting Amplifier (MAX3264) takes 5-1200 mV
The TIA (MAX3266) has 2.26 kΩ transimpedence
So Iout from the PD must be at least 2.212μA to drive the Limiting Amplifier
The TIA also cannot take more than 4mA and operate normally
VCSEL and PD Selection Optical Link Budget
The Laser Driver (MAX3287) can only produce current modulation between 2-30 mA
Based on the necessary input current to the TIA we can determine which PDs have adequate responsivity
The output of the Laser Driver determines which VCSELs will work
VCSEL and PD Selection
All the PDs have adequate responsivities and thus worst case output currents
The Advanced Optical Components HFE438x-521 VCSEL, with a worst case Imod of 43.705 is outside the range of the Laser Driver
Vendor Quotes
VCSELs Lasermate: The part is available
1-9 units - $32.00 10 units - $25.00 10,000 units - $7.95
Roithner Lasertechnik: The part is discontinued, they have 10 left
25 Euros/ unit for all of them
Vendor Quotes PDs
OSI Fibercomm FCI-125G-006HR: 9 are in stock
1-9 units - $10 101-500 units - $5
OSI Fibercomm FCI-125G-010HR: 12 are in stock
1-9 units - $10 101-500 units - $5
Vendor Quotes
PDs Hamamatsu S5971: none are in stock
$6.72 regardless, but a minimum order of $50
Additional Concerns The Oepic VCSEL is 10Gbps
The company gives samples, so it may fit into our budget
For the large scale budget it may be to costly It may not work with the other parts
The rise/fall time on the Laser Driver data sheet is a minimum of 250, most of our VCSELs do not meet this requirement
The capacitances of some of our PDs are high
Lasermate also makes a SC-ROSA PD
GANTT Chart
Goals for Next Week
Complete Optical Link Budget and choose components
Build the test board (if the parts have come in)
Begin financial budgeting Possibly order our VCSELs and PDs