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