GIGABIT ETHERNET DESIGNECE164.02 - Spring 2004

Group 1

Presentation 5 – Yashar Pirzadeh

Week 6 Progress Summary

Updated Schematic Design with Recommended Updates

Made Initial Board Layout and First Revisions Show Practice Board Transmitter Tests Again Review Optical Link Budget Ordering Parts (including Passives) Updated Gantt Chart

Gantt Chart

Practice Board

Transmitter Receiver

Transmitter Assembly (cont.)

Back of Board (scraping to eliminate bad grounds)

Transmitter Testing

10 dB Attenuation – BER = 0E-9 for 30 seconds

Transmitter Testing

10 dB Attenuation – BER = 10E-9 for 30 seconds

Transmitter Testing

Failure = 50 dB, BER= 10E-7 for 30 seconds

Transmitter Testing

Bit Error Rate Readings @ 10 dB Attenuation (10E-9)

Optical Link Budget

Decided on Hamamatsu PD – $18-20 for 1-99 quantity– $6.50 for 10,000+ quantity

No luck with VCSEL Passives ordered within next forty-eight

hours via credit card to be reimbursed– Budget for these calculated and presented next

week

Optical Link Budget Considerations

VCSEL– Lowest Imin is above the lowest Ith

– Provides enough current to drive VCSEL– Those who cannot drive current eliminated

Hamamatsu PD– Picture shows 0.85pF capacitor, 0.010 mA

current– Our current is much higher but capacitance

worse– Rough extrapolation: it should work– Those who didn’t pass this test eliminated

Review of Schematic Changes

Minimal: Removed RC Circuit from Receiver

Important Considerations:– Tight loops, filters, and power supply location

Transmitter Schematic Design

Original Receiver Schematic Design

Revised Receiver Schematic Design

Review of Board Layout Changes

Overall– More overall symmetry– 45 degree angles for wires, no reflection of high

frequency signals Transmitter

– VCSEL straight angle into 3287 through capacitor– Problem: Capacitor about 2mm, only 4 mm space

before transmission line issues– Missing portions from Tx schematic included

Board Layout Revisions (contd.)

Receiver:– Curve the shield around receiver, ground it– Keep power away from high frequency signals

Original Board Layout

Revised Board Layout

Next Week’s Agenda (and beyond)

Spring Break Hopefully board is available Begin building board with

available parts Nag vendors whose parts are

missing Formal Budget Update Gantt Chart

THE END

Group Members– Russell Cook– Yashar Pirzadeh– James Dezelle