Gigabit%20Ethernet%20PMD

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Gigabit Ethernet PMD

• Opto-Link Inc. Presentation 5

Vinh Nguyen February 24, 2005
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Gigabit EthernetProgress Summary
Completed Tasks
Next Weeks Tasks

• Fixed errors in optical link budget
• Finished initial schematic design
• Schematic approved with minor alterations
• Added details to budget
• Began looking at board layout

• Complete initial board layout
• Board layout design review
• Order passives and connectors?

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Gantt Chart
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Corrected Optical Link Budget
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Transmitter Schematic
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Receiver Schematic
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Estimated Budget
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Board Layout and Transmission Lines

• We looked into the possibility of using short 50O
  matched transmission lines to improve performance
• Equations for the capacitance per unit length and
  inductance per unit length of a microstrip
  transmission line are fairly easy to find
• Why bother doing the math when you can use the
  Internet?

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Microstrip Transmission Line Calculator

• Microstrip transmission line calculator at
• http//www.emclab.umr.edu/pcbtlc2/microstrip.html
• Used 50O target impedance and parameters from the
  ExpressPCB website
• A 50O transmission line will have a width of
  0.10604-0.11668 (2.69mm-2.96mm)

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Problems with Line Size

• Transmission lines will be very wide on the
  boards
• Even if we minimize line length, we will still
  use up a lot of space

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Transmission Line Width Comparison
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Even Short Transmission Lines Take Up A Lot of
Space
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Transmission Line Summary

• Using transmission lines would probably improve
  performance
• It would be hard to fit the transmission lines on
  the MiniBoards
• Larger boards would result in increased costs

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Next Week

• Make adjustments to schematic
• Complete initial board layout
• Board layout design review
• Research and order passives?
• Refine budget

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References

• ECE164 Group 2 Presentations. (April 17, 2004).
  ECE164 Group 2 Website. Retrieved February 24,
  2005 from http//www.ee.duke.edu/mbrooke/EE164.02
  /Spring_2004/group_2/presentations.html
• University of Missouri-Rolla Electromagnetic
  Compatibility Laboratory. (February 23, 2005).
  Microstrip. Retrieved February 24, 2005 from
  http//www.emclab.umr.edu/pcbtlc2/microstrip.html
• Various vendor and manufacturer websites