Senior Design Project: Group IV

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Senior Design Project Group IV
Gigabit Ethernet Optical Transceiver Group
Members Jinesh Karia Rakesh Soni James
Cummings Elisa Hurwitz Bishan Patel
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In the past week..

• Finished soldering Transmitter..
• Ran into wall of problems
• Failed to get eye diagrams
• Countless hours on debugging (sometimes till 4 in
  the morning!!!!!)
• Board surgery done on more than one incident
• Plans for the last few days

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Problems Faced

• Power connectors - defective part
• While changing power connectors, a little more
  force and the traces came off
• Board layout had two main problem
• Ibias Imod currents were feeding the wrong pin
  of the VCSEL
• Pin 11 was left floating instead of Vcc
• Ground plane was not cut as needed

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Problems continued

• Differential input to Maxim chip had different DC
  and AC components
• Voltages on the pin 4 and pin 5 were not up to
  the specs
• Only able to obtain a eye diagram for D28.5 which
  has significant jitter

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Solutions
Anode

• Surgery was performed to fix the Itotal problem
• Replaced the missing traces
• Plans for new board

Imod
Ibias
Cathode
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Eye Diagram
D 21.5 The only one that worked
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Problems still being looked at..

• AC component at pin 4 vs pin 5
• Compared to working board huge difference in DC
  value
• 2 volts compared to 5 volts on working board

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Finding a solution FAST

• All four VCSELs were tried, without success
• Changed Maxim 3267 chip twice
• Replaced Rmod
• Checked Values all around the board
• VCSEL was tested to be working on Nickolass
  testing board
• Did not make a difference

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Next Step

• Possible problem with Imod
• VCSEL could be damaged
• More debugging
• Second board fabrication should be in on Monday

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GANTT CHART
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Work to be done

• Get that Transmitter Working real FAST!
• Finish working on the Final Paper.