GIGABIT ETHERNET DESIGN ECE164.02 - Spring 2004

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GIGABIT ETHERNET DESIGNECE164.02 - Spring 2004

• Presentation 3

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Introduction

• Tested Transmitter Evaluation Board
• Eye Testing
• BER Testing
• Built Practice Board Receiver
• Intro to Design
• Exposure to Surface Soldering
• Tested Practice Board
• Eye Testing
• Attenuation Effects
• BER Testing
• Modified Gantt Chart

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Evaluation - Transmitter Testing

• Test Setup for
• Reading in Scope

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Evaluation - Transmitter Testing

• Ugly Eye Shown
• No attenuation
• Ran out of film
• Disk Problems with Oscilloscope

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More ProblemsEvaluation - Transmitter Testing

• Poor BER
• High Error Rate
• Again, no more space on digital camera

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Evaluation Receiver Testing

• Test Setup to Scope for the Evaluation Receiver
  Circuit

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Evaluation Receiver Testing

• Very Descent Eye
• No attenuation
• Small Undesirable Line on Right-hand Side
• No detectable errors

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Adding Attenuation

• As expected, the eye degrades with more and more
  attenuation
• (20 dB shown for eye) (34 dB shown for
  BER)
• BER 4.8E-07

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Getting Our Feet Wet

• Soldering
• Flux is Useful for surface that are not sticky
• Need good contact for a good signal

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Building Receiver

• Better feel for how the circuit works and where
  the signal is going
• Surface Soldering is not frustrating
• Proper Power Supply Connectors Unavailable Used
  wires to begin testing

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Practice Receiver Testing

• Setup for eye testing in oscilloscope

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Practice Receiver Testing

• Differential Outputs Verification
• Pretty much symmetric waveforms

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Practice Receiver Testing

• Poor Eye with no attenuation
• But

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Practice Receiver Testing

• Adding 10 dB attenuation results in a very clean
  eye
• Why?

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Practice Receiver Testing

• 20 dB

40 dB
50 dB
30 dB
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Practice Receiver Testing

• BER insignificant for 10-30 dB range (as shown),
  but was high when no attenuation was applied

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Circuit Design Layout

• Building the Practice Board introduces Circuit
  Design Layout by way of example
• These are scheduled in later weeks

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Gantt Chart
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Next Week

• Optical Link Budget has been delayed, It will be
  a top concern in the coming week
• Transmitter Construction Assembly
• PCB Design Layout