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Allen Duncan Curtis Grens Kenny Haulk Chris Lambrecht Nassisa-Geda Techane

Allen Duncan Curtis Grens Kenny Haulk Chris Lambrecht Nassisa-Geda Techane. April 24, 2003. Group Management - Overview. Overall Progress. Devised Effective Group Management Plan Researched & Selected Necessary Components Prepared Comprehensive Optical Link Budget

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Allen Duncan Curtis Grens Kenny Haulk Chris Lambrecht Nassisa-Geda Techane

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  1. Allen DuncanCurtis GrensKenny HaulkChris LambrechtNassisa-Geda Techane April 24, 2003

  2. Group Management - Overview

  3. Overall Progress • Devised Effective Group Management Plan • Researched & Selected Necessary Components • Prepared Comprehensive Optical Link Budget • Designed Schematics and PCB Layout for Gigabit Ethernet TX/RX • Assembled and Tested • Analyzed & Debugged Variety of Problems with Transceiver • Satisfied IEEE 802.3z Standards • Evaluated Performance Characteristics, e.g., Alignment Tolerance • Stayed Within Research/Development Budget of $350

  4. Testing • Baseline Testing • Attenuation Testing • 5 dB • 10 dB • Alignment Tolerance

  5. Baseline Transceiver Tests • Initial Results: Baseline Tx Results Baseline Rx Results • Observations • No Problems with Baseline Testing

  6. Receiver Sensitivity – Attenuation • Initial Results: 5 dB Rx Results with Tx “On” 5 dB Rx Results with Tx “off”

  7. Receiver Sensitivity – Attenuation • Observations • Rx gives better eye when Tx is “on” • Rx with Tx on is better but still poor • Hypotheses • Possible reasons why results differ when Tx is on • Crosstalk • Possible causes to Rx degradation • Crosstalk • Poor PD characteristics • Poor connections

  8. Receiver Sensitivity – Attenuation • Discovering the Problem • Test Simultaneous Operation w/ RX Input Disconnected • Result: Bit-Pattern Present • Conclusion: Crosstalk Evident

  9. Receiver Sensitivity – Attenuation • Determining the Problem • Checked all connections • Result: Found Atten. Were not firmly connected • Analysis: Eyes were cleared up considerably Firm Connect, Tx Off Firm Connect, Tx On

  10. Receiver Sensitivity – Attenuation • Additional Problems • With Tx on, eye-diagram is still cloudy • Crosstalk still a problem • Possible Solution: Shielding

  11. X-Talk experiments: Shielding • Shielding between entire TX and RX Aluminum Shield Setup between TX and RX

  12. Receiver Sensitivity – Attenuation • Shielding • Significant improvement in shielding Tx and Rx Tx on, no shielding Tx on, shielded

  13. Receiver Sensitivity – Attenuation • Conclusion • EMI caused significant degradation of signal with 5 dB or more attenuation • Improved with shielding • Connectors must have secure connections • Firm connection resulted in a receiver eye • Crosstalk can be very misleading!

  14. Performance Characteristics – Alignment Tolerance • Region where we get acceptable results is basically circular • Although, we may have estimated the center wrong • Able to get a good eye, at center, up to 820um away

  15. Rx Sensitivity – Alignment Tolerance

  16. Important Details: IEC Eye-Safe Optical Power Output Limit: 1 mW Typical Optical Power Output of GDS1250: 0.364 mW 5 dB Attenuation from GDS1250 TX:

  17. Wrap-Up • Basic Functionality Confirmed • Probably Complies with IEEE 802.3x Standards • Room To Improve Performance w/ Better Shielding and/or Improved Layout • Overall, A Working Gigabit Optoelectronic Link

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