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ECE 135 Final Presentation The Three … aka

ECE 135 Final Presentation The Three … aka. Pat Cleary with Kevin Parker & Bryan Chavez April 21 st , 2005. ECE 135 Final Presentation The VCSEL Kings … aka. Pat Cleary with Kevin Parker & Bryan Chavez April 21 st , 2005. ECE 135 Final Presentation RIO! … aka. Pat Cleary

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ECE 135 Final Presentation The Three … aka

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  1. ECE 135 Final PresentationThe Three … aka Pat Cleary with Kevin Parker & Bryan Chavez April 21st, 2005

  2. ECE 135 Final PresentationThe VCSEL Kings … aka Pat Cleary with Kevin Parker & Bryan Chavez April 21st, 2005

  3. ECE 135 Final PresentationRIO! … aka Pat Cleary with Kevin Parker & Bryan Chavez April 21st, 2005

  4. ECE 135 Final Presentation BtrLaytDanNvr Pat Cleary with Kevin Parker & Bryan Chavez April 21st, 2005

  5. IntroductionThe Goal: An IEEE 802.3 Standard Gigabit Ethernet LinkThe Components:Group and time management plan, background research, part selection, optical link budget, circuit design and layout, construction, and troubleshooting.

  6. Initial GANTT Chart

  7. Group Management

  8. Background Research: Overview

  9. Background Research: Tx

  10. Background Research: Rx

  11. Background Research for Four-Corners Analysis • Eye safe limit → Pmax = 1 mW • From the 802.3 standard → extinction ratio = 9dB • Thus we see that Pmin = Pmax *10^(-9/10) • Pmin = .12589 mW

  12. VCSEL Four Corner Analysis HFE439x-521

  13. ROSA Selection HFD3180-108

  14. Optical Link Budget

  15. Additional VCSEL Purchase LC-TOSA • 20 Free VCSELs Obtained

  16. Introduction to Test Equipment

  17. Introduction to Test Equipment

  18. Tx Test Board Construction …

  19. … And Immediate Correction • Soldered Output Pins in Correct Locations

  20. Tx Test Board Performance • “Best” Eye Diagram • PRBS7 Pattern • Troubleshooting Necessary

  21. Tx Test Board Troubleshooting Grand Conclusions • Outputs and Inputs Reversed • If one truly only learns through failure, we’ve learned a LOT already!

  22. More Tx Test Board Work

  23. Tx Test Board Quality Control • Input in Input • Output in Output

  24. Tx Test Board Performance • No attenuation • PRBS7 Pattern Still not successful

  25. Tx Test Board Conclusions • Eye still not well defined • Potentiometer has minor effect on performance • Conclusion: Board permanently damaged from attempts to drive in reverse direction • Result: If continued testing is necessary a new board is needed

  26. Completed Tx Test Board – Take 2 ← ← Outputs

  27. Tx Test Board Performance 0 dB 10 dB ● PRBS7 Pattern ● 3 minute interval ● BER < 10^-9 (For > 0 dB) 70 dB

  28. Tx Test Board Performance(Continued) ● 70 db ● AC coupled ● 70 db ● Scaled down using potentiometer

  29. Tx Test Board (Take 2) Conclusions • Eye diagrams are very well-defined • Potentiometer scales the eye dramatically • Attenuation has minimal affect on eye • Low BER rate suggests quality performance • The Three are capable of building a working Tx board!

  30. Tx & Rx Schematics Tx Rx

  31. TxRx PCB Layout Agressive Conservative

  32. Board 1A Construction

  33. Board 1A Troubleshooting • No Success with Tx or Rx • High-Pitched Noise and a Smoking Ferrite Bead… • Short Discovered Between Power Supply and Ground (Not from Layout)

  34. Board 1B Construction • The Three’s Tried-and-True Strategy: Start Over • Results: Nothing Breaks During Testing!!!!!

  35. Board 1B Troubleshooting • Receiver Circuit Functions Perfetto • Continuing Issues with Tx

  36. Rx Test Setup

  37. PRBS7 Pattern 9 dB BER < 10^-11 5 minute duration Proper operation verified! Yay Rx Results

  38. Board 1B Transmitter Testing • Left and Right Inputs to VCSEL • Signals Want to Be Eyes… Not Quite There • VCSEL Not Lasing • An Attempt at Board 1Γ Tx Also Unsuccessful

  39. Aggressive Tx Modifications • Soldered all passives super carefully • Used a 25k potentiometer to modulate Ibias instead of 1k potentiometer • Adjusted the VCSEL orientation for forward-biasing • Adjusted pot values to safe levels before testing

  40. Aggressive Tx Test Setup

  41. Aggressive Tx Probing Laser Driver Inputs Laser Driver Outputs Data - Data - Data + Data +

  42. Aggressive Tx Results • LASING!!!! • Adjusting Imod and Ibias showed improved results

  43. Aggressive Tx Results (cont.) Working!!!!!!!!

  44. Loopback Testing for Aggressive Design • PRBS7 Pattern • 7 dB Attenuation • Super Yay • Too Good to Be True? ….

  45. Not This Time! • Signal at 8 dB Attenuation is Lower Quality…As Expected • BER < 0.0E-10 • Removal of an Optical Fiber Produces a Lost Signal • Verified Successful Completion of Gigabit Ethernet

  46. Final Budget

  47. Bill of Materials

  48. Final GANTT

  49. The Three – Pratt Worthy!

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