1. Allen Duncan Curtis Grens Kenny Haulk Chris Lambrecht Nassisa-Geda Techane
April 24, 2003

2. Group Management - Overview
Group Leader
Chris Lambrecht
Writing/Editing Reports
Nassisa-Geda Techane
Schematic/PCB Layout Design
Kenny Haulk
Budget/Vendor Relations
Allen Duncan
Assembly/Testing
Curtis Grens

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
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: 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