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

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

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

Testing Baseline Testing Attenuation Testing 5 dB 10 dB Alignment Tolerance

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

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

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

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

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

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

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

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

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!

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

Rx Sensitivity – Alignment Tolerance

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:

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