ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005...

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ECE 135 – The Three ECE 135 – The Three Presentation 10 Presentation 10 Bryan Chavez Bryan Chavez with Pat Cleary & Kevin Parker with Pat Cleary & Kevin Parker April 14 April 14 th th , 2005 , 2005

Transcript of ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005...

Page 1: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

ECE 135 – The ThreeECE 135 – The Three Presentation 10 Presentation 10

Bryan ChavezBryan Chavezwith Pat Cleary & Kevin Parkerwith Pat Cleary & Kevin Parker

April 14April 14thth, 2005 , 2005

Page 2: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Work SummaryWork Summary

Troubleshoot Board 1Troubleshoot Board 1ΓΓ

Soldered Aggressive Tx on Board 1Soldered Aggressive Tx on Board 1

Tested Aggressive Tx Board 1Tested Aggressive Tx Board 1

Verified Conservative Rx Board 1Verified Conservative Rx Board 1

Page 3: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

GANTT ChartGANTT Chart

Page 4: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Troubleshooting Board 1Troubleshooting Board 1ΓΓ

Pots adjusted to high resistance valuesPots adjusted to high resistance valuesReplaced VCSEL with 100 Ohm resistorReplaced VCSEL with 100 Ohm resistorNo heating and no blown ferrite beads!No heating and no blown ferrite beads!Probing showed inputs to the LD cleanProbing showed inputs to the LD cleanOutputs of the LD dirty (vague outlines of an eye Outputs of the LD dirty (vague outlines of an eye diagram)diagram)Further probing caused a short in the circuit … blew Further probing caused a short in the circuit … blew another ferrite beadanother ferrite beadReplaced ferrite bead … but it blew up again as power Replaced ferrite bead … but it blew up again as power was plugged inwas plugged inCannot locate short in the circuitCannot locate short in the circuitLow on passives so decided to move on to Aggressive Low on passives so decided to move on to Aggressive Tx designTx design

Page 5: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Aggressive Tx ModificationsAggressive Tx Modifications

Soldered all passives super carefully Soldered all passives super carefully

Used a 25k potentiometer to modulate IUsed a 25k potentiometer to modulate Ibias bias

instead of 1k potentiometerinstead of 1k potentiometer

Adjusted the VCSEL orientation for Adjusted the VCSEL orientation for forward-biasingforward-biasing

Adjusted pot values to safe levels before Adjusted pot values to safe levels before testingtesting

Page 6: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Aggressive Tx ProbingAggressive Tx ProbingLaser Driver Inputs Laser Driver Outputs

Data -

Data +

Data -

Data +

Page 7: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Aggressive Tx Test SetupAggressive Tx Test Setup

Page 8: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Aggressive Tx ResultsAggressive Tx Results

LASING!!!!LASING!!!!

Adjusting IAdjusting Imodmod

and Iand Ibias bias

showed showed improved improved resultsresults

Page 9: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Aggressive Tx Results (cont.)Aggressive Tx Results (cont.)

Working!!!!!!!!

Page 10: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Conservative Rx Test SetupConservative Rx Test Setup

Page 11: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Conservative Rx ResultsConservative Rx Results

PRBS7 PatternPRBS7 Pattern9 dB9 dBBER < 10^-11BER < 10^-115 minute duration5 minute durationProper operation verified!Proper operation verified!

Page 12: ECE 135 – The Three Presentation 10 Bryan Chavez with Pat Cleary & Kevin Parker April 14 th, 2005 April 14 th, 2005.

Future WorkFuture Work

Solder Aggressive Rx on Board 1Solder Aggressive Rx on Board 1

Test Aggressive Rx on Board 1Test Aggressive Rx on Board 1

Perform Loop-back testPerform Loop-back test

Order More PassivesOrder More Passives

Order 2Order 2ndnd Board Fabrication if Board Fabrication if necessarynecessary