Optical Gigabit Ethernet
Group F.O.R.E.March 31, 2005
Ronen Adato
Progress Overview
Completed Midterm Report Soldered and Tested 2
Conservative Design Boards
Conservative Board 1 Soldered all
components and tested the Rx circuit for a clear eye
Errors in part selection prevented BER testing for the Rx circuit, and any Tx circuit testing
Rx Circuit Test Setup
Eye Produced by Rx Circuit, Signal PRBS 7
Conservative Board 1 QMAs were sent instead of SMAs
We elected to attempt and use these incorrect parts
A clear eye was produced by the Rx circuit, but the coaxial cables had to be held tightly into the QMAs
BER testing of the Rx circuit was impossible as a consistent signal could not be achieved with the QMAs
Tx circuit was not tested as this would have been very difficult with the QMAs
Conservative Board 2 SMAs were removed
from the test board to be used in the prototype
The QMAs were removed from the original board
Attempts to insert the SMAs into the holes occupied by the QMAs resulted in the destruction of a trace
Board 1 With QMAs Removed
The Destroyed Trace
Conservative Board 2 The VCSEL and ROSA
were de-soldered and a new board was constructed
The VCSEL was recycled while a new ROSA was used
The Limiting Amplifier (MAX3264) was incorrectly placed and had to be removed and re-soldered
The Second Conservative Board
Conservative Board 2 The Rx circuit
failed to produce an eye It was determined
that the LA (MAX3264) had been damaged
Rx Circuit Waveform Measured Before LA
Rx Circuit Waveform Measured After LA
Conservative Board 2 The Tx circuit was
tested and does not work
The VCSEL is not lasing Voltage measurements
were taken throughout the circuit
In general, the entire loop around the VCSEL has a 5V dc voltage
Potentiometer adjustments changed nothing
We suspect our VCSEL may not be functioning
GANTT Chart
Tasks for Next Week
Replace the LA in the Rx circuit and retest, including BER measurements
Fix and test the Tx circuit The VCSEL will probably be replaced
Loop-back test the entire board Solder and test the aggressive
design
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