Transcript Presentation 8

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