DHPT Link Optimization Leonard Germic University of Bonn July - - PowerPoint PPT Presentation

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Oct 31, 2023 321 likes •477 views

DHPT Link Optimization Leonard Germic University of Bonn July 2016 germic@physik.uni-bonn.de 1 Virtex 5/6 MGT Receiver specs and BER Height @ BER Width @ BER Width @ BER 1E-12 SP SP -0.5 0 0.5

SLIDE 1

germic@physik.uni-bonn.de 1

DHPT Link Optimization

Leonard Germic University of Bonn ボン大学 July 2016

SLIDE 2

Virtex 5/6 MGT Receiver specs and

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SP Width @ BER Height @ BER BER SP

0.5

Width @ BER 1E-12

SLIDE 3

Pre-emphasis

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BIAS BIASD DEL

Pre-emphasized signal
Three parameters for optimization

BIAS, BIASD and DEL

SLIDE 4

Digital BER test

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Digital test: 7bit LFSR (random bit) sequence
Xilinx BERT core checks if data is correctly transmitted
Minimum logic signal difference (~125mV high-low)

“The Analyzer software displays a “link” signal until there are five consecutive cycles with errors[...]” (Xilinx)

Extraction of minBER and width@1E-6

*.txt file SP BER LinkUp? minBER width@1E-6

SLIDE 5

Analysis of BERT

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Digital test: 7bit LFSR (random bit) sequence
Xilinx BERT core checks if data is correctly transmitted
Minimum logic signal difference (~125mV high-low)
If link is stable BER is recorded
Extraction of minBER and width@1E-6

*.txt file SP BER LinkUp? minBER width@1E-6

SLIDE 6

Analysis of BERT

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Introducing cuts:
cutWidth > 32SP (¼ of )
cutBER > 1E-9

combined (gray triangle) Example of Bathtub plots and the cuts

SLIDE 7

Analysis of BERT

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Introducing cuts:
cutWidth > 32SP (¼ of )
cutBER > 1E-9

combined (gray triangle) Example of Bathtub plots and the cuts Diagonal as measure of opening

SLIDE 8

Optimization proposal for CML driver settings

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Left: #SP(DEL=0,BER=1e-6,cableLength=15m; BIAS,BIASD)
White space corresponds to width=0
Right: minBer(DEL=0,BER=1e-6,cableLength=15m; BIAS,BIASD)
White space corresponds to not linked MGT

B I A S BIASD BIASD 1eX

SLIDE 9

Optimization proposal for CML driver settings

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Left: #SP(DEL=2,BER=1e-6,cableLength=15m; BIAS,BIASD)
White space corresponds to width=0
Right: minBer(DEL=2,BER=1e-6,cableLength=15m; BIAS,BIASD)
White space corresponds to not linked MGT

B I A S BIASD BIASD 1eX

SLIDE 10

Optimization proposal for CML driver settings

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Normalized combined value

D(BER=1e-6,cableLength=15; BIAS,BIASD) = 1/max(D(DEL)) x (width² + minBer²)

This highly constraint parameter space can be

used to extract a parameter pair (BIAS,BIASD) for each DEL paramter and cable length DEL=0 DEL=2

B I A S BIASD

Normalized to the max value of each data set – Values are not comparable between different DEL settings!!!

BIASD BIASD 0.0 1.0 0.0 1.0

SLIDE 11

Optimization proposal for CML driver settings

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DEL=0 DEL=1 DEL=2 DEL=3 Normalized to the max value of all data sets – Values are comparable between different DEL settings!!!

B I A S B I A S BIASD BIASD 0.0 1.0 0.0 1.0 0.0 1.0 0.0 1.0

SLIDE 12

Optimization proposal for CML driver settings

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Extraction of #(BIAS,BIASD) pairs for different cable lengths and DEL settings @

different BER thresholds BER 1e-6 BER 1e-8

~20 pairs For DEL=2 @ BER1e-8 and 15m cable

SLIDE 13

Conclusion

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Need a BERT core in the DHE for the final experiment
The test procedure so far (in the DHE software) does not take into account that the

best Sampling Point SP is not the center of the eye

SLIDE 14

Thank you

germic@physik.uni-bonn.de