DHPT Link Optimization Leonard Germic University of Bonn July 2016 ボン大学 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 germic@physik.uni-bonn.de 2
Pre-emphasis ● Pre-emphasized signal ● Three parameters for optimization BIAS, BIASD and DEL BIAS BIASD DEL germic@physik.uni-bonn.de 3
Digital BER test ● Digital test: 7bit LFSR (random bit) sequence ● Xilinx BERT core checks if data is correctly transmitted ● Minimum logic signal difference (~125mV high-low) *.txt file “The Analyzer software displays a “link” signal SP BER LinkUp? until there are five consecutive cycles with errors[...]” (Xilinx) ● Extraction of minBER and width@1E-6 minBER width@1E-6 germic@physik.uni-bonn.de 4
Analysis of BERT ● Digital test: 7bit LFSR (random bit) sequence ● Xilinx BERT core checks if data is correctly transmitted ● Minimum logic signal difference (~125mV high-low) *.txt file ● If link is stable BER is recorded SP BER LinkUp? ● Extraction of minBER and width@1E-6 minBER width@1E-6 germic@physik.uni-bonn.de 5
Analysis of BERT ● Introducing cuts: ● cutWidth > 32SP (¼ of ) ● cutBER > 1E-9 combined (gray triangle) Example of Bathtub plots and the cuts germic@physik.uni-bonn.de 6
Analysis of BERT ● Introducing cuts: ● cutWidth > 32SP (¼ of ) ● cutBER > 1E-9 combined (gray triangle) Example of Bathtub plots and the cuts Diagonal as measure of opening germic@physik.uni-bonn.de 7
Optimization proposal for CML driver settings ● 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 1eX B I A S BIASD BIASD germic@physik.uni-bonn.de 8
Optimization proposal for CML driver settings ● 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 1eX B I A S BIASD BIASD germic@physik.uni-bonn.de 9
Optimization proposal for CML driver settings ● Normalized combined value ● This highly constraint parameter space can be D(BER=1e-6,cableLength=15; BIAS,BIASD) used to extract a parameter pair (BIAS,BIASD) = 1/max( D(DEL) ) x (width² + minBer²) for each DEL paramter and cable length 1.0 1.0 B I DEL=0 DEL=2 A S 0.0 0.0 BIASD BIASD BIASD Normalized to the max value of each data set – Values are not comparable between different DEL settings!!! germic@physik.uni-bonn.de 10
Optimization proposal for CML driver settings 1.0 1.0 B I A DEL=0 DEL=1 S 0.0 0.0 BIASD BIASD 1.0 1.0 B I A DEL=2 DEL=3 S 0.0 0.0 Normalized to the max value of all data sets – Values are comparable between different DEL settings!!! germic@physik.uni-bonn.de 11
Optimization proposal for CML driver settings ● 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 germic@physik.uni-bonn.de 12
Conclusion ● 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 germic@physik.uni-bonn.de 13
Thank you germic@physik.uni-bonn.de 14
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