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DDR3-PRELAYOUT SIMULATION

Question asked by agxinmj on Apr 13, 2015

Hellow every one

I simulated a P1010 Processor interfaced  to 5 ddr3 chips single rank memory

case 1: I kept all the length TL111=TL113=TL119=TL121=TL123=TL125=0.5inch

 

ddr3-sch-ok.PNG

now my eye digram is good at U61.K3

Capture-DDR-BETTER.PNG

But in the same schematic I reduced the length of the segments to 0.2 inch

dpt.PNG

now my eye wave form is ever worse i canged the drive strength to full and half but still my eye wave form is worse

what should i adjust at this length to get a better wave form

Capture-dpt.PNG

since my stub lengths are reduced my eye should be better but it is gettig worse

please help to identify the problem.thanks for helping in advance

thanks and regards

AGXIN.J

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