Challenge 6 : Advanced STA - calculate slack timing report
Hi All,
to test your practical concepts related to Advanced STA, I have added more challenge.
what will be slack of above Timing report.
Comment your answer and share your views.
Challenge 14 : Advanced STA
Setup Slack = + 9.6813 ns without statistical adjustment
ReplyDeleteHello,
DeleteThank you for trying to answer.
In case of regular STA report, agree with you that slack = RT - AT.
However, as it is Advanced STA timing report and sensitivity is already there in timing report, statistical adjustment also needs to be considered.
Please calculate updated slack number.
ReplyDeleteHere sigma used is 3 ( standard deviation) calculated based on the corner value)
Mean slack = 9.8822 − 0.1897 = 9.6925 ns
Sensit Slack = √(0.0051² + (−0.0013)²) = 0.0049ns
Slack = mean_slack - 3 x sensit_slack = 9.6925 - 3 x 0.0049 =9.6778 ns
Statistical adjustment = Slack - ( required time - arrival time) = 9.6778 - (9.8862 -0.2049) = -0.0035 ns
Hi Prasad,
DeleteCongratulations 🎉..!
Yes. Your answer of slack = +9.6778ns is 💯 % correct.
There is alternative method as well to calculate sensit/sigma slack. (I will cover details on upcoming post)
Hi Prasad, if can you let us know from where you got these formula to calculate slack in advance timing report.
DeleteStatistical adjustment is added at the end of report timing to show if there is any slack adjustment,Since POCV timing data is represented by a distribution with mean and sigma, you cannot add or subtract two corner values from two distributions. You need to add or subtract two distributions statistically.
Deletestatistical adjustment = slack ‡ unadjusted slack
slack = mean_slack - K * sigma_slack
unadjusted_slack = required time - arrival time
(+) hold path
(-) setup path
Deletesmall clarification how they get sigma as 3 from the report
generally sigma value will be mentioned in the path header. but in the above report it was croped. by seeing values we can calculate sigma value by using below formula.
incr corner = incr mean + sigma * incr sensit
in the launch path buff1/Z pin will take as an example
0.0299 = 0.0260+ sigma*0.0013
sigma*0.013 = 0.0039
sigma = 0.0039/0.0013 = 3
Yes...
DeleteHiding sigma in report was intentional.
Even if it is not mentioned, based on. Sensit and Mean you can get the sigma number.
If I want to learn advance sta
ReplyDeletej.bhasker book is enough?
I would say that book should be better to start with.. (in my initial days, I used to refer it)
DeleteRegarding advance OCV, you might need to refer online resources.