Timing problem in cts

Hi

My question is i am using 2 scenarios func worst and func best.my default scenario is func worst .i did placement and it worked fine.i did cts too in default scenario and after that if i do report timing clock is propagated by default with out set propagated clocks command in icc

When i change to func best the clock is not propagated it is showing idle.what is the reason? If i give the command set propagated clocks then in the report for hold it is taking propagated clocks but with huge clk network delay.this is my main problem.why it is taking so huge values for hold when it is taking value for setup? Why clock is not propagated for hold scenario?

I have main clocks and also virtual clocks in the design.another issue is report timing to any clock path for both setup and hold also is giving path unconstrained? Why is it so??

Please clarify i am specifying all the required files sdc scenario info and all.

This is my show stopper.please give me a solution ASAP.

Why are you doing one mode at a time? You should do something like MMMC (multi mode multi corner).

Hi are you saying to active all scenarios instead of one scenario at a time ? what is the benifit ? how it is going to help my issue?

cyrax747 said:

Hi are you saying to active all scenarios instead of one scenario at a time ? what is the benifit ? how it is going to help my issue?

Click to expand...

you should because MMMC is the industry standard for years. BC/WC is still ok. But what you are doing is WC THEN BC. This is not helpful and in many instances will be a nightmare for timing closure. Of course you will see hold issues when everything suddenly became faster!

so i have to put active all scenarios and give a run ? cts by default taking worst only.how to do for best also???

cyrax747 said:

so i have to put active all scenarios and give a run ? cts by default taking worst only.how to do for best also???

Click to expand...

that depends on your tool. I use mostly cadence, and CCOPT takes all scenarios into consideration.

even though there is more tran my clk network delay is more when i am doing hold analysis.setup is fine...only one net is bringing more cap and tran.