Questions about single analysis SDF

[jerry2007]

Hello everyone, my sdf looks like

(IOPATH A Z (0.195::0.202)(0.225::0.236))

how come only min/max are there but no typical value (verilog has all three)? is it then assumed as 0?

thanks in advance!

-Jerry

 

[sam536]

Re: sdf questions

SDF depends on the analysis type,whether your design uses a single operating condition or bc_wc/OCV operating conditions .

For single analysis type the SDF delay triplet has three identical values, for example instance, (15.0:15.0:15.0).

For BC_WC and OCV , the SDF triplet contains only two delays for the two different operating conditions, for example , (15.0::20.0).

In this case, the typical value of the SDF triplet is not used.


Regards,
Sam

 

[jerry2007]

Re: sdf questions

Thanks for the explanation, Sam.

I did set analysis mode to 'single' with only one library (with encounter), but I also used 'timingderate -early/late', maybe that changed the analysis mode to OCV? so with only one library (no max/mix lib), do i need to set timing derating factors?

what's strange is that back-annotation fails (setup viol) for both min/max and only passes for typ (seems to be actually 0 in this case). So I guess it's not that my backannotation is wrong but the backend design really has timing problems?

Thanks again!

-Jerry