Re: STA doubt
Sorry , I didnt use any other STA tools. All below information regarding Synopsys Prime time.
1) In PT, SDF is the high precedence for Annotation compared to aby other information. So, if you annotate SDF, Interconnect delays ,R's and C's from DSPF will not be used for calculatiing the pin-to-pin delays. What ever the info SDF contains, PT ALWAYS use the annotate capacitance to calculate the transition times, since SDF doesnt contain transition information. if there are no annotated parasitics, PT will use cap information derived from WLM to calc transition time.
2)Its overhead of reading the DSPF . It doesnt make sense to annotate the DSPF on a design, which is already has SDF applied to it. Insted read set_load file for parasitics. This will generally having cap and transition times, which are more pesimistic than derived using DSPF, but read time will be much faster...
Regards,
Sam