WLM @STA -> required?

[ivlsi]

Hi All,

Here are some quotes: "For the STA analysis in the several PVT corners, several WLM might be required - each one of them reflect different characteristics for the different PVT corners."

Now I'm asking: "Ever is the WLM required for STA?" WLM is just estimation and STA usually works on the back-annotated design/netlist... Am I missing something?

Thank you!

 

[oratie]

You may do STA on different stage of you design, even without real placement (based only on synthesized gate-level netlist. In such case, WLM in needed. But, for final STA (sign-off), when you have your design placed and routed, you should use RC values from real extraction, son no WLM is required.

 

[ivlsi]

What about "max_transition" & "max_capacitance" check? Where should the values be taken from?

 

[oratie]

Again, during intermediate STA you may use WLM. If you already have placed and routed design, you should RC values from real extraction.