Spef file capacitance fields

[identical]

The spef file has two different fields for capacitance

First we have the total capacitance right beside the net name

Then , we have the separate capacitance on each port (Detailed cap field).

Any reason why we need the separate cap field when we have the total cap? Does the separate cap field add up to the total cap?

 

[oratie]

If you are thinking only on wire delay - the total caps are enough. But, we want to calculate crosstalk - then we need to know cross-coupling caps for each wires.