putting the node capacitance in output

[melkord]

Hi,

while I can put node capacitance of instances to the output, I cannot put the node capacitance of the node at the top level to the output.
Is there a way to do that without creating a symbol for my top level and then instantiate it (assuming it works that way, I have not tried it) ?

 

[Dominik Przyborowski]

Special characters in terminal name might be an issue. Try add \ before _ and + signs in the net names.

 

[melkord]

Special characters in terminal name might be an issue. Try add \ before _ and + signs in the net names.

I tried the other nodes which do not have special character at the top level, the same problem.

 

[dick_freebird]

Instances "know" their own capacitance (or
rather, Virtuoso knows how to ask Spectre for
that result).

What you are asking for, is for Virtuoso to
collect all the attached devices and sum
their capacitances. For that you'd have to
give it some instructions, or make the
calculator expression that can be printed
(probably easier than trying to train it to
aggregate devices-for-node, and recognize
which of each device's capacitances to use
based on network topology - like if you are
looking at a FET with its drain attached to
this output, you'd like cgd, cds, cdb but not
cgs - so there's a "picking" task in there,
that wants to be smart).

Capacitances reside in the devices, not the
nodes. Nodes are dumb, they don't know
nuthin' besides who's attached and what's
the voltage.

Now if you had a clean layout through LVS,
you could select devices attached to the
output net, make a list and get the sum
of relevant sub-capacitances which you
could represent as a pcapacitor.

 

[Dominik Przyborowski]

Seems that issue is with "/" in your expression.