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Measurements >> RF Measurements >> node capacitance
https://designers-guide.org/forum/YaBB.pl?num=1166501875

Message started by sivacharan on Dec 18^th, 2006, 8:17pm

Title: node capacitance
Post by sivacharan on Dec 18^th, 2006, 8:17pm

If i want to see the total capacitance occuring at a particular node, which simulation will be useful in spectreRF??

Thank you.

Title: Re: node capacitance
Post by Ken Kundert on Dec 18^th, 2006, 10:22pm

If you are running standalone you would run an info analysis ...

Quote:

printCapacitanceTable info what=captab

If you are running in Artist, you might be able to specify that this through the Artist UI, but I am not familiar with how you would do that. Alternatively, you can put that statement in a file and tell Artist to include it in the netlist.

-Ken

Title: Re: node capacitance
Post by ACWWong on Dec 19^th, 2006, 2:53am

In artistADE, you can tick the captab button in choose analyses->dc->options or choose analyses->tran->options.
In DC you get the node capacitances calcualted from the dc op point.
in tran you can get the node capacitances at different time points using "infotimes"

Title: Re: node capacitance
Post by sivacharan on Dec 19^th, 2006, 11:14pm

when i see the dc operating point of an nmos or pmos, the spectre tool is showing the -ve capacitance for cgs and cds ...etc.
what does it mean??

thank you.

Title: Re: node capacitance
Post by ACWWong on Dec 20^th, 2006, 3:23am

sivacharan wrote on Dec 19^th, 2006, 11:14pm:

when i see the dc operating point of an nmos or pmos, the spectre tool is showing the -ve capacitance for cgs and cds ...etc.
what does it mean??

See the following relevant post.
http://www.designers-guide.org/Forum/YaBB.pl?num=1160834621
Please bear in mind that the dc-opertaing points for any transistor are model parameters, whereas as captab gives total capacitance on nodes/nets in a circuit.