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Other CAD Tools >> Physical Verification, Extraction and Analysis >> Filtering out tiny capacitors from Calibre XRC ?
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Message started by David Sobel on Apr 12^th, 2006, 11:20am

Title: Filtering out tiny capacitors from Calibre XRC ?
Post by David Sobel on Apr 12^th, 2006, 11:20am

Hi,

I am using Calibre XRC to perfrom post-layout extraction. I am extracting to a "calibre view" so that I can include the extracted netlist in Artist for subsequent simulation. I am extracting "C + CC" to get the node<->ground and node<->node capacitance of my design.

I am finding that the output netlist has a bunch of TINY caps (i.e. c=1e-30) that I don't really think I need. The inclusion of these caps "clutters" the extracted netlist, making it harder to visually inspect the netlist. Also, I imagine that it complicates the netlist and slows down the simulation.

I would like to filter out all the "tiny" capacitors from my extracted view, but I don't know how. Can anyone inform me how to do it?

Thank you very much!!
David

P.S. fyi, I am using Calibre's GUI interface for this task, in case that's of relevance.

Title: Re: Filtering out tiny capacitors from Calibre XRC
Post by Paul on Apr 12^th, 2006, 1:43pm

Hi David,

did you try adding a PEX THRESHOLD statement to your extraction rules? You can look up the exact syntax in the SVRF Manual.

Paul

Title: Re: Filtering out tiny capacitors from Calibre XRC
Post by David Sobel on Apr 12^th, 2006, 2:19pm

Paul,
Thanks for the help. Since I'm doing a lumped C simulation (i.e. no parasitic R's), the command I'm looking for is actually:

PEX REDUCE LUMPED C < xxxxx

where xxxxx is the min cap value I care about. Any node-to-node coupling caps smaller than xxxxx just are ignored and added to the node-to-ground cap for the two nodes in question.

Best,
David