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Filtering out tiny capacitors from Calibre XRC ? (Read 5656 times)
David Sobel
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Filtering out tiny capacitors from Calibre XRC ?
Apr 12th, 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.
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Paul
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Re: Filtering out tiny capacitors from Calibre XRC
Reply #1 - Apr 12th, 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
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David Sobel
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Re: Filtering out tiny capacitors from Calibre XRC
Reply #2 - Apr 12th, 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
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