Dear Todd, The netlist I used (..sp file) is a transistor-level netlist which was extracted from the layout. Therefore, the netlist I used to create the IBIS buffer should already have parasitic effects catered inside. My question was more for the .s2i file. Inside this file, there's a parameter [C_comp] that we have to include. If my netlist already has the parasitic effects catered, do I still need to input the C_comp value explicitly in the .s2i file? Thank you. Best regards, Mei Yee MCPD, Avago Technologies (Malaysia) Tel no.: +604-6108515 ________________________________ From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Todd Westerhoff Sent: Monday, September 29, 2008 8:59 PM To: ibis-users@server.eda.org Subject: Re: [IBIS-Users] RE: [IBIS] C_comp value Mei-Yee, Can you expand on the phrase "the netlist I used for the pad is an extracted netlist"? Do you mean the transistor-level netlist used to create the IBIS buffer model in the first place ... that is, a transistor level netlist used to perform simulation under controlled conditions, the results of which were post-processed to create the IBIS buffer model? If that's what you meant, and the transistor level netlist you started with included the output buffer's capacitance, then the conversion program (s2ibis3 or other) you used should have calculated and included C_Comp automatically in your buffer model. Arpad is correct that the V-T curves in the IBIS model should include the effects of C_Comp, and the IBIS simulator needs to combine the V-T data and C_Comp during simulation without double-counting the effect of C_Comp. ... but I'm trying to understand whether your question was whether or not C_Comp was to be added explicitly to the original transistor level netlist. The usual answer to that question is - no. Todd. Todd Westerhoff VP, Software Products SiSoft 6 Clock Tower Place, Suite 250 Maynard, MA 01754 (978) 461-0449 x24 twesterh@sisoft.com www.sisoft.com NG,MEI-YEE wrote: Hi Arpad, Just one quick question, if the netlist I used for the pad is an extracted netlist, does that mean the C_comp value is already incorporated inside (parasitics and all)? In that case, if I still put in an additional C_comp value, it would mean that I'm double-counting the C_comp? Thank you. Best regards, Mei Yee MCPD, Avago Technologies (Malaysia) Tel no.: +604-6108515 ________________________________ From: owner-ibis-users@server.eda.org [mailto:owner-ibis-users@server.eda.org] On Behalf Of Muranyi, Arpad Sent: Friday, September 26, 2008 9:03 PM To: ibis@server.eda.org Cc: ibis-users@server.eda.org Subject: [IBIS-Users] RE: [IBIS] C_comp value Timmy, You can do it either way, it depends on your needs. If you want to correlate to your SPICE model, match it to that, if you want to correlate to real life, match it to your measurements. Arpad ==================================================== ________________________________ From: owner-ibis@server.eda.org [mailto:owner-ibis@server.eda.org] On Behalf Of Timmy Leon Sent: Thursday, September 25, 2008 8:46 PM To: ibis@server.eda.org Cc: ibis-users@server.eda.org Subject: [IBIS] C_comp value Dear Sir/Madam, I have a question regarding the c_comp value that we should put in IBIS model. Should the c_comp value be based on measurement, or can we tune value so that IBIS model correlate with its spice model or measurements? Thank you. 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