Subject: Re: [IBIS-Users] C-Comp
From: Kim Helliwell (kimgh@apple.com)
Date: Fri Jul 18 2003 - 13:30:51 PDT
I'm just curious how this would be folded in with the 4-part C_comp
(BIRD 76.1). Will we end up with 2 (or even 4) more C_comp
values? Or does just 1 value adequately characterize the
receiver?
Kim
On Friday, July 18, 2003, at 10:10 AM, Robert Haller wrote:
> IBIS users,
>
> At today's IBIS open forum call, the issue was raised concerning the
> limitations of Ccomp in the present IBIS spec. This issue is being
> added to the next ibis open forum agenda technical discussion.
>
> I would like to solicit feedback from Model developers and users for
> proposed changes, as well as voice my own opinion.
>
> Present syntax
>
> | typ min max
> |
> C_comp 3.90pF 3.10pF 4.80pF
>
> My personal experience has shown that I/O buffer often have different
> C_comp when driving and receiving. To keep things simple, I would
> suggest that a simple extension to the C_comp would be to specify a
> C_comp driving and C_comp receiving for Model_type = I/O
>
> regards,
> bob
> --
> Robert J. Haller (rhaller@sisoft.com)
> Principal Consultant
> Signal Integrity Software Inc.
> 6 Clock Tower Place, Suite 250
> Maynard, MA 01754
> Phone: (978) 461-0449, ext 15
>
>
>
> Roy Leventhal wrote:
>> Anshuli,
>> Be aware that capacitive behavior is included in the V-T behavioral
>> curves
>> and/or the slew rates based on them. Unsophisticated providers of
>> simulation
>> software (hopefully, few remain) can thus mistakenly "double count"
>> the
>> effects of Ccomp unless they adjust for its presence in the circuit.
>> So, why is Ccomp included? To account for the capacitive loading on
>> the
>> circuit, direct or reflected wave, and it is the total capacitive
>> loading
>> looking into the die pad.
>> Best Regards,
>> Roy
>
>
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>
Kim Helliwell
Apple Computer
kimgh@apple.com
408 974 9936
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