[SI-LIST] Re: IBIS min, typ and max. values

  • From: Sudhanshu SINGH <sudhanshu.singh@xxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 26 May 2010 20:15:35 +0530

Hello All,

Reagrding c_comp as put previously in this mail, I have a query that,
why c_comp values extracted in typ, min or max conditions are not put
respectively in same typ, min or max columns in IBIS.


As Section 5.1.3.1 of cookbook ver4 says:

Note that when constructing the IBIS file the numerically largest value of
C_comp is listed as the "max" value while the numerically smallest value of
C_comp is listed as the "min" value. C_comp min and max values do not
necessarily correlate with the min and max conditions under which the I-V
and switching data was gathered. The actual association of C_comp corner
values with simulation corners is performed at the tool level.


Thanks and Regards,
Sudhanshu

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Hermann Ruckerbauer
Sent: Wednesday, May 26, 2010 2:23 PM
To: Lynne D. Green
Cc: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS min, typ and max. values

Thanks to all who replied (that fast).
I just love the List and everybody sharing his knowhnow there !!!!

BTW: Happy Birthday!!!!

Hermann

EKH - EyeKnowHow
Hermann Ruckerbauer
www.EyeKnowHow.de
Hermann.Ruckerbauer@xxxxxxxxxxxxx
Veilchenstrasse 1
94554 Moos
Tel.:   +49 (0)9938 / 902 083
Mobile: +49 (0)176  / 787 787 77
Fax:    +49 (0)3212 / 121 9008


schrieb Lynne D. Green:
> Hello, Hermann,
>
> Note that the "SPICE"  temperature is JUNCTION temperature, not
> ambient. IBIS [Temperature] is also junction temperature. The junction
> is hotter than ambient.
>
> Since the TYP temperature is only 25C, it is likely that ambient was
> used instead of junction when creating the model. Generally,
> increasing TYP and HOT temperatures by 25C is used to account for self
> heating when simulating to create I/O models for IBIS.  COLD
> temperature is not adjusted.
>
> Note the Max [Temperature] is higher in bipolar I/O and lower in CMOS
> I/O.
>
> Hope this helps.
>
> Lynne Green
> Chair, IBIS Model Committee
>
>
>
> Hermann Ruckerbauer wrote:
>> Hello *,
>>
>> I hope somebody can help me with interpreting some things in an IBIS
>> file
>> I'm just working with an IBIS file where the min, typ, max values are
>> arranged in the following way:
>>
>>                                        typ               
>> min                 max
>>
>> C_comp                       0.284pF             0.409pF            
>> 0.264pF
>> [Voltage Range]              1.200V              1.100V             
>> 1.300V
>> [Temperature Range]          25                  125                 125
>>
>> The C_comp min is the largest value and the Temperature is in there
>> twice with 125C.
>> The same order is used for RAC and CAC for a terminator (largest value
>> in the min column)
>>
>>
>> e. g. in a Micron IBIS file is even some comment on having 0C as max.
>> temperature :
>>
>> | Junction Temperature (Ambient temp is 25C typ, 85C min, 0C max)
>> |                                       typ                
>> min                   max     
>> [Temperature Range]        40.0               100.0                 0.0
>>
>> Regarding C_comp the Micron model lists it in the different order:
>> |                                    typ                  
>> min                    
>> max                                                        
>> C_comp                      2.466pF             2.316pF            
>> 2.616pF
>>
>> In the IBIS spec I found the comment that C_comp is independent of
>> fabrication process and therefore to generate worst case it can make
>> sense to use the largest C_comp for slow process ==> in the min column.
>> Basically this makes sense to me, but does it then make sense to use the
>> smalles C_comp value in the min column  ?
>>
>> So my questions would be:
>> Is there any common usage of the min column regarding parameters like
>> C_Comp, RAC, CAC (and maybe ohters) ?
>> Usually I would expect low temperature for fast devices, so having 0C in
>> the max column make sense, but does it make sense to have 125C in min
>> and max column ?
>>
>> Any feedback is highly appreciated!
>>
>> Thanks and regards
>>
>> Hermann
>>
>> EKH - EyeKnowHow
>> Hermann Ruckerbauer
>> www.EyeKnowHow.de
>> Hermann.Ruckerbauer@xxxxxxxxxxxxx
>> Veilchenstrasse 1
>> 94554 Moos
>> Tel.:    +49 (0)9938 / 902 083
>> Mobile:    +49 (0)176  / 787 787 77
>> Fax:    +49 (0)3212 / 121 9008
>>
>>
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