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

  • From: Sudhanshu SINGH <sudhanshu.singh@xxxxxx>
  • To: <si-list@xxxxxxxxxxxxx>, "'Muranyi, Arpad'" <Arpad_Muranyi@xxxxxxxxxx>
  • Date: Thu, 27 May 2010 18:40:01 +0530

Hello All,

In my case I have seen that spice Vs IBIS correlation is better if the
c_comp values are put in typ/min/max tables exactly as they are extracted.

Even if the magnitude wise order is not strictly followed as in the IBIS
spec.

What is then the best approach to put c_comp values in IBIS tables?

Thanks in advance,

Best Regards,
Sudhanshu


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Muranyi, Arpad
Sent: Thursday, May 27, 2010 5:00 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS min, typ and max. values

Hermann,

I am not sure where you got the idea from that the IBIS spec
says "one can place the largest value in the min Column in
order to have the worst slow case covered".  If you look in
Section 9 of the specification, you will find the following:

| The "min" and "max" columns for all remaining keywords and
subparameters
| will contain the smallest and largest magnitude values. This applies
to the
| [Model] subparameter C_comp as well even if the correlation to the
voltage,
| temperature, and process variations are known because information
about such
| correlation is not available in all cases.

Thanks,

Arpad
==============================================================

-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of Hermann Ruckerbauer
Sent: Wednesday, May 26, 2010 10:29 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: IBIS min, typ and max. values

Hello Sudhanshu,
that's interesting.
In this case the spec and the IBIS cookbook mention it differently ...
The cookbook mentiones to use the same order (smallest value in the min
column) and let the tool decide, while the Spec mentiones, that one can
place the largest value in the min Column in order to have the worst
slow case covered ...

Any feedback from the tool vendors how they implemented this selection ?

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


schrieb Sudhanshu SINGH:
> 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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