Re: [IBIS-Users] IBIS-SPICE correlation

Hi,

You have no problem with your model as your first rising
and falling edges overlay very well. The second rising
edge in the IBIS is leading the SPICE.
There is some differences in the stimulus pulse definition
between IBIS and SPICE. I?ll give you this example:

SPICE: Pulse(0 Vdd 0n 1n 2n 20n 40n)
Then the corresponding IBIS stimulus is: State one
duration = 21n, State two duration = 19n.

I think you have this definition mess-interpreted somehow
as you have already good overlay with SPICE in the first
rising and falling edges.
So, my recommendations are:
- First, check the VT data delays compared to SPICE
- Second, check the pulse definition and compare it to
SPICE pulse definition.

BR,
Hazem Hegazy

On Mon, 15 Mar 2004 15:48:24 -0800
  "Mohan, Prabhu" <Prabhu.Mohan@actel.com> wrote:
>Hi
>I am trying to correlate IBIS vs. Spice. The simulation
>seems to be off on
>the rising edge. IBIS seems to start switching a little
>bit earlier than
>Spice on the rising edge (refer the attachment, red-IBIS,
>yellow-SPICE). I'm
>not sure what is causing it. Does anyone have any
>suggestion as to where the
>error might be coming from?
>Thanks
>Prabhu
>
>-----Original Message-----
>From: Muranyi, Arpad [mailto:arpad.muranyi@intel.com]
>Sent: Friday, March 12, 2004 9:59 AM
>To: Ibis-Users (E-mail)
>Subject: [IBIS-Users] RE: Question regarding .pkg versus
>simple RLC
>
>
>Frank,
>
>From a syntax point of view, you can make models with the
>same exact data in all formats (if you use the lowest
>common syntax). However, since the more elaborate
>formats
>allow you more detail, chances are that you will not find
>numerical matches. It will all depend on the extraction
>methodologies, and assumptions.
>
>Arpad Muranyi
>Intel Corporation
>==========================================================
>
>
>
>> -----Original Message-----
>> From: Frank Dunlap [mailto:owner-ibis-users@eda.org]
>> On
>Behalf Of Frank Dunlap
>> Sent: Wednesday, March 10, 2004 6:09 PM
>> To: Ibis-Users (E-mail)
>> Subject: Question regarding .pkg versus simple RLC
>>
>> Presumably, a .pkg file provides "more" information than
>>the simple
>RLC in the [Pin] section of an IBIS model. Assuming
>that's the case, do
>simulators actually take advantage of this additional
>information? Are
>there cases where a .pkg file is preferred? Are there
>cases when it's
>not preferred, such as where its added complexity may
>cause problems?
>>
>> Furthermore, is there a straightforward relationship
>>between RLC
>values that would appear under the [Pin] section in an
>IBIS model, and
>corresponding values that would appear in a .pkg file?
>>
>> Here's an example from the [Pin] section of an IBIS
>>model:
>>
>> [Pin] signal_name model_name R_pin L_pin
>> C_pin
>> AE6 HINT# V33OP 2.170 8.506nH
>> 6.636pF
>> AE5 HRW# V33OP 2.165 8.475nH
>> 5.865pF
>> C16 S_A00 V33OP 1.332 3.287nH
>> 3.472pF
>>
>> Here's an example from a .pkg file:
>>
>> [Resistance Matrix] Banded_matrix
>> [Bandwidth] 0
>> [Row] 2255
>> 1.74791e+000
>> [Row] 2253
>> 1.74386e+000
>> .
>> [Inductance Matrix] Sparse_matrix
>> [Row] 2255
>> 2255 1.21125e-008
>> 2253 1.70009e-010
>> B19 1.73505e-010
>> [Row] 2253
>> 2253 1.25283e-008
>> J21 1.22831e-010
>> F20 1.89512e-010
>> K21 4.09167e-010
>> .
>> [Capacitance Matrix] Sparse_matrix
>> [Row] 2255
>> 2255 4.40327e-012
>> 2253 -2.82931e-015
>> B19 -1.47570e-015
>> [Row] 2253
>> 2253 4.33757e-012
>> J21 -1.04449e-014
>> F20 -2.65107e-015
>> K21 -8.93602e-015
>>
>>
>> The .pkg and [Pin] information are from two different
>>data sets. I'm
>sorry, but I don't have both .pkg and [Pin] information
>from a common
>data set.
>>
>>
>> Thanks in advance for any guidance,
>>
>> Frank
>>
>
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Hazem Hegazy$IBIS modeling manager$Quality

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Received on Tue Mar 16 06:24:02 2004