Checking and Using the IBIS Model File
Usually you will need an IBIS file containing a model for an entire component.
Although s2ibis2 is able to produce this, SpiTran is designed to support
the common case where a SPICE file contains the model for only one buffer.
SpiTran generates an s2ibis control file that specifies a fictitious component
containing only one pin. The component is always named Component-Name.
Other IBIS information such as manufacturer is set to dummy values by SpiTran.
Checking the IBIS File
Always check the IBIS file produced by s2ibis2, before you extract the
buffer model. A good tool for doing this is the freely available ibischk3
program. More sophisticated graphical tools are also available, such as
WinIBIS from HyperLynx. This tool will check the IBIS file and allow you
to view the VI curves and waveforms in the IBIS file. See the FREE
Tools for IBIS modeling web page to locate a suitable tool. You can
modify your SpiTran startup script to invoke a checking tool automatically
after each s2ibis2 execution, since SpiTran runs the startup script to
execute the translation.
Extracting the Buffer Model
The portion of the IBIS file that contains data for the buffer model can
be saved and inserted into other IBIS files that contain data for a complete
component. The IBIS file header looks something like:
|************************************************************************
| IBIS file iobuff.ibs created by s2ibis2 version 1.1
| North Carolina State University Electronics Research Laboratory 1995
|************************************************************************
|
[IBIS ver] 2.1
[File name] iobuff.ibs
[File Rev] 0.1
[Date] Aug 24, 1999
[Source] Spice simulations on CADENCE spice models
[Notes] This Model was done by Pradeep Mishra
[Disclaimer] This is for modelling purposes only.Accuracy is not guaranteed
[Copyright] CADENCE DESIGN SYSTEMS INC
|
|************************************************************************
| Component Component-Name
|************************************************************************
|
[Component] Component-Name
[Manufacturer] Manufacturer-Name
[Package]
| variable typ min max
R_pkg 0.0000 0.0000 0.0000
L_pkg 0.0000H 0.0000H 0.0000H
C_pkg 0.0000F 0.0000F 0.0000F
|
[Pin] signal_name model_name R_pin L_pin C_pin
pad pad iobuff
| inputinput none
| ena ena none
vdd vdd POWER
vss vss GND
The data segment for the buffer begins with a statement like:
[Model] iobuff
and ends with a comment like:
| End [Model] iobuff
You should copy this this portion and save it into a file, the contents
of which can be inserted into any IBIS file that needs it.
Before you remove the IBIS file header, however, you should check the
model.