# 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.