Creating An IBIS File

Creating An IBIS File

By Timothy Coyle

A Visual Tour of An IBIS File

We have been talking about IBIS ‘models’ and IBIS ‘files’ and now we are really going to break down the terminology and talk about the actual IBIS file with an .ibs extension that holds all of the actual data.

The above image is a screenshot of an IBIS file displayed in an IBIS editor application. While an IBIS file is in ASCII text format and can be viewed in a simple text editor it is advantageous to use an IBIS editor for the enhanced features.

Keywords In An IBIS File

The IBIS Specification contains keywords as defined by brackets [keyword] and under these keywords can be sub keywords. These keywords and sub keywords are used along with the specification syntax to define how the IBIS data curves are placed in the overall file By placing data in these various keywords and sub keywords all of the necessary information a simulator needs to recreate the behavior of a buffer is available.

In the above image showing the IBIS file in an IBIS editor on the left hand side the different IBIS keywords and sub keywords are displayed in a tree view. On the right hand side the actual IBIS keywords with defined data is shown. For example, one of the required keywords is [IBIS Ver] that defines what version of the IBIS Specification the IBIS file is in compliance with. In this example it is version number 4.2.

If we zoom in on the [Model] keyword as shown in the above image we can see this is where the actual IV and VT data curves are placed. This is also why some people use the IBIS model terminology interchangeably with the IBIS file terminology. There are keywords and sub keywords that are used to define a model name, a model type, and other parameters from the IBIS Specification.

IBIS Syntax and Keyword Usage

The IBIS Specification is like any standard such as USB or an electrical wiring codebook in that there are a lot of different rules for using the defined syntax and not all of the keywords and sub keywords are required. We will go over in later chapters the different keywords and how they are used but it should be noted that through experience you will learn which keywords are important and which ones you can ignore.

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