Syed B. Huq, National Semiconductor Corp.
Electronic Design Dec2nd 1996(Side bar)
The I/O Buffer Information Specification (IBIS) modeling format was originally developed by Intel and is now being driven by the IBIS forum with over 35 members, consisting of EDA vendors, computer manufacturers, semiconductor vendors and universities. The initial standard, IBISv1.0 was released in April 1993 and is capable of modeling standard TTL or CMOS I/O structures. Later that year, an enhanced version, IBISv1.1 was released - the major changes consisted of more comments to the original specification.
IBISv2.0 was ratified in 1994 and represents a considerable improvement over IBISv1.1. Some of the added features include: Multiple rail support (ie. V+ and V- supply for RS-232), ECL, terminator models, open drain models, differential I/O, controlled slew rate/GTO buffers and defination of complex package parameters.
In late 1994, IBISv2.1 added more comments to clarify v2.0 and today, IBIS is an approved standard from the EIA(Electronic Industry Association), now referred to as ANSI/EIA-656. Work in now under way to entend IBIS for International Standardization.
Currently, the standards committee is working on adding additional features to the forthcoming v3.0 specification. Some of the new features will include: An enhanced package/connector defination, stored charge effect in diodes, feedback support, multiple drive level capabilities, parameter scaling effects and a refinement of the simultaneous switching output model.
The software parser (which is commonly known as the “Golden Parser”)validates the IBIS model file. The function of the Golden Parser is to check the syntax of the IBIS model file to confirm that the data format meets the IBIS specification. The object code of the parser is available for free from the forum. Simulator vendors or member companies may also purchase the source code for a fee.
Future versions of the IBIS standard will be backwards compatible with previous versions so all models created today using the present version of the specification are guranteed to work with future versions of IBIS. The IBIS forum is continually defining new and improved ways of modeling complex and unique I/O structures and interconnects.