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Happy Thirteenth Birthday IBIS – Guest Post from Michael Mirmak

Posted December 13th, 2008 · Please leave a comment · Guest Post


Signal Integrity Tips continues our mini-celebration of the anniversary of IBIS 2.1 ANSI/EIA-656 with this guest post from Michael Mirmak, Chair, IBIS Open Forum. Michael writes:

The year 1995 was certainly one of firsts and achievements. NASDAQ crossed the 1000 mark for the first time. Microsoft released Windows 95. eBay and Yahoo! were founded. The first planet outside our solar system was discovered. And, as Colin kindly noted, IBIS 2.1 was formally approved as a US national standard, ANSI/EIA-656 on December 13th, 1995.

IBIS, the I/O Buffer Information Specification, was by then already a “toddler,” as version 1.0 had been released to the public in June, 1993. It was the answer to a strong industry desire for a non-proprietary behavioral format for buffer signal integrity data that could be shared between EDA tools, system designers and IC vendors alike.

Version 2.1 was revolutionary, with the size of the specification almost tripling due to the added features. The simple ramps used to represent buffer transitions were supplemented with tables of voltage-versus-time data. Support for differential pins, as well as ECL buffer types, was included. Matrix-based package models were added, allowing both true pin- and pad-based analysis using a single buffer model. As a national standard and a practical approach, IBIS 2.1 defined a basic structure which has remained useful ever since.

Much has happened over the intervening 13 years. IBIS 3.2 and 4.0 defined new measurement thresholds, added driver scheduling, improved package support and even created a board description format. IBIS 4.1 and 4.2 brought IBIS together with the analog/mixed-signal world, allowing Verilog-AMS and VHDL-AMS code, as well as Berkeley SPICE elements, to be integrated into the IBIS structure. Now, with the approval of IBIS 5.0 in August of this year, combined power delivery and signal integrity modeling using the simple table-driven IBIS approach becomes a reality. And with the addition of the Algorithmic Modeling Interface (AMI), the specification expands to cover advanced serial-differential equalizer behaviors.

Not a bad list of accomplishments for a teenager.

Happy birthday, IBIS and thanks to its many contributors and users over the years.

– Michael Mirmak
Chair, IBIS Open Forum

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