science

Input/output Buffer Information Specification

Input/output Buffer Information Specification is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Input/output Buffer Information Specification rather than just read about it. In short: Input/output Buffer Information Specification (IBIS) is a specification of a method for integrated circuit vendors to provide information about the input/output buffers of their product to their prospective customers without revealing the intellectual property of their implementation and without requiring proprietary encryption keys. From version 5.0, specification contains two separate types of models, "traditional…

Key takeaways

Input/output Buffer Information Specification belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Input/output Buffer Information Specification to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Input/output Buffer Information Specification from memory before moving on to harder problems.

Reference excerpt

Input/output Buffer Information Specification (IBIS) is a specification of a method for integrated circuit vendors to provide information about the input/output buffers of their product to their prospective customers without revealing the intellectual property of their implementation and without requiring proprietary encryption keys. From version 5.0, specification contains two separate types of models, "traditional IBIS" and "IBIS-AMI." The traditional model is generated in text format and consists of a number of tables that captures current vs. voltage (IV) and voltage vs. time (Vt) characteristics of the buffer, as well as the values of certain parasitic components. It is a standard data exchange format for exchanging modeling information among semiconductor device suppliers, simulation software suppliers, and end users. Traditional IBIS models are generally used instead of SPICE models to perform various board level signal integrity (SI) simulations and timing analyses. IBIS models could be used to verify signal integrity requirements, especially for high-speed products. IBIS-AMI models run in a special-purpose SerDes channel simulator, not in a SPICE-like simulator, and consist of two text files (*.ibs and *.ami) plus a platform-specific machine code executable file (*.dll on Windows, *.so on Linux). IBIS-AMI support statistical and so-called time-domain channel simulations, and three types of IC model ("impulse-only," "GetWave-only," and "dual mode")

History Intel initiated IBIS in the early 1990s. Intel needed to have all of its divisions to present a common standardized model format to its external customers. This prompted Intel to solicit EDA vendors to participate in the development of a common model format. The first IBIS model, version 1.0, was aimed at describing CMOS circuits and TTL I/O buffers. As IBIS evolved with the participation of more companies and industry members, an IBIS Open Forum was created to promote the application of IBIS as a simulation tool format and to make sure that a standard exists. Many semiconductor vendors supply IBIS models and many EDA vendors sell IBIS-compliant software tools. In 1995 the IBIS Open Forum teamed with the American National Standards Institute/Electronic Industries Alliance (ANSI/EIA). IBIS version 2.1 was the first version released by the new alliance. It added the ability to simulate ECL and PECL buffers as well as differential lines. IBIS 3.2 allows for a package model description along with an electrical board description. IBIS Version 5.0 was ratified by the IBIS Open Forum on August 29, 2008. Compared to the previous version (IBIS 4.2, ANSI/EIA-656-B), it adds a new flow based not on SPICE transient but on a channel simulator (called algorithmic model application program interface or AMI flow), power integrity, and EMC checking features. For power integrity, it uses Touchstone 2.0 S-parameter files with per-port reference impedance specification. Version 5.1 was ratified on August 24, 2012. Important changes included the so-called "flow BIRD" which resolved many ambiguities in the IBIS AMI flow. The IBIS Open Forum became an official subcommittee of TechAmerica in January 2009. Upon its purchase of the standards program of TechAmerica in July 2013, SAE International became the parent of IBIS Open Forum. IBIS is an "industry program" within the SAE Industry Technologies Consortia (SAE ITC) trade association.

Evolution IBIS is an evolving standard with many proposed changes submitted to IBIS Open Forum for consideration. Proposed changes are called BIRDs (Buffer Issue Resolution Documents), a play on the word ibis, a type of bird. Version 6.0 was ratified on September 20, 2013. Changes included an IBIS‐AMI extension for mid-channel repeaters, new parameters for jitter and noise in IBIS-AMI, and analog buffer modeling improvements. Version 6.1 was ratified on September 11, 2015. Changes included support of PAM-4 in IBIS-AMI, the addition of a new Initial Delay keyword, and additional options for overclocking. Version 7.0 was ratified on March 15, 2019. Changes included support for Touchstone and IBI-ISS (SPICE) modeling of interconnections, and modeling of back-channel link training protocols using IBIS-AMI models. Work on enhancing the specification can be tracked in the work-in-progress section of the IBIS Open Forum website.

Notes

External links IBIS Home

Worked examples

Example 1 — a first encounter with Input/output Buffer Information Specification

Start with the simplest possible case. Write down what Input/output Buffer Information Specification claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Input/output Buffer Information Specification before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Input/output Buffer Information Specification ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Input/output Buffer Information Specification

In research: Input/output Buffer Information Specification appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Input/output Buffer Information Specification in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Input/output Buffer Information Specification is common in secondary-school and first-year university syllabi. It links to neighbouring topics Electronic design automation, so understanding it makes those chapters shorter.
In everyday life: Look for Input/output Buffer Information Specification outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Input/output Buffer Information Specification in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Input/output Buffer Information Specification means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Input/output Buffer Information Specification out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Input/output Buffer Information Specification in simple terms?

Why does Input/output Buffer Information Specification matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Input/output Buffer Information Specification?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Input/output Buffer Information Specification.