|
| What is IBIS? |
| I/O Buffer Information Specification is a fast and accurate Behavioral
method of modeling I/O buffers based on V/I curve data derived from
measurements or full circuit simulation. Uses a standardized software
parsable format to create the Behavioral Information needed to model
Analog characteristics of IC's. Can be used by almost any Analog
Simulators/EDA tools in the Industry. |
| ' |
| IBIS vs. Spice |
| Spice
Models |
Table
Models |
IBIS
(& Behavioral Models) |
| 
|
Buffer centric |
|
Buffer and component centric |
|
Component centric |
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Requires Process and Netlist Information.
Reveals Intellectual Property. |
|
Buffer models using tables, netlist information
still needed. |
|
Hides Process and netlist information. |
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| Advantages of IBIS |
|
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Protection of Proprietary Information. |
|
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Accurate model as non-linear aspects of I/O are used,
Package parasitic and ESD structure considered also. |
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Design wins before Silicon is out. |
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Signal Integrity, and Transition Response Simulation
on PCB. |
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Faster simulation time compared to structural methods. |
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Compatibility with all Industry wide simulation platforms. |
|
Behavioral Diagram of IBIS
This behavioral diagram shows the most important building
blocks required to create an IBIS model. |
 |
| ' |
| Block Diagram of CMOS Buffer |
| A basic IBIS model consists of the following for each buffer
on a chip: |
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Four I-V curves: |
| |
| – |
pull-up & Power clamp |
| – |
pull-down & GND clamp |
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Two ramps: |
| |
| – |
dV/dt_rise |
| – |
dV/dt_fall |
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Die capacitance - C_comp |
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Packaging - RLC values |
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| IBIS Basics |
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Text file |
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Keywords in square brackets: |
| |
| – |
Header information for file name, date, and so forth; |
| – |
Component name [Component]; |
| – |
Pinout [Pin]; and |
| – |
Model Sections [Model] |
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Subparameters |
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RLC package parameters |
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| – |
Only self packaging resistance, capacitance, and inductance
[Package] , [Pin]; |
| – |
Complete RLC matrix (self and mutual parameters) [Package
Model]; and |
| – |
Define Package Model], embedded in IBIS file (.ibs)
or in external file (.pkg). |
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| More Information |
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