What is IBIS-AMI?

The IBIS Algorithmic Modeling Interface (AMI) is a modelling standard for SerDes PHYs, that enables a fast, accurate, statistically significant simulation of multi-gigabit serial links.

IBIS-AMI was developed as an extension of standard IBIS models by the IBIS Open Forum, a consortium of EDA, semiconductor and systems companies. This has been part of the IBIS standard since Rev 5.0.

While traditional IBIS models describe the IC buffer driving and receiving characteristics, they cannot include any description of programmable (DSP like) behaviour like those present in IC communication architectures in PCI Express Gen3, USB, SATA, DisplayPort and others.

Basic Structure of IBIS-AMI Models

IBIS-AMI models comprise two main elements:
•The Analog part, just as in traditional IBIS, includes things like the component pindefinition, package parasitics, basic voltage/ current curves and input capacitance values, expressed in textual form.
•Algorithmic models, implemented using Dynamic Linked Library (DLL) code.

Importing IBIS-AMI Models

Import IBIS-AMI models into your simulation library just as you can with traditional IBIS, using Simulation Library Browser, even though the model data is very different.

Assigning AMI Models

You can assign AMI models in Scenario Editor, launched from eCADSTAR Schematic Editor or eCADSTAR PCB Editor. These can be differential topologies extracted from schematic data, real physical layouts or topologies created entirely by yourself to conduct generic pre-design studies. AMI models are for detailed channel analysis, so they are assigned here, after a transmission-line topology has been extracted, edited or drawn, rather than directly to components within the design.

Channel Characterization and Setting Up AMI Analysis

Prior to performing a channel analysis, the transmission behaviour of the channel can be checked by optional characterization steps, evaluating the frequency domain response resulting in S-Parameters and the transfer function, as well the time domain impulse response of the channel. There are comprehensive initial steps to verify channels to the standards you want to meet.

Simulating to Determine Key Channel Performance Data

It’s important to know expected channel performance because optimized I/O enhances the performance of your entire product. Key parameters such as Bit Error Rate (BER) are presented clearly.