Overview of AMI (Algorithmic Modeling Interface)

AMI is a behavioral modeling standard for SerDes transceivers. AMI for Serdes devices is typically adaptive filtering. With adaptive filtering, the device’s filter coefficients of the device get are optimized on-the-fly, based on the channel. But many Serdes use static filtering, where the filter coefficients do not change on their own. For these devices, traditional IBIS or Spice models can be used, and no AMI is required. 

AMI addresses following challenges in high-speed link analyses: 

• Capture Tx and Rx functionalities in end-to-end channel simulations 
• Achieve high simulation throughput to enable computations of millions of bits
• Protect IC vendors' IP 
• Model interoperability and portability

Each AMI model is a combination of an analog model and an algorithmic model and consists of three files: .ibs, .ami and DLL. Analog model is specified in the .ibs file. DLL is the executable of the algorithmic model, whose parameters are specified in the .ami file

Analog model is an IBIS model specified by the .ibs file.  

• For Tx, IBIS model represents output impedance and transition slew rates.  
• For Rx, IBIS model represents termination. 

The DLL executable supports a set of standard C function APIs that models Tx/Rx functionalities including Gain, Equalization and CDR (Clock and Data Recovery). Algorithmic model parameters are specified in the .ami file. 

You can build AMI models using AMI Builder in Topology Explorer.

This document introduces AMI Builder functionality and walks you through the creation of typical SerDes transmitter and receiver AMI models.

Team SimTech

Cadence Design Systems