Library Characterization Tidbits: Recharacterize What Matters - Save Time!

30 Apr 2020 • 2 minute read

Recently, I read an article about how failure is the stepping stone to success in life. It instantly struck a chord and a thought came zinging from nowhere about what happens to the failed arcs of a standard cell? Do I need to rerun characterization for the failed cell from the very beginning to validate if the troubleshooting I did had the desired effect?

Well, as much as it is possible for our brain to think of two or more totally unrelated ideas at a time, it is possible for the Cadence^® Liberate^TM Characterization solution to characterize only the failed or new arcs of a standard cell!

On deeper study, I found that Liberate gives you a high degree of control over how you rerun the characterization for failed cells or add a missing arc for a specific cell after the initial characterization. In addition, it allows you to rerun a specific measurement for all the cells if you change a Liberate parameter’s value and can merge the newly characterized data with an existing characterized database.

To know more about how Liberate can automatically characterize the failed cells by reading the library database (LDB), refer to the Liberate: Standard Cell Characterization of Only Failed or New Arcs application note available on the Cadence Support portal. In this document, the following commonly encountered characterization scenarios have been discussed with examples:

Scenario 1: Setting up an initial characterization run
Shows how to set the cells for characterization, run the initial characterization for all cells, and then generate the LDB having the characterized data.

Scenario 2: Recharacterizing only the cells that failed during the initial run
Illustrates how to read an LDB from a previous characterization run and then rerun characterization only for the failed arcs. Also covers examples of writing the final LDB and then the final .lib after recharacterization of failed arcs.

Scenario 3: Adding a missing arc to an existing database after the initial characterization run
Demonstrates how to perform initial characterization on only the arcs defined in a cell template, and then create and characterize a minimized cell template that has only the missing arcs. Thereafter, shows how to merge the new arcs into the initially characterized library.

Scenario 4: Recharacterizing specific arcs as per updated settings
Explains how to create a modified template and a Tcl file for characterization with updated settings, run the characterization for the specific arcs, and then merge them into the existing library.

Related Resources

For more information on Cadence circuit design products and services, visit www.cadence.com.

About Library Characterization Tidbits

Library Characterization Tidbits is a blog series aimed at providing insight into the useful software and documentation enhancements in the LIBERATE release. In addition, this series would broadcast the voice of different bloggers and experts, who would share their knowledge and experience about all the tools in Liberate Characterization Portfolio. To receive notifications about new blogs in this series, click Subscribe and submit your email ID in the Subscriptions box.

Happy Reading!

Abha Rawat