Library Characterization Tidbits: Creating Statistical Libraries for Standard Cells and IO Cells

Hello everyone!

I am Aravind R, Principal Support AE at Cadence, and I have been supporting various users at our customer sites to generate and validate various formats of standard cell and IO libraries using the Cadence^® Liberate^TM Characterization Portfolio.

In the previous blog published in this series, we shared that the Cadence Liberate Characterization solution could be used for characterizing standard cell libraries. This time let’s see how you can use the Liberate^TM Variety^TM statistical characterization solution of the Cadence Liberate Characterization Portfolio for generating the following statistical characterization models for standard cell libraries:

• Advanced on-chip variation (AOCV) tables
• Statistical on-chip variation (SOCV) tables
• Liberty Variation Format (LVF)

 Statistical characterization of standard cell libraries using Liberate Variety is broadly divided into the following five stages:

1. Define Settings, Templates, Variation parameters for the required cell, and the related Process, Voltage, Temperature (PVT) conditions for the statistical characterization run.
2. Read SPICE netlist into Liberate to process the standard cells and statistical SPICE models or models with Monte Carlo support, for Inside-View functional recognition and vector generation.
3. Run Statistical characterization using a full SPICE solver like Spectre^® APS and characterize using mismatch analysis or Monte Carlo analysis that covers all the timing arcs. Liberate Variety provides user with the flexibility to perform characterization for systematic (global) as well as random (local) variations.
4. Generate the sensitivity files. In this stage, after the completion of the characterization run for all the timing arcs, the statistical results are written in to a sensitivity file.
5. Merge the sensitivity file generated from Liberate Variety into the nominal characterization data generated from Liberate to generate a final LVF Liberty (.lib) file.

Unlike the features that Liberate Variety offers, the Liberate Trio characterization solution is a one-stop solution that uses a unified flow to generate both nominal and statistical characterization data in a single run for standard cells, IO’s, and complex multi-bit cells.

To assist you in understanding the process from tool installation and configuration to all five stages mentioned above, we have a Rapid Adoption Kit (RAK) available on the Cadence Support portal. This RAK provides a walkthrough of the Tcl command interface of Liberate characterization and instructs the new users step-by-step to generate statistical standard cell libraries using Liberate Variety and Liberate Trio.

To download the RAK and the related tutorial, click Liberate Variety - LVF characterization setup for standard cells or Liberate Trio – Unified flow for statistical (LVF) and nominal characterization. You can also search for this RAK on the page accessed from the Resources – Rapid Adoption Kits menu of the Cadence Support.

Related Resources

For more information about working with the Liberate Characterization solution, see the following references:

• Liberate Characterization Reference Manual
• Liberate Variety Statistical Characterization Reference Manual

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!

Aravind R