CharLib: An open-source standard cell library characterizer

• 🔩 Supports combinational and sequential cells
• 📈 Plots timing and I/O voltages
• 🧑‍💻 Easy-to-use, with YAML-based configuration
• 🐍 Implemented in Python 3 with a modified PySpice backend
• 🌶️ Compatible with ngspice and Xyce

Introduction

CharLib is an open-source standard cell library characterizer. The current version supports timing characterization of combinational and sequential cells.

Installation

CharLib can be installed from PyPI using pip:

# Install our customized version of PySpice
pip install git+https://github.com/infinitymdm/PySpice

# Install CharLib
pip install charlib

Make sure you also have a compatible circuit simulator. ngspice and xyce are currently supported.

Usage

charlib run path/to/library/config/

CharLib searches the specified directory for a YAML file containing a valid cell library configuration, then characterizes the specified cells. See yaml.md for information on constructing a config file.

The general process for using CharLib is as follows:

1. Acquire SPICE files and transistor models for the cells you want to characterize
2. Write a configuration YAML file for the library
3. Run CharLib

References

[1] M. Mellor and J. E. Stine, "CharLib: An open source standard cell library characterizer", IEEE Midwest Symposium on Circuits and Systems, 2024 (in press).
[2] Synopsys, "What is Library Characterization?", https://www.synopsys.com/glossary/what-is-library-characterization.html, 2023
[3] S. Nishizawa and T. Nakura, "libretto: An Open Cell Timing Characterizer for Open Source VLSI Design," IEICE Transactions on Fundamentals of Electronics, Communications and Computer Sciences, 論文ID 2022VLP0007, [早期公開] 公開日 2022/09/13, Online ISSN 1745-1337, Print ISSN 0916-8508, https://doi.org/10.1587/transfun.2022VLP0007, https://www.jstage.jst.go.jp/article/transfun/advpub/0/advpub_2022VLP0007/_article/-char/ja,
[4] I. K. Rachit and M. S. Bhat, "AutoLibGen: An open source tool for standard cell library characterization at 65nm technology," 2008 International Conference on Electronic Design, Penang, Malaysia, 2008, pp. 1-6, doi: 10.1109/ICED.2008.4786726.
[5] E. Salman, A. Dasdan, F. Taraporevala, K. Kucukcakar and E. G. Friedman, "Exploiting Setup-Hold-Time Interdependence in Static Timing Analysis," IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems, vol. 26, no. 6, pp. 1114-1125, June 2007, doi: 10.1109/TCAD.2006.885834.