Synopsys Timing Constraints And Optimization User: Guide 2021

This guide explains key Synopsys timing constraint concepts and practical optimization techniques for digital IC design flows circa 2021. It covers SDC fundamentals, constraint types, common pitfalls, strategies for improving timing, and recommended flows for static timing analysis (STA) and synthesis/implementation with Synopsys tools (Design Compiler, PrimeTime, IC Compiler/IC Compiler II). Use this as a practical reference to write or refine constraints and to guide timing closure efforts.

The 2021 guide heavily emphasizes constraint quality. Synopsys introduced stricter linting for SDC (Synopsys Design Constraints).

The 2021 guide dedicates Chapter 8 to "Optimization for Area and Power under Timing Constraints."

The Synopsys Timing Constraints and Optimization User Guide (2021) is essential for any team aiming to close timing efficiently on 7nm/5nm and smaller geometries. Its focus on physical-aware constraints and DSTA makes it a critical upgrade from pre-2020 methodologies. Engineers should prioritize chapters 4 (Clocks), 8 (Exceptions), and 12 (Constraint Debugging) before tapeout.

Note: This text is a synthesized technical summary based on the public documentation structure of Synopsys tools. For exact command syntax and legal usage, refer to the official PDF available via a valid Synopsys SolvNet+ subscription.

Introduction

Synopsys Timing Constraints and Optimization User Guide 2021 is a comprehensive guide that provides detailed information on how to use Synopsys tools to constrain and optimize digital designs for timing performance. The guide covers the basics of timing constraints, optimization techniques, and best practices for achieving optimal timing results.

Understanding Timing Constraints

Timing constraints are used to specify the timing requirements of a digital design. They define the relationships between signals and the timing relationships between different parts of the design. There are several types of timing constraints, including:

Defining Timing Constraints

To define timing constraints, you need to use a constraints file, which is a text file that contains a set of commands that specify the timing requirements of the design. The constraints file is used by Synopsys tools to analyze and optimize the design.

Here are some common commands used to define timing constraints:

Optimization Techniques

Synopsys tools provide several optimization techniques to improve the timing performance of a design. These techniques include:

Using Synopsys Tools for Timing Optimization synopsys timing constraints and optimization user guide 2021

Synopsys provides a range of tools for timing optimization, including:

Best Practices for Timing Optimization

Here are some best practices for timing optimization:

Example Use Case

Here is an example use case for timing optimization:

Step-by-Step Solution

Here is a step-by-step solution to the example use case: This guide explains key Synopsys timing constraint concepts

create_clock -name clk -period 10 -waveform 0 5
set_input_delay -max 3 -clock clk [get_ports input_port]
set_output_delay -max 2 -clock clk [get_ports output_port]

dc_shell -f design.tcl -o design.sv

pt_shell -f design.tcl -o design.rpt

Conclusion

In conclusion, Synopsys Timing Constraints and Optimization User Guide 2021 provides a comprehensive guide to constraining and optimizing digital designs for timing performance. By following the guidelines and best practices outlined in this guide, designers can achieve optimal timing results and ensure that their designs meet the required specifications.

References

Appendix

Here is an appendix of useful commands and syntax:

Clock gating saves power but kills timing if done wrong. The 2021 guide dedicates an entire chapter to Clock Gating Path Optimization.

Don't read it front to back. Do this instead: Note: This text is a synthesized technical summary

The 2021 guide is famous for its "Exception Handling" chapter. It categorizes exceptions by severity.

The guide introduces a "Board-Aware" constraint flow.