Synopsys Timing Constraints And Optimization User Guide 2021 -

: The guide explains how to interpret "slack"—the difference between the required arrival time and the actual arrival time. A negative slack indicates a timing violation that must be addressed through optimization.

: These account for the propagation delays external to the chip. The guide details how to use set_input_delay and set_output_delay to model the environment at the chip’s boundary.

: Leveraging clock gating and multi-threshold CMOS (MTCMOS) cells to reduce both dynamic and leakage power during the timing-closure process. 4. Advanced Features in the 2021 Release synopsys timing constraints and optimization user guide 2021

Timing constraints are the "instructions" that tell synthesis and implementation tools how fast a design must run. Without accurate constraints, optimization results are essentially meaningless.

: When the standard single-cycle timing model is too restrictive, exceptions are used: : The guide explains how to interpret "slack"—the

The 2021 guide emphasizes PrimeTime as the industry "golden" signoff tool.

: Start with "loose" constraints to explore the design space, then tighten them as the physical floorplan matures. The guide details how to use set_input_delay and

: Use report_timing with detailed options to identify if a violation is caused by logic depth, high fan-out, or poor placement.

: Optimizing logic across hierarchical boundaries to remove redundant gates and improve timing.

The 2021 documentation introduced enhanced support for advanced process nodes (7nm and below) where parasitic effects are dominant.