The 2021 manual places heavy emphasis on modeling jitter and skew. By defining setup and hold uncertainty, you build a "safety margin" into your design. 3. I/O Constraints: The Interface Challenge
If data arrives too fast and mixes with old data, the software adds tiny delays to slow it down.
# Reserves 1.5ns of the clock period for external setup and board routing set_output_delay -max 1.5 -clock SYS_CLK [get_ports data_out] Use code with caution. 4. Advanced Timing Constraints: Path Exceptions synopsys timing constraints and optimization user guide 2021
"When creating a generated clock using create_generated_clock , always specify the -source object as the master clock pin. In 2021, the -divide_by or -multiply_by options are recommended over -edges for simple frequency division to improve propagation accuracy. For non-integer division, use -edge_shift with care, as it may introduce glitches if the source clock edge alignment is not validated."
: Swapping High-Threshold Voltage (HVT) cells into non-critical paths to reduce leakage while retaining Low-Threshold Voltage (LVT) cells strictly on critical paths. The 2021 manual places heavy emphasis on modeling
: Start with "loose" constraints to explore the design space, then tighten them as the physical floorplan matures.
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. I/O Constraints: The Interface Challenge If data arrives
Comprehensive Guide to Synopsys Timing Constraints and Optimization