Do not use the default settings. The 2021 guide explicitly warns against using compile_ultra without the -timing_high_effort flag. The default is "balanced," which leaves 5-7% performance on the table.
This defines the amount of time a signal takes to reach your chip's input port from an external launching register, relative to a reference clock.
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Fine-tune constraints to explore trade-offs between performance, power, and area. synopsys timing constraints and optimization user guide 2021
create_generated_clock -name DIV_CLK -source [get_ports sys_clk] -divide_by 2 [get_pins clk_div_reg/Q] Use code with caution. set_clock_uncertainty
Look for long Incr values in the report. If a single gate takes an unusually long time, it is likely driving a high-capacitance net. Apply set_max_capacitance or insert an intermediate buffer.
Are there specific or interfaces (like Source-Synchronous DDR) you need to address? Do not use the default settings
The final verdict—positive slack means you passed; negative means it's back to the drawing board.
The Synopsys Design Constraints (SDC) file acts as the universal language between these tools. It communicates design intent, electrical boundaries, and performance goals. If a constraint is missing or poorly written in SDC, the synthesis engine may over-optimize a non-critical path (wasting power and area) or completely ignore a critical timing violation. 2. Core Clock Constraints: The Foundation of STA
What are your and technology node (e.g., 7nm, 28nm)? This defines the amount of time a signal
: Constraining the external environment for the chip's ports.
Many designs use , which are clocks derived from a master clock. These are common in designs with clock dividers. The user guide covers how to define generated clocks with the create_generated_clock command, specifying the relationship between it and its source master clock, including division factors, phase shifts, and duty cycle changes. Getting generated clocks correct is crucial for accurate multi-clock domain analysis.