Synopsys Timing Constraints And Optimization User Guide 2021 Direct
Note: The engine will actively sacrifice area and power to fix a Max Transition or a Setup timing violation. Key Optimization Commands High-Effort Optimization
Identify whether the bottleneck stems from excessive logic levels, poor clock skew, or overly aggressive boundary delays.
If the logic depth is too high for the target frequency, you must modify your original RTL code to implement manual pipelining.
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: Specifying clock latency, uncertainty (jitter/skew), and transition times. Clock Groups : Managing asynchronous or exclusive clock domains with set_clock_groups 3. Constraining I/O Interfaces Input Delays
| | Example SDC Command | Description | | :--- | :--- | :--- | | Basic Clock | create_clock -period 5.0 [get_ports CLK] | Creates a clock on port CLK with a period of 5.0 ns and default 50% duty cycle. | | Generated Clock | create_generated_clock -source [get_ports CLK] -divide_by 2 [get_pins U1/Q] | Creates a clock at pin U1/Q that is half the frequency of the master clock at CLK . | | Virtual Clock | create_clock -period 10.0 -name VIRT_CLK | Defines an ideal clock VIRT_CLK to be used for I/O constraints. |
Dynamically adjusting cell size and inserting buffers to balance load and timing. C. Multi-Scenario Optimization Note: The engine will actively sacrifice area and
Before jumping into SDC commands, the user guide lays a strong foundation with key timing concepts.
The manual is typically organized into these key functional areas:
Based on standard Synopsys documentation frameworks, the content is typically organized into the following functional sections: Do you need to know about a specific
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set_clock_transition 0.08 [get_clocks SYS_CLK] set_clock_latency -source 0.4 [get_clocks SYS_CLK] Use code with caution. 4. Constraining Input and Output Interfaces
Synopsys Timing Constraints and Optimization User Guide 2021: Achieving Optimal PPA
Timing closure involves ensuring that the final, routed netlist meets both setup and hold timing requirements. The guide explains how to configure tools to prioritize these optimizations. It mentions that while hold violations can often be fixed automatically in the layout flow by adding delay buffers, fixes for setup violations typically require more significant changes like logic restructuring or cell sizing.
