Whether you are writing your first create_clock command or debugging a complex multi-cycle path violation, the 2021 edition remains a must-have reference for any digital engineer aiming for successful tapeout. Mastering the guide means mastering the art of telling the tool exactly what your design does, so it can optimize it perfectly for what it must do.
: 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.
Are you primarily focusing on or sign-off timing (PrimeTime) ?
The guide introduces a "Board-Aware" constraint flow. synopsys timing constraints and optimization user guide 2021
Use report_timing extensively. Do not just look at violations; understand the path's structure.
Properly defining virtual clocks for input/output delay constraints to ensure accurate interface timing. B. Input and Output Delays
Not every path in a chip needs to meet a single-cycle timing requirement. The 2021 guide highlights how to properly use exceptions to prevent the tool from "fixing" paths that aren't broken: Whether you are writing your first create_clock command
: Setting input and output delays ( set_input_delay , set_output_delay ) to model the external environment around the chip.
A common pitfall addressed in the guide is neglecting the and capacitive load on these ports. Without these, the timing engine assumes an ideal (and unrealistic) transition time. 4. Advanced Timing Exceptions
The guide stresses that an improperly defined clock is the root of 90% of timing violations. The guide details how to use set_input_delay and
To maximize performance, engineers utilize specific compilation directives within Design Compiler:
: Models the delay from the clock source to the definition point (source latency) or from the definition point to the register clock pins (network latency).
By leveraging Synopsys' timing constraints and optimization capabilities, designers can create innovative, high-performance ICs that meet the demands of today's complex electronic systems.
By default, Synopsys tools assume that data must travel from a launching flip-flop to a capturing flip-flop within exactly . When design intent violates this default behavior, you must declare timing exceptions. False Paths