Synopsys - Timing Constraints And Optimization User Guide 2021 ((new))

Total Negative Slack (TNS) and Worst Negative Slack (WNS). Power: Dynamic and static leakage power. Area: Total gate count/silicon footprint.

The user guide provides detailed instruction on generating and interpreting timing reports. The report_timing command is the primary tool for this, and it has many options. For example, the -normalized_slack option can be used to analyze normalized slack and identify paths most critical to performance. For paths with very small normalized slack values, using the -significant_digits option displays enough fractional digits to see the important differences. These detailed reports help designers locate the root causes of timing violations.

This article unpacks the critical methodologies, command structures, and optimization strategies detailed in the 2021 guide. Whether you are a seasoned ASIC engineer or a recent graduate, understanding this document is essential for achieving timing closure efficiently. synopsys timing constraints and optimization user guide 2021

set_input_delay defines the amount of time a signal requires to arrive at an input port relative to a clock edge outside the design.

A sophisticated technique covered in the guide is . This is particularly useful for latch-based designs or paths with multiple clock cycles. Normalized slack is calculated as: Total Negative Slack (TNS) and Worst Negative Slack (WNS)

STA is the method used to verify that a digital design will meet its timing requirements. It does this by analyzing all possible timing paths under worst-case conditions. Instead of simulating logical operations, STA calculates the maximum possible delay through each logic element. It calculates the (timing margin) to check for two primary types of violations:

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. The user guide provides detailed instruction on generating

During early synthesis (Design Compiler), clocks are treated as , meaning they have zero delay and perfect transition times. In physical implementation (IC Compiler II) and post-layout verification (PrimeTime), you transition to propagated clocks to account for real clock tree delays. Core Clock Constraints