Transition Violation | Physical Design | Logical DRC

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In the Physical Design/Implementation stage of chip design, we address both timing and transition violations. Let's assume the timing violations have been resolved in all corners, but a few transition violations remain to be fixed. Despite having a clean timing analysis, it is still necessary to address these transition violations.


Transition violations are associated with rise and fall times, and it is crucial to meet the targeted limits to ensure the proper functioning of the chip. Even if a path meets timing requirements with a transition violation, it may only have a small margin. Such paths are susceptible to being affected by random process variations, which can result in functional and timing failures. 

Now, let's explore practical methods to fix these violations.

In the design flow, EDA tools often prioritize logical design rule check (DRC) fixes over maximum delay considerations. However, it is possible to modify this priority based on design analysis and requirements.

Even after multiple stages of optimization, such as placement, clock tree synthesis (CTS), and routing, there may still be numerous remaining transition violations to resolve.

To begin with, focus on fixing setup timing violations, if any, using signoff tools. Resolving setup violations often leads to the correction of transition violations as well, as it involves cell resizing and buffer insertion algorithms.

Additionally, utilizing a specific template provided by the EDA tool vendor, designed to address maximum transition violations exclusively, can be highly effective. This approach ensures minimal impact on other design parameters.

Various standard practices can be employed to tackle transition violations, such as upsizing critical cells, strategically inserting buffers, employing load splitting techniques, and adjusting cell placement for improved signal flow.

Vt-swap and layer promotion are techniques that can significantly assist in resolving transition violations, especially during the final stages of tape-out.

Please feel free to post your insights and views in the comment section below.

Stay tuned for more fascinating and insightful topics.

#pd #physicaldesign #drc #logicaldrc #india #semiconductor #vlsi #infineon #transition #sizing #upsizing #vtswap

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