The-OpenROAD-Project / The-OpenROAD-Project/OpenROAD-flow-scripts
Small change in clock period leads to wide swing in CTS TNS
@precisionmoon is already working on this.
Since Feb 11, 2026.
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Description
Subject
Describe the bug
Found during frequency sweep of asap7 ibex, where a small change in clock period leads to a much wider swing in CTS TNS. @maliberty requested filing GH issue to see if we can drive down the range.
| Clock Period | CTS TNS |
|---|---|
| 1001.8 ps | -49915 ps |
| 1009.3 ps | -18862 ps |
The overall CTS WNS/TNS chart looks like:
Expected Behavior
Reduced variation in TNS
Environment
b3f8033f64550f9601c8453d2cf7c178d7902133 - orfs git commit tag
To Reproduce
"min" value tarball: https://drive.google.com/file/d/1eAX7XIo6DWB1Y2afe-tg0q_fdV3dVwfW/view?usp=drive_link
"max" value tarball: https://drive.google.com/file/d/1IFMWERyTzKmT9rTYGk26U1r9auk30BAY/view?usp=drive_link
Relevant log output
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Additional Context
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