SPEF/SDF file for GLS

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sharath666

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Hi all,

Can anyone tell me why is only the SDF file used for GLS? Why don't we use the SPEF for the same?. Can the delays in the SPEF be back annotated?

Regards,
Sharath
 

Hi,

SPEF is format of extracted parasitics, it can be also under another format like SPBF, ...
SDF: standard delay format is a timing format used by simulators.

I think that some simulators can read directly SPEF file like ncsim, if not you have just to generate the sdf file which is just a re-write of the contain of SPEF file.

Regards,
 

I don't think NCSIM can read SPEF directly. SPEF is standard parasitic exchange format and does not contain delay value directly.

Cheers
Sameer
 

Sorry, what I had in mind was prime time for STA.
I used it one time with the command read_parasitics.
For ncsim, I am not sure I have to check it.
Thanks Sameer for your post,

Redards
 

mail4idle2 said:
SDF is nothing but extracted out of spef.
Click to expand...

Is it? I thought SDF is generated earlier in the flow (using primetime) & SPEF is generated later using STAR-RC. Anyways, I think the answer to my question might be that there is no way to backannotate the SPEF delays.....
 

SPEF contain resistance & capacitance not delays, which is extracted out of layout of the design. SDF contain delays of interconnect and cell delays. The timing tool like Prime time can read in SPEF and calculate delay based on SPEF values which will be used for GLS. The tool can also generate SDF file,which directly contain delay, from SPEF file as well.
 

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