Differences between SPEF and SDF which are used in static timing analysis

Could any one explain me in detail about the differences between SPEF and SDF which are used in static timing analysis..??

Any good article explained with a design would also be fine.

spef format

Hi Reddy,

SPEF Stands for Standard Parasitic Extraction Format.

SPEF file is generated by parasitic extractors like CALIBRE XRC.SPEF is fed to STA tool to do post layout Static Timing Analysis.

SDF stands for Standard Delay Format

SDF is widely used for transferring the Delay information between tools.Normally SDF is used in Pre Layout Static Timing Analysis.

Regards

spef file format

Hi,

SPEF file describes spice netlist and RC infromation.
After running LVS(LVS correctly), you can generate SPEF file from RC extraction tool(Xcalibre,Calibre-XRC--Mentor Star-RCXT--synopsys) or APR tool.

As for SDF file, it describes cell delay(from synthesis library) and interconnect delay(from SPEF file).
You can generate it from APR tool and PrimeTime(STA analysis tool).
If you want to get accuracy SDF file to do STA analysis.
I recommend you can use rc extraction tool to generate SPEF file and load into PrimeTime to generate SDF file to do STA analysis.

Best Regards,
Chyau

spef sdf

SPEF is for physical layout,
SDF is mostly for front end.

spf spef

SDF consists cell delays & interconnect delays. at synthesis level this file is used for timing analysis. that interconnect delays are only an estimation. its not the real & exact interconnect delays. after compleate place & route only we can get the exact interconnect delays.

after P&R, parasitic & interconnect delays are extracted using tools, that info is SPEF file. this file will be fedback to static timing analysis tools to do timing analysis on filnal p&r netlist.

Added after 20 seconds:


SDF consists cell delays & interconnect delays. at synthesis level this file is used for timing analysis. that interconnect delays are only an estimation. its not the real & exact interconnect delays. after compleate place & route only we can get the exact interconnect delays.

after P&R, parasitic & interconnect delays are extracted using tools, that info is SPEF file. this file will be fedback to static timing analysis tools to do timing analysis on filnal p&r netlist.

spef extraction

- spef contains RC values; these RCs are annotated in the STA tool [like PT] and delay calculated.
- sdf already contains the calculated delays; so the STA tool simply has to compute the path delays.

.spef file

Hi,
You can also use the SPEF to generate a SDF (with Primetime) and
then use this SDF for post layout simulation

sdf synopsys

SPEF includes resistance and capacitance parasitics.
SPEF also has a syntax that allows the modeling of capacitance between different nets, so it is used by the PrimeTime SI (crosstalk) and PrimeTime.

Sdf contains the calculated delays,it do not contain any information about capacitance or transition times.so it is only used by the PrimeTime.

what is spef file

chyau said:

Hi,

SPEF file describes spice netlist and RC infromation.
After running LVS(LVS correctly), you can generate SPEF file from RC extraction tool(Xcalibre,Calibre-XRC--Mentor Star-RCXT--synopsys) or APR tool.

As for SDF file, it describes cell delay(from synthesis library) and interconnect delay(from SPEF file).
You can generate it from APR tool and PrimeTime(STA analysis tool).
If you want to get accuracy SDF file to do STA analysis.
I recommend you can use rc extraction tool to generate SPEF file and load into PrimeTime to generate SDF file to do STA analysis.

Best Regards,
Chyau

Click to expand...

Do you mean to generate a new SDF file? Then when the input SDF file is generated? By DC in synthesis process?

primetime sdf

You should generate spef (spf) file first after apr, then you can generate sdf file with this spef file by primetime or other tools.