Liberty format capacitance definition

[battosai]

Hello

I am currently composing a liberty timing file for an analog block to be used in a larger digital simulation. The pin description for most pins are only described by their direction, capacitance and rise_ -and fall_capacitance. What I can't figure out is how these latter values are defined? Should these values represent the equivalent capacitance that generates the same rise and fall times?

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Code C - [expand]
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pin (AdcEnQxSI) {
        direction : input;
        capacitance : value;
        rise_capacitance : value;
        rise_capacitance_range (value_min, value_max);
        fall_capacitance : value;
        fall_capacitance_range (value_min, value_max);
    } /* End Pin */

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[graphene]

can you please specify as in which tool you use, additional details.

I think you can simply ignore these as these are mostly done /created by tools like Liberate/ELC.... it is not something to be focussed unless you have a specific problem.

 

[battosai]

I am not using a specific tool to create the .lib file..

I am using cadence ADE to simulate the analog block. The simulation is controlled by an ocean script to iterate through all corners and list items to be specified in my timing arcs and. The results are then formatted for the lookup tables in the .lib file and written to a file.
The .lib file is then written by hand.. hence my question..

 

[rca]

1-The liberty is not usable for digital simulation. The liberty is atiming/area/cap/trans/power information's for synthesis/PnR/STA tools.
2-The liberty format is describe here www.opensourceliberty.org.