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Importing a def file (made in encounter) into virtuoso.

Mikutine

Dear users,

I've made a design in Encounter with the Nangate OpenCell Library. Everything is placed and routed, and I have extracted the def file.

I want to use that def file, so I can import it in Virtuoso, because I have to add some shape pins in there. The first thing I did, is make an new library, where I attached the technology file from the FreePDK45 of Nangate.

When I want to import the def file in Virtuoso, I fill in the following in the Virtuoso DEF In form:

-DEFin File Name: "the path to the def file"

-Target Library Name: "the new library that I've made with the attached technology file

-Ref. Technology Libraries: "the nangate opencell library"

-Target Cell Name: "the name of cell''

-Target View Name: "the name of layout" 

I get the following errors:

'The library "router_lib" is already attached to technology library "NCSU_TechLib_FreePDK45". Cannot replace this with a derived technology database unless the original attached technology library is part of the new references. defin translations has failed'

So it basically says that the attached technology file to the new library, and the ref. technology library are conflicting. But when I try to import it without one of these two libraries/technology file, I get some missing information about via's.

Can somebody explain me how I can fix this? Thank you in advance! 

  • hello,

     The 'Ref. Technology Libraries' makes sense to use in case you create a fully new library and you would like this new library to reference a library (inherit technology information from that libraries) but in your case you have already created the new library prior to import your DEF then you don't need to specify any library into the 'Ref. Technology Libraries' field.

    You have certainly missing vias due to the following reasons:

    1. your default vias (custom vias in Virtuoso techfile) are not defined in your technology library "NCSU_TechLib_FreePDK45"
      • custom vias: fixed vias defined as a lib cell view but defined in you techfile under customVias section
    2. your via generate rules (std vias in Virtuoso techfile) are not defined in your  "technology library "NCSU_TechLib_FreePDK45"
      • standard vias: parametrized vias based on technology rules defined in standarVia section of your techfile

     Basically you have missing vias information due to techfile not up to date.

    A solution would be:

    1. create your library to import DEF using as reference "NCSU_TechLib_FreePDK45" 
    2. into this new library import a the LEF technology but with only vias information both GENERATE and DEFAULT
    3. importing your DEF to see if it works

    Thanks,

    Alex

     

  • Dear Alex,

    Basically, I understand what you are trying to say. But I think there is a misunderstanding.

    As far as I know, the via information is in the standard cell library (Nangate OpenCellLibrary). This is the library that I've used to synthesize a design (in Synopsys Design Compiler) and place&route (in Encounter). 

    Now I want to import that design back into Virtuoso, because I have to edit something in the layout (add some shape pins). I think for this, you need the technology library (NCSU_TechLib_FreePDK45). But doesn't it need at the same time that standard cell library that I used pryor to do synthesize, place&route?

    I've heard that it is easier to import a design through a gds (stream) file. But then again, I need a technology library. But it gives me the same conflicts.

    So, if you maybe have a solution for this?

    Thank you in advance.

    Kind regards,

     Milovan 

     

  • I tried to do what you've said, to make a new library with attaching the technology library 'NCSU_TechLib_FreePDK45' and then import the LEF file with only the via information. Well, I did that, and I get the following errors: 'Constraint validRoutingVias does not match the referenced technology database'. I get a bunch of these errors. Only for different vias. I tried a couple of other things. Like making libraries with the 'NCSU_TechLib_FreePDK45' as the technology file. And when I try to import this def file, I get errors that some siteDEF was not found. This seems logical as I made that design with the standard cell library. When importing this design, I think it should have some reference to that library. Another error was: A matching via rule Via#Array-0 is used for this via since there is no via rule specified. It seems as there are no rules specified for the via GENERATE where the rules for the arrays are. The other thing I tried is making a library with the 'NangateOpenCellLibrary' as the attached technology file. This library I've used to synthesize, place&route the design. Here I don't get the siteDEF errors, but I do get the Via#Array errors. I'm really stuck now, so I hope somebody can help me. Thank you in advance!

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