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lef unit confusion

Holdsworth
Hello there, I'm a bit confused with LEF unit: I've a LEF file with DATABASE MICRONS 2000 ; However, the LEF/DEF language reference interprets one LEF distance unit as multiplied when converted into database units. In other words, if for a LAYER M1 WIDTH 0.10 ; , does this mean that the actual width of M1 is (0.1*2000)um ?

  •  No, the M1 width is 0.10 microns. The numbers in the LEF are always in microns, but the tech LEF also happens to be where you specify what the DB Units are for the design. The numbers in the DEF file are in DB Units. The statement DATABASE MICRONS 2000 means that for any numbers in the DEF file, to convert to microns, you divide by 2000. (A long time ago, the tool GUIs would display things in DB Units also, but I believe everything is displayed in microns now.)

    Sometimes the LEF will have DATABASE MICRONS 1000, or some other number. It depends on the technology and what the manufacturing grid is.

     

  • Do you know how to set the LEF UNITS DATABASE MICRONS?  The digital vendor is asking for 2000, but the default in the technology file is creating MICRON UNITS as 100.  I am exporting a flat abstract viewcell with only ports and metal blocking layers using the File, Export, LEF.

     

    Thanks,

          MD

  •  You can just edit the LEF manually to change the DATABASE MICRONS line to whatever you want. 

    If you want this to happen automatically when you export LEF, then I *think* it's a setting in the DFII tech file, but it's been a long time since I played in that arena. ;-)

    - Kari

  • Thanks for the reply.  I was guessing as much as I noticed that the coordinates seem to be correct and since you will be importing in, the units will adjust accordingly to whatever is in the LEF file.  I searched around in the techfile, but didn't see the specific unit under the CONTROLS portion or the P&R portion.

     

    Thanks,

     

         MD

     

  • Hello Kari. What would be the effect when my PNR tech lef has DATABASE MICRONS set to 2000 and the technology file in my virtuoso is set to 1000? Would it introduced possible DRC errors when the PNR def file is imported to virtuoso?
  • It's been a long time since I've worked in Virtuoso, but I think this will be ok. Run DRC and if you see lots of really strange errors, that that could be the culprit.

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