6 Replies Latest reply on Mar 28, 2013 3:34 PM by skumar61

    SRAM XRC extraction

    c_camezc
      I am running xrc on a custom sram (640words X 360 bits) in umc130.  The LVS(xrc) 
      directory currently has about 46GB of cache**.dat files and the job is not finished yet.  I am guessing that these files go away after the final parasitc netlist is built up.
      What are typical settings for extracting srams as far as min cap or min res.  I am running in hierarchical mode and mentor version is

      //  Calibre v2008.4_37.26    Wed Jan 7 15:21:19 PST 2009

      //  Litho Libraries v2008.4_37.26  Wed Jan  7 15:19:22 PST 2009

      //

      Any help is appreciated
        • 1. Re: SRAM XRC extraction
          sabyasachi_mallick

          Hi,

           

          If this is a memory design, you need to run gate-level extraction.

          Please refer to pg-46 of the xRC User's Manual 2008.4 version for further details.

           

          Thanks,

          Sabya

          • 2. Re: SRAM XRC extraction
            c_camezc

            Hi,

             

            What I am trying to do is extract parasitics for the sram.  The sram is what is being designed and will need to simulated with extracted parasitcs.

             

            Your suggestion is valid is I am instantiating an sram in a larger block.  This is not the case here.

             

            Carlos

            • 3. Re: SRAM XRC extraction
              sabyasachi_mallick

              Hi,

               

              In that case, you will need to define the standard cells(leaf cells) of sram as xcells and still do the gate level extraction.

               

              -Sabya

              • 4. Re: SRAM XRC extraction
                karen_chow

                Hi Carlos. Just to check, are you running a hierarchical extraction? For example, in your pdb stage, are you setting the -full flag?

                 

                calibre -xrc -pdb -rcc -xcell xcellfile -full rules | tee pdb.log

                 

                Also, the xcell file determines your final hierarchy of the output netlist. For SRAMs, it's best to not include the lowest level bit cells in your hierarchy, but to instead choose a mid-level hierarchy and up as your xcell list.

                • 5. Re: SRAM XRC extraction
                  zlz

                  I tried to follow your suggestions.

                  1. calibre -xrc -pdb -rcc -xcell xcell -full rules | tee pdb.log

                  2. And in xell file, I have only two xcell defined:

                  8tsram 8tsram

                  array_4x4 array_4x4

                  3. In rules file, I added a line,

                  LVS PUSH DEVICES SEPARATE PROPERTIES xcell

                   

                  The result is still a flat extraction, warning messages are:

                  WARNING: Cell "8tsram" listed in the XCELL file has no devices and will not be extracted as an XCELL.

                  WARNING: Cell "array_4x4" listed in the XCELL file has no devices and will not be extracted as an XCELL.

                   

                  Do you have any idea why the hierachical extraction doesn't happen at all? Anything wrong with the line I added to rules file?

                  BTW, I can't download application note with a guest account here. I'm using university tools without direct tech support. A specific example will be appreciated.

                   

                  Liz

                  • 6. Re: SRAM XRC extraction
                    skumar61

                    Hi

                     

                    Can anybody help me in this

                     

                    My design is made of standard cells and other custom made standard cell

                     

                     

                    I am getting the same error as above .I want to get extraction for the top level only without smashing standard cells. but pex always smashes everything in transistor .I have been using gate level option  in pex

                     

                     

                    Can  somebody point to the other option .I am university student I am using Calibre 2010 version  . Is it something new in the newer version of the tool

                     

                    Everytime I run It complains

                    WARNING: Cell "ckinv01" listed in the XCELL file has no devices and will not be extracted as an XCELL.

                    WARNING: Cell "ckinv02" listed in the XCELL file has no devices and will not be extracted as an XCELL.

                     

                    Thanks

                    Sushil