2 Replies Latest reply on Feb 15, 2009 3:59 PM by banderson

    LVS falure for block in toplevel

    nagaraj.kumbar

      Hi, I have a analog block which comes clean during stand alone lvs but fails when hooked up at the top level. Interfaces have clean connections.  If this block is black boxed during lvs (LVS BOX command) top level finds some extra cells in the top level. which it says they are found at the location of black box.

      If the block is flattened during lvs. the results shows property errors on some devices in the block and the error margin is 100%. Any one face similar issues? or tips to debug?

       

      Thanks

        • 1. Re: LVS falure for block in toplevel
          chris_balcom

           

          Hi Nagaraj,

           

           

          I have not seen that combination of symtoms before, but it sounds like a problem I would be able to help with. Here's something you could try if you like... You could go to SupportNet and open a Service Request (SR). You could copy/paste the problem from this thread and mention that Chris Balcom would like to participate in the debug if possible. I look forward to helping.

           

           

          -chris

           

           

          • 2. Re: LVS falure for block in toplevel
            banderson

            I had the same problem, welcome to all the changes you have to do with your rule files.

            You will end up with a different set of rule files to use at top level versus intermediate levels.

             

            The black box thing got me until I used: LVS NETLIST BOX CONTENTS NO

             

            For the extra cells that are added, check the results of the *.sp file (calibre -spice creates the .sp file from the gds).

            If you see a seed promotion, spend the time to find out why, it is probably losing a power connection somewhere.

            LVS EXPAND SEED PROMOTIONS YES

             

            You have to spend a lot of time massaging hcells, filter options, and lvs report options to get the top level right.

            You have may have virtual connections with the colon :. At the top level, turn off all of those virtual connections

            allowed at top level. For the hierarchy, use

            LAYOUT RENAME TEXT "/://"

             

            also check your source bus label nomenclature, versus the layout for busses

             

            the following worked for me to bring the busses inline and match with other-

            where the bus nomenclature from place and route of synthesized blocks were

            different from the hand created schematic blocks

             

            LAYOUT RENAME TEXT "/\\[/</g" "/\\]/>/g"