3 Replies Latest reply on Dec 22, 2012 11:36 AM by samantha_lizak

    AUTO, HCELL and XCELL option in LVS


      I am not clarified with hcell and xcell optins in LVS. My intepretation is in both the cases of xcell and hcell exact transistor to transistor comparison is done. And in auto modebasically automatic comparison for lvs is performed. Will I get any supportive document for this.

        • 1. Re: AUTO, HCELL and XCELL option in LVS

          I don't quite understand your question.  Is this what you are looking for?


          "Hierarchy Control with Xcells


          When performing hierarchical extraction, you define your design's hierarchy for the Calibre xRC tool by identifying the lower-level cells in the design hierarchy.


          You define this hierarchy by creating a cell correspondence list that matches source and layout names. This cell correspondence list, also known as an hcell list, is input into the Calibre nmLVS-H tool using the "-hcell" switch. An xcell list is derived from the hcell list; the xcell list can only contain cells that were named in the hcell list. The xcell list is specified as part of the Calibre xRC invocation."



          (From the Calibre xRC User's Manual.)


          As to whether the hcell (or xcell) list affects whether comparison is transistor-to-transistor... no, not really.  The lists affect the representation within Calibre, and may affect how the output is presented, but the comparison is done the same regardless for LVS.  (For xRC gate-level extraction the xcells represent areas to not do parasitic extraction; presumably the xcells are device cells and have device models.)


          For more on what hcells do and how to choose them for LVS, see  http://supportnet.mentor.com/docs/201211063/docs/htmldocs/mgchelp.htm#context=calbr_ver_user&id=304&tab=0&topic=hcells . (Calibre Verification User's Manual.)


          Hope this helps-



          • 2. Re: AUTO, HCELL and XCELL option in LVS


              Thank you. I was mainly looking for whats is the difference between xcell

            and hcell option in calibre lvs.

            "calibre -64 -lvs -xcell ". In xcell list

            mainly transistor model lists will be there.



            On Sat, Dec 22, 2012 at 1:58 AM, samantha_lizak

            • 3. Re: AUTO, HCELL and XCELL option in LVS

              LVS mostly ignores  the -xcell switch; xcells are for parasitic extraction use only and the xcell list is usually formatted differently from an hcell list.  I see in the most recent version of the Calibre Verification User's Manual that nmLVS-H now accepts an -xcell switch, but it still requires a list of hcells.  It is only when a cell appears in both the xcell and hcell list that anything is different. (And according to the documentation, the difference is only that LVS guarantees to not expand the cell.)


              Most of the time for LVS, you will be dealing only with hcells.


              Hope that clears it up-