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Help on pcells

venuuuuu

  hi all,

     I created pcells(only layouts) and I have schematic. I need to generate layout from schematic through "Genfrom source" option. In some other processes I observed pcells has the views "auCd1" ,"auLvs", "layout","spectre", "symbol".....etc. What is the purpose of theese cells?

    And i have another problem. In schematic Instance had the properties "Gate Length(l), Number of Fingers(nf), Finger Width(fw)". But When I am designing Pcells containg the parameters as above, it is saying that "pcell evaluation failed". 

If my parameters are like GateLength,NumberofFingers ,FingerWidth then pcell oparates normally. I think tool(5141) is not taking the spaces in the parameters.

  • Andrew Beckett

    For the first question, the symbol is a representation of the component that can be placed in a higher level schematic - so it's something that just has the pins of the component and some graphic to represent it. The other views, e.g. auCdl, auLvs, spectre etc are usually copies of the symbol and are used to act as "stopping views" for netlisting. When designs are netlisted by specific netlisters, there will be some kind of switch view list and a stop view list. The switch view list is an ordered list of views to try to expand into, and if the view expanded into is one of the stop view list, it will stop expanding the hierarchy. The default for each of the netlisters is to have a stop list containing the name of the netlister - so generally if a cell has a spectre view, the spectre netlister will stop expanding when it hits that cell. This way you can mark which are primitive components in any netlister.

    You should not have spaces in the parameter names. In fact it would be quite hard to do so (you'd have to escape them in the pcDefinePCell() call). With CDF you can always give your parameters meaningful prompts, whilst keeping the parameter name space-free.

    Regards,

    Andrew.

  • venuuuuu

     hi Andrew,

                   I changed the parameters width as "wf" and length as "l". When i was use generate from source in VXL then they did not took parameters as per schematic( In sch parameter "Gate Length(l), Finger Width(w)"). It take width and length as zero..

  • Andrew Beckett

    You have not provided enough information to know what parameters you have defined where, so I would have to guess what your problem is - and that's rather difficult. It does however seem that you are rather uncertain as to what you're doing, so going to customer support where you can show them all your data would be wise. You might also want to consider some training - we have courses on SKILL and developing pcells using SKILL (see the Support & Training links at the top of the page).

    Regards,

    Andrew.

     

  • venuuuuu

    hi Andrew,

          Thank you for sharing your knowledge.  Can I creat pcells in PDK by 5141 version? Or is there any other tool for creating pcells. As per my knowledge I can create pcell in layout with less features by using tools->pcell.

  • Andrew Beckett

    Of course you can develop pcells in IC5141. You can do it either using SKILL, using the graphical pcell editor (which is a little limited because it's rather elderly) or using PAS (the PDK Automation System).

    Andrew.

  • venuuuuu

       Hi Andrew,

                              Can you tell path for PAS(Sorry, I dont know where it is.)? Among the all as you suggested in last post, which one is used to do PDK?

  • Andrew Beckett

    PAS would need to be downloaded and installed - the latest version on downloads.cadence.com is PAS31. It also is licensed - so you'd need the product for this (e.g. product PASGTE). Best to contact your local Cadence Support or your Account Manager.

    Regards,

    Andrew.

  • venuuuuu

     Thank you Andrew for your valueble reply.

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