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layer numbers rule deck

oldnick

I'm wondering if there is a way to get cadence to report the numbers it assigns to layers.

I'm trying to modify an lvs rule deck to recognise a specific structure. To do this I need to create a recognition layer/region which comprises a layer named CTM2, however this layer is not declared in the lvs rule deck.

If we look at TGOX in as declared in the ruledeck, 

layer   MAP     21      DATATYPE        0       10021

layer   TGX_drw                                             10021

there are 3 numbers associated with it. For the layer I want to add I know two of them, but not the 3rd.

layer MAP  92   DATATYPE            0        ?????

layer CTM2_drw                                         ?????

As far as my understanding goes, the 0 specifies the data type and the first number is the layer number it is mapped to by the stream tool. I think the 3rd number is one that cadence uses to identify it. For most layers in the rule file, the 3rd number is usually the 1st number with either 10 or 100 appended to the front, although a few times it is something completely different, so, I can't really have a guess. Is there some way I can get cadence to report this number? I've been looking for ages but can't find anything. Or are my assumptions wrong and the solution something different?

Cheers,

Nick

  • Andrew Beckett

    Nick,


    You didn't mention which LVS tool you are using. That rule deck looks like a Calibre rule deck (based on the syntax) and so it's not "Cadence" identifying anything (there is no such tool as "Cadence", and anyway Calibre is a Mentor Graphics tool, not a Cadence tool).

    Cadence's PVS tool has a similar construct:

    layer_def CapMetal 1001;
    layer_map 14 -datatype 0 1001;

    The layer numbers used for PVS (and I suspect Calibre) are completely arbitrary - you can use what you want, provided they don't clash with any other layer.

    The first layer number and datatype number do correspond to stream numbers.

    Similarly Virtuoso (and OA) has also its own layer numbers. This is because the tools use a numerical designation for the layer indexing for efficiency - but I don't think it is that critical what you choose. People might use some kind of convention such as you've observed simply to ease the  management of choosing the layer numbers.

    Kind Regards,

    Andrew.

  • oldnick
    It's PVS I'm using. I apologise for referring to virtuoso as Cadence, everywhere I have worked has always referred to virtuoso simply as Cadence. Are you sure the number is arbitrary, I've been led to believe that it is the number that virtuoso assigns to the layer (hence my question asking if there was a way to get virtuoso (cadence) to report this number, I can get virtuoso to order the layers based on this number but I can't get it to report it) , so in the rule deck, layer MAP 21 DATATYPE 0 10021, is the instruction to map the layer 10021 to layer 21. If the number is arbitrary, then why is it included in the rule deck?
  • Andrew Beckett

    OK, but that still looks like a Calibre rule deck you're using. However, the concepts are similar.

    I have checked again, and the layer number (the one at the end) is internal to PVS (and internal to Calibre for Calibre too, I expect). It's certainly nothing to do with the layer number in the Virtuoso tech file, and is somewhat arbitrary. It just defines what layer numbers are used in the PVS database.

    I suspect this implementation detail could have been hidden from users, but it may be that certain of the tools allow for re-use of existing PVS databases in which case you want the layer numbers to be the same from run to run.

    I don't really see why you need Virtuoso to report this number though.

    Regards,

    Andrew.

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