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devices parameters are changed are cdb2oa conversion

vdsv

Hi, i have converted a library from cdb2oa and there is a weird issue.

Devices that are standalone, do not have any multiplier defined are not affected and the layout views are not blown up.

However, devices that have multiplier defined have their parameters changed. For e.g.: device with multiplier 3 now appears as a device with length 3x of original but multiplier as 1.

Also, devices in series (or stacked devices) are merged in certain layouts.

Any insights with this issue will be valuable.

Thanks a lot.

  • Andrew Beckett

    I've never seen this before (and to be honest, I can't see how cdb2oa could do this itself) - my guess is that maybe there's a PDK incompatibility between the CDB and OA versions (I don't know though).

    What you should do is contact customer support so that we can take a look at the data in more detail to explain this very odd behaviour.

    Regards,

    Andrew.

  • vdsv
    Thank you Andrew. It is could mostly likely be an issue with the PDK. This is 0.5 um process. During CDB2OA migration, i turned on "Retain CDB parameters" and "Use defaults from CDF". I copied CDF parameters from pcells in older pdk to pcells in new pdk. Then i also tried modifying CDF parameters of new cells and add the "mult" parameter again. Looks like, this could also be due to the way multiple pcells are instanced in IC5.1x and IC6.1. It could as well be that the multiple instances are now instanced using <N:1> and not [N:1] and IC6.1 therefore creates a much bigger device as it cannot handle the old multiplier, or the way it is specified. After all these experiments, i am fixing the layout manually and halt the root cause analysis of CDB2OA changing device dimensions. Thank You for the response. Best Regards, Vandana
  • Andrew Beckett

    That doesn't make sense. Iterated instances have always been specified as <N:1> and [N:1] doesn't mean anything in Virtuoso (CDB or OA). m-factors also would be the same provided that the PDK is the same. 

    So my assumption is that there's a difference in the two PDKs (maybe they use different parameter names between the two PDKs), but without seeing the data I couldn't be sure, which is why I suggested you contact customer support.

    Kind Regards,

    Andrew.

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