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Assura LVS QRC extraction of only metal structure

MartinK

Hi all,

 

I’m using Assura 4.1.1. and I ran into the issue of having multiple (or at least two) pins on same metal in terms of same net. In principle I would like to extract the RC Network of an arbitrary metal structure.

So considering the simplest example: a metal line with a pin at each end, I managed it to get it LVS clean using

?allowMultPinsOnNet t.

(In schematic I have an iprobe between the pins and tell LVS to short the iprobe using filterDevice( "iprobe" short("PLUS" "MINUS")) )

But extraction fails because Assura keeps only one pin and discards any other, as it also written in the command reference:

‘Even though multiple pins are assigned to a net, Assura only keeps one of the pins, but

no warning is issued to the runname.erc file.’

 

So, how do I get Assura to extract a simple metal line?

 

Thanks a lot!

Martin

  • Andrew Beckett

    Martin,

    Assuming you have them in your design kit, I would put some small metal resistors in each end of the metal track to force there to be a real "component" at each end. This shouldn't have any significant impact on the resistance because it would just be one square (say - maybe even a fraction of a square) - but enough that LVS has something to chew on.

    Andrew.

  • MartinK
    Thanks Andrew, in the end I found something like this (a resistor for LVS purpose) in the PDK. So it seems the solution is somehow PDK dependent. What, if nothing like this is available in the PDK. In there a solution or workaround that might work for any PDK?
  • Andrew Beckett
    Martin - not as far as I know (that said, I've not looked into this in great depth recently). It's a fairly unusual thing to do, I guess, and having some kind of metal resistor or pseudo net-splitting device in the PDK is pretty common nowadays. Andrew

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