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Parameters and pcells in ADE XL

kvntien

Hi all,

 I have a schematic pcell that generates an n-stage chain of (non-pcell) instances, each with different instance parameters.  To do this, I have a pcell string parameter 'numStages' (also defined in the CDF for the cell), and something in the pcDefinePCell let block like

n = atoi( numStages )
for( inst 1 n ....

I'd like to be able to sweep this parameter for optimisation in ADE by assigning it a design variable. First problem I ran into is, of course, when pcell evaluation happens, numStages is a text string representing a design variable, so atoi( numStages ) is nil. To get around that, I have

if( n == nil then n=round( VAR( numStages ) ) ) 

Not the most foolproof, but at least it seems to work in ADE L. When I try to move it to ADE XL for global optimisation, it fails: all instances of the pcell at every design point are instantiated as if numStages were set equal to the value it takes on in the first design point.

Is this due to the pcell evaluation only happening once, then ADE XL just changing the parameter declaration line in subsequent netlists? Either way, does anyone have any insight into how I can make this work? Or is this a fool's errand... 

Thanks,
Kevin 

Parents
  • kvntien

    Thanks for the response, Andrew!

    I'd already tried using the parameter sweep, and indeed, the conversion to a Spectre parameter seems to throw off the entire thing, and it does not work. I'm a little surprised that you say re-netlisting is performed for the parameter sweep... does that only occur if a CDF change is detected? Since the numStages parameter isn't actually referred to anywhere in the cell after pcell eval, it never shows up in the CDF, which means no re-netlisting, I guess?

    You also mention that a modification is done in memory; which modification exactly? The one for a parameter as opposed to a design variable? Can you perhaps provide some insight into how ADE XL effects netlist changes for design variables vs. component parameter sweeps? I'd given up on trying to vary numStages days ago, but now I'm just curious as to how this all works. The docs for ADE XL weren't too forthcoming about the details...

    Thanks,
    Kevin 

Reply
  • kvntien

    Thanks for the response, Andrew!

    I'd already tried using the parameter sweep, and indeed, the conversion to a Spectre parameter seems to throw off the entire thing, and it does not work. I'm a little surprised that you say re-netlisting is performed for the parameter sweep... does that only occur if a CDF change is detected? Since the numStages parameter isn't actually referred to anywhere in the cell after pcell eval, it never shows up in the CDF, which means no re-netlisting, I guess?

    You also mention that a modification is done in memory; which modification exactly? The one for a parameter as opposed to a design variable? Can you perhaps provide some insight into how ADE XL effects netlist changes for design variables vs. component parameter sweeps? I'd given up on trying to vary numStages days ago, but now I'm just curious as to how this all works. The docs for ADE XL weren't too forthcoming about the details...

    Thanks,
    Kevin 

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