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Can a pcell invoke an Ocean script?

Mohellayali82

dear all

 

i have a question regarding the feasability of what i want to do with pcells

so i want to cretae a pcell called inverter, and the parameter i pass to it would be a "gm" (the transconductance of the inverter)

so once the user introduce the gm he wants, the pcell invoke then an ocean script which calculates the width of the pmos and the nmos and the number of finger to meet this gm and then return the 3 parameters wn wp nfing

 

so far i am able to create an inverter pcell starting fron the wn wp nfing, but i want to automate the step gm--> (wn, wp, nfing)

do you think its possible, can soembody give a hint about this

 

many thanks in advance 

 

  • In theory this would be possible (particularly if it's a schematic pcell) provided you only ever wanted to open it within Virtuoso (external applications such as stream out or ITKDB apps wouldn't work because you'd be using functions that are not legal in pcells, because they are not guaranteed to work).

    However, it is really not a good idea. pcells should evaluate reasonably quickly - if you're suggesting that you run a simulation (or more than one) and then compute the dimensions based on the results of simulation, it's not going to be quick. Remember that this would get re-triggered any time you change a parameter on the instance, or indeed any time you reopen the instance in a new virtuoso session.

    It would be better to use some kind of optimisation approach (e.g. ADE GXL in IC61) to size the dimensions appropriately based on simulation, and then this would harden the design. I see no benefit in having to repeatedly re-simulate the design (and in fact there would be danger that the design changes over time due to (for example) changes in the model files).

    Regards,

    Andrew.

  • Thank you Andrew, i will investigate what you told me

     

    Best regards 

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