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Set Symbol parameters and pass parameters to its schematic device

FormerMember
FormerMember
Hi all,

We create a symbol from schematic.

The symbol which we created has adjustable options for l and w (length and width).

Now we use this symbol in other schematic and we want to set the l and w.

We want to pass area value (l*w) to this symbol’s schematic device(for example, a diode).

The spectre can accept parameters description.

We want to substitute all parameters with real numbers because we want to do the LVS netlist output.

Could you help us to solve this problem?

Thanks for your help!

Best regards, E-Jen
Parents

  • But Calibre is perfectly capable of evaluating the expression - so why would you do this?

    A callback cannot solve this problem. If you have a block (say "myblock") which accepts CDF parameters w and l, and within myblock you have an instance of a diode which needs an area, as I said, the diode should allow the area to be set as pPar("w")*pPar("l").

    Imagine instead that you wanted to do this with a callback. You have two instances of myblock, one with w=1u,l=1u and one with w=2u,l=3u. If you (somehow) set the area on the diode instance inside myblock to be w*l for one instance, it will be wrong for the other. Potentially you could have a pseudo-flattening netlister which creates a separate subckt for each variant, but that's a lot of work (I wrote one of these many years ago (about 20) when Dracula's expression evaluation didn't really work yet), and complete overkill when the Verification tool can evaluate the expression. Essentially you need the expression to be evalated as the design is elaborated in the tool that reads the netlist - be it the simulator or the LVS tool.

    Regards,

    Andrew.

Reply

  • But Calibre is perfectly capable of evaluating the expression - so why would you do this?

    A callback cannot solve this problem. If you have a block (say "myblock") which accepts CDF parameters w and l, and within myblock you have an instance of a diode which needs an area, as I said, the diode should allow the area to be set as pPar("w")*pPar("l").

    Imagine instead that you wanted to do this with a callback. You have two instances of myblock, one with w=1u,l=1u and one with w=2u,l=3u. If you (somehow) set the area on the diode instance inside myblock to be w*l for one instance, it will be wrong for the other. Potentially you could have a pseudo-flattening netlister which creates a separate subckt for each variant, but that's a lot of work (I wrote one of these many years ago (about 20) when Dracula's expression evaluation didn't really work yet), and complete overkill when the Verification tool can evaluate the expression. Essentially you need the expression to be evalated as the design is elaborated in the tool that reads the netlist - be it the simulator or the LVS tool.

    Regards,

    Andrew.

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