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Spectre stopping on symbol

Justin S

While generating a Spectre netlist, is there any way to force a cell to be netlisted as empty? I am planning to replace the cell with a separate .scs model file, but I need the connections to be made at the higher level.

I believe the normal method would be to create a 'spectre' cell view and use that as a stop point. However, I do not have write access to the library containing the cell. If I try to set the symbol view as the stop point, I get an error during Spectre netlisting:

    Netlist Error: Cannot find any info on instance "i0" in cell-view "library1" "cell1" "schematic"

I thought about trying to change the library via the config view / hierarchy editor, but that does not seem to be an option for schematic-based design data. I also tried using the "Specify SPICE source file" option in the hierarchy editor, but that is also giving the "Cannot find any info" error.

The only two options I can see remaining are: (1) copy the hierarchy so I can change to a different, writable, library, or (2) bind-to-open on this cell and postprocess/hack the generated netlist to add the connections myself

Am I missing anything here? Thanks!

Parents
  • Andrew Beckett

    The issue is that in order to stop at a cellView, you also need simulation information to be set up in the CDF for that cell. In this case it seems that you don't have the CDF defined which is why it says "cannot find any info...".

    In theory you could just change the effective CDF (which doesn't require write access) to update the CDF, but then this would need to be loaded in your .cdsinit to ensure it is set up in each session (also means that if you're using ADE XL/Explorer/Assembler where the netlisting might be done in the background, it will initialise). You have to be careful, because File->Refresh can cause this to be discarded if you choose to refresh the CDF. This does work though and it's quite simple to set up:

    1. Go to Tools->CDF->Edit in the CIW, and pick the cell and choose "Effective" as the CDF Layer
    2. On the Simulation Information tab pick spectre as the simulator, and specify the names of the terminals on the block in the termOrder field, in the same order that they will be in your external model file. The names need to match the names on the symbol, but the order should be in the order in the external subckt.
    3. Hit Apply
    4. Change the CDF Layer to User and then fill in the File Name in the top right, and hit the CDF Dump button (not the Save button). 

    This produces a SKILL file which defines the user CDF (i.e. in-memory only) for the non-writable cell. To use it, just use: load("/path/to/dumped.cdf") in your .cdsinit

    Andrew.

Reply
  • Andrew Beckett

    The issue is that in order to stop at a cellView, you also need simulation information to be set up in the CDF for that cell. In this case it seems that you don't have the CDF defined which is why it says "cannot find any info...".

    In theory you could just change the effective CDF (which doesn't require write access) to update the CDF, but then this would need to be loaded in your .cdsinit to ensure it is set up in each session (also means that if you're using ADE XL/Explorer/Assembler where the netlisting might be done in the background, it will initialise). You have to be careful, because File->Refresh can cause this to be discarded if you choose to refresh the CDF. This does work though and it's quite simple to set up:

    1. Go to Tools->CDF->Edit in the CIW, and pick the cell and choose "Effective" as the CDF Layer
    2. On the Simulation Information tab pick spectre as the simulator, and specify the names of the terminals on the block in the termOrder field, in the same order that they will be in your external model file. The names need to match the names on the symbol, but the order should be in the order in the external subckt.
    3. Hit Apply
    4. Change the CDF Layer to User and then fill in the File Name in the top right, and hit the CDF Dump button (not the Save button). 

    This produces a SKILL file which defines the user CDF (i.e. in-memory only) for the non-writable cell. To use it, just use: load("/path/to/dumped.cdf") in your .cdsinit

    Andrew.

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