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Stimulating an internal node from a higher hierarchy level

Johanny Saenz

Hi all.

I'm creating a test bench for an APS matrix. Due to my diode voltages won't be measured or controlled, I haven't defined them as pins in my DUT. However, I would like to generate stimuli from my test bench to a lower hierarchy level, that is inside my DUT.

How can I stimulate those nodes from a higher hierarchy level without any pin definitions in my DUT? Is that possible? 

It would be something like:

VSTIM  DUT/nst gnd dc=1

where nst is a node inside DUT instance. 

Thanks in advance. 

  • Andrew Beckett

    Is this stimulus in a schematic or from an include file? Is this for spectre? Which IC version are you using?

    Andrew

  • Johanny Saenz
    in reply to Andrew Beckett

    The stimulus is in the schematic (VerilogA view). I'm simulating it from Assembler Virtuoso. 

    Versions:

    Spectre 15.1  @ IC1.6.7

  • Andrew Beckett
    in reply to Johanny Saenz

    You can add an instance of deepprobe from analogLib (unless you're using a really old IC6.1.7 version - if so, you can get this from an article on support.cadence.com - search for "deepprobe"). This gives you a component with a single pin, and a property - which you'd set to "DUT.nst" - and you can then connect your voltage source to the pin.

    Andrew

  • Johanny Saenz
    in reply to Andrew Beckett

    Thanks, Andrew.

    Do you know how can access a node in a higher hierarchy?

    Something like ../DUT ?

  • Andrew Beckett
    in reply to Johanny Saenz

    This is not possible - Spectre has a limitation that you can only make hierarchical references to lower nodes (part of the reason would be that each child node is unique, but higher-level nodes could be common across multiple instances which could lead to strange behaviour). There is an enhancement request to allow nodes to be referenced from the top scope, but that's not been implemented yet.

    Regards,

    Andrew

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