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Spectre: use models on a per module basis?

dontpanic

Hello! Is it possible to tell Spectre to use different models for the same devices in different modules? Our design kit has standard and "PRE_SIMU" models (=include contact-to-poly caps and parasitic contact and gate resistances) for the MOS devices, and we would like to use these PRE_SIMU models only for the devices in specific modules, at different moments in the design cycle:

-In the early design phases, use PRE_SIMU models only for the critical blocks in the system, and standard for the rest (speeds up simulation time)
-In the later design phases, use PEX views for the already laid-out critical blocks, and PRE_SIMU models for everything else not yet laid-out.

Currently all I can do is define these models globally for all the devices using the Model Library Setup window (need just to include a section from the model libraries). However, as soon as I use PEX views, I need to switch back to the standard models, as using PRE_SIMU globally would yield incorrect results due to double-counting of parasitics in the modules with PEX views. Thus the accuracy of our simulations gets compromised as we proceed into the implementation cycle and start to add PEX views.

...any ideas on how to overcome this problem?


Thanks in advance for any help.

Jorge.

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  • Andrew Beckett

    Hi Jorge,

    ADE XL (and ADE Explorer/Assembler in IC617) has a capability called "MTS" (Multi Technology Simulation) which enables this. You have to do the following:

    1. You must have a config for the design and have it as the config that you're simulating in a test
    2. Over the test name in ADE XL/Explorer/Assembler use Right Mouse->Simulator, or in the test editor use Setup->Simulator and enable the Multi-Technology Mode checkbox
    3. Then using Right Mouse->MTS Options over the test (it's near the bottom of the menu) you can enable different model files for different cells, or for different instances. You can also control a few other parameters (such as the temperature, scale factors and so on).

    This then produces a scoped netlist for spectre where the models are included at the appropriate points in the design hierarchy; you can have the same model names used in different parts of the design hierarchy.

    Theoretically this was an ADE GXL feature, but since IC616 (at least) it's been available in ADE XL without needing a GXL license.

    Regards,

    Andrew.

Reply
  • Andrew Beckett

    Hi Jorge,

    ADE XL (and ADE Explorer/Assembler in IC617) has a capability called "MTS" (Multi Technology Simulation) which enables this. You have to do the following:

    1. You must have a config for the design and have it as the config that you're simulating in a test
    2. Over the test name in ADE XL/Explorer/Assembler use Right Mouse->Simulator, or in the test editor use Setup->Simulator and enable the Multi-Technology Mode checkbox
    3. Then using Right Mouse->MTS Options over the test (it's near the bottom of the menu) you can enable different model files for different cells, or for different instances. You can also control a few other parameters (such as the temperature, scale factors and so on).

    This then produces a scoped netlist for spectre where the models are included at the appropriate points in the design hierarchy; you can have the same model names used in different parts of the design hierarchy.

    Theoretically this was an ADE GXL feature, but since IC616 (at least) it's been available in ADE XL without needing a GXL license.

    Regards,

    Andrew.

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