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Sigrity - Tip of the week: How to use multiple IBIS models for LPDDR5X controller (DQ + WCK)

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Parallel Bus Analysis (PBA) and Topology Workbench allow only one controller block, which can load only one IBIS file at a time.

The simplest approach is to open both IBIS files in a text editor, copy the WCK model block from its IBIS file into the controller’s IBIS file, and then assign the WCK pins to this imported model.

The workaround is to merge both IBIS models into one combined IBIS file. This allows SystemSI/TopXp to read both DQ and WCK models from a single IBIS file while mapping each model to its corresponding pins. Thus, this approach merges the content of both files while keeping them logically separate under different [Model] names. 

You can use the following template format:

-----------------------------------------------------------

[IBIS Ver] 5.0
[Comment] Combined IBIS for DQ + WCK

[Component] DDR_Controller
  [Pin]
  1   DQ0     DQ_Model
  2   DQ1     DQ_Model
  3   WCK0    WCK_Model
  ...
[End Component]

[Model] DQ_Model
  ... (contents from the first IBIS file)

[Model] WCK_Model
  ... (contents from the second IBIS file)

--------------------------------------------------------------------

Steps:

  1. Open the DQ IBIS file in a text editor.

  2. Copy the entire WCK model block from the second IBIS file.

  3. Paste it below the DQ model block.

  4. Add a single combined [Component] section with all the pins assigned correctly.

  5. Ensure the following:

    • Only one [IBIS Ver] line exists.

    • Only one [Component] block exists.

    • Each pin references the intended model name.

Once merged, the combined IBIS file can be assigned to the controller block without tool limitations.

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