Which files are inputs, outputs, or conditional restart data?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
A file's role depends on the stage. A routed DEF or extracted parasitic file can be an output of one run and an input to a later analysis or restart; the extension alone does not define the flow.
Technical Explanation
For a fresh implementation, a mapped netlist and approved library, technology, timing, and applicable power data form the core handoff. The floorplan can be generated locally or imported. Scan information is relevant when scan optimization is required. Activity data is relevant to the selected power tasks. This is a more useful classification than a rigid list of 'mandatory files' copied from an unrelated project. As implementation progresses, the flow saves databases, exports updated netlists and physical data, and produces extracted parasitics and reports. Full layout formats such as GDSII or OASIS belong to layout assembly and downstream manufacturing/verification handoffs. A macro's full layout can be an upstream reference for assembly even when the block's final layout is a downstream output. For a restart, ask what the saved database already contains and which external references it still requires. Imported results must correspond to the same stage and revision. A placed checkpoint paired with a netlist from a later ECO can be inconsistent even though both were valid outputs when originally created.
Common Mistake
Saying GDS is always a required initial input for standard-cell placement, or treating a saved database as automatically self-contained.
Follow-up Question & Model Response
What should a handoff manifest say beyond the path? Record the role, stage, revision, producer, compatibility requirements, and intended consuming step.
Practical Example
A floorplanning team exports floorplan.def; place and route consumes it. Later, a route-stage export called routed.def becomes a deliverable to another tool. Both are DEF files, but their contents and expected use differ.
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