How does a power domain differ from a voltage area?
From PDVerse PnR Interview Handbook · pdVerse Mentor Guide
Short Answer
A power domain describes logical power intent; a voltage area is the physical region where its cells may be placed. They are related but not interchangeable.
Technical Explanation
One says which electrical rules apply; the other says where those cells may physically live. The floorplan must support supplies, isolation, level shifters, retention, switch corridors, boundary cells, utilisation, alignment, and macro compatibility.
Formula Or Decision Rule
Decision rule: every domain cell must have a legal physical region and access to the supplies and interface cells it needs.
What To Check
• Warning sign: The logical domain exists but its voltage area is missing, too small, or creates unusable slivers. • Inspect: choose one affected region, macro, row, pin, path, or net and trace the physical cause. • Correct: Correct the region and associated physical-cell plan, then rerun multivoltage and floorplan checks.
Command Checks & Actions
• create_voltage_area -power_domains <domain_list> -region <region_list> -name <voltage_area>: creates a physical region for one or more power domains
• report_design -floorplan: reports the floorplan state understood by the tool
Run only the commands needed for this question. Save the report with the floorplan version and analysis context.Healthy, Suspicious & Hard-stop Results
• Healthy: A power domain describes logical power intent; a voltage area is the physical region where its cells may be placed. They are related but not interchangeable. • Suspicious: The logical domain exists but its voltage area is missing, too small, or creates unusable slivers. • Hard stop: required legality or physical feasibility is missing or unexplained. Correct the region and associated physical-cell plan, then rerun multivoltage and floorplan checks.
Common Mistake
Do not hide the symptom with an arbitrary utilisation, halo, channel, blockage, pin move, or die-size change. The logical domain exists but its voltage area is missing, too small, or creates unusable slivers.
What The Interviewer Is Testing
The interviewer is testing whether you can connect “How does a power domain differ from a voltage area?” to measurable physical evidence and an owned correction.
Practical Example
Symptom: The logical domain exists but its voltage area is missing, too small, or creates unusable slivers. Corrective path: Correct the region and associated physical-cell plan, then rerun multivoltage and floorplan checks.
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