Common PD Issues

Frequent Problem Areas

Timing failures due to long interconnects or poor placement.

Routing congestion around macros or narrow channels.

Power integrity issues like IR drop and electromigration.

DRC violations from spacing, density, or via constraints.

Typical Fixes

Improve floorplan and add whitespace near dense regions.

Buffer long nets and re-balance critical paths.

Strengthen the PDN and add decap cells where needed.

Run incremental DRC and fix violations early.

Prevention

Set realistic constraints and validate them early.

Use congestion and IR analysis during floorplan and placement.

Keep signoff checks in the loop throughout implementation.

Related Topics

• Congestion Analysis
• IR Analysis
• PD Verification

Common Physical Design Issues in the Physical Design Flow

Common Physical Design Issues is not an isolated step in backend implementation. Many PD failures are cross-domain problems where timing, congestion, power integrity, and verification interact, so a structured debug approach is more effective than isolated fixes. In a practical ASIC flow, engineers revisit this topic at least twice: once to prevent problems early, and again after optimization when the design context changes because of timing fixes, buffering, or routing decisions.

When using this page for learning or interview preparation, separate the topic into inputs, tool actions, and outputs. Inputs define what data must be clean before you start. Tool actions describe what the engine is optimizing. Outputs show whether the run is actually improving design quality. The most useful reviews combine those three views instead of memorizing a short definition.

Practical Checklist

Use this quick checklist while studying or debugging common physical design issues. It helps turn theory into repeatable engineering practice and also improves project documentation quality.

• Start with the failing report and identify whether the cause is timing, routing, power, or rule based
• Check upstream steps such as floorplanning or constraints before applying local fixes
• Validate fixes across all relevant corners and modes to avoid regressions
• Record common symptoms and proven solutions for future projects
• Use signoff correlation to confirm the issue is actually closed

Track the result of each change with measurable data instead of intuition alone. Track issue category, root cause, attempted fixes, and the final report improvement so repeated problems become easier to diagnose. Keeping a small log of assumptions, changes, and outcomes will make this topic easier to revise later and easier to explain in interviews or design reviews.