Placement
Placement assigns every standard cell to a legal site while optimizing timing, congestion, power, and density.
The placer must minimize harmful wire length without creating local density that the router cannot handle.
Moving two timing-critical cells closer can reduce net delay, but packing them into an already congested channel may cause a larger routing problem.
Physical Design flow
Follow each stage in sequence. Every stage produces information needed by the next.
Placement—visualized
This technical view uses the actual structures and relationships associated with this stage, followed by its key terms.
Understand every concept
Standard-cell placement
What it is: Standard-cell placement is a core concept within Placement. It describes the information, structure, or analysis engineers use at this stage of the Physical Design flow.
Why it matters: Understanding it helps you interpret the stage correctly, avoid incorrect assumptions, and connect the result to the next implementation or signoff step.
Where it fits: This topic belongs to module 4, Placement, and its output supports the stages that follow.
Practical example: Engineer workflow: Run initial timing- and congestion-driven placement. Moving two timing-critical cells closer can reduce net delay, but packing them into an already congested channel may cause a larger routing problem.
Legalization
What it is: Legalization is a core concept within Placement. It describes the information, structure, or analysis engineers use at this stage of the Physical Design flow.
Why it matters: Understanding it helps you interpret the stage correctly, avoid incorrect assumptions, and connect the result to the next implementation or signoff step.
Where it fits: This topic belongs to module 4, Placement, and its output supports the stages that follow.
Practical example: Engineer workflow: Inspect density, pin access, and global-route overflow. Moving two timing-critical cells closer can reduce net delay, but packing them into an already congested channel may cause a larger routing problem.
Timing and congestion optimization
What it is: Timing and congestion optimization is a core concept within Placement. It describes the information, structure, or analysis engineers use at this stage of the Physical Design flow.
Why it matters: Understanding it helps you interpret the stage correctly, avoid incorrect assumptions, and connect the result to the next implementation or signoff step.
Where it fits: This topic belongs to module 4, Placement, and its output supports the stages that follow.
Practical example: Engineer workflow: Optimize critical paths and high-fanout networks. Moving two timing-critical cells closer can reduce net delay, but packing them into an already congested channel may cause a larger routing problem.
Work through it step by step
- 1
Standard-cell placement
Run initial timing- and congestion-driven placement.
- 2
Legalization
Inspect density, pin access, and global-route overflow.
- 3
Timing and congestion optimization
Optimize critical paths and high-fanout networks.
- 4
Standard-cell placement
Legalize cells and verify placement checks.
Explore each topic
01Standard-cell placement
Understand the concept, connect it to the ASIC flow, study the report or behavior it produces, and apply it in a guided exercise. Check the result against the module goal before moving forward.
02Legalization
Understand the concept, connect it to the ASIC flow, study the report or behavior it produces, and apply it in a guided exercise. Check the result against the module goal before moving forward.
03Timing and congestion optimization
Understand the concept, connect it to the ASIC flow, study the report or behavior it produces, and apply it in a guided exercise. Check the result against the module goal before moving forward.
Completion checklist
- ✓ All cells are legal
- ✓ Density is balanced
- ✓ Critical path movement is sensible
- ✓ Global-route overflow is controlled
Practise with open-source tools
These are official third-party GitHub projects selected for this learning path.