Power Analysis
Measure and control power early and often.
Types of Power
Dynamic power comes from switching activity and load capacitance.
Leakage power comes from transistor and gate leakage in idle states.
Short-circuit power appears briefly during transitions.
Analysis Flow
Collect activity data (VCD or SAIF) from simulation.
Run power estimation using library models and realistic parasitics.
Compare against budgets and thermal limits.
Optimization Levers
Clock gating reduces dynamic switching.
Multi-Vt and power gating reduce leakage.
Lowering toggle rates and capacitive loads saves power.
Related Topics
Power Analysis in the Physical Design Flow
Power Analysis is not an isolated step in backend implementation. Power analysis connects design activity to implementation quality by quantifying dynamic and leakage power across blocks, modes, and workloads. 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 power analysis. It helps turn theory into repeatable engineering practice and also improves project documentation quality.
- Check whether analysis is vectorless or activity-driven and document assumptions
- Review clock network contribution because it often dominates dynamic power
- Correlate high-power regions with placement density and IR drop hotspots
- Use multi-mode comparisons to identify realistic worst-case scenarios
- Re-evaluate power after timing ECOs, buffering, and clock-tree changes
Track the result of each change with measurable data instead of intuition alone. Compare block-level and top-level numbers, switching assumptions, and the split between internal, switching, and leakage components. 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.