Power, IR Drop, EM, Thermal and Reliability
Analyze power consumption and ensure supply, interconnect, temperature and aging remain within lifetime limits.
Overview
Power analysis combines cell internal power, net switching power, leakage and clock activity. Accuracy depends on realistic activity, modes, voltage, temperature, extracted capacitance and library characterization.
Power integrity evaluates static and dynamic voltage drop. Electromigration checks current-density-driven wear. Thermal gradients and aging mechanisms alter delay, leakage and lifetime, requiring coupled analysis and guardbands.
Learning objectives
Build vector-based and vectorless power analyses
Interpret static and dynamic IR drop
Reason about EM, thermal and aging limits
Plan fixes without causing new timing or routing failures
Core concepts
Dynamic power
Switching-related power proportional to activity, capacitance, voltage squared and frequency.
IR drop
Supply-voltage loss caused by current flowing through resistance.
Electromigration
Current-driven atomic transport that can form opens or shorts over time.
Thermal resistance
Temperature rise per unit dissipated power for a thermal path.
BTI
Bias temperature instability that shifts transistor characteristics with stress.
Power integrity
Ability of the supply network to maintain voltage and current quality across operation.
Engineering workflow
Create activity model
Select modes, traces, probabilities and clock behavior.
• Simulation activity
• Workloads
• SAIF/VCD or vectorless model
Analyze power
Calculate cell, net, leakage and clock components by hierarchy.
• Netlist/layout
• Libraries
• Power report
• Power map
Solve integrity and thermal
Apply current to extracted supply and thermal networks.
• PDN
• Package model
• IR/EM/temperature maps
Repair and qualify
Add metal/vias, resize, spread, gate or alter package cooling.
• Violations
• Closed limits
• Lifetime evidence
Metrics and interpretation
Peak dynamic IR
Worst transient supply droop under a stated activity window.
Current density
Current per conductor cross-sectional area compared with qualified limits.
Junction temperature
Estimated silicon temperature at workload and ambient conditions.
Lifetime margin
Difference between modeled wear-out life and product requirement.
Signoff checklist and pitfalls
Evidence checklist
- Activity represents required workloads and modes
- Package and board impedances are modeled where needed
- IR/EM limits pass across corners
- Thermal map feeds timing and leakage analysis
- Aging/lifetime assumptions match product mission profile
Common pitfalls
•
Using uniform toggle rates•
Checking static IR only•
Fixing EM with routing that worsens congestion•
Ignoring package and thermal coupling