Power-Aware Design and Verification: Building Low-Power, High-Performance Chips

Introduction

In today’s semiconductor industry, power efficiency is as critical as performance and area.
With the explosive growth of mobile devices, IoT, automotive electronics, and data centres,
energy consumption directly impacts battery life, thermal management, and operating costs.
This makes power-aware design and verification a cornerstone of modern SoC (System-on-
Chip) development.
Modern SoC (System-on-Chip) designs are expected to deliver high performance without
compromising on energy efficiency. Whether it's smartphones aiming for longer battery life,
automotive chips requiring thermal reliability, or data centre accelerators focused on reducing
operational costs, power-aware design and verification are at the core of achieving these
goals.
Unlike traditional design methodologies that concentrated primarily on speed and silicon
area, today’s engineers must treat power as a first-class design metric.

The Three Pillars of Power in Chip Design

1. Dynamic Power – Power consumed due to switching activity.
    Pdynamic=C×V2×f
    (where C = capacitance, V = supply voltage, f = frequency)

Low-Power Design Techniques

1. Clock Gating

• Disables clock signals to inactive modules.
• Reduces dynamic power (caused by switching activity).
  

2. Power Gating
Switch off the supply to unused blocks using power switches.

• Requires isolation cells at boundaries.
• Requires state retention registers if the state must be preserved.

3. Multi-Voltage Domains (MVD)
a. Performance-critical blocks run at higher voltage.
b. Peripheral/low-speed logic runs at reduced voltage.
c. Level shifters are inserted to handle domain crossings.

4. Dynamic Voltage and Frequency Scaling (DVFS)

• Adjusts voltage and clock frequency based on workload.
• Common in CPUs/GPUs for balancing performance vs. power..

5. State Retention and Isolation

• Special cells preserve logic state when blocks are powered down.
• Isolation cells prevent invalid signal propagation between ON and OFF domains.
• Retention flops hold values when a domain is powered down. Example in UPF

Power Intent with UPF 

Functional RTL alone does not describe power behaviour. That’s why power intent files are used:
UPF (Unified Power Format – IEEE 1801)
Example (UPF): This describes power domains, switches, and isolation in a tool-independent way.

Power-Aware Verification

Designing low-power systems is only half the battle—verification ensures correctness under complex power scenarios. Traditional RTL simulation cannot capture power intent; therefore, power-aware verification relies on standards such as UPF (Unified Power Format) or CPF (Common Power Format).

Key Aspects of Power-Aware Verification

1. Static Checks

•  Ensure correct placement of isolation cells, level shifters, and retention registers.
•  Verify power-domain connectivity against UPF/CPF constraints.

2. Dynamic Simulation

•  Simulate power sequences (ON/OFF, DVFS transitions) alongside functional RTL.
•  Validate that state retention and isolation logic behave as expected.

3. Formal Verification

•  Prove that power control logic meets specifications.
•  Exhaustively checks power intent without requiring test vectors.

4. Gate-Level Power Analysis

•  Post-synthesis and post-layout simulations estimate real switching activity.
• Helps fine-tune clock gating, DVFS, and leakage reduction strategies.

Challenges in Power-Aware Design and Verification

• Complexity: Multiple power domains and operating modes increase verification effort.
• Performance vs. Power Trade-off: Aggressive power reduction may impact timing closure.
• Tool Integration: Maintaining consistency between RTL, UPF/CPF, synthesis, and verification tools.
• Late-Stage Issues: Missing isolation or incorrect retention logic often leads to costly re-spins.

Conclusion

Power-aware design and verification are not optional anymore; they are essential for building competitive SoCs. By combining RTL techniques (gating, DVFS, multi-voltage domains) with formal UPF-based verification, engineers can achieve significant power savings without compromising performance.
As chips move into AI accelerators, 5G modems, and autonomous vehicles, mastering power-aware methodologies will be one of the key skills for the next generation of chip designers.