A 33nW Fully Autonomous SoC With Distributed Cooperative Energy Harvesting and Multi-Chip Power Management for...

Area of Science:

• Integrated Circuits
• Energy Harvesting
• Low-Power Electronics

Background:

• Traditional sensing systems require significant power, limiting their deployment in remote or resource-constrained environments.
• Existing solutions often lack autonomy and efficient energy management for continuous operation.
• Developing ultra-low-power (ULP) integrated systems is crucial for enabling pervasive sensing.

Purpose of the Study:

• To present a fully autonomous system-on-chip (SoC) for ULP sensing applications in fiber environments.
• To demonstrate simultaneous energy harvesting, cooperative performance scaling, power sharing, and booting among in-fiber SoCs.
• To achieve nanowatt power levels for sensing and computation.

Main Methods:

• Development of a custom switched capacitor energy harvesting and power management unit (EHPMU).
• Integration of a ULP RISC-V digital core and temperature sensor.
• Implementation of ripple boot-up and cooperative dynamic voltage and frequency scaling (DVFS).
• Fabrication using 65 nm technology and integration into a mm-scale polymer fiber.

Main Results:

• Achieved 33 nW total chip power consumption under 92 Lux lighting.
• Reduced EHPMU control power to 2.7 nW.
• Decreased required illuminance for operation by over 7x (down to 12 Lux) using power sharing and cooperative DVFS.
• Demonstrated feasibility of autonomous ULP on-body sensing in fiber.

Conclusions:

• The proposed SoC enables fully autonomous and ULP sensing in challenging fiber environments.
• The integrated energy harvesting, power management, and cooperative scaling techniques significantly reduce power requirements.
• This work paves the way for self-sustaining, distributed sensing systems in resource-limited applications.