Power Management Unit for Solar Energy Harvester Assisted Batteryless Wireless Sensor Node.

Area of Science:

• Integrated Circuits
• Energy Harvesting
• Wireless Sensor Networks

Background:

• Low-power wireless sensor nodes, like RFID tags, require efficient power management solutions.
• Photovoltaic energy harvesting offers a sustainable power source for autonomous devices.
• Existing systems often struggle with startup efficiency and energy management for intermittent operation.

Purpose of the Study:

• To develop an energy-efficient monolithic Power Management Unit (PMU) for low-power wireless sensor nodes.
• To enable self-sufficient startup and efficient energy management using photovoltaic cells.
• To enhance the operational range and autonomy of devices such as RFID sensor tags.

Main Methods:

• Design of a monolithic PMU integrating a charge pump optimized for photovoltaic cells.
• Implementation of a half-floating architecture to minimize charging losses in stray capacitors.
• Inclusion of an energy monitor for managing stored energy and enabling discontinuous operation modes.
• Fabrication using a standard 180 nm CMOS technology occupying 0.97 mm².

Main Results:

• Self-sufficient startup achieved with light source luminosity ≥ 500 lux using a 1.42 cm² solar cell.
• Measured efficiency exceeding 60%, delivering 13.14 μW at 1.8 V.
• Harvested energy sufficient for a standard UHF RFID sensor tag's communication range up to 21 m.

Conclusions:

• The developed PMU provides an efficient and autonomous power solution for energy harvesting applications.
• The design enables reliable operation of low-power wireless sensor nodes, extending their functionality and range.
• This technology facilitates the development of self-powered autonomous sensor systems for various IoT applications.