New ultralow-power circuit improves efficiency of energy harvesting to more than 80%. Image source: MITResearchers from the Massachusetts Institute of Technology (MIT) have developed a power converter chip that they say is capable of harvesting more than 80% of the energy coming into it, even at low power levels characteristic of small solar cells.

Before this chip, ultralow-power converters could only achieve efficiencies of 40-50%.

The researchers’ chip is able to achieve higher efficiencies, while also taking on additional responsibilities, such as using a solar cell to charge a battery or directly power a device. Those functions all share one inductor—the chip’s main electrical component—which saves on circuit board space, but also further increases the circuit complexity, all while maintaining a low power consumption.

"We still want to have battery-charging capability, and we still want to provide a regulated output voltage," says Dina Reda El-Damak, an MIT graduate student in electrical engineering and computer science. "We need to regulate the input to extract the maximum power, and we really want to do all these tasks with inductor sharing and see which operational mode is the best. And we want to do it without compromising the performance, at very limited input power levels—10 nanowatts to 1 microwatt—for the Internet of Things."

The prototype chip was manufactured through the Taiwan Semiconductor Manufacturing Co.'s University Shuttle Program.