CEA-Leti Develops First IC for Piezoelectric Resonator DC-DC Conversion

Scientists at the University of California, San Diego and CEA-Leti have jointly developed a breakthrough piezoelectric-based DC-DC converter that unifies all power switches onto a single chip to increase power density. This new power topology not only surpasses existing topologies, but also combines the advantages of piezoelectric converters with capacitive DC-DC converters.

Compared with traditional bulky and heavy inductors, the power converters developed by the team are much smaller in size. These devices can be widely used in various DC-DC conversion scenarios, including smartphones, computers, server farms, and AR/VR headsets.

The relevant research results have been published in the paper "20-2.2V DC-DC Converter Based on Integrated Double-Sided Series/Parallel Piezoelectric Resonators Achieves 310% Loss Reduction", which was released at the ISSCC 2024 conference held in San Francisco on February 20.

“The double-sided series/shunt piezoelectric resonator (DSPPR) is the first IC for PR-based power conversion that reduces losses by up to 310% compared to existing technologies,” the paper reports.

“This innovative approach improves performance, especially at low voltage conversion ratios, an area where it has previously been difficult to maintain high efficiency and optimal utilization of piezoelectric materials,” said Patrick Mercier, a professor in the Department of Electrical and Computer Engineering at UC San Diego and one of the authors of the paper.

The paper explains that the hybrid DSPPR converter exploits the ability of integrated circuits to provide complex power stages in a small area and enables high-efficiency device operation with a voltage conversion ratio (VCR) of less than 0.1 compared to discrete designs.

“This IC provides a unique opportunity to integrate all power switches onto a single chip, significantly reducing the PCB footprint and improving phase control accuracy,” said Gael Pillonnet, Scientific Director of the Silicon Components Division at CEA-Leti.

Furthermore, incorporating additional capacitor-based converter stages before and after the piezoelectric DC-DC converter further improves performance. “This strategic integration reduces the need for piezoelectric material, allowing the converter to be more compact and significantly smaller overall,” Pillonnet said. “The marginal increase of less than 10% for the additional capacitors pales in comparison to the substantial gains brought by the proposed topology.”

"DC-DC converters, especially in the low VCR range, are the focus of our work and have a wide range of applications in various fields, such as high-power computing servers, automotive systems, USB chargers, and battery-powered devices," said Brian Liu, a doctoral student in Mercier's research group and one of the lead authors of the paper.