First IC for piezoelectric resonator DC-DC conversion achieves a 310% loss reduction

CEA-Leti scientists and the University of California San Diego have created a ground-breaking piezoelectric-based DC-DC converter that unifies all power switches onto a single chip to increase power density. This new power topology stretches beyond existing topologies and blends the advantages of piezoelectric converters with capacitive-based DC-DC converters.

The power converters the team developed are considerably smaller than the huge, bulky inductors currently employed for this role. The devices could eventually be utilised for any DC-DC conversation, from smartphones to computers to server farms and AR/VR headsets.

The results were presented in the paper, 'An Integrated Dual-side Series/Parallel Piezoelectric Resonator-based 20-to-2.2V DC-DC Converter Achieving a 310% Loss Reduction', on February 20 at ISSCC 2024 in San Francisco.

"The Dual-side Series/Parallel Piezoelectric Resonator (DSPPR) is the first IC used for PR-based power conversion and achieves up to 310% loss reduction over prior-art published and co-designed discrete designs for VCRs<0.125," the paper reports.

"This innovative approach enhances performance, especially at low voltage conversion ratios – an area where prior works struggled to sustain both high efficiency and optimal utilisation of piezoelectric materials," said Patrick Mercier, a professor in the Department of Electrical and Computer Engineering at UC San Diego and a senior author of the paper.

The paper explains that a hybrid DSPPR converter exploits integrated circuits' ability to provide sophisticated power stages in a small area compared to discrete designs and allows efficient device operation at a VCR of less than 0.1.

"The IC provides a distinct opportunity to consolidate all power switches onto a single chip, significantly diminishing the PCB footprint and enhancing phase-control precision," said Gael Pillonnet, scientific director of CEA-Leti's Silicon Component Division.

In addition, the piezoelectric DC-DC converter contributes to performance improvement, including additional capacitive-based converter stages, both pre- and post-.

"This strategic integration reduces the demand on piezoelectric material, resulting in a more compact converter with a notably smaller total volume. The marginal increase in additional capacitors, which is less than 10%, pales in comparison to the substantial gains facilitated by the proposed topology," Pillonnet said.

"The DC-DC converter, particularly in the low VCR range, which was a focus of our work, has widespread applications in various sectors, such as high-power computing servers, automotive systems, USB chargers, and battery-powered devices," said Wen-Chin Brian Liu, a PhD student in Mercier's research group and the lead author of the paper.