A Stacked Radial Mode Lithium Niobate Transformer for DC-DC Conversion

Abstract

Piezoelectric devices offer an alternative energy storage mechanism for power converters to eliminate inductors and improve power density. Recent piezoelectric resonator-based DC-DC converters demonstrate high power density and efficiency, yet resonator-based designs restrict efficient operation to near-unity conversion ratios. Piezoelectric transformers could provide isolation and efficient operation at larger conversion ratios, but existing piezoelectric transformer-based converters are limited by the low performance of available piezoelectric devices. This work explores the potential of radial mode lithium niobate for power conversion, which offers high quality factor and impedance that scales independent of frequency. Analysis details the fabrication and characterization of a stacked radial mode lithium niobate piezoelectric transformer, and a prototype DC-DC converter tests the fabricated piezoelectric transformer to evaluate its performance.

Radial mode lithium niobate resonator with 10 mm diameter, 0.1 mm thickness, 23.4% coupling, and 40,000 peak quality factor.

Piezoelectric transformer based converter with two layer, radial mode lithium niobate piezoelectric transformer.