Flexural-Mode Lithium Niobate on Silicon MEMS Transformer

This work presents a novel third order flexural-mode lithium niobate on silicon MEMS piezoelectric transformer (PT), designed for passive voltage gain and impedance transformation without the need for magnetic components. The PT was designed using COMSOL Multiphysics simulations and fabricated using a 2 μm lithium niobate film bonded to a platinum-coated silicon on insulator (SOI) wafer. The device operates in an out-of-plane flexural mode enabled by a silicon elastic layer, achieves an equivalent transformation ratio of 1:2.1, an open circuit voltage gain of 4.85, and a peak efficiency of 58%. Vector network analyzer (VNA) measurements yielded a quality factor (Q) and effective electromechanical coupling factor ($k_{eff}^2$) of ~335 and ~2.2%, respectively.