Lithium Niobate Resonators for Power Conversion: Spurious Mode Suppression Via an Active Ring

TL;DR

This paper introduces a novel active ring design in lithium niobate resonators that suppresses spurious modes, enhances power conversion efficiency, and reduces breakdown risks, advancing acoustic resonator applications.

Contribution

A new thickened active ring design in lithium niobate resonators effectively suppresses spurious modes while maintaining high Q and k2, and mitigates voltage breakdown issues.

Findings

Achieves large spurious mode suppression region.

Maintains high quality factor (Q) and electromechanical coupling (k2).

Reduces resistance at resonance and mitigates breakdown effects.

Abstract

In an effort to shift the paradigm of power conversion, acoustic resonators pose as compact alternatives for lossy magnetic inductors. Currently, the acoustic resonator's restricted inductive region between its series and parallel resonances constitutes a major bottleneck, which is further diminished due to spurious modes. Prior work has partially addressed this issue by the introduction of various design guidelines tailored to the material and the mode of interest, but can only provide a limited spurious-free region. Alternatively, a separated grounded ring on LN operating in the first order symmetric lamb mode (S1), maintains optimal device performance with a large fractional spurious mode suppressed region, but has been shown to experience voltage breakdown at high power near the ring at different potentials. Hence, we propose a new spurious mode suppressing design leveraging a thickened active ring in lithium niobate (LN), maintaining high Q and k2 while also reducing resistance at resonance (Rr), and mitigating breakdown effects.