Spurious-Free Lithium Niobate Bulk Acoustic Resonator for Piezoelectric Power Conversion

TL;DR

This paper introduces a lithium niobate bulk acoustic resonator with a novel grounded ring structure that achieves high quality factor and suppresses spurious modes, enhancing piezoelectric power conversion efficiency.

Contribution

The paper presents a new resonator design that significantly reduces spurious modes and improves performance metrics like Q and kt2 compared to existing designs.

Findings

Achieved Q of 4000 and kt2 of 30% in the resonator.

Demonstrated 62% fractional suppression of spurious modes.

Validated the design experimentally with promising results.

Abstract

Recently, piezoelectric power conversion has shown great benefits from replacing the bulky and lossy magnetic inductor in a traditional power converter with a piezoelectric resonator due to its compact size and low loss. However, the converter performance is ultimately limited by existing resonator designs, specifically by moderate quality factor (Q), moderate electromechanical coupling (kt2), and spurious modes near resonance. This work reports a spurious-free lithium niobate (LiNbO3) thickness-extensional mode bulk acoustic resonator design, demonstrating Q of 4000 and kt2 of 30% with a fractional suppressed region of 62%. We first propose a novel grounded ring structure for spurious-free resonator design, then validate its performance experimentally. Upon further work, this design could be extended to applications requiring spurious suppression, such as filters, tunable oscillators, transformers, etc.