Study of angular gain in lobe-like modes for annular ring bulk acoustic wave (BAW) gyroscopes

Wineglass modes are the modes of choice in bulk acoustic wave (BAW) micro-ring gyroscopes owing to their high angular gain and high quality factor in vacuum. The quality factors of most mechanical modes, including the wineglass modes, are significantly lower in liquid medium ambience. While acoustic damping in fluids adversely impacts quality factor in modes with longitudinal motion, certain in-plane flexural modes in such resonators retain higher quality factors in liquid media. In this paper, we study the angular gain of a family of such in-plane flexural modes, termed as lobe-like modes. We present a simulation framework to validate the high quality factors of these modes in liquid medium ambience. We study the angular gain for these modes, and present a design insight to optimize the geometry of the micro-rings to maximize the angular gain.