Modeling the effect of anchor geometry on the quality factor of bulk mode resonators

High quality factor (Q) resonators are desired for numerous applications such as clocks and gyroscopes. For bulk acoustic wave resonators, energy dissipation through the anchors (i.e. anchor loss or anchor damping) can often limit Q. This work explores several designs of anchor geometries for a width extensional resonator with experimental results confirming that the geometry of the anchor can have a large effect on the mode shape as well as the quality factor. We present a Perfectly Matched Layer (PML) COMSOL model which is able to predict Q for several anchor loss limited anchor designs. Temperature dependencies of f and Q are also reported and favorable designs are set forth.