COM-based Modeling of SAW Scattering at Reflector Outer Edges in I.H.P. SAW Resonator

I.H.P. SAW resonators achieve high quality factor since the energy leakage to substrate and transverse leakage through the busbar can be suppressed. The remain leakage factors, from the edges of IDT and reflector, called end leakage, are discussed herein. To include the impact of end leakage caused by the SAW scattering at the outer edges of reflector, a modified COM model is introduced, in which the reflector is divided into low loss and high loss parts. The latter is added to simulate the end leakage. Impact of end leakage to
$Q$
and longitudinal responses is also investigated. Furthermore, the nonlinear effect is also discussed using the proposed model because longitudinal responses generate strong third-order harmonics by the mixture with main mode. It is revealed that end leakage is unignorable for both linear and nonlinear longitudinal responses.