FEM modeling of an entire 5-IDT CRF/DMS filter

A CRF/DMS filter is simulated using “Layers” software [1-2]. We analyze a few different CRF/DMS structures, including the 10-port CRF device with passband frequency close to 1842.5 MHz including 5 IDTs, 8 “gap IDTs” and 2 reflectors. This TC SAW structure has a thick SiO
₂
over layer covering 274 Cu electrodes on a 128° LiNbO
₃
substrate. In addition to the electrical network parameters for the filter, a visualization of acoustic field and power flow is presented. The simulation reveals the resonances in the structure, radiation of energy at the interfaces between IDTs, and helps to see the origin of notches in passband including parasitic acoustic modes. We simulate 801 frequency points and present acoustic fields, power flows, and generated bulk waves inside the entire device for select frequencies of interest. On a PC with 32 processors and 128 GB RAM, a complicated device having 15 “building blocks” (274 electrodes) was simulated, with about 6 second simulation time per frequency point (~1.3 hours total time). Losses due to bulk wave generation are numerically estimated.