Finite element analysis of second order effects on the frequency response of a SAW device

Electrode perturbation of the surface may cause significant second order effects on the frequency response of SAW devices. These effects in a Y-Z lithium niobate filter are analyzed using a recently developed finite element model. The analyses have shown that for aluminum electrodes of fixed thickness, the second order effects on the frequency response become increasingly significant as the device is scaled smaller to have higher central frequencies. Typically, for aluminum electrodes of thickness 2000 Å, the frequency response is significantly distorted for the device of the central frequency at above 2 GHz. Quantitative analyses of the second order effects in the device of various center frequencies provide insights for designing high performance SAW devices for high frequency applications