Electrical Performances Of A Surface Acoustic Wave Device With Inter-Digital Transducers Electrodes In Local Resonances

In this paper, we investigate numerically the coupling of the Rayleigh mode with the micro-wall resonance modes in inter-digital transducers (IDTs) electrodes of surface acoustic wave (SAW) devices. We perform a finite element analysis (FEA) of the SAW features using an implemented model using comsol Multiphysics(R) software. The SAW structure comprises identical transmitter and receiver IDTs electrodes, with different electrode heights (h(e)). The proposed FEA study is based on the extraction of reflection (S-11) and transmission (S-21) coefficients of the SAW device. The IDTs are considered to be a micro-wall phononic crystal acting as local resonators at frequencies inside the SAW passband. The locally resonance gap is strongly dependent on the h(e) value, and S-11 and S-21 parameters are affected by the SAW energy absorption in the IDTs system. We have chosen two h(e) values (0.5 and 3 mu m) to study low and high aspect ratios of micro-walls, corresponding respectively to Bragg-type and resonance-type bandgaps appearing near the SAW central frequency. At the SAW resonance frequency, the return (S-11) and the insertion (S-21) losses are reduced. S-21 is reduced by 12.73 and 18.49 dB for h(e) = 0.5 and 3 mu m, respectively, accompanied by an increase in the quality factor, and S-11 parameter is reduced by 1.357 and 4.98 dB for h(e) = 0.5 and 3 mu m, respectively.