SAW transversely guided mode spurious elimination by optimization of conversion efficiency using W/W0 electrode structure

High-order surface acoustic wave (SAW) transversely guided modes sometimes appear as unwilling spurious responses on the frequency characteristics of SAW devices. This paper describes a new method to eliminate the high-order transversely guided mode spurious responses by setting the electrode overlap region to be smaller than the aperture width of IDT, which is called W/W0 electrode structure. It is experimentally demonstrated that S2 high-order transversely mode can be eliminated about 30 dB compare to conventional type IDT, and experimental results of a filter, which have different W/W0 value in their input and output electrodes aiming at simultaneous elimination of some number of the high-order transversely guided modes, are shown