Experimental Studies on Acoustic Energy Loss in Surface Acoustic Wave Filters Using Grating Waveguides

Abstract

The acoustic energy loss in surface acoustic wave filters using grating waveguides is investigated experimentally. The propagation loss in the waveguide formed on a ST-cut quartz with aluminum grids, which have the period detuned from that of the Bragg condition, is evaluated to be small as 2 × 10 −3 dB/wavelength. However, it is revealed that the extra energy loss arises with a short waveguide length and before surface acoustic waves (SAWs) launched by the interdigital transducer (IDT) enter the waveguide. Based on the experimental studies on these extra energy losses, the insertion loss in the reflector filter using a SAW grating waveguide is reduced by 2 dB by increasing the aluminum film thickness.

Development and Application of SAW Filter

“…In the second year, in 2001, Jun Tsutsumi studied the acoustic energy loss of the grating waveguide SAW filter. Based on the experiment, it was concluded that by increasing the thickness of the aluminum film, the insertion loss of the mirror filter using the SAW grating waveguide could be reduced by 2 dB [ 73 ]. For the layered surface acoustic wave device, it is not only affected by the substrate, but also affected by the interdigitated metal electrodes.…”