Studies of Surface Acoustic Wave Interdigitated Transducers

Abstract

<p>The subject of this Thesis is the theoretical and experimental investigation of the capabilities and the limitations of Surface Acoustic Wave (SAW) Interdigitated Interdigital Transducer (IIDT) filters. These devices provide the means of achieving low-loss SAW filters with percentage bandwidths exceeding 10%. During the course of developing an analytical tool for IIDTs, a menu driven computer program based on a modified version of the Coupling of Modes (COM) theory was written to allow the frequency response of arbitrary SAW device structures, composed of transducers, reflector arrays and spaces, to be evaluated without further programming. Several IIDT filters were fabricated and tested with the aim of reducing the inherent ripple in the frequency response of the structures. Techniques are proposed for achieving losses of less than 6 dB with acceptable ripple suppression. In addition, some studies are performed on IIDT comb filters and their application to multimode oscillators.</p>