Signal flow graph analysis of diffraction and reflection in SAW filters

Abstract

A building-block approach for the simultaneous analysis of diffraction, refraction and multiple reflections within multi-transducer surface acoustic wave (SAW) filters is presented. Each reflector or transducer is treated as a 'black box' unit element which is described by the angular spectra of the emitted SAWs and a scattering matrix representing refraction and reflection of the partial waves of the angular-spectrum-of-waves (ASoW) formalism. The unit element parameters are calculated by existing SAW simulators. The interdependence between the forward- and backward-propagating wave profiles within the device is described by a signal flow graph. An analysis of a two-port resonator is presented and compared with measurements. The diffraction loss within the device is accurately predicted.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>