Modelagem de dispositivos de ondas acústicas de superfície com foco em simulação em ambientes de circuitos

Abstract

Surface acoustic wave devices are widely used as high quality factor filters for telecommunications. In recent years they have been investigated as sensors, which creates a need for application-specific electronic systems that interact with the sensor. To design such circuits, it is important to understand the peculiarities of the devices, which can be a barrier for system designers. In this work, we propose and discuss different models that can be simulated in any project environment, thus facilitating the project of systems that interact with surface acoustic wave delay lines. In the context of this work, delay lines are devices in which a signal is delayed by a constant time between piezoelectric transducers and their models can be divided in two categories: a lumped-element model, based on frequency dependent impedances implemented by applying the Foster and Mittag-Leffler theorems, and a distributed-element model, based on transmission lines. These two categories result in models compatible to the real device in terms of frequency response. In the time domain simulations, however, the important theoretical differences between the models result in an unstable behavior only in the lumped-element model, such that it is not suitable for transient simulations.