Modelling the aging of surface-acoustic-wave devices

The authors present a study of the phase-aging kinetics of a 591.2-MHz quartz-crystal surface-acoustic-wave (SAW) filter intended for application in an undersea telecommunication system. At aging temperatures from 50 to 140°C, a previously established SAW-device aging model describes the time dependence of the phase aging very well. The results of an investigation of the temperature dependence of the coefficients in this aging model make it possible to extend the model, capturing both the time and the temperature dependence of the degradation. The authors then identify and assess the sources of variation (or error) affecting the data, model and estimate the distributions of the errors, and incorporate these error distributions in the extended aging model. This leads to a composite aging model that describes the time and temperature dependence of the complete phase-aging distribution. The authors use this composite model to predict end-of-life phase-aging distributions, demonstrating that the devices exhibit the high level of stability required by the application