AN AGING MODEL FOR SURFACE-ACOUSTIC-WAVE DEVICES

We 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-degrees-C, a previously established SAW-device aging model describes the time dependence of the phase aging. The results of an investigation of the temperature dependence of the coefficients in this aging model allow us to extend the model, capturing both the time and the temperature dependence of the degradation. We 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. We 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.