Power Durability Dependence on Temperature, Input Power, and Structure of Electrodes in SAW Filters

摘要

The dependence of power durability on temperature and input power has been studied in detail by using SAW filters with AlMgCu/Ti/AlMgCu/Ti four-layered electrodes. In SAW filters, acceleration factors of degradation are temperature and input power. These two factors are not independent in actual SAW filters, but it is necessary to control the conditions to keep the independence of these two factors in accelerated deterioration tests. As the results of power durability estimation of four-layered electrodes taking account of the above point, the activation energy of diffusion showed the value of the bulk diffusion level in tests using 800-MHz-band filters, and the dependence of the input power increased in proportion to the frequency of the input power. We also successfully improved the power durability of four-layered electrodes by modifying the layered structure and increasing the Mg content of the AlMgCu alloy layers. In the former case, the dependence on input power did not change but the absolute level versus the input power was improved. In the latter case the dependence on input power and the absolute level versus the input power did not change but the dependence on temperature increased.