Transformation of Heat Conductivities for Accurate Thermal Modelling of SAW Resonators

Self-Heating in the surface acoustic resonators (SAW) is critical to the power handling, miniaturization, and prevention of frequency drift due to the temperature (T) increasement. This effect origins from the coupling of thermal, elastic and electric fields. FEM simulation is a promising way to understand the intrinsic characteristics of this effect. In thermal simulations, if the thickness of the bottom substrate in real and simulation are not equal, the thermal simulation sets need extra treatment to make sure the simulation is correct, which means the results should be uniform no matter how thick the substrate in simulation is. Based on the coordinate stretching principles, this work proposed a transformation of heat conductivity of substrate during thermal simulations to guarantee that the simulation results meets requirements above. The validation of transformation are tested by astringency of simulations results.