Full wave simulation of SAW filter package and SAW pattern inside package

With miniaturization of RF-SAW filter package, we should not only take the electromagnetic effects of package into consideration but also the electromagnetic effects of pattern on the SAW substrate. In this paper, the high frequency structure simulator (HFSS) is employed to investigate the crosstalk effects on SAW substrate and mutual coupling effects between pattern on the SAW substrate and package. Special attention has been paid to model SAW filter pattern. It is found that an RF SAW filter device is sensitive to crosstalk between package and pads on the substrate. So the crosstalk effects must be taken into account in the design process. Our approach has been applied to two cases. One is SMD package 3mm·3mm with ladder type SAW filter at 881 MHz and the other is flip chip package 2.5 mm·2.0 mm with ladder type SAW filter at 1842.5 MHz. Measurement is also carried out to verify our results. Good agreements are obtained.