Electromagnetic Parasitic Extraction Based on SAW Filter
Considering the electromagnetic parasitic parameters of the encapsulated tube shell and layout,the passband of an RF surface acoustic wave(SAW)filter narrows,and the standing wave increases.This paper propo-ses a method to quickly extract the electromagnetic parasitic effects in the package shell and layout and accurately simulate their influence on filter performance.First,FEM electromagnetic simulation software was used to extract the electromagnetic parasitic parameters of the encapsulated tube shell.Then,circuit simulation software was em-ployed to co-simulate the designed filter with the extracted packaging parasitic parameters and filter layout.This ap-proach eliminates the need for repeated electromagnetic simulations in FEM software,improving time efficiency.The method was verified on a SAW filter with a center frequency of 1 268 MHz,a passband insertion loss of less than 1 dB,an in-band standing wave of less than 1.6,an in-band fluctuation of 0.5 dB,and a bandwidth of 24 MHz(relative bandwidth of 1.8%).The SAW resonators used in this design were de-embedded,allowing for more accu-rate simulation of the measured filter results.
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