DESIGN OPTIONS FOR SAW IF FILTERS USED IN WIRELESS APPLICATIONS

The boom of the wireless industry throughout the world has created a t remendous market for the components going into the wireless systems. S urface acoustic wave (SAW) filters are one such component experiencing this increased demand. This article describes designs tailored for SA W IF filters used in wireless systems. An overdesigned SAW filter requ iring a larger substrate package than necessary will produce disastrou s effects on the product's competitiveness. The design approach descri bed in this article involves the selection of the proper eigen functio n depending on the specification and critical placement of these eigen functions to obtain the desired pass band and stop band characteristi cs. In addition, the optimal use of transfer functions of both transdu cers is determined. A table is provided that lists the various options available to optimize the design, depending on the specifications. Th e approaches published previously using eigen functions ave discussed along with their limitations, and SAW IF filters used in wireless appl ications that benefit from the presented design approach are listed.