SAW filters with high out-of-band rejection

To achieve a high out-of-band rejection in surface acoustic wave (SAW) filters, a construction that includes a cascade of some elements (interdigital transducers (IDT) and multistrip couplers (MSC)) is used. In this case each element must maintain a comparatively low frequency selectivity. A simple model and a high-speed calculation process can be employed for its design. The proposed construction has an apodized transducer with a metal coating instead of a passive electrode region as an input and a broadband withdrawal weighted unapodized IDT as an output transducer. One or two group-type multistrip couplers provide additional frequency selectivity. The original synthesis algorithms are developed for a design of an IDT and MSC structure