Miniaturization and advanced functionalities of SAW devices

Apart from the active semiconductor chips a multitude of surface acoustic w ave (SAW) filters are the key components that make modern RF circuits for m obile telecommunication and multimedia applications work. The latter are th e most sophisticated and delicate species of passive components of which to day's RF applications contain several hundred. While active integration has led to decreasing numbers of semiconductors inside a phone, at the time be ing, the passive components outnumber the actives by far. Obviously, the hi ghest potential for further miniaturization lies in the passive components. As the market asks for further miniaturized mobile phones and digital tune rs EPCOS AG, Munich, Germany, tackles this challenge not only by further sh rinking the SAW filters, but also by integrating additional functions into the SAW filters, which were originally not SAW related at all. This paper b riefly presents several applications for such highly miniaturized SAW filte rs offering superior filter performance combined with additional features l ike impedance transformation, balun functionality, or double balanced opera tion, allowing for smaller and cheaper designs by effectively reducing prin ted-circuit-board space, as well as component count.