Miniaturization and advanced functionalities of SAW devices

Abstract

Apart from the active semiconductor chips a multitude of surface acoustic wave filters (SAW filters) are the key components that make modem RF circuits for mobile telecommunication and multimedia applications work. The latter are the most sophisticated and delicate species of passive components of which today's RF applications contain several hundred. While active integration has led to decreasing numbers of semiconductors inside a phone, at the time being the passive components outnumber the actives by far. Obviously, the highest potential for further miniaturization lies in the passive components. As the market asks for further miniaturized mobile phones and digital tuners EPCOS tackles this challenge not only by further shrinking the SAW filters but also by integrating additional functions into the SAW filters which were originally not SAW related at all. This paper briefly presents several applications for such highly miniaturized SAW filters offering superior filter performance combined with additional features like impedance transformation, balun functionality or double balanced operation, allowing for smaller and cheaper designs by effectively reducing PCB space as well as component count.

Wafer Level SAW RF Filter Packaging With Through Wafer Via Interconnection

“…But it's difficult to make the smaller size package because they need space for chip SMT (Surface Mount Technology) and encapsulation. [1][2][3][4][5][6] WLP (Wafer Level Package) is prospected on the smaller size, lower height, less weight and higher performance for the SAW filter. To realize the WLP SAW filter, wafer level technology has to be studied on wafer bonding, wafer thinning and via drilling.…”

A New Modular Design for Test and Application PCBs of SAW RF Filters to Ensure Precisely Predictable Filter Characteristics

“…Center frequencies have shifted from 1 GHz to above 2 GHz. At the same time, further functionality has been added to the pure filtering function [1]. Two examples of such additional functions are impedance transformation or balun functionality.…”