MEMS in RF-filter applications: Thin film bulk-acoustic-wave technology

RF-filters based on MEMS technology have started to substitute conventional filters in mobile phones as they offer clear performance and size advantages. Bulk Acoustic Wave (BAW) and FBAR technologies today dominate the market for US-PCS duplexers and transmit filters which are needed between the power amplifier and antenna in mobile phone applications. No other RF-MEMS component has yet emerged in mobile phone applications. The working principle and fundamentals of RF-MEMS filters - and in particular Thin Film Bulk-Acoustic-Wave (BAW) filters - will be summarized in a comprehensive form. Requirements and key performance parameters for filters in next generation mobile phone applications will be reviewed in detail. The presentation will include an outlook on future RF architectures and consolidate the demand for filters. BAW and FBAR technologies in Wafer-Level-Package enable to build complete "System-in-Package" (SiP) RF-modules using cheap substrates and established assembly methods as will be reviewed in detail. The state-of-the-art in BAW filters as well as future technology trends will be presented. Supplementary information will cover manufacturing and commercialization issues.