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 - are summarized in a comprehensive form. Requirements and key performance parameters for filters in next generation mobile phone applications are reviewed in detail. The presentation includes an outlook on future RF architectures and consolidates the demand for filters. BAW and FBAR technologies in wafer-level-packaging enable the building of complete "system-in-package" (SiP) RF-modules using cheap substrates and established assembly methods as are reviewed in detail. The state-of-the-art in BAW filters and future technology trends are presented. Supplementary information covers manufacturing and commercialization issues.

[1]  J. Larson,et al.  Ultra-miniature high-Q filters and duplexers using FBAR technology , 2001, 2001 IEEE International Solid-State Circuits Conference. Digest of Technical Papers. ISSCC (Cat. No.01CH37177).

[2]  Kenneth Meade Lakin,et al.  High Q microwave acoustic resonators and filters , 1993, 1993 IEEE MTT-S International Microwave Symposium Digest.

[3]  R. Aigner,et al.  Bulk-acoustic-wave filters: performance optimization and volume manufacturing , 2003, IEEE MTT-S International Microwave Symposium Digest, 2003.

[4]  R. Aigner,et al.  Advancement of MEMS into RF-filter applications , 2002, Digest. International Electron Devices Meeting,.

[5]  R. Aigner,et al.  Integration of bulk acoustic wave filters: concepts and trends , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[6]  M. Franosch,et al.  Wafer-level-package for Bulk Acoustic Wave (BAW) filters , 2004, 2004 IEEE MTT-S International Microwave Symposium Digest (IEEE Cat. No.04CH37535).

[7]  Joel F. Rosenbaum,et al.  Bulk Acoustic Wave Theory and Devices , 1988 .

[8]  T. Verhoeven,et al.  High-Q FBAR filters in a wafer-level chip-scale package , 2002, 2002 IEEE International Solid-State Circuits Conference. Digest of Technical Papers (Cat. No.02CH37315).