RF-MEMS switchable inductors for tunable bandwidth BAW filters

This paper presents a method for reconfiguring the bandwidth of Bulk Acoustic Wave (BAW) ladder filters by adding switchable inductors to their shunt resonators. Inductance values are controlled by selecting the number of turn in spiral inductor using micro-electro-mechanical (MEMS) switches. For this purpose, a MEMS inductor has been designed, fabricated and characterized in terms of inductance value, quality factor, and resonance frequency. A measurement-based model of this inductor has been implemented in a circuit simulator to build a reconfigurable RF Ladder BAW filter intended for handset applications. The simulation results show that, using this switchable inductor, it is possible to increase the filter bandwidth by up to 25% with an improved out-of-band rejection and without degrading its selectivity.

[1]  Roc Berenguer,et al.  Design and Test of Integrated Inductors for RF Applications , 2003 .

[2]  A. Malczewski,et al.  RF MEMS‐based tunable filters , 2001 .

[3]  Gabriel M. Rebeiz,et al.  MEMS Switch Library , 2004 .

[4]  Gabriel M. Rebeiz,et al.  RF MEMS switches and switch circuits , 2001 .

[5]  Robert Aigner,et al.  A miniature BAW duplexer using flip-chip on LTCC , 2003, IEEE Symposium on Ultrasonics, 2003.

[6]  Wolfgang J. R. Hoefer,et al.  Tunable microwave and millimeter-wave band-pass filters , 1991 .

[7]  R. Aigner.  MEMS in RF-filter applications: thin film bulk-acoustic-wave technology , 2005, The 13th International Conference on Solid-State Sensors, Actuators and Microsystems, 2005. Digest of Technical Papers. TRANSDUCERS '05..

[8]  Kenneth Meade Lakin,et al.  A review of thin-film resonator technology , 2003 .

[9]  Pei-Zen Chang,et al.  The method for integrating FBAR with circuitry on CMOS chip , 2004, Proceedings of the 2004 IEEE International Frequency Control Symposium and Exposition, 2004..

[10]  Kenneth Meade Lakin,et al.  Modeling of thin film resonators and filters , 1992, 1992 IEEE Microwave Symposium Digest MTT-S.

[11]  R. Circa,et al.  Reconfigurable receiver approach for 4G terminals and beyond , 2005, The 3rd International IEEE-NEWCAS Conference, 2005..

[12]  J. Burghartz,et al.  On the design of RF spiral inductors on silicon , 2003 .

[13]  Ping Zhang,et al.  A Seamless Vertical Handover Scheme for End-to-End Reconfigurability Systems , 2008, VTC Spring 2008 - IEEE Vehicular Technology Conference.

[14]  Jr. R. Wyndrum.  Microwave filters, impedance-matching networks, and coupling structures , 1965 .

[15]  H. Okazaki,et al.  Reconfigurable RF Circuits for Future Band-Free Mobile Terminals , 2007, 2007 International Symposium on Signals, Systems and Electronics.

[16]  V. Stavroulaki,et al.  End-to-End Reconfigurability in Heterogeneous Wireless Systems - Software and Cognitive Radio Solutions enriched by Policy- and Context-based Decision Making , 2007, 2007 16th IST Mobile and Wireless Communications Summit.