Hindawi Publishing Corporation International Journal of Microwave Science and Technology Volume 2013, Article ID 459767, 6 pages http://dx.doi.org/10.1155/2013/459767 Research Article Wideband Lithium Niobate FBAR Filters Thomas Baron, 1 Eric Lebrasseur, 1 Florent Bassignot, 1 Haixia Wang, 1 Sylvain Ballandras, 1 Ji Fan, 2 Lise Catherinot, 2 Matthieu Chatras, 2 Philippe Monfraix, 3 and Laetitia Estagerie 4 1 FEM TO-ST UMR 6174 CNRS-UFC-ENSMM-UTBM, ENSMM, 26 Chemin de l’Epitaphe, 25030 Besanc ¸on Cedex, France 2 Xlim, UMR 6172 CNRS, Universit´ e de Limoges, 87060 Limoges, France 3 ales Alenia Space, CCEL/LPH/EA, Toulouse, France 4 CNES, 18 Avenu Edouard Belin, 31401 Toulouse Cedex 9, France Correspondence should be addressed to omas Baron; thomas.baron@femto-st.fr Received 5 October 2012; Accepted 17 December 2012 Academic Editor: Priyanka Mondal Copyright © 2013 omas Baron et al. is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Filters based on film bulk acoustic resonators (FBARs) are widely used for mobile phone applications, but they can also address wideband aerospace requirements. ese devices need high electromechanical coupling coefficients to achieve large band pass filters. e piezoelectric material LiNbO 3 complies with such specifications and is compatible with standard fabrication processes. In this work, simple metal—LiNbO 3 —metal structures have been developed to fabricate single FBAR elements directly connected to each other on a single chip. A fabrication process based on LiNbO 3 /silicon Au-Au bonding and LiNbO 3 lapping/polishing has been developed and is proposed in this paper. Electrical measurements of these FBAR filters are proposed and commented exhibiting filters with 8% of fractional bandwidth and 3.3 dB of insertion losses. Electrical measurements show possibilities to obtain 14% of fractional bandwidth. ese devices have been packaged, allowing for power handling, thermal, and ferroelectric tests, corresponding to spatial conditions. 1. Introduction Acoustic waves, using surface or bulk propagation, are used in numerous applications in frequency generation, control, or filtering in modern wireless communication systems [1– 3]. With the growing demand for multimedia and mobile applications, new generations of telecommunication satellites require higher performances, higher functionalities, and still stronger cost and size constraints [4, 5]. In that context, bulk acoustic waves (BAWs) or film bulk acoustic resonator (FBAR) devices can offer many potentialities for smart RF components or systems. For instance, this technology is now used as alternative to surface acoustic waves (SAWs) filters in handset duplexers for UMTS and DCS standards around 2 GHz with aluminium nitride piezoelectric layers [6]. is material is mainly processed for local oscillators or narrowband filtering operations (<5%) [7–12]. To achieve large bandwidth filters with fractional band- width over 10%, higher coupling coefficient materials are required. ese materials should be compatible with batch processes as those used for the micro-electromechanical systems (MEMS). e filter conception shows great interest for different orientation cut of LiNbO 3 . A specific microfabri- cation process has been developed to achieve such resonators and filters. ese devices are characterized to obtain filters behaviour. Finally, packaging of these devices allows testing power, thermal, and ferroelectric behaviours. 2. Conception BAW filters based on electrical couplings are usually designed with series or shunt resonators. By this way, two main topologies are used: the ladder [13] and the lattice [14] ones. ladder topology (Figure 1) is the easiest method to achieve BAW filter. Such a filter exhibits high selectivity but low out- of-band rejection. As one can see in Figure 1, separation between resonance and antiresonance frequencies has a direct impact on the bandwidth of Ladder filter. Piezoelectric materials with high electromechanical coupling coefficient allow the conception of large band pass filters. Indeed, (1) describes the dependence