Micromachined bulk acoustical-wave RF filters

We present the performance of RF filters based on thin film bulk acoustical resonator (FBAR) technology for wireless communication applications. The filter is fabricated using surface micromachining processes and is hermetically sealed using wafer-level packaging with solder bumps on each electrical terminal, ready for flip-chip assembly. The size of the filter is less than 1 mm² and the height is less than 0.35 mm. The typical broadband attenuation is better than 35 dB and passband insertion loss is less than 2 dB. The small size and good temperature stability make FBAR filters ideal choice for handset applications.