FBAR Rx filters for handset front-end modules with wafer-level packaging

We present results of balanced Rx filters based on thin-film bulk acoustic resonator (FBAR) technology for GSM handset front-end module applications. The balanced filtering is achieved by using a lattice filter topology. The filter is hermetically sealed using wafer-level packaging with solder bumps on each terminal, ready for flip-chip assembly. The size of the filter is less than 1 mm∧2 and the height is less than 0.35 mm. The typical broadband rejection is better than 35 dB, and in-band insertion loss is less than 2 dB. The small size and good temperature stability make FBAR filters an ideal choice for front-end module applications.