Micromachined FBAR RF filters for advanced handset applications

In this paper, fully integrated FBAR (Film Bulk Acoustic Wave Resonator) RF BPFs (Band Pass Filters) and a duplexer have been designed, fabricated, and characterized for advanced mobile/wireless communication systems by using silicon bulk micromachining technology. Two different RF band pass filters are realized by combining 6 to 7 resonators in series and parallel connection for two chip FBAR duplexer for CDMA PCS applications. AlN, Mo, and silicon nitride are utilized for realizing the proposed FBAR BPFs and duplexer as a piezoelectric material, electrodes, and a supporting membrane, respectively. The fabricated FBAR filters have insertion loss of -1.46 dB and -1.86 dB, return loss of -13 dB and -10 dB, and stop band rejection of -14 dB, and -33 dB, center frequency of 1.88 GHz and 1.96 GHz, and size of 1.3 mm /spl times/ 1.5 mm, respectively. The demonstrated FBAR duplexer for CDMA PCS applications has insertion loss of -1.3 dB (Min.) and absolute attenuation of -42 dB (Min.) at Tx to Antenna port, while it has insertion loss of -2.3 dB (Min.) and absolute attenuation of -52 dB (Min.) at Antenna to Rx port.