Fabrication of monolithic 1-Chip FBAR duplexer for W-CDMA handsets

FBAR filters and duplexers have high power handling capability, high Q factors, good thermal stability, a low volume, a low cost and IC compatibility their applications have been gradually increased in RF systems. However, there is no published papers and research about FBAR 1-chip duplexer, which was fabricated with Tx and Rx filters because that is a very challenging task. We report for the first time that a monolithic 1-chip RF filter is achieved with the size of 2.5 mm times 2.5 mm using a suspended membrane thin film bulk acoustic resonator (FBAR) technology to meet stringent demand for miniaturization and monolithic integration of duplexers in RF communication systems. In this work, a novel 1-chip duplexer is designed by EM(electromagnetic) simulation and RF circuit simulation using HFSS and ADS. The highest insertion losses in the pass-band (1920-1980, 2110-2170 MHz) are measured below 3.5 dB. In the Rx band(2110-2170 MHz) the attenuation is the over 45 and the attenuation in the Rx band is the over 54 dB.