Miniaturization of FBAR duplexer using PCB embedded high Q spiral inductors

In this paper, extremely miniaturized film bulk acoustic resonator (FBAR) duplexer was newly designed and fabricated for advanced mobile/wireless applications by using PCB embedded vertically stacked high Q spiral inductors. Proposed FBAR duplexer was comprised of FBAR Tx/Rx filters and PCB embedded shunt high Q inductors. The fabricated FBAR duplexer has insertion loss of -3.0 dB_Max in pass-band and absolute attenuation of -41 dB_min at transmitter to antenna ports, while it has insertion loss of -3.4 dB_Max in pass-band and absolute attenuation of -51 dB_min at antenna to receiver ports. The simulation and measurement of the fabricated FBAR duplexer were well-matched, respectively. The fabricated duplexer has a size of 3.0 mm × 2.5 mm which is the smallest in the reported ones so far. Since it has excellent performance characteristics and small size/volume, it can be directly applied for US-PCS handsets.