A 5 mm ×5 mm ×1.37 mm hermetic FBAR duplexer for PCS handsets with wafer-scale packaging

We describe the design and measured performance of a 5 mm ×5 mm ×1.37 mm antenna duplexer for the U.S. PCS band (Tx: 1850-1910 MHz, Rx: 1930-1990 MHz) for cellular handsets based on FBAR (film acoustic resonator) technology. The FBARs are fabricated in a silicon-based IC process technology and are hermetically sealed in a wafer-level packaging process. Two dice, Tx and Rx, are attached to a 4-level printed circuit board, ball-bonded, and encapsulated in plastic to form the final product. Guaranteed worst-case Tx insertion loss is 3.5 dB, worst-case Rx insertion loss is 4.0 dB. Minimum rejection is 50/40 dB in the Tx/Rx bands, guaranteed isolation is >52/42 dB.