PCS 1900 MHz duplexer using thin film bulk acoustic resonators (FBARs)

An ultra-miniature duplexer (5 × 8 × 2.2 mm3) consisting of two FBAR filters and nine passive components operating at 1900 MHz is described. The minimum insertion loss for the Tx and Rx bands is better than –3 dB. Isolation between the Tx and Rx ports exceeds 50 dB over most of the Tx band and 46 dB in the Rx band. The FBAR filters handle up to 2 W throughout the passband.