A 900 MHz ladder-type SAW filter duplexer

A low-cost hybrid-integrated SAW filter duplexer consisting of receiver top filter, transmitter final-stage filter and antenna terminal has been developed. The prototype design was oriented at the GSM system specifications in the 900 MHz-band. Three-stage ladder-type SAW filters have been designed to perform the duplexing function by the use of only one transmission line. The complete duplexer has an insertion loss of 1.2 dB in the Tx path (Tx) and 2.1 dB in the Rx path (Rx). The 3 dB-bandwidth is 40.1 MHz (Tx) and 47.4 MHz (Rx), respectively.