Ultra-miniaturized and high performance PCS SAW duplexer with steep cut-off filters

This paper describes PCS SAW duplexer using unique design methods in order to realize steep cut-off performance, which are based on ladder and DMS design for Tx and Rx, respectively. It is found that SAW resonator having narrow electrode fingers makes transverse leakage of SAW energy suppress around resonant frequency, so that band edge and skirt performance of Tx filter is much improved. For Rx part, new DMS (Double Mode SAW) is proposed which uses inductors and capacitors in the device effectively to realize higher rejection and better cut-off performance. We have succeeded to realize ultra-miniaturized PCS SAW duplexers for the US and Korean market using these technologies.