A design of antenna duplexer using ladder type SAW filters

This paper describes a design technology of a small antenna duplexer, especially package conditions, by using ladder type SAW filters. This requires not only optimizing the filter design but also the electrode materials and the package design which has matching circuitry for the duplexer configuration. The matching circuitry was incorporated into a microstrip structural pattern which is designed onto the surface of a multilayer ceramic package. To avoid the deterioration of in-band VSWR and reflection coefficient of the stop-band after rotating phase caused by the matching pattern, the characteristic impedance of the matching pattern was designed to be 1.06 times Zo. To obtain the high stop-band attenuation and Tx-Rx isolation characteristics, the package parasitic inductance was used by the multilayer structure design of the package.