Design of Duplexer "Inserts" for Mobile Phone Module Applications

Especially in the context of the upcoming requirement put on wireless terminals, such as mobile phones, to support both multiple standards and multiple bands there has been a continuous trend of integrating and miniaturizing the front-ends of wireless terminals. This has been achieved by means of shrinking the sizes of key components as well as integrating them along with many passive and also some active components in front-end modules. As some mobile communication standards are based on full duplex operation, SAW or FBAR duplexers need to be integrated into such modules. They are among the most demanding passive acoustic components regarding their simulation and design due to their high performance regarding both the isolation in the Tx and Rx bands as well as the suppression of the Rx and Tx bands by the Tx and Rx filters, respectively. Hence, up to now duplexers have been available only as standalone components. The paper reports about integrating the functionality of duplexers into modules. While mounting the SAW or FBAR dies on top of the modules using available technologies, the LTCC sections of the duplexers are seamlessly dissolved within the modules. We call the result duplexer "inserts". Focusing on electromagnetic issues regarding simulation and design of duplexer "inserts" we present experimental results of a feasibility study comprising prototypical W-CDMA 850 and W-CDMA 1900 duplexer "inserts"