The front-end module is located on the smartphone’s main board, where Samsung has proposed a different configuration of its LTE front end. Murata’s FAJ15 was only found in the Galaxy S7’s U.S. version, where it shares the front end with Qorvo and Broadcom.
The FAJ15 is dedicated to LTE low band. It is made with several filter dies assembled on a ceramic substrate. The filters are either bare dies or packages molded into FEM molding. As piezoelectric for SAW technology, the substrate dies are either LN (lithium niobium oxide) or LT (lithium tantalum oxide). The FEM contains two SAW technologies: STD-SAW (standard SAW) and TC-SAW (thermally compensated SAW). This report only focuses on the duplexer for the Band 8 LTE integrated in the FEM. This band’s specification required very low thermal drift, so the thermo-compensated layers are integrated to provide better performance relating to thermal changes.
The complete chip fabrication process and a cost estimate of the Band 8 component are presented in this report, along with a brief substrate packaging comparison with FEMs from Qorvo and Broadcom.