A GPS/BT/WiFi triple-mode RF FEM using Si- and LTCC-based embedded technologies

This paper presents a compact GPS/BT/WiFi triple-band triple-mode RF front-end module (FEM) with Si-based embedded actives and LTCC-based embedded passives. The proposed RF FEM consists of a triplexer, baluns, matching circuits in the LTCC substrate, and a PA, an LNA, a SAW filter on the LTCC substrate. Furthermore, the proposed FEM has a silicon module on top of the LTCC substrate in which three active devices and several DC blocking capacitors are embedded using cavity structure and IPD process. The size of the proposed RF FEM is only 5.0 mm × 6.0 mm with an LTCC substrate thickness of 0.85 mm. The measured results show that in GPS path, we obtain a gain of 15.4 dB, and a noise figure of 2.2 dB at 1.575 GHz. In WiFi 2.4-GHz band, the Rx path provides a gain of 15 dB considering 3-dB power split with an amplitude imbalance of 1.2 dB and a phase difference of about 178°–182°. In WiFi 5-GHz band, the Rx path provides a gain of 8.3 dB with an amplitude imbalance of 0.8 dB and a phase difference of 177°–181°. Also, the RF FEM provides a P1dB of more than 20 dBm and sufficient adjacent channel power characteristics at both frequency bands.