A Compact Flip Chip Single Die WiFi FEM for Smart Phone Application

Cindy Yuen, Kirk Laursen, Duc Chu, Yi-Ching Pao, Epic Communications, Inc. CA, USA

Abstract — A flip chip single die WiFi FEM is developed using Bi-FET (HBT+E/D-PHEMT) technology for smart phone application. High thermal conductive copper-pillar bumps were developed for the flip chip process. This FEM flip chip die consists of a high-pass filter (HPF), a 2GHz WiFi PA with on-chip regulator, PAON logic and detector circuit, and an SP3T. It showed good over-voltage and over-temperature performance when mounted on test LTCC module. Thermal modeling and design optimization kept junction temperatures comparable to wirebond versions of the design. A complete WiFi front-end LTCC module was developed using flip chip FEIC, integrated balun and SAW filter, with 3.2mmx3.2mm size for Smart Phone Application. Index Terms — Flip Chip, Copper Pillar, Solder Bump, Front- End IC, LTCC, WiFi, FEM, Smart Phone.