A 3x3mm2 embedded-wafer-level packaged WCDMA GaAs HBT power amplifier module with integrated Si DC power management IC

This paper presents a highly compact 3 times 3 mm² WCDMA power amplifier (PA) module which integrates a GaAs HBT MMIC PA and a Si DC power management IC into one single package. A closed-loop controlled DC-DC buck converter allows the power management IC to adaptively optimize the PA collector voltage as a function of output power and thereby reduce current consumption under backoff operation. A novel embedded-wafer-level-package (EWLP) technology is developed for module miniaturization. Redistribution layers and bumps are formed on the Si IC to create the wafer level package (WLP). The EWLP is then fabricated by embedding the WLP IC inside the core of the module. The MMIC PA is mounted on the surface of the module, creating a vertical integration for size reduction. The PA module (PAM) achieves excellent current reduction over a wide range of output power (Pout) up to 27.5 dBm, while maintaining ACLR1 below -40 dBc. At 16 dBm and 24 dBm Pout, the current consumptions are reduced from 162 mA and 370 mA, to 65 mA and 237 mA, respectively, compared to the conventional PA.