Through-silicon vias enable next-generation SiGe power amplifiers for wireless communications

We feature a 0.35-µm SiGe BiCMOS technology (SiGe 5PAe) that is optimized for power amplifier (PA) applications. The key feature of this technology is a novel low-inductance ground to the package using through-silicon vias (TSVs) that results in a competitive solution for future multiband and multimode PA integration. The tungsten-filled, multifinger, bar-shaped TSV delivers more than a 75% reduction in inductance compared to a traditional wirebond. This enables higher frequency applications with a roughly 20% reduction in die area without compromising the technology reliability for use conditions in a low-cost plastic QFN (quad flat no leads) package. In this paper we demonstrate the commercial feasibility of the TSV, its RF performance, its reliability, and its usefulness in a demanding WiMAX® (Worldwide Interoperability for Microwave Access) PA application.