Seminar Abstract: During the last several years, the speed and the level of integration of monolithic microwave integrated circuits (MMICs) have increased drastically. Today’s circuits are able to operate at frequencies up to the sub-millimeter-wave range (≥ 300 GHz) and combine highly sophisticated systems within one single chip (System-on-Chip or SoC). These chips have to be encapsulated in packages or modules to make their features available for the clients. Due to the fact that most of these systems require RF interconnections to external antennas or succeeding systems, their packages have to fulfill stringent requirements on machining and alignment as well as the packaging materials used. For frequencies beyond 100 GHz this normally involves high-quality but bulky waveguides encapsulated in machined metal housings. Metallic RF modules offer high performance but are very expensive and result in a low level of integration. Due to the huge effort involved in creation of the packages, the price for a module is no longer limited by the inserted MMICs but by the packaging costs. To address a mass market for MMICs operating in the high millimeter-wave range such metal modules are not feasible and have to be replaced by cheaper packaging materials, which, however, come with additional problems. The plastic packaging materials are quite lossy and the RF interconnection of such a package is limited in performance due to the lead and wire-bond inductances of approximately 1 nH/mm, which prohibits frequencies above 20 GHz.

This presentation introduces the idea of a low-cost fully integrated surface-mountable millimeter-wave radar sensor. Different packaging topologies are compared with the potential of integrating the whole radar front-end together with the antennas into a single QFN (Quad-Flat-No-Lead) package. Since no high frequency RF interconnections are necessary on/off the package, the standard plastic packages come with another advantage, which is their usability within low-cost Surface Mount Technologies (SMTs). Thus, a highly complex system-in-package (SiP) can be picked and placed and finally soldered automatically onto the surface of a printed circuit board (PCB). This however makes it necessary to integrate the antenna together with the MMIC into a single package. In that case, only DC and baseband signals have to be conducted through the package-to-board interconnections and thus the requirements for these interconnections are greatly relaxed. Different options on how a fully integrated millimeter-wave system can be realized within a surface mountable package will be presented with measurements comparing different concepts for a low cost surface mountable 120 GHz radar sensor in a QFN package.