Single-package integration of RF blocks for a 5 GHz WLAN application

Transceivers for future digital telecommunications applications (third generation cellular, wireless LAN) need to be portable (compact), battery-powered and wireless. Today's single-chip solutions for RF front-ends do not yield complete system integration. For example, they typically still need external components for impedance matching, for antenna switches, for power amplifiers and for RF bandpass filters (BPFs). Furthermore, problems of substrate coupling (either manifesting as analog crosstalk or as noise coupling from the digital part to the analog part on mixed-signal chip) become more important with increasing integration. A system-in-a-package (SiP) approach can address these problems. High quality components can be integrated in the package, avoiding lower quality on-chip passives or circumventing expensive chip technology adaptations. Virtually all external components can be integrated, as shown in this paper for the case of the bandpass filters and the impedance matching. Even the antenna is a candidate for integration in the package. Further, a clever chip partitioning can reduce the substrate coupling problem. Partitioning also allows using the best IC-technoiogy for each component. This paper reports on a fully integrated single-package RF prototype module for a 5 GHz WLAN receiver front-end, which is intended to demonstrate the concept of SiP integration. The approach, that is illustrated here with prototype RF blocks for a 5 GHz WLAN application, is implemented with a thin film multichip module (MCM-D) interconnect technology. This technology also allows the integration of high quality passive components. With these passives, low-loss filters can be implemented. The use of passives, filters and off-the-shelf, active, bare die components opens the way to successful system integration.