RF MEMS has been identified as an area which has the potential to provide a major impact on existing system architectures in sensors and communications by reducing weight, cost, size, and power dissipation by a few orders of magnitude. Key MEMS devices for current RF architectures are switches in radar systems and filters in communication systems. This paper discusses a new family of MEMS switches and Si-micromachined circuits appropriate for use in modern communications systems. Future communications needs require increasing system functionality to meet performance expectations of new highly integrated sensors and instruments commonly planned for the new generation of satellites. To maximize data transfer and minimize operation cost, future communication systems are forced to move to higher frequencies. Communication circuit miniaturization can be achieved by implementing a number of enabling technologies based on RF MEMS and Si micromachining. These technologies include new circuit and component architectures, low-cost adaptive and re-configurable phased array antennas, millimeter-wave devices, advanced materials and novel integration techniques, integrated systems on a chip, and new packaging methods for high-frequency electronics. RF micromachining and MEMS technology promise to provide an innovative approach in the development of effective and low-cost circuits and systems, and is expected to have significant application in low-cost antenna arrays and re-configurable apertures.
New system architectures benefit from recent advancements in high-density, multi-layer circuit applications. In power dividing networks, in which power is split from one to four or more signal paths, the transmission line characteristics become significant since longer lines are typically required. In fact, line loss may become the dominant loss mechanism despite the presence of power splitting elements, such as Wilkinson dividers, and reactive tee junctions. Thus, choosing a transmission line for the entire network is one of the most critical steps in circuit design, since the proper choice of transmission line geometry may lead to reduced parasitics and minimized overall circuit loss. Furthermore, the use of MEMS switches may introduce a substantial modification to the system architecture, as they introduce better RF performance and lower power consumption requirements.

This presentation will discuss the use of MEMS devices and Si micromachining for the development of three-dimensional circuits with on-wafer packaging. Specifically, examples of various circuits printed on a high-resistivity wafer and shielded using on-wafer etched cavities will be presented and discussed. The shielding cavities not only provide mechanical protection to the air bridges utilized in the circuit but eliminate parasitic modes which may be excited due to the presence of a back-side metal plane. Substantial performance improvement is observed in the circuits, which are packaged on wafer. Further discussion on the impact of the presence of the MEMS devices on circuit performance will be provided at the conference.