RF MEMS for digitally-controlled front-end components

Abstract

Summary form only given, as follows. In recent years the field of microelectromechanical systems (MEMS) has grown very fast and merged with many defense and commercial applications. Much of this activity has been driven by the ability of MEMS to miniaturize, reduce the cost, and improve the performance of transducers and actuators previously fabricated by hybrid techniques. These benefits have stemmed from the compatibility of MEMS with silicon-based microelectronics and surface micromachining. A recent development along these lines is RF MEMS which, broadly speaking, is a new class of passive devices (e.g., switches) and circuit components (e.g., tunable transmission lines) composed of or controlled by MEMS. The most investigated RF MEMS device has been the electrostatic switch, consisting of either a thin metallic cantilever, diaphragm, or some other form of membrane that when pulled down to a bottom electrode shorts or opens a high frequency transmission line. For example, working on the DARPA MAFET-3 Program, Texas Instruments has recently demonstrated a "BowTIe" switch having an on-state-insertion and return loss of 0.15 dB and -20 dB, respectively, at 20 GHz when fabricated across the center conductor of a coplanar waveguide. Other organizations in the DARPA Program are pursuing RF MEMS cantilevers for switchable antennas and filters (Hughes Research Labs), and quasioptical beam-steering grids (Rockwell and Northrop Grumman). In all of these applications, the RF MEMS is promising a major positive impact on performance and cost-a rare occurrence for any technology just entering the RF arena.