Radio-frequency MEMS

Article By:

De Los Santos, Héctor J. NanoMEMS Research, LLC, Irvine, California.

Last reviewed:2010

DOI:https://doi.org/10.1036/1097-8542.YB100173

Radio-frequency micro-electro-mechanical systems (RF MEMS) is a technology aimed at the realization of high-quality components to enable superior circuits (that is, capable of operation over wider frequency bandwidths and exhibiting lower losses) for wireless communications systems. RF MEMS adds to conventional integrated circuit technology two main fabrication techniques, namely, surface micromachining and bulk micromachining, to reduce the extraneous capacitive and resistive effects introduced by the substrate/wafer by virtue of the fact that the components are naturally embedded in it. Because of their extraneous nature, these effects are called parasitic; they are parasites to the desired components being implemented. Surface micromachining reduces component parasitics by suspending them over the substrate. Bulk micromachining, on the other hand, reduces parasitics by removing the substrate in a core region underneath the components. This decoupling from the substrate results in fully three-dimensional components, such as capacitors, varactors, inductors, resonators, switches, and transmission lines, that not only exhibit a minimum of substrate parasitics, but that may also be caused to undergo mechanical motion upon the application of electrostatic or magnetic forces. This latter feature is very valuable for producing reconfigurable circuits and systems that may adapt to operating conditions to maintain optimum performance. The elements of RF MEMS may be construed as depicted in Fig. 1.

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