Micromechanical RF filters and reference oscillators based on recently demonstrated vibrating on-chip micromechani-cal resonators with Q's >10,000 at 1.5 GHz, are described as an attractive solution to the increasing count of RF components (e.g., filters) expected to be needed by future multi-band wireless devices. With Q's this high in on-chip abun-dance, such devices might also enable a paradigm-shift in transceiver design where the advantages of high-Q are emphasized, rather than suppressed, resulting in enhanced robustness and power savings. An overview of the latest in vi-brating RF MEMS technology is presented with an addendum on remaining issues to be addressed for insertion into tomorrow's handsets.
With Q's in the tens to hundreds of thousands, micromachined vibrating resonators are proposed as IC-compatible tanks for use in the highly selective filters of communications subsystems. To date, bandpass filters consisting of spring- coupled micro-mechanical resonators have been demonstrated in a frequency range from HF to VHF. In particular, two- resonator micromechanical bandpass filters have been demonstrated with frequencies up to 35 MHz, percent bandwidths on the order of 0.2%, and insertion losses less than 2 dB. In addition, free-free beam, single-pole resonators have recently been realized with frequencies up to 92 MHz and Q's around 8,000. Evidence suggests that the ultimate frequency range of this high-Q tank technology depends upon material limitations, as well as design constraints--in particular, to the degree of electromechanical coupling achievable in micro-scale resonators.
An overview of the key micromachining technologies that enable communications applications for MEMS is presented with a focus on frequency-selective devices. In particular, micromechanical filters are briefly reviewed and key technologies needed to extend their frequencies into the high VHF and UHF ranges are anticipated. Series resistance in interconnect or structural materials is shown to be a common concern for virtually all RF MEMS components, from mechanical vibrating beams, to high-Q inductors and tunable capacitors, to switches and antennas. Environmental parasites--such as feedthrough capacitance, eddy currents, and molecular contaminants--are identified as major performance limiters for RF MEMS. Strategies for eliminating them via combination of monolithic integration and encapsulation packaging are described.
An overview of the key micromachining technologies that enable communications applications for MEMS is presented with a focus on frequency-selective devices. In particular, micromechanical filters are briefly reviewed and key technologies needed to extend their frequencies into the high VHF and UHF ranges are anticipated. Series resistance in interconnect or structural materials is shown to be a common concern for virtually all RF MEMS components, from mechanical vibrating beams, to high-Q inductors and tunable capacitors, to switches and antennas. Environmental parasites--such as feedthrough capacitance, eddy currents, and molecular contaminants--are identified as major performance limiters for RF MEMS. Strategies for eliminating them via combination of monolithic integration and encapsulation packaging are described.
An overview of the key micromachining technologies that enable communications applications for MEMS is presented with a focus on frequency-selective devices. In particular, micromechanical filters are briefly reviewed and key technologies needed to extend their frequencies into the high VHF and UHF ranges are anticipated. Series resistance in interconnect or structural materials is shown to be a common concern for virtually all RF MEMS components, from mechanical vibrating beams, to high-Q inductors and tunable capacitors, to switches and antennas. Environmental parasites--such as feedthrough capacitance, eddy currents, and molecular contaminants--are identified as major performance limiters for RF MEMS. Strategies for eliminating them via combination of monolithic integration and encapsulation packaging are described.
An overview of the key micromachining technologies that enable communications applications for MEMS is presented with a focus on frequency-selective devices. In particular, micromechanical filters are briefly reviewed and key technologies needed to extend their frequencies into the high VHF and UHF ranges are anticipated. Series resistance in interconnect or structural materials is shown to be a common concern for virtually all RF MEMS components, from mechanical vibrating beams, to high-Q inductors and tunable capacitors, to switches and antennas. Environmental parasites --such as feedthrough capacitance, eddy currents, and molecular contaminants -- are identified as major performance limiters for RF MEMS. Strategies for eliminating them via combinations of monolithic integration and encapsulation packaging are described.
An overview of the key micromachining technologies that enable communications applications for MEMS is presented with a focus on frequency-selective devices. In particular, micromechanical filters are briefly reviewed and key technologies needed to extend their frequencies into the high VHF and UHF ranges are anticipated. Series resistance in interconnect or structural materials is shown to be a common concern for virtually all RF MEMS components, from mechanical vibrating beams, to high-Q inductors and tunable capacitors, to switches and antennas. Environmental parasites -- such as feedthrough capacitance, eddy currents, and molecular contaminants -- are identified as major performance limiters for RF MEMS. Strategies for eliminating them via combinations of monolithic integration and encapsulation packaging are described.
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