A Novel Frequency Addressable Micro Switch Array

Abstract

Addressable switch arrays are widely used in telecommunication, radar and satellite systems for many applications, such as switch network controlling, modularity and expansion. The existing method to achieve addressability of the switch is to design a grid structure switch array and to individually actuate switches with multiplexed control lines , . The MEMS switch array presented in this work addresses individual switches according to the unique intrinsic resonance frequencies of different mechanical structures driven by electro-magnetic force. This approach eliminates the need to have a dedicated control line for each switch, which readily enables the switch array with minimal complexity of control line design thus minimizes the overall footprint. The frequency addressable switch array (FASA) is fabricated directly on printed circuit boards using patented laminate MEMS technology. Instead of building everything bottom-up, three layers including top cantilever structure, middle spacer, bottom electrode and coils are fabricated separately through different processes and later laminated together. The switches are electro-magnetically actuated at operation voltage (~1V), which is much lower than the one of the conventional electrostatic actuation (>30V) . Alternating electro-magnetic force is exerted on a mini neodymium magnet by a series of coils. Only when the maximum vibration stroke is obtained at the resonant frequency of individual switch, the mini magnet mounted on the top cantilever will make contact with the bottom electrode for signal transmission. The quality factors of the switches were measured to be nearly 100 with air damping. The related switch density (defined by the number of the switches per kHz in desired frequency range for individual addressing) in the array is around 10 per kHz. By improving the quality factor of the switch such as hermetic packaging avoiding the air damping, a high value (>200 per kHz) of the switch density is expected.