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RF-switches and passive components

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The main research activity performed by the group in the last years was the development of a technology for the fabrication of RF-MEM switches, which started in 2003 within the ESA/ESTEC contract Nr. 14628/NL/CK-“MEM Switch”. This type of technology, and the following improvements are now the basis of all our activities in the field of the RF MEMS. The outcome of the original research project was a 8 mask fabrication process, that provides polysilicon lines and resistors, metal lines, two levels of electroplated gold and a level of evaporated gold. Suspended parts are made with photoresist as sacrificial layer in order to use oxygen plasma to free the structures, avoiding sticking problems. With this process it is possible to obtain suspended bridges, metal underpass, polysilicon or metal actuation electrodes, metal - gold capacitors (DC block capacitors), and all the possible combinations of these building blocks. Within this technological frame different kinds of single switches have been obtained and tested, both in series and shunt configuration. The following developments included optional process variations such as

  • double level of poly doping, to reduce the contact resistances
  • quartz as starting substrate for very high frequency applications (up to 120 GHz)
  • 200 micron-thick high resistivity silicon as starting substrate and  back metallization for strip line implementation
  • many others, tailored on specific needs,  with a total number of masks varying from 8 to 11.
  • More than 30 fabrication batches have been produced so far with this type of technology, allowing the realization of many type of different devices that are far beyond the single switching unit.
        
       
       

    Application cases: 

    • MEMS switches: Single Pole Single Throw (SPST), SPDT, SP4T, DPDT…

    • Tunable phase shifters and true time delay networks

    • Reconfigurable and tunable filters

    • Reconfigurable matching networks

    • Programmable power dividers/combiners

    • Reconfigurable antennas and reflectarrays

    Research topics: