Radio Frequency Micromechanical Switch

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RF MEMS switches were first invented and reduced to practice in 1993 as a means of achieving the low RF loss afforded by MEMS and micromachining technology. The use of a capacitive coupling mechanism entirely eliminates issues associated with dry contact, metal-metal ohmic switching. Over the years, investments by government and corporate IR&D have evolved these switches considerably. Presently, capacitive MEMS switches, and MEMS switches in general, provide the lowest loss means for switching and routing RF, microwave, and millimeter-wave signals. Over the past decade processing improvements, material refinements, and RF and mechanical design changes have allowed MEMS capacitive switches to demonstrate ultra-low loss (<0.1>+66 dBm

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Radio Frequency Micromechanical Switch

  1. 1. Presented by:-Jitendra Jangid1
  2. 2.  Electrostatic Switch Electro Magnetic switch Cantilever switch Switch using hall effect Pizeo-resistivity switch Cantilever switch using chemical process Optical switch2
  3. 3.  Electrostatic switch :1. large gap of at least 100 micro meter between the electrostaticplates is requiredto prevent arcing during a possible high voltage surge on theorder of 2000 volts2. Maximum device size of 1mm x 1mm3. Device withstand 3 Amps current for one second for the contactpart of the relay.3
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  7. 7.  When Fe is larger than Fm, the electrodesmove closer; the distance between theelectrodes is reduced. However when the distance between the 2electrodes is lesser than 2/3 of the originalgap, the electrode collapses. This phenomenon is known as pull-in. This phenomenon is commonly used ing-switch design7
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  9. 9. It takes large time for switching it required additional reference voltage tomoving effectively9
  10. 10.  When voltage is applied to the electrodes, the electrostaticforce acting on the electrodes pulls down the cantileverbeam toward the ground. When the beam is pulled away from its equilibrium position,stresses accumulate in the beam . The stresses form aresultant force to counterbalance the electrostatic force. When the applied voltage is removed, the counter-balancing force returns the beam back to its normalposition. This force, which is the sum of the stresses in thebeam, is referred to as the restoring force that "restores"the beam to its original position. The shorting bar is a thin layer of gold foil located below thecantilever beam and moving along with the beam.10
  11. 11.  Advantage: Good Sensitivity Excellent temperature stability Integrated electronics enable 0.01A orsmaller resolution Limitation: Small signal Undesired electrostatic actuation11
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  18. 18.  The piezoresistive effect describes thechanging electrical resistance of a materialdue to applied mechanical stress.18
  19. 19. Advantage :- Large sensitivity of simple resistors Very easy to fabricate and low cost.Limitation: Too sensitive to temperature changes19
  20. 20.  The Hall effect refers to the potentialdifference (Hall voltage) on the opposite sidesof an Electrical conductor through which anelectric current is flowing, created by amagnetic field applied perpendicular to thecurrent20
  21. 21. Advantage: Immune to dust, dirt and water whenappropriately packaged.Limitation: Very low signal level, an amplifier isrequired.21
  22. 22.  Space division switches – 2D MEMS – 3D MEMS optical switches • Spectral domain processors – Wavelength-selective switches22
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  28. 28. ◦ Low Size◦ High switching speed◦ High sensitivity◦ Low noise◦ Reduced cost◦ Batch Processing28
  29. 29. Thank you29

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