23-08-2012, 05:15 PM
LOW VOLTAGE AND LOW POWER RF MEMS SERIES AND SHUNT SWITCHES
08-LOW VOLTAGE AND LOW POWER RF MEMS SWITCHES.pptx (Size: 1.82 MB / Downloads: 44)
INTRODUCTION
WIRELESS communication has made an explosive growth of emerging consumer markets,military applications of RF, microwave, and millimeter-wave circuits and systems.
The RF switch is one of the essential components to handle RF signals.
RF microelectromechanical systems (MEMS) switches have been introduced for low insertion loss, high isolation, and low power consumption.
RF MEMS SWITHCHES
RF MEMS swithches used electrostatic actuation.
Two challenges:
High actuation voltage
Low mechanical stability
To overcome this:
spring type approach
push-pull approach
Large force exerted from electromagnetic actuation allows RF switches to have a mechanically robust structure.
Electromagnetic actuation requires relatively large power because constant current has to be applied during a given switching period.
Electromagnetic actuation requires relatively large power and high isolation
MECHANICAL CHARACTERISTICS
The fabricated MEMS series- and shunt-type switches have
been actuated by electromagnetic force induced on the coils from external permanent magnets.
To apply an external magnetic field, the diced RF MEMS switch is fixed on a PCB and wire bonded and is inserted between the two permanent magnets.
External magnetic intensity is 0.22 T at the actuation point.
CONCLUSION
The proposed switch uses electromagnetic force only during switching transition periods and for the rest of the holding period it uses electrostatic force to maintain low-power consumption.
They have successfully implemented both series- and shunt-type RF MEMS switches using the proposed actuation scheme.