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RF MEMS switched capacitors are capacitive fixed-fixed beam switches with a low capacitance ratio. RF MEMS varactors are capacitive fixed-fixed beam switches which are biased below pull-in voltage. Other examples of RF MEMS switches are ohmic cantilever switches, and capacitive single pole N throw (SPNT) switches based on the axial gap wobble ...
Differential variable capacitors also have two independent stators, but unlike in the butterfly capacitor where capacities on both sides increase equally as the rotor is turned, in a differential variable capacitor one section's capacity will increase while the other section's decreases, keeping the sum of the two stator capacitances constant.
A MEMS magnetic field sensor is a small-scale microelectromechanical systems (MEMS) device for detecting and measuring magnetic fields (magnetometer). Many of these operate by detecting effects of the Lorentz force : a change in voltage or resonant frequency may be measured electronically, or a mechanical displacement may be measured optically.
An early example of a MEMS device is the resonant-gate transistor, an adaptation of the MOSFET, developed by Robert A. Wickstrom for Harvey C. Nathanson in 1965. [4] Another early example is the resonistor, an electromechanical monolithic resonator patented by Raymond J. Wilfinger between 1966 and 1971.
An example is a nickel rod that tends to deform when it is placed in an external magnetic field. Another example is wrapping a series of electromagnetic induction coils around a metal tube in which a Terfenol-D material is placed. The coils generate a moving magnetic field that courses wavelike down the successive windings along the stator tube.
Example of a simple oscillator that requires a capacitor to function. A capacitor can possess spring-like qualities in an oscillator circuit. In the image example, a capacitor acts to influence the biasing voltage at the npn transistor's base.
All diodes exhibit this variable junction capacitance, but varactors are manufactured to exploit the effect and increase the capacitance variation. The figure shows an example of a cross section of a varactor with the depletion layer formed of a p–n junction. This depletion layer can also be made of a MOS or a Schottky diode.
MEMS clock generators are useful in complex systems that require multiple frequencies, such as data servers and telecom switches. MEMS real-time clocks are used in systems that require precise time measurements. Smart meters for gas and electricity are an example that is consuming significant quantities of these devices.