Army

Tunable MEMS inductor

For power and communication systems

Electronics

Upon application of a control signal to the actuator (30), the actuator moves the tuner (24). In doing so, the spacing (19) between the tuner and the magnetic core (14) in the vicinity of the air gap (17) is altered to vary the overall inductance of the device. See the patent for full description of the drawing.

Tunable inductors are used as frequency control elements in communication systems allowing communication networks to be used in different frequency bands. Variable inductors can be used to alter the resonant frequency of inductor-capacitor tanks used in voltage controlled oscillators and other RF circuits and to control bandwidth and cutoff frequency of tunable filters.

In power systems, tunable inductors can change the impedance of matching networks during operation, allowing load matching for more efficient power delivery. But true precise and continuous tuning of inductors is difficult to attain and current approaches only allow a handful of specific inductance levels to be obtained.

In order to create an inductor with true tunability, Army researchers have devised a microelectrical-mechanical system (MEMS) inductor which comprises a magnetic core with an air gap. In order to vary the inductance, the inductor includes a tuner that is moveable relative to the magnetic core in the vicinity of the air gap.

An actuator is attached to the tuner which moves the tuner relative to the magnetic core. The variation of the spacing between the tuner and the magnetic core varies the effective air gap and thereby the inductance. This tunable inductor allows for a tuning ratio an order-of-magnitude greater than that of conventional tuning inductors.

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