KR101086680B1 - Variable capacitor and inductor - Google Patents

Abstract

The present invention relates to a variable capacitor and a variable inductor.

The variable capacitor according to the present invention includes a first variable capacitor unit for continuously varying capacitance using a MEMS (Micro Electro Mechanical Systems) electrostatic driving method, and a plurality of unit variable units connected in parallel with the first variable capacitor unit, respectively. A second variable capacitor unit, wherein the unit variable unit includes a unit capacitor and a unit switch connected in series with each other, determines an initial capacitance according to the operation of the unit switches, and varies the initial capacitance according to the operation of the first variable capacitor unit. It is characterized in that it continuously varies within the variable range of the capacitor portion.

According to the present invention, a continuous variable range can be extended by efficiently combining a variable element having a continuous variable range and a variable element having a discontinuous variable range, and thus, a very wide and continuous variable range compared to a conventional variable element. Can be provided.

Micro Electro Mechanical Systems (MEMS), variable capacitors, variable inductors

Description

Variable Capacitors & Variable Inductors {VARIABLE CAPACITOR AND INDUCTOR}

The present invention relates to a variable capacitor and a variable inductor.

The method of continuously varying capacitance using a Micro Electro Mechanical Systems (hereinafter referred to as MEMS) is a method of varying the separation distance between two plates constituting a capacitor (Reference: DJ Young and BE Boser, "A micromachined variable capacitor for monolithic low-noise VCO's" Tech.Digest, 1996 Solid-State Sensor and Actuator Workshop, pp. 86-89, Joon 1996.) , changing the overlap area between two plates. (Reference: Borwick, RL, et.al, "A high Q, large tuning range MEMS capacitor for RF filter system." Sensor and Actuator A, 103, pp.33-41, 2003) , and the dielectric constant of the capacitor (Reference: J.-B. Yoon and CT-C. Nguyen, "A high-Q tunable mmicromechanical capacitor with moving dielectric for RF application," in Technical Digest, IEEE Int. Electron Devices Meeting, Sanfrancisco, can be divided into California, pp. 489-492. DEC. 11-13, 2000.) The.

On the other hand, the method of continuously changing the inductance using MEMS, a method of changing the mutual inductance between the two conductors by changing the distance between the conductors constituting the inductor (Ref. 1: Victor M. Lubecke, Bradley Barber, Edward Chan, Daniel Lopez, Mihal E. Gross and Petter Gammel, "Self-Assembling MEMS Variable and Fixed RF Inductors", IEEE Trans.Microwave Theory and Tech., Vol. 49, No. 11, November 2001.) , (Reference Document 2: Imed Zine-El-Abidine and Michal Okoniewski, "A tunable radio frequency MEMS inductor using Metal MUMs", Journal of Micromechanics and Microengineering 14 (2004) S17-22), and varying the distance between the inductor and the adjacent coil Method of changing the coupling coefficient between coils (US Pat. No. 7,138,898 B2, "Variable Inductor", Investor: Hirosh Ishikawa, Kawasaki) , (Reference: Imed Zine-El-Anidine, Michal Okoniewski and Jhon G) McRory, "Tunable radio frequency MEMS inductors with thermal bimorph actuator ", J. Micromech. Microeng. 15 (2005) 2063-2068) .

As described above, methods for continuously changing capacitance and inductance have a disadvantage in that the amount of change in capacitance and inductance is greatly limited by the continuous mechanical displacement of the driving means of the MEMS.

Figure 1a is a view showing a conventional variable capacitor using a MEMS. FIG. 1B is a diagram illustrating a change in separation distance according to a pull-in voltage of the variable capacitor illustrated in FIG. 1A.

As shown in FIG. 1A, in the case of a variable capacitor whose capacitance is changed by changing the separation distance g _o between two plates 10a and 10b, the change in the separation distance g _o is a phenomenon that is a pull of the MEMS. Due to this there is a limit in changing the separation distance (10a, 10b) between the two plates (10a, 10b). Here, the pull-in phenomenon means that when the applied voltage is more than a predetermined threshold, the equilibrium state of the force is broken between the mechanical restoring force of the MEMS element and the electrostatic force formed by the voltage applied between the two plates, so that the separation distance between the two plates is rapidly increased. It means the phenomenon of becoming smaller. As shown in FIG. 1B, in general, the change in the separation distance g _o between the two plates 10a, 10b is limited to one third of the initial separation distance. As a result, the continuous rate of change of capacitance becomes difficult to exceed 50%.

A method of discontinuously varying capacitance using MEMS is to change the capacitance according to the state of the switch using a capacitive-type switch (see Ref. J. Brank, J. Yao, M. Everber, A. Malczewski, K.Varian, and CLGoldsmith, "RF MEMS-based tunable filters," Int. J. RF Microwave CAE, Vol. 11, pp. 276-284, Sep. 2001.) and DC-type switches By adding an additional metal-insulator-metal (MIM) capacitor, it is possible to divide the capacitance value.

A method of discontinuously varying inductance by using MEMS is a method of increasing the length of a conductor of an inductor using a switch (Korean Patent Application No. 10-2001-0027062 "Variable Inductor Using a High Frequency Microelectromechanical System Switch") (See Shifang Zhou, Xi-Qing Sun and William N Carr. "A monolithic variable inductor network using microrelay with combined thermal and electrostatic actuation", Journal of Micromechanics and Microenginneering 9 (1999) 45-50)) It can be divided into the method of changing the inductance of (Mina Rais-Zadeh, Paul A. Kohl, and Farrokh, "MEMS switched tunable inductors", IEEE J. Microelectromechanical Systems, Vol. 17, No. 1, February 2008.) .

However, these methods of discontinuously changing capacitance and inductance have a disadvantage of changing discontinuously because the capacitance and inductance are changed by using a switch. Therefore, the above-described prior art has a great difficulty in implementing a variable capacitor and a variable inductor having a continuous and very large variable range.

An object of the present invention for solving the above problems is to provide a variable capacitor having a continuous and extended variable range.

It is also another object to provide a variable inductor having a continuous and extended variable range.

The variable capacitor according to the present invention includes a first variable capacitor unit for continuously varying capacitance using a MEMS (Micro Electro Mechanical Systems) electrostatic driving method, and a plurality of unit variable units connected in parallel with the first variable capacitor unit, respectively. And a second variable capacitor unit, wherein the unit variable unit includes a unit capacitor and a unit switch connected in series with each other, and determines an initial capacitance according to the operation of the unit switches, and sets the initial capacitance according to the operation of the first variable capacitor unit. It is characterized by continuously varying within the variable range of the variable capacitor portion.

The first variable capacitor unit,

A lower electrode formed on the insulating substrate, an upper electrode spaced apart from the lower electrode, and a support portion connecting the insulating substrate and the upper electrode and supporting the upper electrode from the insulating substrate so as to be spaced apart from the lower electrode,

A first driving voltage is applied between the lower electrode and the upper electrode, the upper electrode is moved in the direction of the lower electrode by the first electrostatic force between the lower electrode and the upper electrode generated by the first driving voltage, and the lower electrode according to the position movement. It is preferable that the capacitance value change according to the change of the separation distance between the upper electrode and the upper electrode.

It is preferable that a 1st drive voltage is below the pull-in voltage of a support part.

Unit capacitors,

A metal-insulator-metal capacitor including a first metal layer formed on the insulating substrate, an insulating layer formed on the first metal layer, and a second metal layer formed on the insulating layer,

Unit switch,

A MEMS switch including a fixed electrode formed on the insulating substrate, and a floating electrode formed on the fixed electrode so as to face the fixed electrode.

The second metal layer is connected to the upper electrode of the first variable capacitor portion,

The flow electrode is connected to the lower electrode of the first variable capacitor portion,

The second variable capacitor unit,

A second driving voltage is applied between the fixed electrode and the floating electrode, and the moving electrode is moved in the direction of the fixed electrode by a second electrostatic force between the fixed electrode and the floating electrode generated by the second driving voltage, whereby the floating electrode and the first metal layer are moved. It is preferred that this is electrically connected.

Preferably, the second driving voltage is equal to or greater than the pull-in voltage of the floating electrode.

The variable capacitor according to the present invention comprises a first variable capacitor unit for continuously varying capacitance using a MEMS (Micro Electro Mechanical Systems) electrostatic driving method, and a capacitor type MEMS switch connected in parallel with the first variable capacitor unit, respectively. A second variable capacitor unit including a plurality of capacitors, the initial capacitance determined according to the operation of the capacitor-type MEMS switches, and the initial capacitance continuously changed within a variable range of the first variable capacitor unit according to the operation of the first variable capacitor unit; Characterized in that.

The first variable capacitor unit,

A lower electrode formed on the insulating substrate, an upper electrode spaced apart from the lower electrode, and a support part connecting the insulating substrate and the upper electrode and supporting the upper electrode from the insulating substrate so as to be spaced apart from the lower electrode; The first driving voltage is applied between the upper electrodes, the upper electrode moves in the direction of the lower electrode by the first electrostatic force between the lower electrode and the upper electrode generated by the first driving voltage, and the lower electrode and the upper electrode according to the position movement. It is preferable that the capacitance value change in accordance with the change in the separation distance between the livers.

It is preferable that a 1st drive voltage is below the pull-in voltage of a support part.

Capacitor type MEMS switch,

A fixed electrode formed on the insulating substrate, a metal layer electrically insulated from the fixed electrode, a dielectric layer formed on the metal layer, and a floating electrode formed to be spaced apart from the fixed electrode and the dielectric layer,

A second driving voltage is applied between the fixed electrode and the floating electrode, and the moving electrode is positioned in the direction of the fixed electrode by a second electrostatic force generated between the fixed electrode and the floating electrode generated by the second driving voltage, thereby physically moving the floating electrode and the dielectric layer. Contact with

The metal layer is connected to the upper electrode of the first variable capacitor portion,

The flow electrode is preferably connected to the lower electrode of the first variable capacitor unit.

Preferably, the second driving voltage is equal to or greater than the pull-in voltage of the floating electrode.

The variable inductor according to the present invention includes a meander inductor and a plurality of driving electrodes interleaved with the conductor of the meander inductor, and the conductor of the meander inductor is formed by an electric field generated between the meander inductor and the driving electrode. A second variable inductor unit continuously varying inductance as the separation distance therebetween, a second unit switch including a solenoid inductor connected in series with the meander inductor, and a plurality of unit switches for adjusting the coil length of the solenoid inductor And a variable inductor unit, determining an initial inductance according to an operation of a selected unit switch among the plurality of unit switches, and continuously varying an initial inductance within a variable range of the first variable inductor unit according to an operation of the first variable inductor unit. It is done.

The meander inductor is

One side is fixed on the insulating substrate, the other side is formed in a curved form spaced apart from the insulating substrate,

The plurality of drive electrodes,

One side is fixed on the insulating substrate, and the other side is formed in a curved shape spaced apart from the insulating substrate, it is composed of a cross shape between the leads of the meander type inductor,

The first variable inductor unit,

A first driving voltage is applied between the meander type inductor and the driving electrode, and some conductors of the meander type inductor are moved in the direction of the insulating substrate by an electric field between the driving electrode generated by the first driving voltage and some leads of the meander type inductor. , It is preferable that the inductance value changes as the distance between the conductors of the meander inductor changes according to the position shift.

The meander inductor is

Consists of heterogeneous materials, heterogeneous materials are formed to have a stress difference with each other,

The driving electrode is

It is made of a heterogeneous material, the heterogeneous material is preferably formed to have a stress difference with each other.

Preferably, the first driving voltage is equal to or less than the pull-in voltage of the meander type inductor.

A plurality of unit switches,

A fixed electrode formed on the insulating substrate, a drain electrode formed on the insulating substrate and electrically insulated from the fixed electrode and connected to each other, and connected to a position for dividing the coil length of the solenoid type inductor, and spaced apart from the fixed electrode and the drain electrode, respectively. It includes a flow electrode formed to,

A second driving voltage is applied between the fixed electrode and the floating electrode, and the moving electrode is moved in the direction of the fixed electrode by the electrostatic force between the fixed electrode and the floating electrode generated by the second driving voltage, thereby electrically flowing the floating electrode and the drain electrode. It is preferred to be connected.

Preferably, the second driving voltage is equal to or greater than the pull-in voltage of the floating electrode.

The variable capacitor and the variable inductor according to the present invention can extend the continuous variable range by efficiently combining the variable element having the continuous variable range and the variable element having the discontinuous variable range, and thus, the variable capacitor and the variable inductor can be greatly compared with the conventional variable element. It can provide a wide and continuous variable range.

In addition, since the variable range can be continuously extended without increasing the voltage for driving the MEMS driver, the variable capacitor and the variable inductor according to the present invention can be applied to low voltage variable devices suitable for mobile applications such as mobile phones.

In addition, the variable capacitor and the variable inductor according to the present invention, when applied to the front-end of the wireless transceiver, can easily cope with the input resistance of the antenna that changes according to the surrounding environment, and the output resistance of the power amplifier that changes over time, The power transmission efficiency of the radio transceiver can be improved.

In addition, the variable capacitor and the variable inductor according to the present invention can improve the center frequency of the voltage controlled oscillator when applied to the LC-tank of the broadband voltage controlled oscillator.

Before describing embodiments of the present invention, the basic principles of the present invention will be briefly described.

2 is a view illustrating a basic principle of a variable capacitor and a variable inductor according to an embodiment of the present invention.

Conventional variable devices have the advantage of having a continuous variable range, but has the disadvantage that the tuning value (Tuning value) is limited by the mechanical driving means of the MEMS.

On the other hand, the conventional variable elements having a discontinuous variable range have the advantage that the variable range is large because the switch is used, but has a disadvantage that the variable range is discontinuous.

In order to solve the limitations of the above-described conventional variable element, in the embodiment of the present invention, the variable range is continuous, but the variable range is small, and the variable element is discontinuous but the variable element is variable. In addition, a variable element having a very large variable range will be described in detail.

As shown in FIG. 2, the variable element according to the present invention has a characteristic in which the continuous variable range is extended by linearly changing the discontinuous variable range in accordance with the variable capacitance of the variable element having the continuous variable range. do.

Hereinafter, a variable capacitor and a variable inductor according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1. Variable Capacitor

[First Embodiment]

3A is a top view of the variable capacitor 300a showing the overall configuration of the variable capacitor 300a according to the first embodiment of the present invention.

Referring to FIG. 3A, the variable capacitor 300a according to the first embodiment of the present invention is formed on the insulating substrate 310, and the first variable capacitor unit 320 and the second variable capacitor unit 330 connected in parallel are provided. It includes.

First Variable Capacitor 320

1) composition

FIG. 3B is a side view illustrating the first variable capacitor unit 320 shown in FIG. 3A in the direction of A-A '.

3B and 3A, the first variable capacitor unit 320 may include a lower electrode 321 formed on the insulating substrate 310, an upper electrode 323 spaced apart from the lower electrode 321, and an insulating substrate. A plurality of support portions 325a, 325b, 325c, and 325d which connects the 310 and the upper electrode 323 and supports the upper electrode 323 from the insulating substrate 310 to be spaced apart from the lower electrode 321 are provided. Include.

The insulating substrate 310 may be formed of a glass substrate, a ceramic substrate, a silicon substrate, or the like having insulating properties and being formed flat with high precision. Here, when the insulating substrate 310 is conductive like a silicon substrate, it is preferable that an insulating layer such as silicon oxide is formed on the upper surface thereof.

The lower electrode 321 may be formed on the insulating substrate 310. An insulating layer 322 may be formed on the lower electrode 321 to prevent electrical short with the upper electrode 323 during the electrostatic driving. The lower electrode 321 may be connected to the first terminal 327a for receiving the first driving voltage.

The upper electrode 323 is spaced apart from the lower electrode 321 by a support part 325a, 325b, 325c, and 325d.

The supporting parts 325a, 325b, 325c, and 325d are fixed to the insulating substrate 310 so that one side of the upper electrode 323 is spaced apart from the lower electrode 321 so as to be supported by the insulating substrate 310. It is preferable to have a cantilever shape connected to the upper electrode 323. Here, the separation distance between the lower electrode 321 and the upper electrode 323 may be determined according to the height of the support parts 325a, 325b, 325c, and 325d. Any one of the supporting parts 325a, 325b, 325c, and 325d may be connected to the second terminal 327b to apply a first driving voltage to the upper electrode 323.

2) operation

The first variable capacitor unit 320 may continuously vary the capacitance value using a MEMS (Micro Electro Mechanical Systems) electrostatic driving method.

When a first driving voltage is applied between the lower electrode 321 and the upper electrode 323 through the first terminal 327a and the second terminal 327b shown in FIG. 3A, the lower electrode 321 and the upper electrode ( An electrostatic force is generated between the 323 and the upper electrode 323 is moved toward the lower electrode 321 by the electrostatic force. Accordingly, the separation distance between the lower electrode 321 and the upper electrode 323 is changed to change the capacitance value between the lower electrode 321 and the upper electrode 323.

As described above, the first variable capacitor unit 320 may continuously change the capacitance value according to a change in the separation distance between the lower electrode 321 and the upper electrode 323 due to the first driving voltage. In order for the first variable capacitor unit 320 to have a continuously variable range, the first driving voltage is preferably equal to or less than the pull-in voltage of the support units 325a, 325b, 325c, and 325d. Here, the pull-in voltage means that the balance of force is broken between the mechanical restoring force of the supporting parts 325a, 325b, 325c, and 325d and the electrostatic force formed by the applied voltage between the lower electrode 321 and the upper electrode 323. It refers to a voltage such that the separation distance between the electrode 321 and the upper electrode 323 is sharply reduced. During the electrostatic driving of the first variable capacitor unit 320, the support units 325a, 325b, 325c, and 325d serve as mechanical springs for controlling the separation distance between the lower electrode 321 and the upper electrode 323. When the first driving voltage is greater than the pull-in voltages of the supporting parts 325a, 325b, 325c, and 325d, the upper electrode 323 moves rapidly toward the lower electrode 321, thereby rapidly increasing the capacitance. Therefore, it is preferable that the first driving voltage applied to the first variable capacitor unit 320 has a range below the pull-in voltage of the support units 325a, 325b, 325c, and 325d.

Second Variable Capacitor 330

1) composition

3C is a side view illustrating the third unit variable part 330c of the unit variable parts 330a, 330b, and 330c of the second variable capacitor part 330 shown in FIG. 3A in the direction B-B '. The second variable capacitor unit 330 illustrated in FIG. 3A is illustrated to include three unit variable units 330a, 330b, and 330c connected in parallel with the first variable capacitor unit 320, respectively. In addition, the number of unit variable parts 330a, 330b, and 330c may be determined according to an application field.

3C and 3A, the third unit variable part 330c may be formed on the insulating substrate 310 and may include a unit capacitor 331 and a unit switch 333 connected in series with each other.

The unit capacitor 331 may be a metal-insulator-metal capacitor. Preferably, the first metal layer 331a formed on the insulating substrate 310, the insulating layer 331b formed on the first metal layer 331a, and the second metal layer 331c formed on the insulating layer 331b are formed. It may be a MIM capacitor including.

As shown in FIG. 3C, the first metal layer 331a has a larger area than the dielectric layer 331b and the second metal layer 331c so as to be electrically connected to the flow electrode 333c during the electrostatic driving of the unit switch 333. And extended in the unit switch 333 direction.

The unit switch 333 may include a fixed electrode 333a and a flow electrode 333c.

The fixed electrode 333a may be formed on the insulating substrate 310. An insulating layer 333b may be formed on the fixed electrode 333a to prevent electrical short with the flow electrode 333c.

The floating electrode 333c may be formed to face the fixed electrode 333a at a predetermined distance from the fixed electrode 333a. Preferably, one side may be fixed to the insulating substrate 310 and the other side may have a cantilever shape spaced apart from the fixed electrode 333a at a predetermined distance. A dimple 333d may be formed at the other end of the flow electrode 333c so that an electrical short with the fixed electrode 333a does not occur. Here, the dimple 333d may be formed to protrude at a position where the flow electrode 333c is in contact with the fixed electrode 333a during the electrostatic driving of the unit switch 333.

The first variable capacitor unit 320 and the plurality of unit variable units 330a, 330b, and 330c may be connected in parallel with each other. Preferably, the first electrode 327a connected to the lower electrode 321 of the first variable capacitor unit 320 has a flow electrode 333c formed in the second variable capacitor unit 330 through the first electric conductor 329a. ), Respectively. In addition, the second metal layer 331c having the second terminal 327b connected to the upper electrode 323 of the first variable capacitor unit 320 formed in the second variable capacitor unit 330 through the second electric conductor 329b. And may be connected respectively.

2) operation

Assuming that only the third unit variable unit 330c of the plurality of unit variable units 330a, 330b, and 330c shown in FIG. 3A is driven, the fixed electrode 333a and the flow electrode of the third unit variable unit 330c The second driving voltage is applied between 333c. Accordingly, a second electrostatic force is generated between the fixed electrode 333a and the flow electrode 333c, and the flow electrode 333c is bent toward the fixed electrode 333a by the second electrostatic force. Accordingly, the flow electrode 333c may be electrically connected to the first metal layer 331a of the third unit capacitor 333 through the dimple 333d. In this case, the second driving voltage applied between the fixed electrode 333a and the floating electrode 333c is preferably equal to or higher than the pull-in voltage of the floating electrode 333c for the quick switch operation of the floating electrode 333c.

In the case described above, the capacitance value of the second variable capacitor unit 330 may be the capacitance value of the third unit capacitor 331 configured in the third unit variable unit 330c. Here, since the unit variable units 330a, 330b, and 330c are connected in parallel to each other, the total capacitance value of the second variable capacitor unit 330 may be discontinuously changed according to the number of unit switches turned on. In addition, when the capacitance values of the unit capacitors are different, the total capacitance value of the second variable capacitor unit 330 may be discontinuously changed depending on not only the number of unit switches turned on but also which unit switches are turned on.

Accordingly, the capacitance of the second variable capacitor unit 330 varies discontinuously according to the turn-on number of the unit switches and the capacitance value of the unit capacitors, but is discontinuous due to the continuous variable characteristic of the first variable capacitor unit 320. Since the variable range may be continuously changed within the variable period, the variable range of the second variable capacitor unit 330 may have a continuous characteristic.

Table 1 below shows the capacitance C _var of the first variable capacitor unit 320 has a variable range of 0.5 pF, and the capacitances C ₁ , C ₂ , and C _{3 of the} unit capacitors configured in the unit variable units 330a, 330b, and 330c. Is 0.5pF, 1pF, and 2pF, respectively, the capacitance change of the variable capacitor 300a according to the first embodiment of the present invention is shown. Stages 1 to 8 described in Table 1 below divide the variable range of the capacitance according to the operation of the unit switches configured in the second variable capacitor unit 330.

TABLE 1

Referring to Table 1, an initial capacitance value may be determined according to which unit switch operates in the second variable capacitor unit 330 and how many unit switches operate, and the initial capacitance value may be determined by using the first variable capacitor unit ( According to the operation of the 320, it may be constantly increased or decreased within the variable range of the first variable capacitor unit 320.

Meanwhile, when the capacitances C ₁ , C ₂ , and C ₃ of the unit capacitors configured in the unit variable parts 330a, 330b, and 330c are the same, the initial capacitance value may be determined according to the number of unit switches turned on.

Equivalent Circuit

3D is a diagram illustrating an equivalent circuit of the variable capacitor 300a according to the first embodiment of the present invention.

C _var illustrated in FIG. 3D represents the capacitance of the first variable capacitor unit 320, and C ₁ , C ₂ , and C ₃ represent the capacitances of the unit capacitors configured in the unit variable units 330a, 330b, and 330c. Respectively, SW ₁ , SW ₂ , and SW ₃ represent unit switches configured in the unit variable parts 330a, 330b, and 330c, respectively. Here, the number of C ₁ , C ₂ , C ₃ and SW ₁ , SW ₂ , SW ₃ can be adjusted according to the variable range of the application field.

[First Modification]

The variable capacitor 300b according to the first modified example of the present invention has a different configuration than the variable capacitor 300a of the first embodiment. Hereinafter, a detailed description of the first variable capacitor unit 320 according to the first modified example is omitted since the first embodiment has been described, and the second variable capacitor unit 340 will be described in detail. Incidentally, the same components as those in the above-described first embodiment will be denoted by the same reference numerals.

4A is a top view of the variable capacitor 300b showing the overall configuration of the variable capacitor 300b according to the first modification of the present invention.

Referring to FIG. 4A, the variable capacitor 300b according to the first modified example of the present invention may include a capacitor type MEMS switch connected in parallel with the first variable capacitor unit 320 and the first variable capacitor unit 320, respectively. The second variable capacitor unit 340 includes a plurality of 340a, 340b, and 340c.

<Second Variable Capacitor 340>

1) composition

Unlike the unit variable units 330a, 330b, and 330c including the pair of unit capacitors and the unit switches described in the first embodiment, the second variable capacitor unit 340 is formed of a single physical capacitor and a switch. Capacitor type MEMS switches 340a, 340b, and 340c may be included.

FIG. 4B is a side view of the third MEMS switch 340c of the MEMS switches 340a, 340b, and 340c of the second variable capacitor unit 340 shown in FIG. 4A in a direction C-C '.

Referring to FIG. 4B, the third MEMS switch 340c may include a fixed electrode 341, a metal layer 343, a dielectric layer 345, and a flow electrode 347.

The fixed electrode 341 may be formed on the insulating substrate 310. An insulating layer 342 may be formed on the fixed electrode 341 to prevent electrical short with the flow electrode 347.

The metal layer 343 is formed on the insulating substrate 310 and may be electrically insulated from the fixed electrode 341.

Dielectric layer 345 may be formed on metal layer 343.

The flow electrode 347 is formed on the fixed electrode 341 and may be formed to be spaced apart from the fixed electrode 341 at a predetermined distance. Preferably, one side may be fixed to the insulating substrate 310 and the other side may have a cantilever shape spaced apart from the fixed electrode 341 at a predetermined distance. In addition, in order to increase the capacitance between the fixed electrode 341 and the flow electrode 347, the contact area between the flow electrode 347 and the dielectric layer 345 should be large. Accordingly, as shown in FIG. 4A, grooves 347a are formed on the other side of the flow electrode 347 so that the flow electrode 347 can be easily bent during the electrostatic driving of the MEMS switches 340a, 340b, and 340c. Do.

The first variable capacitor unit 320 and the plurality of MEMS switches 340a, 340b, and 340c may be connected in parallel, respectively. Preferably, the first electrode 327a connected to the lower electrode 321 of the first variable capacitor unit 320 is a flow electrode 347 formed in the second variable capacitor unit 330 through the first electric conductor 329a. Can be associated with each other. In addition, the second terminal 327b connected to the upper electrode 323 of the first variable capacitor unit 320 is respectively formed of the metal layer 343 formed in the second variable capacitor unit 330 through the second electric conductor 329b. Can be connected.

2) operation

The MEMS switch 340c may have two types of capacitances, up-state capacitance Cup and down-state capacitance Cdown, depending on whether the switch is operated.

2-1) Up-Capacitance (Cup)

When the second driving voltage is not applied between the fixed electrode 341 and the floating electrode 347, the capacitor Cup has an up-state capacitance Cup between the metal layer 343 and the floating electrode 347. It is desirable to be designed to be small.

2-2) Down-Capacitance (Cdown)

When a second driving voltage is applied between the fixed electrode 341 and the floating electrode 347, an electrostatic force is generated between the fixed electrode 341 and the floating electrode 347. As a result, the flow electrode 347 is bent toward the fixed electrode 341. As shown in FIG. 4C, the flow electrode 347 is in physical contact with the dielectric layer 345. At this time, the flow electrode 347 and the metal layer 343 has a capacitance (Cdown) of the down-state, the value is preferably very large compared to the capacitance (Cup) of the up-state. In addition, the second driving voltage applied between the floating electrode 347 and the fixed electrode 341 maximizes the rapid switching of the floating electrode 347 and the contact area between the floating electrode 347 and the dielectric layer 345. For this purpose, it is preferable that the pull-in voltage of the floating electrode 347 is higher than that. Here, the pull-in voltage means that the equilibrium state of the force is broken between the electrostatic force formed by the applied voltage between the flow electrode 347 and the fixed electrode 341 and the mechanical restoring force of the flow electrode 347, so that it is fixed with the flow electrode 341. It refers to a voltage that allows the separation distance of the electrode 341 to be sharply reduced. The capacitance Cdown between the flow electrode 347 and the dielectric layer 345 may be determined according to the area of the overlapping region between the flow electrode 347 and the dielectric layer 345, which is preferably designed for an application.

Equivalent Circuit

4D illustrates an equivalent circuit of the variable capacitor 300b according to the first modification of the present invention.

C _var shown in FIG. 4D represents a capacitance of the first variable capacitor unit 320 having a continuous variable range, and C ₄ , C ₅ , and C ₆ represent MEMS switches 340a, 340b, and 340c having a discontinuous variable range. Denotes the capacitance of each). Here, the number of MEMS switches 340a, 340b, and 340c may be adjusted according to the variable range of the application field.

As shown in FIG. 4D, the first variable capacitor unit 320 denoted by C _var is preferably connected in parallel with the MEMS switches 340a, 340b, and 340c denoted by C ₄ , C ₅ , and C ₆ , respectively.

The capacitor-type MEMS switches 340a, 340b, and 340c represented by C ₄ , C ₅ , and C ₆ each have an up-state capacitance C _up and a down-state capacitance C _down depending on the on / off operation state. Have). In addition, the first variable capacitor unit 320 denoted by C _var has a continuous capacitance range according to the first driving voltage. Here, the capacitance of the second variable capacitor unit 340 having a discontinuous variable range may be determined by a parallel combination of capacitances C ₄ , C ₅ , and C ₆ of the MEMS switches 340a, 340b, and 340c.

Therefore, between the discontinuous variable section and the section of the second variable capacitor section 340, by the first variable capacitor section 320, so as to be constantly increased or decreased within the variable range of the first variable capacitor section 320. do.

2. Variable Inductor

[First Embodiment]

5A is a top view of the variable inductor 500 showing the overall configuration of the variable inductor 500 according to the second embodiment of the present invention.

Referring to FIG. 5A, the variable inductor 500 according to the second exemplary embodiment of the present invention is formed on an insulating substrate 510, and includes a first variable inductor 520 and a second variable inductor 330 connected in series with each other. 530).

<First Variable Inductor 520>

1) composition

5B is a side view illustrating the first variable inductor unit 520 illustrated in FIG. 5A in the direction D-D ′.

5B and 5A, the first variable inductor unit 520 may include a meander type inductor 521 formed on the insulating substrate 510, and a plurality of driving electrodes 523.

The insulating substrate 510 may be formed of a glass substrate, a ceramic substrate, a silicon substrate, or the like having insulating properties and being formed flat with high precision. In addition, when the insulating substrate 510 is conductive like a silicon substrate, an insulating layer such as silicon oxide is preferably formed on the upper surface thereof.

As shown in FIG. 5B, the meander type inductor 521 may have a shape in which electrical wires are continuously twisted and continuously. In addition, the meander type inductor 521 is formed to have a curved shape in which one side is fixed on the insulating substrate 510, the other side is spaced apart from the insulating substrate 510, and rolled up. desirable. As such, in order for the meander inductor 521 to have a curved shape, the meander inductor 521 is preferably made of a heterogeneous material. Here, the heterogeneous material may be composed of an upper material 521a and a lower material 521b. The upper material 521a may be made of a metal material having high electrical conductivity such as gold, copper, or silver. The lower material 521b may be made of an insulating material such as a silicon oxide film or a silicon nitride film to prevent electrical short with the driving electrode 523. In addition, in order for the meander inductor 521 to have a curved shape, the upper material 521a and the lower material 521b are preferably manufactured to have a stress difference. Here, the upper material 521a may be formed to have a tensile stress, and the lower material 521b may be formed to have a compressive stress.

As shown in FIG. 5A, one end of the meander type inductor 521 may be connected to Port 1, and the other end thereof may be connected to one end of the solenoid inductor 531 configured in the second variable inductor 530.

As illustrated in FIG. 5A, the plurality of driving electrodes 523 may be formed in a shape interposed between portions of the conductive lines of the meander type inductor 521. In addition, as shown in FIG. 5B, the plurality of driving electrodes 523 is fixed on the insulating substrate 510, and the other side of the driving electrodes 523 is spaced apart from the insulating substrate 510 and has a curved shape that is rolled up. It is preferable. As described above, in order for the plurality of driving electrodes 523 to have a curved shape, the plurality of driving electrodes 523 may also be made of different materials. Here, the heterogeneous material may be composed of an upper material 523a and a lower material 523b. The upper material 523a may be made of a material having high resistivity such as silicon carbide and polysilicon to prevent leakage of the RF signal. The lower material 523b may be made of an insulating material such as a silicon oxide film. Thus, the heterogeneous material is preferably formed to have a stress difference. For this purpose, the upper material 523a is formed to have a tensile stress, and the lower material 523b has a compressive stress. It is preferable that it is formed so that.

2) operation

First, when no voltage is applied to the meander type inductor 521 and the driving electrode 523, as shown in FIG. 5B, the meander type inductor 521 and the driving electrode 523 maintain their initial shape.

Next, when a first driving voltage is applied to the meander type inductor 521 and the driving electrode 523, a potential difference is formed between the meander type inductor 521 and the driving electrode 523, thereby forming an electric field. Is formed. A force is formed in the direction of the insulating substrate 510 by an electric field formed between the meander type inductor 521 and the driving electrode 523. As a result, as shown in FIG. 5C, the meander type inductor 521 and the driving electrode ( 523 is bent toward the insulating substrate 510.

The portion where such a phenomenon occurs corresponds to the portion 523a where the conducting wires of the driving electrode 523 and the meander inductor 521 are interleaved. On the other hand, since the lead portion 523b of the meander inductor 521 that is not interlocked with the driving electrode 523 is hardly affected by the driving electrode 523, the initial shape is maintained as shown in FIG. 5D. . Accordingly, the separation distance between the lead portion 523a of the meander inductor 521 with the driving electrode 523 interleaved with the lead portion 523b of the meander inductor 521 unaffected by the driving electrode 523. a) is increased. As a result, mutual inductance changes between two lead portions 523a and 523b of the meander type inductor 521. At this time, in order to continuously change the inductance value, it is preferable that the first driving voltage applied between the meander type inductor 521 and the driving electrode 523 is less than the pull-in voltage of the meander type inductor 521. Here, the pull-in voltage means that the balance between the electrostatic force between the driving electrode 523 and the meander inductor 521 and the mechanical restoring force of the conductor of the meander inductor 521 is broken, and thus the conductor of the meander inductor 521 becomes the insulating substrate 510. It means a voltage to be rapidly moved in the direction. Accordingly, the first variable inductor unit 521 may continuously vary the inductance value according to a change in the separation distance a between the conductor lines according to the driving voltage applied between the meander type inductor 521 and the driving electrode 523. .

<Second Variable Inductor 530>

1) composition

FIG. 5E is a side view illustrating the second variable inductor unit 530 illustrated in FIG. 5A in the direction F-F ′.

5E and 5A, the second variable inductor unit 530 may include a solenoid inductor 531 formed on the insulating substrate 510 and a plurality of unit switches 533, 535, 537, and 539. have. Here, the number of unit switches 533, 535, 537, 539 can be adjusted according to the application.

As illustrated in FIG. 5E, the solenoid inductor 531 may include a bottom lead 531 a formed on the insulating substrate 510, an upper lead 531 c spaced apart from the bottom lead 531 a, and a bottom lead 531 a and an upper portion thereof. The conductive wire 531c may be formed of a pillar wire 531b for electrically and physically connecting the conductive wire 531c. The bottom lead 531a and the top lead 531c may be spaced apart from each other by tens of micrometers by the column lead 531b. The bottom lead 531a, the column lead 531b, and the top lead 531c are preferably made of a metal having high electrical conductivity, such as gold, copper, or silver, for high quality factor of the solenoid inductor 531.

One end of the solenoid inductor 531 may be connected to the other end of the meander type inductor 521. In addition, in the solenoid inductor 531, unit switches 533, 535, 537, and 539 may be connected to positions for dividing the coil length so as to adjust the coil length of the solenoid inductor 531. More specifically, the unit switches 533, 535, 537, and 539 may be connected between the coil length dividing position of the solenoid inductor 531 and Port 2, respectively. The unit switches 533, 535, 537, and 539 are illustrated in FIG. 5E. As shown in FIG. 1, each of the fixed electrode 535a, the drain electrode 535c, and the flow electrode 535d may be included.

The fixed electrode 535a is formed on the insulating substrate 510, and an insulating film 535b may be formed on the insulating electrode 535d to prevent electrical short with the floating electrode 535d.

The drain electrode 535c is formed on the insulating substrate 535c and may be formed to be electrically insulated from the fixed electrode 535a. Each of the drain electrodes configured in the unit switches 533, 535, 537, and 539 may be connected to each other through the pillar conductor 532a and the electrical conductor 532b, and the electrical conductor 532 may be connected to Port 2. In addition, the electrical conductor 532b is preferably spaced apart from the insulating substrate 510 by the pillar conductor 532a as shown in FIG. 5E for high quality factor.

As shown in FIGS. 5E and 5A, the floating electrode 535d may be formed to be spaced apart from the fixed electrode 535a and the drain electrode 535c. More specifically, one side of the solenoid inductor 531 is respectively connected to the position that divides the coil length, the other side has a cantilever shape spaced apart from the fixed electrode 535a and the drain electrode 535c at a predetermined distance. Can be. In addition, a dimple 535e may be formed at the other end of the floating electrode 535d so that an electric short does not occur with the fixed electrode 535a.

The fluid conductor 535d, the column conductor 532a, and the electric conductor 532b are preferably formed of a material having high electrical conductivity, such as gold, copper, and silver. In order to obtain a low contact resistance between the dimple 535e and the drain electrode 535c of the unit switches 533, 532, 537, and 539, the dimple 535e and the drain electrode 535c are made of gold or an alloy of gold and lead. It is preferable that it is formed.

2) operation

When the second driving voltage is applied between the fixed electrode 535a and the floating electrode 535d of the second unit switch 532 among the unit switches 533, 535, 537, and 539 illustrated in FIG. 5A, the fixed electrode 535a is applied. ) And the moving electrode 535d move in the direction of the fixed electrode 535a by the electrostatic force generated between the moving electrode 535d. As a result, the flow electrode 535d is electrically connected to the drain electrode 535c through the dimple 535e. Here, the second driving voltage applied between the fixed electrode 535a and the flow electrode 535d is a flow electrode. It is preferable that the pull-in voltage of the flow electrode 535d is equal to or greater than that for the quick switch operation of 535d. Here, the physical length of the solenoid inductor 531 through which the RF signal passes is determined according to which unit switch of the unit switches 533, 535, 537, and 539 is selected, and accordingly, the inductance value of the second variable inductor unit 530 is determined. This is a discontinuous change.

Accordingly, since the second variable inductor 530 and the first variable inductor 520 are connected in series, the inductance value of the variable inductor 500 according to the second embodiment may be a plurality of unit switches 533, 535, 537 and 539 are discontinuously changed depending on which unit switch is selected and operated, but between the discontinuous variable section and the section, the first variable inductor unit 520 is continuously changed due to the continuous variable characteristic of the variable inductor unit 520. It can vary continuously within the variable range of 520.

Equivalent Circuit

5F is a diagram illustrating an equivalent circuit of the variable inductor 500 according to the second embodiment of the present invention.

In FIG. 5F, L ₁ represents the meander inductor 521 inductance configured in the first variable inductor unit 520, and L ₂ , L ₃ , and L ₄ are optional for the unit switches 533, 535, 537, and 539. When the physical length of the solenoid type inductor 531 is changed by the operation, the inductance corresponding thereto is represented, and SW ₁ , SW ₂ , SW ₃ , and SW ₄ represent the plurality of unit switches 533, 535, 537, and 539. Respectively.

The equivalent circuit illustrated in FIG. 5F is a diagram illustrating a case in which the first variable inductor unit 520 and the second unit switch 535 represented by SW ₂ among SW ₁ , SW ₂ , SW ₃ , and SW ₄ operate. As illustrated in FIG. 5F, the inductance between Port 1 and Port 2 may be represented by the sum of L ₁ and L ₂ by the operation of the second unit switch 535.

Second Modification

FIG. 6A illustrates a first variable inductor 520 having a new structure that may replace the first variable inductor 520 illustrated in FIG. 5A.

Hereinafter, the first variable inductor unit 520 according to the second modification of the present invention will be described in detail. In addition, for the same configuration described through the second embodiment will be given the same reference numerals.

<First Variable Inductor 520>

1) composition

As shown in FIG. 6A, the first variable inductor unit 540 includes an inductor 542 and a driving electrode 545 formed on the insulating substrate 510.

The inductor 542 may include an inner lead 543, an outer lead 544, and an input / output lead 541. The inner conductor 543, the outer conductor 544, and the input / output conductor 541 are preferably electrically and physically connected. Here, the input and output lead 541 may be composed of an input lead 541a and an output lead 541b, the input lead 541a is connected to the Port 1 and the external lead 544 shown in Figure 5a, the output lead 541b is connected to one side of the outer conductor 544 and the solenoid inductor 531, and the inner conductor 543 and the outer conductor 544 may be formed to be connected to each other.

FIG. 6B is a side view of the first variable inductor 540 shown in FIG. 6A in the direction of G-G '.

As shown in FIG. 6B, the inductor 542 may be formed to have a curved shape in which one side is fixed on the insulating substrate 510, the other side is spaced apart from the insulating substrate 510, and rolled up. In addition, the inner conductor 543 and the outer conductor 544 are preferably bent at the same curvature and are on the same line in the G-G 'direction.

As described above, in order for the inductor 542 to have a curved shape, the inductor 542 is preferably made of different materials. Here, the heterogeneous material may be composed of an upper material 543a and a lower material 543b. The upper material 543a may be made of a metal material having high electrical conductivity such as gold, copper, or silver. The lower material 543b may be made of an insulating material such as a silicon oxide film or a silicon nitride film to prevent electrical short with the driving electrode 545. In addition, in order for the inductor 542 to have a curved shape, the upper material 543a and the lower material 543b are preferably manufactured to have a stress difference. Here, the upper material 521a may be formed to have a tensile stress, and the lower material 521b may be formed to have a compressive stress.

As shown in FIGS. 6A and 6B, the driving electrode 545 may be configured to be interposed between the internal conductors 543 of the inductor 542. In addition, as shown in FIG. 6B, the driving electrode 545 is preferably formed to have a curved shape in which one side is fixed on the insulating substrate 510, the other side is spaced apart from the insulating substrate, and rolled up. As such, in order for the driving electrode 545 to have a curved shape, the driving electrode 545 is preferably made of a heterogeneous material. Here, the heterogeneous material may be composed of an upper material 545a and a lower material 545b. The upper material 545a may be made of a material having high resistivity such as silicon carbide and polysilicon to prevent leakage of the RF signal. The lower material 545b may be made of an insulating material such as a silicon oxide film. Thus, the heterogeneous material is preferably formed to have a stress difference. For this purpose, the upper material 545a is formed to have a tensile stress, and the lower material 545b has a compressive stress. It is preferable that it is formed so that.

2) operation

First, when no voltage is applied to the inductor 542 and the driving electrode 545, as shown in FIG. 6B, the inductor 542 and the driving electrode 545 maintain their initial shape.

Next, when a driving voltage is applied between the inductor 542 and the driving electrode 545, a potential difference is formed between the inductor 542 and the driving electrode 545, thereby forming an electric field. The force is formed in the direction of the insulating substrate 510 by the electric field formed between the variable inductor 543 and the driving electrode 545, which causes the variable inductor 543 and the driving electrode 545 as shown in FIG. 6C. It is bent in the direction of the insulating substrate 510. At this time, since the inner conductor 543 is adjacent to the driving electrode 545 rather than the outer conductor 544, the electric field formed between the inner conductor 543 and the driving electrode 545 is the outer conductor 544 and the driving electrode 545. It has a much larger value than the electric field formed between). Accordingly, the inner conductor 543 is moved in the direction of the insulating substrate 510, so that the separation distance from the outer conductor 544 is increased from the initial state.

Accordingly, the inductance of the inductor 542 is continuously changed in accordance with the change of the separation distance between the inner conductor 543 and the outer conductor 544 according to the driving voltage applied between the inductor 542 and the driving electrode 545. You can. In this case, the driving voltage applied between the inductor 542 and the driving electrode 545 is preferably equal to or less than the pull-in voltage of the inner conductor 543 and the outer conductor 544.

The variable capacitor and the variable inductor according to the present invention can extend the continuous variable range by efficiently combining the variable element having the continuous variable range and the variable element having the discontinuous variable range, and thus, the variable capacitor and the variable inductor can be greatly compared with the conventional variable element. It can provide a wide and continuous variable range.

In addition, since the variable range can be continuously extended without increasing the voltage for driving the MEMS driver, it can be applied to low voltage variable devices suitable for mobile applications such as mobile phones.

In addition, when applied to the front-end of the wireless transceiver, it is possible to easily cope with the input resistance of the antenna, which changes according to the surrounding environment, and the output resistance of the power amplifier, which varies with time, thereby improving the power transmission efficiency of the wireless transceiver. have.

In addition, when applied to the LC-tank of a wideband voltage controlled oscillator, it is possible to improve the center frequency of the voltage controlled oscillator.

As described above, those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without changing the technical spirit or essential features.

Therefore, the embodiments described above are to be understood in all respects as illustrative and not restrictive, and the scope of the present invention is indicated by the following claims rather than the above description, and the meaning and scope of the claims And all changes or modifications derived from the equivalent concept should be interpreted as being included in the scope of the present invention.

1A and 1B show a conventional variable capacitor using MEMS.

FIG. 1B is a view illustrating a change in separation distance according to a pull-in voltage of the variable capacitor illustrated in FIG. 1A.

2 is a view illustrating a basic principle of a variable capacitor and a variable inductor according to an embodiment of the present invention.

3A to 3B are views showing the configuration of a variable capacitor according to a first embodiment of the present invention.

3D is an equivalent circuit diagram of a variable capacitor according to a first embodiment of the present invention.

4A to 4C are views illustrating a configuration of a second variable capacitor unit according to a first modification of the present invention.

4D is an equivalent circuit diagram of a variable capacitor according to a first modification of the present invention.

5A to 5E are views showing the configuration of a variable inductor according to a second embodiment of the present invention.

5F shows an equivalent circuit of a variable inductor according to a second embodiment of the present invention.

6A to 6D are views showing the configuration of the first variable inductor unit according to the second modification of the present invention.

********* Explanation of symbols for the main parts of the drawings *********

300a, 300b: variable capacitor

320: first variable capacitor unit

330 and 340: second variable capacitor unit

500: variable inductor

520 and 540: first variable inductor unit

530: second variable inductor

Claims (16)

delete delete delete delete delete delete delete delete delete delete A meander inductor, and a plurality of driving electrodes interleaved with the conductors of the meander inductor, wherein the distance between the conductors of the meander inductor is increased by an electric field generated between the meander inductor and the driving electrode. A first variable inductor unit continuously changing inductance as it changes; And A second variable inductor unit including a solenoid inductor connected in series with the meander type inductor, and a plurality of unit switches for adjusting coil lengths of the solenoid inductor; Determining an initial inductance according to an operation of a selected unit switch among the plurality of unit switches, continuously varying the initial inductance within a variable range of the first variable inductor unit according to an operation of the first variable inductor unit, The plurality of unit switches, A fixed electrode formed on the insulating substrate; A drain electrode formed on the insulating substrate and electrically insulated from the fixed electrode and connected to each other; And A flow electrode connected to each of the positions for dividing the coil length of the solenoid type inductor, the flow electrode being formed to be spaced apart from the fixed electrode and the drain electrode, A second driving voltage is applied between the fixed electrode and the floating electrode, and the moving electrode is moved in the direction of the fixed electrode by an electrostatic force between the fixed electrode and the floating electrode generated by the second driving voltage. And a flow electrode and the drain electrode are electrically connected to each other. The method of claim 11, The meander type inductor, One side is fixed on the insulating substrate, the other side is formed in a curved form spaced apart from the insulating substrate, The plurality of drive electrodes, One side is fixed on the insulating substrate, the other side is formed in a curved shape spaced apart from the insulating substrate, it is composed of a shape sandwiched between a portion of the lead of the meander inductor, The first variable inductor unit, A first driving voltage is applied between the meander inductor and the driving electrode, and a part of the conductor of the meander inductor is caused by an electric field between the driving electrode generated by the first driving voltage and a part of the conductor of the meander inductor. The inductance value is moved in the direction of the insulating substrate, the inductance value changes in accordance with the change in the separation distance between the leads of the meander inductor according to the position movement. The method of claim 12, The meander type inductor, Consists of heterogeneous materials, the heterogeneous materials are formed to have a stress difference with each other, The driving electrode is made of a heterogeneous material, the heterogeneous material is formed to have a stress difference with each other, variable inductor. A meander inductor, and a plurality of driving electrodes interleaved with the conductors of the meander inductor, wherein the distance between the conductors of the meander inductor is increased by an electric field generated between the meander inductor and the driving electrode. A first variable inductor unit continuously changing inductance as it changes; And A second variable inductor unit including a solenoid inductor connected in series with the meander type inductor, and a plurality of unit switches for adjusting coil lengths of the solenoid inductor; Determining an initial inductance according to an operation of a selected unit switch among the plurality of unit switches, continuously varying the initial inductance within a variable range of the first variable inductor unit according to an operation of the first variable inductor unit, The meander type inductor, One side is fixed on the insulating substrate, the other side is formed in a curved form spaced apart from the insulating substrate, The plurality of drive electrodes, One side is fixed on the insulating substrate, the other side is formed in a curved shape spaced apart from the insulating substrate, it is composed of a shape sandwiched between a portion of the lead of the meander type inductor, The first variable inductor unit, A first driving voltage is applied between the meander inductor and the driving electrode, and a part of the conductor of the meander inductor is caused by an electric field between the driving electrode generated by the first driving voltage and a part of the conductor of the meander inductor. The positional movement in the direction of the insulating substrate, the inductance value is changed in accordance with the change in the separation distance between the leads of the meander inductor according to the position movement, And the first driving voltage is equal to or less than a pull-in voltage of the meander inductor. delete The method of claim 11, The second driving voltage is greater than or equal to the pull-in voltage of the floating electrode.

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