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WO2009092605A1 - Condensateur accordable microélectromécanique - Google Patents

Condensateur accordable microélectromécanique Download PDF

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Publication number
WO2009092605A1
WO2009092605A1 PCT/EP2009/000442 EP2009000442W WO2009092605A1 WO 2009092605 A1 WO2009092605 A1 WO 2009092605A1 EP 2009000442 W EP2009000442 W EP 2009000442W WO 2009092605 A1 WO2009092605 A1 WO 2009092605A1
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WO
WIPO (PCT)
Prior art keywords
movable
capacitance electrode
electrode
fixed
capacitor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2009/000442
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English (en)
Inventor
Conor O'mahony
Martin Hill
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
University College Cork
Original Assignee
University College Cork
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from EP08394006A external-priority patent/EP2083431A1/fr
Application filed by University College Cork filed Critical University College Cork
Publication of WO2009092605A1 publication Critical patent/WO2009092605A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
    • H01G5/16—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture using variation of distance between electrodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G5/00—Capacitors in which the capacitance is varied by mechanical means, e.g. by turning a shaft; Processes of their manufacture
    • H01G5/38—Multiple capacitors, e.g. ganged
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H59/00—Electrostatic relays; Electro-adhesion relays
    • H01H59/0009—Electrostatic relays; Electro-adhesion relays making use of micromechanics

Definitions

  • the invention relates' to a microelectromechanical systems (MEMS) tunable capacitor or "varactor” and method of controlling same.
  • MEMS microelectromechanical systems
  • Variable capacitors are used in RF systems to tune the frequency of Local Oscillators (LO), to tune filters and to optimise the impedance match between circuit stages over a range of frequencies.
  • LO Local Oscillators
  • MEMS variable capacitor operates by using electrostatic forces to vary the spacing between the capacitor electrodes.
  • MEMS tunable capacitors offer the possibility to achieve a Q factor in excess of 100 and should achieve tuning ranges comparable to or in excess of semiconductor varactors.
  • MEMS tunable capacitors should handle more power than varactor diodes as they cannot be forward biased. They also exhibit low harmonic distortion as the device inertia prevents it from responding to RF frequencies which are 10 4 times the device resonant frequency.
  • CMOS circuitry and with MEMS switches, HF frequency filters, phase shifters, inductors and micromechanical resonators MEMS variable capacitors could contribute towards the goal of developing a single chip radio system.
  • Basic MEMS capacitors consist of a movable structure suspended over a fixed electrode, thereby comprising a capacitor with one movable plate.
  • Vp DC polarization voltage
  • an attractive electrostatic force between them is induced, causing the upper movable electrode to move downwards towards the bottom electrode, until equilibrium between the electrostatic force and mechanical restoring force of the suspensions, is reached.
  • the restoring force provided by the movable plate anchors no longer balances the electrostatic force and the structure becomes mechanically unstable, causing the top plate to spontaneously collapse onto the bottom electrode.
  • This critical voltage is commonly referred to as the "pull-in voltage", Vpi, and has been well documented in the literature.
  • US6,744,335 describes a MEMS tunable capacitor having a movable structure supported by anchors at both ends. There are three electrodes under the movable structure. Upon application of a tuning voltage across the structure and the outer electrodes the structure deflects so that the central portion of the structure and the central electrode form a tunable capacitor.
  • the arrangement of the electrodes means that a capacitance tuning range of greater than 50% can be achieved.
  • EP 1 562 207 'ST MICROELECTRONICS' discloses a switch that has only two states - on or off. There is no tuning or control associated with the switch and is thus not suitable as a tunable capacitor shaping.
  • the invention is directed towards providing an improved MEMS varactor to overcome the above mentioned problems.
  • a micromechanical capacitor comprising: a substrate; at least one fixed capacitance electrode; at least two fixed bias electrodes, which may be electrically connected; a movable capacitance electrode being disposed opposite said fixed bias electrodes and the fixed capacitance electrode and suspended over said electrodes by a support assembly, such that the movable capacitance electrode and the fixed capacitance electrode form a capacitor; wherein the support assembly allows: a first selective deflection of the movable capacitance electrode to form an arched shape over said fixed capacitance electrode upon the application of an electrostatic force between the movable capacitance electrode and fixed bias electrodes, and a second deflection of the arched movable capacitance electrode upon the application of a second electrostatic force between the movable capacitance electrode and fixed capacitance electrode; such that said first and second deflections control and/or tune the capacitance of said capacitor
  • the two step-process of the invention allows for a curved arched shape using planar, flat fabrication technologies and electrostatic actuation using a first deflection, and then controllably bend this shape by a second deflection so that the movable capacitance electrode has no instability points, thus forming a tunable capacitor.
  • the first and second deflections of the movable capacitance electrode allows that (a) the capacitor is continuously tunable and (b) provides a high accurate tuning range.
  • the first and second deflections are used to modify the capacitance between the movable capacitance electrode and fixed capacitance electrode(s).
  • the tunable capacitor of the present invention can be used to optimise the operation of a radio-frequency circuit at multiple frequencies and power levels.
  • parts of the movable capacitance electrode deflect into contact with the substrate fixed electrode, or topography defined on these regions, upon application of electrostatic forces between the movable electrode and the bias electrodes, and the support assembly limits the deflection of parts of the movable electrode, along one axis of the support assembly, to a displacement less than that of those parts in contact in order to create said arched shape.
  • parts of the fixed electrodes and substrate comprise patterned surfaces with pimples and/or airgaps to reduce dielectric charging, or unwanted effects, that may take place between the movable capacitance electrode and the at least one or more of the bias electrodes.
  • the capacitance is varied during a first phase from an initial value to another intermediate value by application of the electrostatic force between the fixed bias electrodes and the movable capacitance electrode to create said arched shape in the movable electrode, wherein said capacitor is further continuously tunable during a second phase to a final value by application of said electrostatic force between the fixed capacitance electrode and arched movable capacitance electrode such that increase in capacitance is achieved by narrowing and lowering the arched shape of the movable capacitance electrode with respect to the fixed capacitance electrode.
  • a micromechanical capacitor comprising: a substrate; at least one fixed capacitance electrode; and a movable capacitance electrode disposed opposite said fixed capacitance electrode, such that these two electrodes form a capacitor; wherein the movable capacitance electrode may be deflected upon the application of electrostatic forces between the fixed capacitance electrode and the movable capacitance electrode to change the capacitance between the movable capacitance electrode and the fixed capacitance electrode.
  • the capacitor further comprises: at least one fixed bias electrode, the movable capacitance electrode being disposed opposite said fixed bias electrode and the fixed capacitance electrode and suspended by a plurality of rigid and resilient supports, such that the movable capacitance electrode and the fixed capacitance electrode form a capacitor; wherein the supports allow: the selective deflection of the movable capacitance electrode into an arched shape defined by the characteristics of the resilient supports, the movable capacitance electrode, and the fixed bias electrode upon the application of electrostatic forces between the movable capacitance electrode and fixed bias electrode, and subsequent further deflection of the movable capacitance electrode upon the application of electrostatic forces between the movable capacitance electrode and fixed capacitance electrode; wherein these deflections change the capacitance between the movable capacitance electrode and the fixed capacitance electrode.
  • the movable capacitance electrode is deformable so that it can repeatably deflect between a position lying flat over the substrate and an arched shape.
  • the capacitor characteristics provide a tunable capacitance to optimise operation of a radio-frequency circuit at multiple frequencies and power levels.
  • parts of the movable capacitance electrode deflect into contact with the substrate, fixed electrode or topography defined on these regions upon application of electrostatic forces between the movable electrode and the bias electrode, and the resilient supports limit the deflection of some parts of the movable electrode to a displacement less than that of other parts in contact in order to create an arched shape.
  • the movable capacitance electrode is coupled to movable bias electrodes so that the movable capacitance electrode can be deflected by application of voltage between the fixed bias electrodes and the movable bias electrodes without voltage on the movable capacitance electrode.
  • a part of the movable capacitance electrode opposite the fixed capacitance electrode has limited deflection after an electrostatic force is applied between the fixed electrodes and the movable electrode, and this part of the movable electrode can be further deflected towards the fixed capacitance electrode after application of electrostatic force between the fixed capacitance electrode and movable capacitance electrode.
  • capacitance between the movable capacitance electrode and the fixed capacitance electrode is increased by applying electrostatic forces between the movable electrode and the fixed electrode; and this increase in capacitance is achieved by narrowing and lowering arched shape of the movable capacitance electrode.
  • the electrostatic force required to achieve an increase in capacitance is defined by the characteristics of the resilient supports, the movable capacitance electrode, the fixed capacitance electrode, and the substrate topography.
  • the capacitance is switchable during a first phase from an initial value to another intermediate value by application of electrostatic force between the fixed bias electrode and the movable capacitance electrode; and is further continuously tunable during a second phase to a final value by application of electrostatic force between the fixed capacitance electrode and movable capacitance electrode.
  • the capacitor does not exhibit pull-in instability during the tuning phase when said first and/or said second electrostatic forces are applied.
  • the electrodes are configured so that steps of causing selective deflection of the movable capacitance electrode and tuning of the capacitor take place in multiple stages according to characteristics of the structure and of method of application of electrostatic forces between the electrodes.
  • the movable capacitance electrode comprises a beam and the resilient support is located approximately mid-way along the beam.
  • the distance between the opposing surfaces of said movable capacitance electrode and said fixed capacitance electrode are on the order of tenths to tens of micrometres.
  • said fixed electrodes, said capacitance electrodes, and said movable electrode are fabricated from a combination of thin film metal and thin film insulator layers.
  • the resilient support comprises an anchor and an arm extending from the anchor to the movable capacitance electrode.
  • the forces needed to deflect the movable capacitance electrode and to tune the capacitor are defined by the geometrical shape of the movable capacitance electrode and of the bias electrode.
  • the invention provides a switchable, tunable micromechanical capacitor, comprising: a substrate; fixed bias electrode(s); fixed capacitance electrode(s); and a movable capacitance electrode disposed opposite both said fixed electrode(s) such that the movable capacitance electrode and the fixed capacitance electrode forms a capacitor; wherein the movable capacitance electrode has the shape of a beam, is supported at each end by rigid anchors attached to the substrate and is supported by resilient support(s) at approximately its mid-point; wherein there is a fixed capacitance electrode under the centre portion of the movable capacitance electrode, and additional fixed bias electrodes on both sides of the fixed capacitance electrode; wherein the movable capacitance electrode may be selectively switched into an arched shape defined by the characteristics of the resilient supports, the movable capacitance electrode, and the fixed bias electrode upon the application of electrostatic forces between the movable capacitance electrode and fixed bias electrode(s), and; wherein parts of the movable capacitance electrode deflect into contact
  • a microelectromechanical capacitor comprising: a substrate; at least one fixed capacitance electrode; a movable arched capacitance electrode being disposed opposite said fixed bias electrodes and the fixed capacitance electrode and suspended over said electrodes by a support assembly in an arched shape, such that the movable capacitance electrode and the fixed capacitance electrode form a capacitor; wherein the support assembly allows a deflection of the arched movable capacitance electrode upon the application of an electrostatic force between the movable capacitance electrode and fixed capacitance electrode; such that said deflection controls and/or tunes the capacitance of said capacitor.
  • a method of controlling and/or tuning a microelectromechanical capacitor comprising the steps of: suspending a movable capacitance electrode over at least two fixed bias electrodes and a fixed capacitance electrode by using a support assembly, such that the movable capacitance electrode and the fixed capacitance electrode form a capacitor; a first deflecting of the movable capacitance electrode to form an arched shape over said fixed capacitance electrode upon the application of a controllable electrostatic force between the movable capacitance electrode and fixed bias electrodes; and a second deflecting of the arched movable capacitance electrode upon the application of a second controllable electrostatic force between the movable capacitance electrode and fixed capacitance electrode, such that said first and second deflecting steps control and/or tune the capacitance of said capacitor.
  • the fixed or movable electrodes form part of an electrical circuit for transmission of electrical signals.
  • Fig. 1 is a perspective view of a MEMS varactor of the invention.
  • Fig. 2 is a perspective view of the MEMS varactor of the invention where resilient supports lateral to the main device are used to define the deflection profile of the structure under an applied electrostatic force.
  • Fig. 3 is a perspective view of the MEMS varactor of the invention where the structure is fabricated as a planar structure supported by a combination of rigid and resilient supports and additional electrodes are added near the rigid supports to allow selective deflection of the planar movable electrode to form an arched movable electrode.
  • Figs. 4(a), 4(b), 5(a), 5(b), 6(a), 6(b), 7(a) and 7(b) show the varactor at various states for progressively increasing capacitance
  • Fig. 8 is a plot of capacitance vs. tuning voltage (voltage applied between fixed and movable capacitance electrodes);
  • Fig. 9 is a set of plots showing electrode shape as a function of tuning voltage
  • Fig. 10 is a plot of capacitance vs. actuation voltage (voltage between bias electrodes and movable electrode);
  • Figs. 11 and 12 are views of an alternative varactor of the invention;
  • Fig. 13 is a diagram of a system comprising an array of varactors of the invention.
  • Figs. 14 and 15 are plots illustrating operation of the system.
  • Fig. 16 is a perspective view of another embodiment of the MEMS varactor of the invention similar to Fig. 3.
  • a switchable and tunable micromechanical capacitor comprises a substrate, fixed bias electrode(s); fixed capacitance electrode(s); and a movable capacitance electrode opposite the fixed bias and fixed capacitance electrodes.
  • the movable capacitance electrode is suspended by rigid and resilient supports, such that it forms a capacitor together with the fixed capacitance electrode.
  • the supports allow selective deflection of the movable capacitance electrode into an arched shape defined by the characteristics of the resilient supports, the movable electrode, and the fixed bias electrodes upon the application of electrostatic forces between the movable capacitance electrode and the fixed bias electrodes. There is further deflection of the arched, movable capacitance electrode upon the application of electrostatic forces between the movable capacitance electrode and fixed capacitance electrode(s). These deflections are used to modify the capacitance between the movable capacitance electrode and fixed capacitance electrode(s).
  • the tunable capacitance may be used to optimise the operation of a radio- frequency circuit at multiple frequencies and power
  • Parts of the movable electrode may be deflected into contact with the substrate, fixed electrode or topography defined on these regions, and the resilient supports limit the deflection of other parts of the movable electrode to a displacement less than that of the parts in contact in order to create an arched shape.
  • the movable capacitance electrode may be fabricated with an inherently arched shape, the ends of the arched shape being in contact with the substrate or topography defined on the substrate.
  • the movable capacitive electrode may be coupled to movable bias electrodes so that it can be deflected by application of voltage between fixed and movable bias electrodes without voltage on the movable capacitive electrode.
  • a varactor 1 of the invention comprises a substrate 2 on which an arched movable capacitance electrode 3 is supported at its ends by the contact with the substrate 2 or topographical features on the substrate, and there is a fixed capacitance electrode 4 on the substrate 2 under the movable electrode 3.
  • Application of electrostatic forces causes the electrode 3 to deflect so that the arch shape is lowered and narrowed until it is fully in contact with the fixed electrode 4.
  • a varactor as illustrated in Fig. 1 with an additional pair of resilient supports 5 supporting the movable capacitance electrode 3 mid-way along its length.
  • the supports 5 apply an additional level of control over the deflection of the movable capacitance electrode 3 towards the fixed capacitance electrode 4.
  • a varactor 1 of the invention comprises a substrate 2 and a support assembly to support a movable capacitor electrode 3 over the substrate 2.
  • a fixed capacitance electrode 4 and two fixed bias electrodes 7 are positioned on the substrate.
  • the support assembly comprises a pair of fixed base supports 6, one positioned at either end of the movable capacitor electrode 3 to form a main axis such that the movable capacitor electrode can be coupled to the base supports 6 to suspend the movable capacitor electrode over the substrate along the main axis.
  • the base supports are rigid to form fixed anchors 6 and the movable capacitor electrode 3 can be in the form of a beam that is flexible.
  • the support assembly further comprises a pair of fixed posts 5, each post offset from each other and substantially orthogonal to the main axis, positioned approximately midway along a main axis defined by the pair of fixed base supports 6.
  • a resilient flexible member 8 is coupled to the fixed posts 5.
  • the resilient member 8 forms a support such that the movable capacitor electrode 3 is mechanically attached to the resilient member and supported by the resilient member 8.
  • the resilient member 8 can be a single piece to form a bridge to support the movable capacitor electrode or in two separate parts, each part supporting a side of the movable capacitor electrode 3.
  • the spring constant of the resilient member is selected to be in proportion with the spring constant of the movable capacitor electrode (beam) 3.
  • the spring constant of the resilient member is designed such that the application of a first electrostatic force ensures that the part of the movable capacitor electrode in the region supported by the resilient member 8 does not materially bend (in comparsion to unsupported sections of the beam) and come into contact with the fixed electrode, so that upon application of electrostatic forces between the movable electrode and the bias electrodes, the deflection of part of the movable electrode is limited to a displacement less than that of other parts in order to create an arched shape.
  • the distance between the fixed capacitance electrode and fixed bias electrodes 7 can also be designed to take account of the spring constant and bending forces when said first and second electrostatic forces are applied.
  • the spring constant of the resilient member 8 prevents the centre of the beam from being pulled towards the substrate, however the first electrostatic force pulls other parts of the beam 3 towards the substrate to define the arch according to a first aspect of the present invention.
  • the spring constant of the resilient member 8 it is then possible to apply the necessary second electrostatic force such that the second electrostatic force applied controls the shape of the arch over the fixed capacitance electrode to fine tune the microelectromechanical electrode.
  • the preferred substrate material is silicon but may also comprise glass, GaAs or other.
  • the substrate may have been previously worked on, e.g. it may contain CMOS circuitry or bulk micromachined components.
  • the anchors 6 and the movable electrode 3 and the resilient supports 5 are surface micromachined from a conductive material such as aluminium, titanium, gold, or a composite layer such as aluminium/oxide.
  • the electrodes 4, 7, are formed from a conductive metal and may be passivated with an insulating layer such as oxide or nitride.
  • the varactor 1 may be manufactured in an integrated process by carrying out the deposition, etch and selective removal of a series of thin films. This is done using semiconductor-related photolithographic processes obvious to those skilled in the art.
  • Fig. 1 Operation of the varactor shown in Fig.1 , Fig. 2 is the same as for the varactor shown in Fig.3 after sufficient voltage has been applied between the fixed bias electrodes 7, located near the rigid anchors, and the movable electrode 3 to cause the movable electrode to deflect to the arched shape shown in Fig. 4(a).
  • An electrostatic force causes two plates to move together when a voltage is applied between the two plates.
  • the device operation is illustrated in Figs. 4 to 7.
  • the device capacitance is measured between the fixed capacitance electrode 4 and the movable capacitance electrode 3.
  • the tuning voltage is applied between the fixed capacitance electrode 4 and the movable capacitance electrode 3.
  • the capacitance between the fixed capacitance electrode 4 and the movable capacitance electrode 3 increases, and the increase is achieved by a combination of the reduction of the maximum gap between the arched, movable capacitance electrode 3 and fixed capacitance electrode 4 and an increase in the fraction of the movable electrode 3 which is in contact with the substrate 2 or the fixed capacitive electrode 4 or some layers interposed between the movable electrode 3 and the substrate 2 and the fixed capacitive electrode 4.
  • the arched portion of the movable electrode 3 is completely deflected into contact with the substrate 2, the fixed capacitive electrode 4 or some layers interposed between the electrode 3 and the substrate 2 and the fixed capacitance electrode 4. This is illustrated in Fig. 7(a) and 7(b).
  • the structure of the varactor provides a much larger capacitance range than a parallel plate model, from 0.5pF to 2.6pF corresponding to a tuning voltage range of 10V.
  • the structure shown in Fig.3 operates as a two-step tunable capacitor where in the first step of operation, a DC actuation voltage in excess of the pull-in voltage is applied between the fixed bias electrodes 7 and the movable electrode 3.
  • the resultant electrostatic force causes the movable electrode 3 to pull-in over the electrodes 7.
  • the resilient supports ⁇ perpendicular to the movable electrode restrain the centre of the movable electrode from deflecting to contact the surface resulting in an arched-shaped electrode as shown in Fig. 4.
  • a tuning voltage is applied, as described above, between the fixed capacitance electrode 4 and the movable electrode 3 to deflect the arch- shaped centre region of the movable electrode 3, changing the capacitance between the movable electrode 3 and the fixed capacitance electrode 4.
  • the change in capacitance as a result of increasing tuning voltage is shown Fig. 8.
  • FIGs. 1 1 and 12 show the layout and 3D schematic of the structure.
  • the movable electrode is actuated into the arch-shaped position by applying an actuation voltage to switch structures connected to each end of the movable electrode.
  • the switch structure dimensions are required to exert sufficient force on the movable electrode to actuate it to the arch-shaped position. This allows more flexibility in the design of actuation and tunable capacitance parts of the structure.
  • the device actuation is determined by the switch plate area and support tether characteristics and by the length and width of the movable electrode.
  • the required tunable capacitance characteristic can be achieved by setting the movable electrode length and width, the length of the lower centre electrode and the dimensions of the centre resilient supports.
  • the movable capacitance electrode in this example is in the form of a beam that has a length of 600 ⁇ m and width of 40 ⁇ m with lOOxlOO ⁇ m 2 switch plates supported by four tethers of length and width 35 ⁇ m and 5 ⁇ m respectively.
  • the tuned capacitor has a length of 390 ⁇ m and the centre support tethers are 60 ⁇ m in length and lO ⁇ m in width.
  • the structure dimensions can be designed to modify the actuation voltage, base capacitance and tuning characteristic of the device.
  • the two-step tunable capacitor can be integrated in an array of tuned capacitor elements by connecting capacitors in parallel as shown in Fig. 13. If the capacitors VCl and VC2 of fig. 13 have the tuning and switched capacitance characteristics of the Fig. 8 and Fig. 10 respectively and have independent tuning voltage control then the combined capacitors could have the tuning characteristic shown in Fig. 14.
  • the phase of operation indicated as A represents the capacitance of the capacitor pair with both VCl and VC2 in the up position (i.e. no actuation voltage applied to the devices). With an actuation voltage applied to VCl the capacitance of the combined capacitive pair can be tuned by varying the tuning voltage applied to VCl as shown in phase B.
  • the capacitance of the combination can be tuned as shown in Phase C. If the capacitors VCl and VC2 have a common tuning voltage then the capacitance tuning operates in the same phases A, B and C but has the characteristic shown in Fig. 15.
  • FIG 16 shows another embodiment of the micromechanical capacitor according to the present invention wherein the movable capacitance electrode is mechanically coupled to and electrically isolated from movable bias electrodes (10).
  • a coupling beam (9) is used to mechanically couple but electrically isolate the movable capacitance electrode (3) from the movable bias electrodes (10) so that, the movable assembly (3) can be deflected into an arched shape over the fixed capacitance electrode by application of voltage between the fixed bias electrodes and the movable bias electrodes.
  • the movable capacitance electrode is mechanically coupled to and electrically isolated from at least one movable bias electrode positioned on a surface of, or within, the support assembly.
  • the at least two fixed bias electrodes described with respect to the operation of the invention can be electrically connected with each other to form a single electrical connection, however it is to be understood that the function of the at least two fixed bias electrodes is to provide enough electrostatic force to ensure that the movable capacitance electrode forms the arch shape as hereinbefore described with respect to the description and/or drawings.
  • the invention offers a micromechanical varactor realised using a novel structure that can be integrated in an RF system to tune the frequency of Local Oscillators (LO), to tune filters and antennae, to optimise the impedance match between circuit stages over a range of frequencies and to allow antenna optimisation.
  • LO Local Oscillators
  • the device also exhibits advantages over existing devices as it has characteristics such as:
  • the device may be fabricated on the same substrate as other passive or active components or may be integrated in a multi-chip system
  • the device is suitable for wafer scale packaging
  • the performance of the capacitor in RF applications may be for efficient RF power transfer through impedance matching with input and output stages.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Micromachines (AREA)

Abstract

La présente invention porte sur un nouveau type de condensateur microélectromécanique qui permet une première déformation sélective d'une électrode mobile de condensateur pour former une forme au-dessus d'une électrode fixe de condensateur lors de l'application d'une force électrostatique entre l'électrode mobile de condensateur et des électrodes de polarisation fixes, et une seconde déformation de l'électrode mobile de condensateur arquée lors de l'application d'une seconde force électrostatique entre l'électrode mobile de condensateur et l'électrode fixe de condensateur; de sorte que lesdites première et seconde déformations règlent et/ou accordent la capacité dudit condensateur. Grâce aux première et seconde déformations de l'électrode mobile de condensateur, (a) le condensateur est accordable de façon continue et (b) une grande plage d'accord précis est obtenue. Les première et seconde déformations sont utilisées pour modifier la capacité entre l'électrode mobile de condensateur et la ou les électrodes fixes de condensateur. Le condensateur accordable de la présente invention peut être utilisé pour optimiser le fonctionnement d'un circuit radiofréquence à de multiples fréquences et de multiples niveaux de puissance.
PCT/EP2009/000442 2008-01-25 2009-01-23 Condensateur accordable microélectromécanique Ceased WO2009092605A1 (fr)

Applications Claiming Priority (6)

Application Number Priority Date Filing Date Title
US665608P 2008-01-25 2008-01-25
EP08394006A EP2083431A1 (fr) 2008-01-25 2008-01-25 Microsystème électromécanique formant un condensateur variable
IE2008/0053 2008-01-25
IE20080053 2008-01-25
EP08394006.4 2008-01-25
US61/006,656 2008-01-25

Publications (1)

Publication Number Publication Date
WO2009092605A1 true WO2009092605A1 (fr) 2009-07-30

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Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8218228B2 (en) 2009-12-18 2012-07-10 Qualcomm Mems Technologies, Inc. Two-terminal variable capacitance MEMS device
WO2014064688A1 (fr) * 2012-10-22 2014-05-01 Technion Research & Development Foundation Ltd. Batterie électromécanique
US8922974B2 (en) 2009-05-28 2014-12-30 Qualcomm Incorporated MEMS varactors

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1193215A2 (fr) * 2000-10-02 2002-04-03 Nokia Corporation Structure micromécanique
FR2865724A1 (fr) * 2004-02-04 2005-08-05 St Microelectronics Sa Microsysteme electromecanique pouvant basculer entre deux positions stables
US20070268095A1 (en) * 2006-05-16 2007-11-22 Tsung-Kuan Allen Chou Micro-electromechanical system (MEMS) trampoline switch/varactor

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1193215A2 (fr) * 2000-10-02 2002-04-03 Nokia Corporation Structure micromécanique
FR2865724A1 (fr) * 2004-02-04 2005-08-05 St Microelectronics Sa Microsysteme electromecanique pouvant basculer entre deux positions stables
US20070268095A1 (en) * 2006-05-16 2007-11-22 Tsung-Kuan Allen Chou Micro-electromechanical system (MEMS) trampoline switch/varactor

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8922974B2 (en) 2009-05-28 2014-12-30 Qualcomm Incorporated MEMS varactors
US8218228B2 (en) 2009-12-18 2012-07-10 Qualcomm Mems Technologies, Inc. Two-terminal variable capacitance MEMS device
WO2014064688A1 (fr) * 2012-10-22 2014-05-01 Technion Research & Development Foundation Ltd. Batterie électromécanique

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