Patent Grant
10784066
The present disclosure relates to radio frequency (RF) switches, or more particularly RF micro electromechanical system (MEMS) switches.
RF MEMS switches have previously been employed in microwave and millimeter-wave communication systems, such as in signal routing for transmit and receive applications, switched-line phase shifters for phased array antennas, and wide-band tuning networks for modern communication systems. MEMS is typically a silicon-based integrated circuit technology with moving mechanical parts that are released by means of etching sacrificial silicon dioxide layers.
The example switch 100 is formed over a coplanar waveguide 101 in which a signal line 110 is formed between ground planes 102, 104 of a substrate 105. The signal line 110 includes an input port 112 and an output port 114 formed on opposing ends of the substrate 105. The cantilever switch includes a post 120 or anchor affixed to the substrate 105 and includes an extension extending over the substrate in a direction perpendicular to the signal line 110. The extension of the cantilever includes a bottom layer 125 of dielectric material, such as silicate, and a top layer 130 of conductive material 130, such as gold. The cantilever further includes a contact bump or dimple 135 positioned underneath the bottom dielectric layer 120 and in alignment with the signal line ports 112, 114. Thus, when the cantilever is bent downward, the dimple 135 contacts the signal line 110, thereby connecting the input and output ports 112, 114.
The switch 100 also includes an electrostatic actuator (not shown) for actuating the cantilever by applying or removing a DC bias voltage between the cantilever and the ground 102, 104 of the coplanar waveguide 101. The cantilever bends downward and upward, in a direction towards and away from the signal line respectively, in response to the applied voltage from the actuator. Other RF MEMS switches may rely on a lateral movement in order to bring the moveable part of a cantilevered switch towards or away from a contact. Each of the moving part and contact may be metal (resistive switch), or one may be metal while the other is dielectric (capacitive switch).
RF MEMS switches, compared to their solid state semiconductor counterparts, exhibit several important advantages such as: superior linearity; low insertion loss; and high isolation. In particular, RF MEMS switches at millimeter wave frequencies are suitable for use in modern telecommunication systems, especially for automotive radar systems, 5G wireless communication, short range indoor microwave links, wide-band transceivers, phased array systems and high precision instrumentation applications.
Compared with PIN diodes and field-effect transistor (FET) switches, RF MEMS switches have been found to offer lower power consumption, higher isolation, lower insertion loss and higher linearity at a lower cost.
RF MEMS switches can encounter several drawbacks, including high actuation voltages, high insertion loss, and poor return loss. These drawbacks are a challenge to designing MEMS switches for operation in the millimeter wave frequency range.
Another problem with RF MEMS switch performance is that it is prone to electromechanical failure after several switching cycles, especially under hot switching conditions. For instance, the switch may fail due to static friction (or stiction) buildup. When the moveable part of the switch is pulled into contact with another component of the system (e.g., a signal line), the static friction can cause the switch to become stuck. It may require a high voltage to overcome the stiction force. But at low voltage, the switch can remain “welded” to the component.
An aspect of the present disclosure is directed to a microelectromechanical switch including: a signal line having each of an input port and an output port, the signal line formed on a substrate between a first ground plane and a second ground plane formed on the substrate; a primary deflectable beam having a first end, a second end, and a deflectable middle portion between the first and second ends, the first end supported by a first post formed over the first ground plane, the second end supported by a second post formed over the second ground plane, and the middle portion of the primary deflectable beam positioned over at least a portion of the input port and at least a portion of the output port, whereby the deflectable middle portion contacts each of the input port and output port when deflected downward; one or more defected ground structures formed in each of the first ground plane and the second ground plane; and for each defected ground structure, a corresponding secondary deflectable beam positioned over the defected ground structure. The switch may further include a first actuator coupled to the primary deflectable beam and configured to apply a first bias voltage to the primary deflectable beam, whereby the first bias voltage causes the primary deflectable beam to deflect downward toward the signal line, and a second actuator coupled to each of the one or more secondary deflectable beams and configured to apply a second bias voltage to each of the secondary deflectable beams, whereby the second bias voltage causes each secondary deflectable beam to deflect downward toward its corresponding defected ground structure.
In some examples, each of the defected ground structures may include a plurality of slots etched into the ground plane and forming a spiral. Also, in some examples, each ground plane may include a first defected ground structure and a second defected ground structure, the length and width of the second defected ground structure being shorter than the length and width of the first defected ground structure. Also, in some examples, the input and output ports may be formed along a first axis of the switch, with the primary deflectable beam extending from the first post to the second post along a second axis perpendicular to the first axis, and the secondary deflectable beams extending in a direction parallel to the first axis.
In some examples, each of the secondary deflectable beams may have a first end supported by a first secondary post and a second end supported by a second secondary post. A bottom surface of each secondary deflectable beam may be suspended over the ground plane and corresponding defected ground structure by its first and second secondary posts. An upper surface of the primary deflectable beam may be less than 4 microns higher than the surface of the signal line. An upper surface of each secondary deflectable beam may be less than 2.5 microns higher than the surface of the ground plane.
In some examples, the middle portion of the primary deflectable beam may have a plurality of perforations forming a lattice structure. The perforations may increase the flexibility of primary deflectable beam. Each corner of the middle portion may extend outward toward the first or second end in a serpentine pattern. The extended corners of one side of the middle portion may meet at the first end, while the extended corners of the other side of the middle portion meet at the second end. In this regard, the primary deflectable beam may be less than 150 μm long and yet sufficiently flexible for the middle portion to deflect 1 μm or more downward. The downward deflection may be in response to application of a bias voltage, such as a voltage of about 17 volts or less. Additionally or alternatively, each secondary deflectable beam may include a plurality of perforations forming a lattice structure. The perforations may increase flexibility of secondary deflectable beam.
In some examples, the switch may achieve insertion loss of less than −2 dB and isolation of greater than −20 dB between 75 GHz and 130 GHz. Also, in some examples, actuation of the primary deflectable beam and non-actuation of the secondary deflectable beams may result in isolation between the input and output ports of about −24 dB or better between 75 GHz and 130 GHz. Similarly, actuation of the secondary deflectable beams and non-actuation of the primary deflectable beam may result in insertion loss of −1.5 dB or better between 75 GHz and 130 GHz.
Another aspect of the present disclosure is directed to a microelectromechanical switch including: a signal line comprising each of an input port and an output port, the signal line formed on a substrate between a first ground plane and a second ground plane formed on the substrate; a beam positioned above the signal line, the beam being configured to move in an out-of plane direction relative to the signal line and ground planes, and including an upper contact configured to contact the signal line; and a metamaterial structure included in one of the upper contact and the signal line. In some examples, the metamaterial structure may include concentric split rings. Also, in some examples, the metamaterial structure has an effective permittivity of 0.05 or less over a bandwidth of at least 50 GHz. Further, in some examples, the metamaterial structure exhibits each of a primarily-reflective property and a primarily-transmissive property within a bandwidth of less than 100 GHz. Yet further, in some examples, the metamaterial structure may generate a repulsive Casimir force for separating the beam and signal line
In some examples, the switch may be a resistive switch. In such examples, the metamaterial structure may be included in the upper contact. An upper surface of the input and output ports of the signal line may be conductive. The beam further may include a bottom conductive layer to contact each of the input and output ports when the beam is actuated. The metamaterial structure may be embedded in the bottom conductive layer. Also, in some examples, the beam may further include a dielectric layer formed above the bottom conductive layer, and a top conductive layer formed above the dielectric layer. The bottom conductive layer may have a permittivity less than that of the dielectric layer. The top conductive layer may have a permittivity greater than that of the dielectric layer. Each of the top and bottom conductive layers may be made of gold. The dielectric layer may be made of one of silicon nitride or silicon mononitride. Also, in some examples, the switch may further include one or a combination of a second metamaterial structure embedded in the top conductive layer, and a top dielectric layer over the top conductive layer having a common composition as the dielectric layer between the top and bottom conductive layers. Each of the top dielectric layer, the top conductive layer, and the dielectric layer may have a length equal to a length of the beam, while the bottom conductive layer has a length equal to a width of the signal line. In some examples, the switch may have an isolation of greater than about −15 dB between 80 GHz and 100 GHz when the switch is off, and an insertion loss of less than about −1 dB between 80 GHz and 100 GHz when the switch is on.
In other examples, the switch may be a capacitive shunt switch. The metamaterial structure may be included in the signal line. The switch may further include a deflectable beam having a first end, a second end, and a deflectable middle portion between the first and second ends, the first end supported by a first post formed over the first ground plane. The second end may be supported by a second post formed over the second ground plane, and the middle portion of the deflectable beam may be positioned over the metamaterial structure in the signal line. The deflectable middle portion may contact the signal line when deflected downward.
In some examples, the switch may further include a conductive strip extending from the first ground plane towards the signal line. The conductive strip may extend to the opposing end of the signal line such that it is positioned at least partially on top of the metamaterial structure. In some instances, the first conductive strip may extend from the first ground plane to the second ground plane.
In some examples, the signal line may include a first metamaterial structure adjacent to the input port and a second metamaterial structure adjacent to the output port. The switch may further include a first conductive strip extending from the first ground plane towards the second ground plane and positioned at least partially on top of the first metamaterial structure, and a second conductive strip extending from the first ground plane towards the second ground plane and positioned at least partially on top of the second metamaterial structure.
In some examples, the switch may include each of a bottom dielectric layer formed on the substrate, each of the ground planes and signal line being formed on the bottom dielectric layer, a conductive post extending downward from one of the ground planes into the bottom dielectric layer, and a conductive beam extending outward from the conductive post towards the signal line. The conductive beam may extend to the opposing end of the signal line such that it is positioned at least partially underneath the metamaterial structure. Additionally, in some examples, the switch may have an isolation of greater than about −15 dB between 30 GHz and 100 GHz when the switch is off, and an insertion loss of less than about −1 dB between 30 GHz and 100 GHz when the switch is on.
The present disclosure provides for RF MEMS switches having improved signal characteristics and reduced vulnerability to stiction.
In the example of
In the example of
The actuation voltage can be further reduced to less than 37V by providing a different perforation arrangement. In the example of
The dimensions of the switch shown in
The switch of
Nonetheless, the isolation characteristics of the shunt switches of
Characteristics of the spiral shaped slots are shown in greater detail in
The DGS structure also includes an opening connecting the beginning of the first slot to the end of the fourth slot. Thus, the first four slots of the DGS structure of
The switch of
Despite the improved isolation characteristics of the switch of
The switch 1100 of
A side view of a single DGS structure of the switch 1100 is shown in
The beam 1151 is connected to an actuator (not shown) to supply a bias voltage, which runs from the beam 1151 to the ground plane 1102 via the feet 1162, 1164. Applying the bias voltage causes the beam 1151 to deflect downward towards the ground plane 1102, thereby affecting the capacitive characteristics of the DGS structure 1131. The amount of voltage applied to the switch 1101 may be continuously variable, and thus the capacitive characteristics of the DGS structure (and its effect on the main MEMS switch of the device) can be varied or tuned.
It has been found that the switch arrangement of
The particular resonance frequency of the DGS structure can vary depending on the height of the air gap between the ground plane and the beam.
An example MEMS shunt switch with DGS structures and overlaid secondary switches is shown in more complete form in
A first DGS structure 1731 and a second DGS structure 1732 are formed in the first ground plane 1702. A third DGS structure 1733 and a fourth DGS structure 1734 are formed in the second ground plane 1704. The first and third DGS structures 1731, 1733 have mirror symmetry along a lengthwise axis X of the primary switch 1710, and are a similar shape. The second and fourth DGS structures 1732, 1734 also have mirror symmetry along a lengthwise axis X of the primary switch 1710, and are a similar shape.
In the example of
In some examples, the dimensions of the different DGS structures can be characterized in terms of lengths “a,” “a1,” and “b,” whereby a is the length of the third slot in one DGS structure, a1 is the length of the third slot in the other DGS structure, and b is the difference in length between the second and third slots in one or both size DGS structures. In some examples, the differently sized DGS structures may be designed to have the same value “b,” such that the difference between the second and third slot lengths is the same for each structure even when the structures are of different sizes.
Each DGS structure is overlaid by a respective secondary shunt switch 1741, 1742, 1743, 1744. Each secondary shunt switch is connected to its respective ground line, and is suspended over its respective DGS structure with an air gap in between. The secondary shunt switches are rectangular, each of the secondary switches positioned lengthwise parallel to the signal line 1720 and perpendicular to the primary shunt switch 1710. The secondary switches positioned above the first DGS structure 1731 and the third DGS structure 1733 have a mirror symmetry with the secondary switches positioned above the second DGS structure 1732 and the fourth DGS structure 1734 along a lengthwise axis X of the primary switch 1710. Additionally, the secondary switches positioned above the first DGS structure 1731 and the second DGS structure 1732 have a mirror symmetry with the secondary switches positioned above the third DGS structure 1733 and the fourth DGS structure 1734 along a lengthwise axis Y of the signal line 1720. The secondary shunt switches 1741, 1742, 1743, 1744 are also perforated. In the example of
In the example of
In operation, the primary switch 1910 may be either ON (bias voltage provided from the first actuator 1962) or OFF (no bias voltage provided by the first actuator 1964). When the primary switch is ON, the primary switch beam deflects downward, resulting in a large shunt capacitance that blocks RF signals from propagating along the signal line 1920. When the primary switch is OFF, the primary switch beam deflects back upward (at rest), reducing the shunt capacitance and permitting RF signals to propagate along the signal line 1920.
When the primary switch 1910 is OFF, the secondary switches 1941-1944 may be turned ON in order to negate the effects of the DGS structures towards insertion and return loss. A bias voltage is applied from the second actuator 1964 to each of the secondary switches 1941-1944, thereby causing the switches to deflect downward toward the DGS structures and create a shunt capacitance blocking the effects of the DGS structure.
Returning to
In the examples of
As seen from the attenuation characteristics of
Table 1 below provides a summary of the actuation voltage, isolation and insertion loss characteristics for the above-described switch designs with air gaps (and cantilever beam heights) of about 2.5 μm:
Measurements are provided for the above example switches and designs. However, it will be readily appreciated that the particular dimensions of the RF MEMS switches, structures, and waveguide components may be altered without deviating from the core concepts of the present disclosure. For instance, the substrate, ground plane and signal line may be made longer or shorter, wider or narrower, and thicker or thinner Additionally, the primary and secondary switches may be designed in different shapes having different lengths, different widths, or different patterns, such as to enable a desired amount of deflection. Similarly, the air gap between switches and the components positioned underneath may be altered. And the shape and size of the DGS structures may also be altered.
The switch operations described above contemplate actuating either the primary switch but not the secondary switches, or actuating the secondary switches but not the primary switch. However, it will be readily appreciated that other forms of operation are possible. For example, in some cases, improved isolation characteristics may be achieved by providing a bias voltage to all of the primary and secondary switches.
Overall, it is shown that providing both the DGS structures and secondary switches can achieve improvements in both insertion loss and isolation. These dual improvements are in contrast to the tradeoffs conventionally seen when using either only a shunt switch (good insertion loss, poor isolation) or only a DGS structure (improved isolation, but worse insertion loss). These findings are further summarized in the charts of
As noted above, the proposed combination of a primary shunt switch, DGS structures and secondary shunt switches, is shown to behave like a metamaterial. In addition to this solution, it is also proposed to improve stiction of the MEMS switch using metamaterial layers within the design of the switch contacts, as described in greater detail herein.
It is possible to reduce the likelihood of stiction by increasing the bias voltage applied to the switch. Alternatively, instead of increasing bias voltage, the electric field of the switch can be increased by distancing the top electrode from ground. This can be accomplished, for example, by sandwiching the conductive layer (e.g., gold) between two dielectric layers (e.g., silicon oxynitride).
As a further alternative, the beam can be modified to maximize its restoring force without having to increase the bias voltage. Improved restoring force is influenced by such parameters as increased plate size, shortened beam length, or increased dielectric thickness.
In addition to controlling the distance between the electrode and ground and controlling the structural parameters of the switch contacts, it is also contemplated in the present disclosure to weaken or reverse the forces applied to the switch contacts due to their proximity. These forces are described in greater detail using the arrangements illustrated in
In the case of two uncharged metal plates positioned closely to one another and in parallel, a force causing the two plates to move towards one another has been observed. This force is referred to as the Casimir force. The Casimir force originates from the interaction of the surfaces with the surrounding electromagnetic spectrum, and exhibits a dependence on the dielectric properties of the surfaces and the medium between the surfaces. Casimir forces between macroscopic surfaces have the same physical origin as atom-surface interactions and those between two atoms or molecules (van de Waals forces), because they originate from quantum fluctuations.
The Casimir force is known to be proportional to the effective permittivity of metal plates. Therefore, by decreasing the effective permittivity on the metal planes, the Casimir force too can be decreased. This can result in reduced forces preventing the plates from separating from one another, thus at least partially mitigating the stiction problem observed in MEMS switches.
However, aside from reducing the Casimir force by reducing permittivity between plates, a repulsive force can actually be generated between the planes if the effective permittivity is sufficiently decreased, such as by using metamaterials. This repulsive force is sometimes referred to as the “repulsive Casimir force,” and in the present application can further be used to resolve the stiction issue by repelling the contacts from one another. Thus, generating a repulsive Casimir force can result in even less of a liability for the contacts to effectively become “welded” together due to stiction.
Casimir interactions (both attractive and repulsive forces) may be realized in engineered materials such as silicon crystals, which can be used for levitation, microwave switches, MEMS oscillators and gyroscopes. Casimir interaction is attractive in magnetic Metamaterials made of nonmagnetic meta-atoms. In contrast, intrinsically magnetic meta-atoms could potentially lead to Casimir repulsion. Chiral Metamaterials made of metallic and dielectric metaatoms are good candidates for Casimir repulsion. One approach is to engineer the material combinations that give rise to Casimir repulsive forces. For example, Casimir repulsive forces have been observed between multilayer walls made of alternating layers of a topological insulator (TI) and a normal insulator. The Casimir repulsion under the influence of the magnetization orientation in the magnetic coatings on TI layer surfaces, the layer thicknesses, and the topological magnetoelectric polarizability, has been demonstrated. For the multilayer structures with parallel magnetization on the TI layer surfaces, it is feasible to enhance the repulsion by increasing the TI layer number, which is due to the accumulation of the contribution to the repulsion from the polarization rotation effect occurring on each TI layer surface. Generally, in the distance region where there is Casimir attraction between semi-infinite TIs, the force may turn into repulsion in the TI multilayer structure, and in the region of repulsion for semi-infinite TI, the repulsive force can be enhanced in magnitude, the enhancement tends to a maximum while the structure contains sufficiently many layers.
In general, Casimir forces between macroscopic surfaces entail separations typically >0.1 um where retardation plays an essential role, while van der Waals forces refer to separations <0.01 um where retardation is insignificant. Advances in theoretical studies and experimental techniques have enabled examination of the Casimir force beyond the configuration of two parallel perfect metal plates. Novel materials and shapes of the interacting bodies enable new opportunities for applications and, at the same time, pose new open questions. On the theoretical side, MTM-Inspired structures can produce a powerful Casimir Effect, which will allow transportation of matter; this implies, in principle, that the effect can be used to attract or push away physical matter. A further complexity of the Casimir force potentially allows greater opportunity for neutralization or for use of Casimir forces to partially cancel Van Der Waals forces. It is to note that polaritonic involvement causes a repulsive Casimir force between Metal and MTM structures. For example, binding TM polaritons govern at shorter distance, inundated by joint repulsion due to anti-binding TM and TE polaritons. Thus, in the case of a hybrid arrangement, surface plasmons can be indicative of the strength and sign of the Casimir force.
In the application of an RF MEMS switch structure, the switch may include a deflectable beam having a shorting bar positioned on a surface of the beam and aligned with the contact of the signal line. The shorting bar may be made of metal, such as a thin layer of gold foil located. When the shorting bar touches the signal line, the metal-to-metal contact surfaces may stick to one another in the form of strong adhesion. This adhesion causes undesirable stiction problems, which in turn may cause the switch to be electrically shorted, and it may take a considerable amount of force to separate the shorting bar from the signal line. The RF MEMS switch generally relies on stresses accumulating in the beam as a result of the beam's deflection in order to counteract the adhesive forces and to return the beam back to its at-rest or equilibrium position. This counteractive force, which is the sum of the stresses in the beam, is referred to as the restoring force that “restores” the beam to its at-rest position. However, this force is not always sufficient to counteract adhesive forces between the metal contacts. By providing a metamaterial structure between the metal contacts, the restoring force of the beam can be supplemented using the repulsive Casimir force generated when the shortening bar touches or comes within proximity to the signal line.
The Casimir force can be controlled by providing a permittivity gradient in the contact of the deflectable beam. The permittivity gradient can be provided by interfacing three layers of media in either decreasing or increasing order of permittivity. In
The switch is formed in a coplanar waveguide 3201 positioned having two ground planes 3202 and 3204 formed above a substrate 3205. The ground planes are separated by a channel and a signal line 3210 is formed lengthwise in the channel. The signal line 3210 includes each of an input port 3212 through which a signal is received (arrow in) and an output port through which the signal is transmitted (arrow out).
The switch includes a cantilevered beam that moves in and out of the plane of the coplanar waveguide in order to move in and out of contact with the signal line 3210. The beam includes multiple layers. In the example of
The ground planes 3202, 3204 and signal line ports 3212, 3214 may be separated from the substrate 3205 by a thin layer of dielectric 3250, such as SiN or SiO2.
Operation of the switch may be controlled by moving an anchor 3270 to which the beam is attached in and out of the plane of the coplanar waveguide 3201. In this case, the ground line 3202 may include a hole 3260 though which a post or anchor 3270 of the beam is positioned. Moving the post 3270 up and down can result in the contacts of the switch separating or contacting one another, respectively.
In the example of
The overall height of the beam when in the closed position may be about 5 μm, relative to the dielectric surface on which the ground planes and signal line are formed. Each of the ground planes and signal line may be 2 μm thick. The beam may then contribute an additional 3 μm to the height of the switch, whereby each of the metal layers 3210, 3230 is about 1 μm thick and the dielectric layer 3220 sandwiched in between may also be about 1 μm. The top layer 3440 may add about an additional 0.2 μm to the height of the switch. The height of the switch may increase by H when open, as shown in
The metamaterial unit cells included in the second metal layer 3230, and optionally in the first metal layer 3210 as well, may have the shape of a split ring resonator. The split rings may be square-shaped.
Different unit cell structures may provide different metamaterial characteristics at the relevant band of frequencies for the RF MEMS switch (e.g., between 60 to 130 GHz). Each of
The metamaterial structure 3401 of
The metamaterial structure 3501 of
The metamaterial structure 3601 of
Additionally, the parameters of the metamaterial cell structures may be varied to produce different transmission and reflection characteristics. For example,
In addition to the use of different metamaterial cell structures and cell structure parameters, the metal layers of the MEMS switch may also be formed with different parameters and dimensions as compared to those parameters and dimensions described above.
Using the transmission and reflection data described above, permeability and permittivity of the metamaterial cells can be extracted using parameter extraction procedures known in the art. The parameter extraction is shown in
The examples of
Different unit cell structures may provide different metamaterial characteristics at the relevant band of frequencies for the RF MEMS switch (e.g., between 60 to 130 GHz). Each of
The metamaterial structure 4401 of
The metamaterial structure 4501 of
Another example switch 4700 is shown in
The switch includes a structure formed over a signal line having an input side 4712 and an output side 4714. A metamaterial structure having an outer split ring 4722 and inner split ring 4724 is formed in the signal line contact between the input side 4712 and output side 4714, through which a signal is received (arrow in) and an output port through which the signal is transmitted (arrow out).
As with the previously described split ring structures, the structure of
Each of the ground planes 4702, 4704 and the signal line are formed from a conductive material such as gold, and are formed on top of a dielectric material 4740 such as silicon nitride (Si3N4), which itself is formed on top of a substrate 4705. One of the ground planes 4702 includes a post 4770 extending downward from the ground plane 4702 into the dielectric material 4740, and a beam 4780 extending from the post 4770 in the direction of the signal line 4714. The edge of the beam 4780 is aligned with the opposing edge of the signal line 4712, 4714, such that the end of beam 4780 is positioned underneath the metamaterial structures 4722, 4724, of the signal line 4712, 4714. In
In the example of
Transmission and reflection characteristics of the switch 4700 over a range of frequencies are shown in
Based on these results, a material parameter extraction can be performed in order to determine the permittivity and permeability of the metamaterial structure. The extraction is shown over a range of frequencies in
In operation, the bias voltage causes a midpoint of the beam 5050 to deflect downward until it comes in contact with the signal line contact, thereby causing the signal line to turn off (or in other cases to turn on). When the bias voltage is removed, the midpoint of the beam 5050 deflects back upward. Because the midpoint of the beam is aligned with the metamaterial structure 5022, 5024 of the signal line contact, the Casimir effect at the interface between the beam and the signal line contact is diminished or even repulsive, thereby reducing the liability of stiction between the beam 5050 and the signal line.
Although not shown in
Performance of the switch 500 is shown in
In
In
Altogether, good insertion loss and return loss characteristics of the RF MEMS Switch in the ON and OFF states are achieved over 30-100 GHz frequency band. This makes the presently described switch a good candidate for high frequency switching operations over a wide bandwidth of frequencies. Accordingly, the switches described in the present disclosure can improve operation and performance of applications requiring high frequencies (e.g., 10 GHz or greater) over a wide bandwidth. Such technologies may include, but are not limited to, 5G communications, switching networks, phase shifters (e.g., in electronically scanned phase array antennas) and Internet of Things (IoT) applications.
In the present disclosure, the metamaterial structures described are split rings. However, those skilled in the art should recognize that other metamaterial structures may be used, provided that those structures provide similar permittivity and permeability characteristics within the desired range of frequencies. For instance, a topology inspired Möbius transformation MTM (metamaterial) structures (meaning a structure that forms a continuous closed path that maps onto itself, or stated another way, the structure may have a topology in which a closed path extends two or more revolutions around an axis (e.g., at or close to the center of the structure) before the closed path is completed) may be considered advantageous for generating repulsive Casimir forces.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.
This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 62/469,752 filed Mar. 10, 2017, the disclosure of which is hereby incorporated herein by reference.
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| Number | Date | Country | |
|---|---|---|---|
| 20180261415 A1 | Sep 2018 | US |
| Number | Date | Country | |
|---|---|---|---|
| 62469752 | Mar 2017 | US |
