Patent Description:
The present disclosure relates to radio frequency (RF) switches, or more particularly to RF micro electromechanical system (MEMS) lateral switches with improved reliability and reduced risk of stiction, and to applications for the switches in switching networks.

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 modem communication systems. In particular, RF MEMS switches (e.g., single-pole multi-throw switches) and switching networks are broadly used in modern telecommunication systems, especially for <NUM>/<NUM>/<NUM> applications and high precision instrumentation.

Document <CIT> discloses a RF-MEMS switch and a fabrication method. The MEMS switch comprises a substrate, a first anchor over the substrate, a first spring connected to the first anchor, an upper electrode, which is connected to the first spring and makes a motion above the substrate. The first spring is elastically deformed, a lower electrode is formed over the substrate and is positioned under the upper electrode. Further, a second spring is connected to the upper electrode and a second anchor is connected to the second spring.

<NPL> discloses a SPDT switch circuit using lateral RF MEMs switches developed on glass to operate from DC to <NUM>.

<NPL> discloses a SP4T micro-machined switch using deep reactive ion etching fabrication technology based on silicon-on-insulator wafer. The measurement results of the SP4T switch show an insertion loss of less than <NUM> dB and isolation of <NUM> dB from DC to <NUM>.

<FIG> illustrates the circuit design of a basic single pole single throw (SPST) lateral RF MEMS switch <NUM>. As shown in <FIG>, the lateral switch includes a coplanar waveguide <NUM>, a cantilever beam <NUM> extending between first and second ports <NUM>, <NUM> of the coplanar waveguide, and an electrostatic actuator (not shown) for actuating the cantilever beam. The actuator is configured to apply a DC bias voltage between the cantilever and the ground line <NUM> of the coplanar waveguide <NUM>, thereby causing the free end of the cantilever beam <NUM> to deflect in the direction of a fixed electrode <NUM>. When sufficient DC bias is applied, the cantilever beam <NUM> deflects enough to contact a mechanical stopper of the second port, resulting in the closing (ON state) of the switch. When the DC bias is lowered or removed, the beam <NUM> returns to its at-rest state (as shown in <FIG>), thereby opening the switch (OFF state).

Compared to PIN diodes or field-effect transistor (FET) switches, RF MEMS switches have been found to offer lower power consumption, higher isolation, lower insertion loss, higher linearity, and lower cost.

One drawback of the lateral switch design 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 between the cantilever beam and the mechanical stopper of the waveguide port. Furthermore, the spring constant of the cantilever beam is often too small to overcome the stiction. Another drawback of the lateral switch design is that, with a large number of output ports, they do not achieve a wide band performance with good repeatability, especially at lower microwave frequencies such as about <NUM>. At lower microwave frequencies, area also plays a major role in the performance of the switch. Isolation and matching also play key roles in the switch, and the effect of isolation degrades gradually with higher number of output ports.

Therefore, there is a need to address these and other drawbacks in the field of MEMS switch design.

A lateral microelectromechanical switch is provided according to a first independent claim. Additional features of the invention are provided on the corresponding dependent claims.

Aspects of the present disclosure provide for an improved design of RF MEMS lateral switches that achieve improved wide band performance with improved repeatability (e.g., lifetime in the order of millions of switches) at lower microwave frequencies. Design in accordance with aspects of the disclosure include an improved RF MEMS switch that is capable of switching a large number of ports in a small chip area, thereby resulting in cost benefits, since area is directly proportional to cost in large-volume manufacturing processes.

One aspect of the present disclosure provides for a microelectromechanical switch including a first port (e.g., input port), one or more second ports (e.g., output ports), a cantilever beam, and a mechanical spring connected to the cantilever beam for providing a mechanical force to move the cantilever beam. The cantilever beam extends from a fixed end in contact with either the first port or one of the second ports, to a free end that is connectable to the other of the first port or said one of the second ports. The first and second ports and cantilever beam is formed in a coplanar waveguide. The switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM>. The total area of the switch is about <NUM><NUM>.

The switch is a lateral switch, such that the mechanical spring provides a mechanical force to move the cantilever beam in a lateral direction. The mechanical spring may be configured in a semi-triangular shape. Alternatively, the mechanical spring may provide a mechanical force to move the cantilever beam in an out-of plane direction. Three mechanical springs may be utilized, each mechanical spring being connected to the cantilever beam and providing a mechanical force to move the cantilever beam. The three mechanical springs may be arranged in a Y-configuration. In any of the examples above, the mechanical spring may be actuated by an electrostatic force.

The switch may further include an actuator applying a bias voltage, whereby deflection of the cantilever beam is at least in part determined by the applied bias voltage. The actuator may be connected to a bias line. The bias line may be formed from titanium tungsten and separated from the coplanar waveguide by a layer of silicon dioxide.

At least one second port includes a mechanical stopper for contacting the free end of the cantilever beam, whereby when the microelectromechanical switch is open, the free end and the mechanical stopper are at a distance from one another that is greater than a distance between the mechanical spring and ground of the coplanar waveguide.

The switch may include at least two second ports. The fixed end of the cantilever beam may be in contact with the first port, and the free end of the cantilever beam may be switchably connectable to each of said two second ports. The cantilever beam may be connected to at least two mechanical springs, each mechanical spring providing a mechanical force to move the cantilever beam towards or away from a respective one of the two second ports. The switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM>.

The switch may include at least three second ports, four second ports, six second ports, seven second ports, eight second ports, ten second ports, eleven second ports, fourteen second ports, or sixteen second ports, which are not according to the present invention and only provided as examples. The switch may include as many cantilever beams as second ports. A fixed end of each cantilever beam may be in contact with a corresponding one of the second ports, and a free end of each cantilever beam may be switchably connectable to a common junction of the first port. Each cantilever beam is connected to a respective mechanical spring. The mechanical spring may providing a mechanical force to move the cantilever beam towards or away from the common junction.

In the case of a switch with three or more second ports not according to the present invention, the switch may exhibit one of return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for a lateral switch configuration, or return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The total area of the switch may be about <NUM><NUM>.

In the case of a switch with four or more second ports not according to the present invention, the switch may exhibit one of return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for a lateral switch configuration, or return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The total area of the switch may be about <NUM><NUM>.

In the case of a switch with six or more second ports not according to the present invention, the switch may have a return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In the case of a switch with seven or more second ports not according to the present invention, the switch may exhibit one of return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for a lateral switch configuration, or return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In the case of a switch with eight or more second ports not according to the present invention, the switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In the case of a switch with ten or more second ports not according to the present invention, the switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In the case of a switch with eleven or more second ports not according to the present invention, the switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In the case of a switch with fourteen or more second ports not according to the present invention, the switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In the case of a switch with sixteen or more second ports not according to the present invention, the switch may exhibit return loss of at most about <NUM> dB, isolation of at most about <NUM> dB, and insertion loss of at most about <NUM> dB at one or more frequencies up to about <NUM> for an out-of-plane switch configuration. The switch may have a total area of about <NUM><NUM>.

In any of the above switch configurations, the common junction may include a plurality of spokes extending radially therefrom, each spoke switchably connectable to the free ends of the respective cantilever beams. The spokes may be evenly distributed around the common junction such that each pair of adjacent spokes forms a common angle.

The present disclosure further provides for a switching network having a plurality of microelectromechanical switches as described herein. The switching network may include a plurality of single pole multiple throw switches as described herein. The switching network may be configured to operate at a frequency of up to about <NUM>, or up to about <NUM>.

The present disclosure not according to the present invention further provides for a switch including first and second terminals, a deflectable beam connected to the first terminal and configured to deflect towards the second terminal, such that the beam contacts the second terminal when it is deflected in the direction of the second terminal, a first electrode and a mechanical spring affixed to the beam, and a second electrode spaced apart from the first electrode. A voltage applied to the second electrode causes the first electrode to move towards or away from the second electrode. When the mechanical spring is in a compressed state if the first electrode moves towards the second electrode, and returns to the at-rest state if the first electrode moves away from the second electrode. In some examples, the mechanical spring provides a force to deflect the beam towards the second terminal. In other examples, the mechanical spring provides a force to deflect the beam away from the second terminal. Also, in some examples, the first and second electrodes are spaced farther apart from one another than the first and second terminals are spaced apart.

<FIG> show an example RF MEMS lateral switch <NUM> in accordance with an aspect of the present disclosure. The lateral switch <NUM> includes a coplanar waveguide (CPW) <NUM>, input and output ports <NUM>, <NUM>, and a cantilever beam <NUM> between the input and output ports. The cantilever beam <NUM> includes a fixed end in contact to the first port <NUM>, and extends out from the first port towards a free end <NUM> that is switchably connectable to the second port <NUM>. Also included is a mechanical spring <NUM>, which is attached to the cantilever beam <NUM> between the input and output ports <NUM>, <NUM>. In the example of <FIG>, the mechanical spring <NUM> is attached at about mid-length or midpoint of the beam. The mechanical spring has a semi-triangular shape, and is positioned between the cantilever beam <NUM> and ground <NUM> of the waveguide. The mechanical force of the spring <NUM> provides an additional mechanical force to move the free end <NUM> of the cantilever beam <NUM> back to its at-rest position when the switch <NUM> is in an OFF state and does not contact the second port <NUM>. In this manner, the spring provides additional assurance that the switch is returned to its at-rest state (and the cantilever beam does not remain deflected), when the switch is turned off.

The semi-triangular shape of the spring <NUM> is shown in greater detail in <FIG>. The spring <NUM> includes a base element <NUM> that is parallel to the beam <NUM>, and two spring elements <NUM> that extend from the base element away from the beam, thereby substantially forming a triangle. The spring includes a contact <NUM> at the point where the spring elements <NUM> meet. The contact is parallel to the base element <NUM>. Thus, the contact is also parallel to the CPW ground <NUM>.

The amount of mechanical force is selected so as to overcome any potential failure of the switch due to stiction, while taking into consideration the effect of the electrostatic force induced when a bias voltage is applied. As in other in-line "DC contact" cantilever switches, electrostatic actuation between the center line and ground causes the cantilever to move in a lateral direction towards the mechanical stopper of the second port. When the cantilever moves, it is necessary that the cantilever contact the second port of the center line without the mechanical spring contacting the ground line, since contacting the ground line would result in a short circuit of the switch. Therefore, a design constraint of the present design, and particularly of the mechanical spring, is that the at-rest distance between the free end of the cantilever beam <NUM> and the mechanical stopper <NUM> of the second port <NUM> ("a" in <FIG>) should be significantly less than the distance between the contact <NUM> of the mechanical spring <NUM> and the CPW ground <NUM> ("b" in <FIG>), so that when a DC bias is applied, the free end of the cantilever beam <NUM> contacts the mechanical stopper <NUM> without the mechanical spring contact <NUM> contacting the ground line <NUM>.

<FIG> show four example RF MEMS lateral switches in accordance with some aspects of the present disclosure. Each of the examples of <FIG> show designs similar to that of <FIG>, except that the properties of the mechanical spring in each design are different. For example, the mechanical spring of the example of <FIG> is notably flatter than the other designs, whereas the mechanical spring of the example of <FIG> is notably more triangular. The tension of the mechanical springs may also vary between the designs, although the geometry and tension of the spring may be mutually exclusive. In this regard, the mechanical spring in the example of <FIG> exhibits greater stability or lifetime (e.g., over numerous switching cycles) as compared to the springs of the other designs.

The different lateral switch designs of <FIG> may be selected from based on the varying performance provided by each design. <FIG> show return loss, isolation, and insertion loss for each of the example designs of <FIG>, respectively. As shown in the figures, simulations of the SPST switch show return loss of better than between about <NUM> - <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> - <NUM> dB at frequencies of up to about <NUM>.

The switches of <FIG> and <FIG> reduce or eliminate the risk of mechanical failure due to dielectric charging, and are capable of operating within a point of stability. Thus, the switches are capable of improving RF power handling under both cold-switching and hot-switching conditions. Moreover, due to the electrostatic actuation of the switch, the cantilever of the switch may be designed with increased stiffness. The cantilever may also be less sensitive to stresses due to its small size and shortened switching time. The switch may also be less sensitive to planarity and stress which significantly improves the overall contact force. The reduced sensitivity in turn improves overall yield.

The example design of <FIG> is a single pole single throw (SPST) switch. However, the design of single pole multiple throw (SPMT) switches may be improved in a similar fashion. <FIG> shows an example RF MEMS single pole double throw (SPDT) lateral switch <NUM> in accordance with an aspect of the present disclosure. The SPDT switch <NUM> includes a coplanar waveguide <NUM> including an input port <NUM>, first and second output ports <NUM>, <NUM>, and a single cantilever beam <NUM> positioned to couple the input port <NUM> with either one of the output ports <NUM>, <NUM> depending on the direction of lateral deflection of the cantilever beam <NUM>. Two mechanical springs <NUM>, <NUM> are laterally attached to opposing sides of the cantilever beam <NUM>. The free end of the cantilever beam <NUM> is positioned to be able to deflect in either lateral direction so as to come in contact with a contact bump <NUM>, <NUM> (comparable to the mechanical stopper shown in <FIG>) of either the first output port <NUM> or the second output port <NUM>, depending on the direction in which the cantilever beam deflects. Deflection is determined based on the bias voltage applied to the actuators <NUM>, <NUM> from each of the bias pads <NUM>, <NUM>. The bias voltage applied at an actuator causes an electrode at the switch to move towards or away from the actuator, thereby either deflecting the cantilever beam toward the output port, or releasing the cantilever beam so that it moves away from the output port. At a given time, one of the actuators may be "ON," while the other is "OFF. " Actuation and release of the cantilever beam <NUM> may aided by the mechanical spring <NUM>, <NUM> on the side of the beam to which the beam deflects. Effectively, the SPDT switch <NUM> operates in the same fashion as the SPST switch <NUM> of <FIG>, except that the SPST switch beam <NUM> operationally closes and opens a switch in only one direction, whereas the SPDT switch beam <NUM> operationally closes and opens a switch in two opposing directions.

<FIG> show simulated return loss, isolation, and insertion loss for each of output ports <NUM> and <NUM>, respectively, for the example SPDT lateral switch design of <FIG>. As shown in the figures, the SPDT switch exhibits return loss of better than about <NUM> dB, isolation (e.g., of one port when another port is activated) by about <NUM> dB or greater, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single pole three throw (SP3T) lateral switch <NUM> in accordance with an aspect of the present disclosure. The input port <NUM> of the lateral switch includes a central junction <NUM>. The switch also includes three output ports <NUM>, <NUM>, <NUM> from which three separate cantilever beams <NUM>, <NUM>, <NUM> that extend to contact the central junction <NUM>. Each cantilever beam includes a mechanical spring that is actuated by a separate actuator. Each actuator is also shown as being biased by a separate bias pad. Like in the example of <FIG>, at a given time, one of the actuators may be biased, such that the cantilever beam associated with that actuator is deflected and contacts its corresponding output port. In the present example, the input port <NUM> and cantilever beams <NUM>, <NUM>, <NUM> are uniformly distributed around the central junction <NUM>, although in other examples, the configuration may not be uniform.

<FIG> shows an average simulated return loss, isolation, and insertion loss for the output ports <NUM>, <NUM>, <NUM> of the example SP3T lateral switch design of <FIG>. As shown in the figures, the SP3T switch exhibits, on average, return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single pole four throw (SP4T) lateral switch <NUM> in accordance with an aspect of the present disclosure. The SP4T switch is similar in design to the SP3T switch in that each output port <NUM>, <NUM>, <NUM>, <NUM> of the switch is connected to a separate cantilever beam <NUM>, <NUM>, <NUM>, <NUM> that extends to contact a mechanical stopper on a central junction <NUM>. The input port <NUM> and the cantilever beams <NUM>, <NUM>, <NUM>, <NUM> are evenly distributed around the central junction <NUM>. Each cantilever beam has its own mechanical spring, actuator and biasing pad to effect deflection of the beam.

<FIG> shows an average simulated return loss, isolation, and insertion loss for the four output ports of the example SP4T lateral switch design of <FIG>. As shown in the figures, the SP4T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single pole seven throw (SP7T) lateral switch <NUM> in accordance with an aspect of the present disclosure. The SP7T switch <NUM> is similar in design to the SP3T and SP4T switches in that each output port <NUM>-<NUM> of the switch is connected to a separate cantilever beam <NUM>-<NUM> that extends to contact a mechanical stopper on a central junction <NUM>. The input port <NUM> and cantilever beams <NUM>-<NUM> are evenly distributed around the central junction <NUM>. Each cantilever beam has its own mechanical spring, actuator and biasing pad to effect deflection of the beam.

<FIG> shows an average simulated return loss, isolation, and insertion loss for the seven ports of the example SP7T lateral switch design of <FIG>. As shown in the figures, the SP7T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows another example RF MEMS switch <NUM> in accordance with an aspect of the present disclosure. Unlike the lateral switch of <FIG>, the switch of <FIG> includes an out-of-plane cantilever beam <NUM> connecting a first port <NUM> to a second port <NUM> in a coplanar waveguide <NUM>. The beam <NUM> is attached to three mechanical springs <NUM>, <NUM>, <NUM> arranged under the beam and relative to one another in a Y-configuration. Unlike the single mechanical spring of <FIG>, which moves side to side (relative to a line drawn between the ports) and within the plane of the waveguide to actuate the lateral switch, the mechanical springs of <FIG> move up and down, orthogonal to the plane of the waveguide. When the springs raise the beam upward, the beam is disconnected from the second port <NUM>, thereby opening the switch. When the springs move the beam downward, the beam is connected to the second port, thereby closing the switch. Function of the mechanical springs may be compared to that described in connection with the lateral switch, except that the springs of <FIG> move in a different direction to accommodate the out-of-plane movement of the cantilever beam.

In the example of <FIG>, the actuation voltage of the switch is between about <NUM> V and about <NUM> V, and the mechanical resonance frequency is about <NUM>. The total area (including bias lines and pads) of the switch is about <NUM><NUM>, which enables the achievement of very compact switching networks without compromising microwave performance.

Benefits of the switch of <FIG> include: (<NUM>) A reduced sensitivity to stress due to its small size and fast switching time; (<NUM>) a reduced sensitivity to planarity and stress due to its being a single-contact cantilever switch (this may significantly improve the overall contact force and improve division of electrostatic force over the various paths surrounding the switch, such as in a phase shifter) (<NUM>) reduced risk of switch failure due to contact failure (e.g., a contact becoming permanently stuck down) or actuator failure (e.g., a contact becoming permanently stuck up); (<NUM>) reduced sensitivity to stress gradients (Residual stress often results in uneven distribution of tip deflection between even identical structures. Hence, different blocks often need different voltages to actuate. The reduction in stress allows for the same voltage to be needed for actuation, thereby decreasing overall yield of the device in which multiple switches are actuated. ); and (<NUM>) improved compactness of multi-switch structures, since the switch may be easily placed on a CPW line. Additional benefits include low cost (batch production) low insertion loss, good input/output matching and moderate isolation response for designs with up to fourteen channels operating at a frequency of up to <NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SPST switch design of <FIG>. As shown in <FIG>, the SPST switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS SP3T switch <NUM>. Like the SPST switch of <FIG>, the SP3T switch of <FIG> uses an out-of-plane configuration for the cantilever beams and springs. The switch includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and three output ports <NUM>, <NUM>, <NUM>. The switch also includes three cantilever beams <NUM>, <NUM>, <NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Also like in <FIG>, each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction <NUM>. The total area of the SP3T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP3T switch design of <FIG>. As shown in <FIG>, the SP3T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS SP4T switch <NUM> in accordance with an aspect of the present disclosure. The SP4T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and four output ports <NUM>, <NUM>, <NUM>, <NUM>. The switch also includes four cantilever beams <NUM>, <NUM>, <NUM>, <NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP4T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP4T switch design of <FIG>. As shown in <FIG>, the SP4T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole six-throw (SP6T) switch <NUM> in accordance with an aspect of the present disclosure. The SP6T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and six output ports <NUM>-<NUM>. The switch also includes four cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP6T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP6T switch design of <FIG>. As shown in <FIG>, the SP6T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole seven-throw (SP7T) switch <NUM> in accordance with an aspect of the present disclosure. The SP7T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and seven output ports <NUM>-<NUM>. The switch also includes seven cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP7T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP7T switch design of <FIG>. As shown in <FIG>, the SP7T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole eight-throw (SP8T) switch <NUM> in accordance with an aspect of the present disclosure. The SP8T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and seven output ports <NUM>-<NUM>. The switch also includes seven cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP8T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP8T switch design of <FIG>. As shown in <FIG>, the SP8T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole ten-throw (SP10T) switch <NUM> in accordance with an aspect of the present disclosure. The SP10T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and seven output ports <NUM>-<NUM>. The switch also includes seven cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP10T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP10T switch design of <FIG>. As shown in <FIG>, the SP10T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole eleven-throw (SP11T) switch <NUM> in accordance with an aspect of the present disclosure. The SP11T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and seven output ports <NUM>-<NUM>. The switch also includes seven cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP11T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP11T switch design of <FIG>. As shown in <FIG>, the SP11T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole fourteen-throw (SP14T) switch <NUM> in accordance with an aspect of the present disclosure. The SP14T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and seven output ports <NUM>-<NUM>. The switch also includes seven cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP14T switch is about <NUM><NUM>.

<FIG> shows simulated return loss, isolation, and insertion loss for the example SP14T switch design of <FIG>. As shown in <FIG>, the SP14T switch exhibits return loss of better than about <NUM> dB, isolation of about <NUM> dB, and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>.

<FIG> shows an example RF MEMS single-pole sixteen-throw (SP16T) switch <NUM> in accordance with an aspect of the present disclosure. The SP16T switch <NUM> includes an input port <NUM> extending to a center of the switch to provide a central junction <NUM>, and seven output ports <NUM>-<NUM>. The switch also includes seven cantilever beams <NUM>-<NUM> each extending from a respective output port and switchably connectable to the central junction by an out-of-plane movement. Each beam includes three springs arranged in a Y-configuration. The input port and beams are evenly distributed around the central junction. The total area of the SP16T switch is about <NUM><NUM> (about <NUM> across, and about <NUM> top to bottom as shown in <FIG>).

<FIG> show simulated return loss, isolation, and insertion loss for the example SP16T switch design of <FIG>. As shown in <FIG>, the SP16T switch exhibits return loss of better than about <NUM> dB and worst case insertion loss of about <NUM> dB at frequencies of up to about <NUM>. <FIG> shows isolation of about <NUM> dB up to similar frequencies.

As compared to the lateral switches of <FIG>, the configurations shown and demonstrated in <FIG> permit the switches to be placed lateral to one another even closer together without introducing difficulties to the fabrication process. Ultimately, this leads to a reduction of overall area of a device incorporating these switches. As shown, the reduction of area may be on the order of square microns or even a few square millimeters.

Matching and loss of a switching network including the above example switches, and particularly the above example SPMT switches, may be improved by reducing the parasitic inductive effects caused by the switches. These effects largely occur between the central junctions of adjacent switches. Parameters such as central junction length (as well as switch footprint, parasitic inductive effects) may be tested using a full wave simulation. The results of the full wave simulation may then be utilized to modify the switch parameters, thereby improving or optimizing performance.

The above example switches feature additional design considerations and constraints. For instance, the CPW discontinuities (e.g., between adjacent switches) may include inductive bends. The purpose of these bends is to eliminate higher order modes. The bias pads of the switches may also be routed in a manner that avoids signal leakage and other parasitic effects without affecting performance. The bias pads and lines may themselves be made of a conductive material (e.g., titanium tungsten), and a film or layer of dielectric material (e.g., silicon dioxide) may be positioned between the bias lines and CPW to prevent shorting.

Another beneficial property of the configuration of above example switches is their symmetry (e.g., equal angle between each throw of a given switch, equal angle between the each of the input/output ports). Additionally, each of the switches (with the exception of the SP3T switch of <FIG>) has a mirror symmetry along an axis extending from the input port to the central junction. This configuration of the above example switches permits them to be placed closer together with one another (in designs that accommodate multiple switches). This means that a device with multiple MEMS RF lateral switches (e.g., a phase shifter) may be designed with greater compactness without any fabrication difficulties. The symmetry is especially beneficial for improving compactness of the design. Ultimately, the presently described switch configuration may lead to reduction of overall area of a device including these switches on the order of square microns or even square millimeters, as compared to other conventional topologies.

Claim 1:
A lateral microelectromechanical switch (<NUM>,<NUM>) comprising:
a coplanar waveguide (<NUM>,<NUM>) comprising
an input port (<NUM>,<NUM>);
one or more output ports (<NUM>,<NUM>); wherein the lateral microelectromechanical switch (<NUM>, <NUM>) further comprises
a cantilever beam (<NUM>), having a first end in contact to the input port (<NUM>,<NUM>), and extending from the first end toward a second end that is switchably connectable to said one of the output ports (<NUM>, <NUM>);
a mechanical spring (<NUM>), connected to the cantilever beam (<NUM>) between the first and second ends, the mechanical spring (<NUM>) configured to provide a mechanical force to move the cantilever beam (<NUM>); characterized in that
the mechanical spring (<NUM>,<NUM>) is positioned between the cantilever beam (<NUM>) and the grounds (<NUM>,<NUM>) of the coplanar waveguide (<NUM>, <NUM>); and
a mechanical stopper (<NUM>,<NUM>) connected to said at least one output ports (<NUM>,<NUM>) and configured to contact the second end of the cantilever beam (<NUM>),
wherein the lateral microelectromechnical switch (<NUM>, <NUM>) is configured such that, when the lateral microelectromechanical switch (<NUM>, <NUM>) is open, the second end and the mechanical stopper (<NUM>,<NUM>) are at a distance from one another that is less than a distance between the mechanical spring (<NUM>,<NUM>) and the ground of the coplanar waveguide (<NUM>,<NUM>); and
wherein the input port (<NUM>, <NUM>), the output ports (<NUM>,<NUM>), and the cantilever beam (<NUM>) are placed between the two grounds (<NUM>, <NUM>) of the coplanar waveguide (<NUM>,<NUM>).