MEMS switch with high off state voltage standoff rating

Abstract

To provide a microelectromechanical system (MEMS) switch apparatus.SOLUTION: An MEMS switch apparatus for handling input voltages higher than a standoff voltage of each MEMS switch in the MEMS switch apparatus may comprise at least one pair of MEMS switches. Each pair of MEMS switches may comprise a first MEMS switch and a second MEMS switch electrically coupled to the first MEMS switch at a midpoint. The first and second MEMS switches may be arranged in a back-to-back configuration. Each pair of MEMS switches may further comprise an input electrically coupled to the first MEMS switch, an output electrically coupled to the second MEMS switch, one or more input components electrically coupled across the first MEMS switch from the input to the midpoint, and one or more output components electrically coupled across the second MEMS switch from the midpoint to the output.SELECTED DRAWING: Figure 2

Description

Background Art

[0001] A typical microelectromechanical system (MEMS) switch closes due to an electrostatic force generated when a voltage is applied to a control terminal.

Summary of the Invention

Problems to be Solved by the Invention

[0002] Unfortunately, the switch may close even when a sufficiently large voltage is applied to its input terminal. The voltage level at which this unintended operation occurs is called the standoff voltage and sets the upper limit of the signal level that can be applied to the switch. Increasing the standoff voltage of a MEMS switch may require redesign, which is not practical. In situations where the input voltage is expected to exceed the standoff voltage of the switch, an alternative solution is needed.

Means for Solving the Problems

[0003] The embodiments described herein are directed to a MEMS switch system comprising two or more individual microelectromechanical system (MEMS) switches. Those MEMS switches are arranged such that the MEMS switch system can withstand a VSO that exceeds the standoff voltage (VSO) of any configured MEMS switch.

[0004] In one aspect, the present invention can be a microelectromechanical system (MEMS) device that corresponds to an input voltage higher than the stand-off voltage of the MEMS switch within the MEMS device. The MEMS device can include at least a pair of MEMS switches. Each pair of MEMS switches can include a first MEMS switch and a second MEMS switch electrically connected to the first MEMS switch at an intermediate point. The first MEMS switch and the second MEMS switch can be installed in a back-to-back configuration. The MEMS device can further include an input part electrically connected to the first MEMS switch, an output part electrically connected to the second MEMS switch, at least one input component electrically connected from the input part to the intermediate point via the first MEMS switch, and at least one output component electrically connected from the intermediate point to the output part via the second MEMS switch.

[0005] In one embodiment, one or more of the at least one input component and the at least one output component can include a passive element. Each of the at least one input component and the at least one output component can include a passive element. One or more of the at least one input component and the at least one output component can include a capacitor. Each of the at least one input component and the at least one output component can include a capacitor.

[0006] The capacitance of the first input component can be four times the capacitance of the second input component, and the capacitance of the first output component can be twice the capacitance of the second output component. The capacitance of the second input component can be the same as the capacitance of the second output component, the capacitance of the third input component can be twice the capacitance of the second input component, and the capacitance of the third output component can be four times the capacitance of the second output component.

[0007] One or more of the at least one input component and the at least one output component may include a resistor. Each of the at least one input component and the at least one output component may include a resistor. One or more of the at least one input component and the at least one output component may include a resistor and a capacitor. Each of the at least one input component and the at least one output component may include a resistor and a capacitor. Two or more pairs of MEMS switches may be electrically connected in series. In one embodiment, three pairs of MEMS switches may be electrically connected in series. One or more of the at least one pair of MEMS switches may be electrically connected to a mode control switch.

[0008] Each of the at least one pair of MEMS switches may be electrically connected to a mode control switch. In a first form, the mode control switch may open and each of the at least one pair of MEMS switches is not electrically connected to ground. In a second form, the mode control switch may close and each of the at least one pair of MEMS switches is electrically connected to ground.

[0009] In other aspects, the present invention can be a method for handling an input voltage higher than the standoff voltage of a microelectromechanical systems (MEMS) device. The method can include providing the MEMS device including at least a pair of MEMS switches. Each pair of MEMS switches can include a first MEMS switch and a second MEMS switch electrically connected to the first MEMS switch at an intermediate point. The first MEMS switch and the second MEMS switch can be arranged in a back-to-back configuration. Each pair of MEMS switches can include an input portion electrically connected to the first MEMS switch, an output portion electrically connected to the second MEMS switch, at least one input component electrically connected from the input portion to the intermediate point through the first MEMS switch, and at least one output component electrically connected from the intermediate point to the output portion through the second MEMS switch. The method can further include dispersing the input voltage from the input portion of the first pair of MEMS switches to the output portion of the last pair of MEMS switches.

[0010] The method can further include connecting the at least a pair of MEMS switches to a mode control switch. The method can further include implementing (i) a first mode in which the mode control switch is open and each of the at least a pair of MEMS switches is not electrically connected to ground, or (ii) a second mode in which the mode control switch is closed and each of the at least a pair of MEMS switches is electrically connected to ground. The method can further include electrically connecting two or more pairs of MEMS switches in series.

[0011] In yet another aspect, the present invention may include a MEMS device that can handle an input voltage higher than the stand-off voltage of a MEMS switch within a microelectromechanical systems (MEMS) system. The MEMS device may include two or more MEMS switches electrically connected in series from a device input to a device output. As components for each of the two or more MEMS switches, the components may be attached via the MEMS switches such that the components are connected in series from the device input to the device output and the input voltage is distributed among the components.

[0012] The foregoing will become apparent from the following detailed description of the exemplary embodiments shown in the accompanying drawings. Throughout the different figures, the same reference numerals refer to the same configurations / components. The drawings are not necessarily to scale; rather, emphasis is placed on illustrating the embodiments.

Brief Description of the Drawings

[0013]

Fig. 1A

Fig. 1B

Fig. 1C

Fig. 2

Fig. 3

Fig. 4

[0014] Exemplary embodiments will be described below.

[0015] The apparatus, system, and method described herein include a dual-mode MEMS system with MEMS switches that can safely withstand input voltages exceeding the standoff voltage without self-activation while operating at standard gate control voltage levels.

[0016] In an aspect of the present invention concept herein, a plurality of switch elements are used in series, and the input voltage is distributed among the switch elements so that none of the MEMS switches of any element in this series architecture closes (operates) even when the input voltage increases. Such an approach does not require a redesign of the basic switch element and does not interfere with the control voltage for normal operation. In some embodiments, an auxiliary control signal can set the switch to either a high input voltage response mode or a normal operation mode.

[0017] In some embodiments, an aspect of the present invention concept herein includes a single-pole single-throw switch having three back-to-back switch elements connected to each other in series, a parallel voltage-dividing network, and a mode control configuration. The standoff voltage per MEMS element remains, for example, 150V, but the apparatus and system described herein can withstand an input voltage of up to 440 volts (peak-to-peak) (Vpp) in the off state and pass, for example, direct current to 18 GHz in the on state.

[0018] FIG. 1A is a diagram showing an open (off) state of a pair 100 of back-to-back MEMS switches 10a, 10b operating normally. The switches 10a, 10b are controlled by an electrostatic force that pulls down the beam portions 12a, 12b of the switches 10a, 10b when a gate voltage (Vg) is applied to the control terminals (gates) 14a, 14b. In some embodiments shown in FIG. 1A and the like, the gate voltage required to close the beam portion is 90V. In some embodiments, the gate voltage is less than 90V. In some embodiments, the gate voltage is greater than 90V.

[0019] The stand-off voltage (V SO ) of a MEMS switch is the maximum voltage that can be applied to the input of the switch while the switch remains in the off state (i.e., open circuit). If it exceeds V SO , the switch may close electrostatically by itself. V SO can be determined by, for example, the shape of the switch (among other physical parameters of the switch). V SO defines the limit of the maximum input voltage that can be applied to the MEMS switch while the switch remains in the off state. The stand-off voltage can be increased, for example, by changing the shape of the switch. However, changing the shape (and other parameters) of the switch can be time-consuming, and the gate control voltage may become high (and in some cases, undesirable).

[0020] In an exemplary embodiment shown in FIG. 1A and the like, the stand-off voltage is approximately 150V. In other embodiments, the stand-off voltage can be greater than 150V or less than 150V.

[0021] In the situation shown in FIG. 1A, the input voltage (Vin) and the output voltage (Vout) are less than V SO . In the situation shown in FIG. 1A, the gate voltage (Vg) of each switch 10a, 10b is 0. In such a setting, both switches 10a, 10b are in the open state.

[0022] Figure 1B is a diagram showing the closed (on) form of a pair 100 of back-to-back MEMS switches 10a, 10b operating normally. In Figure 1B, Vin and Vout are less than V SO is less than. In Figure 1B, the Vg of each switch 10a, 10b is 90Vdc, which exceeds the switch pull-in voltage, so each switch 10a, 10b closes.

[0023] Figure 1C is a diagram showing the closed (on) form of a pair 100 of back-to-back MEMS switches 10a, 10b during abnormal operation. In this third situation, since each Vg is zero, the switch should be open. However, because the input voltage (Vin) exceeds the standoff voltage (V SO ), the switch that should be open is closed. The devices, systems, and methods described herein solve the problems posed by this third situation.

[0024] Figure 2 is a schematic diagram showing an exemplary embodiment of a MEMS system 150 configured to correspond to a value of Vin that exceeds V SO of each individual MEMS switch 10 according to an aspect of the inventive concept, with three pairs 100a - 100c of MEMS switches 10a - 10f connected in series. In some embodiments shown in Figure 2 and the like, the standoff voltage (V SO ) of each individual MEMS switch 10 is 150V. That is, the MEMS system 150 of Figure 2 is configured to correspond to an input voltage of at least 450V in order to solve the problems described in connection with Figures 1A - 1C.

[0025] In the exemplary embodiment shown in FIG. 2, the MEMS system 150 includes three pairs 100a-100c of back-to-back MEMS switches 10a-10f. In another embodiment, the MEMS system 150 includes a different number of pairs 100 of MEMS switches 10. Each switch 10 shown in FIG. 2 has a beam portion 12 and a gate 14 as described in connection with FIGS. 1A-1C. As used herein, a pair 100 of switches 10 is considered back-to-back when the beam portion 12 of the first switch 10 is electrically connected to the beam portion 12 of the second switch 10 in each of the configurations where the first switch 10 is open and the second switch 10 is open, the first switch 10 is closed and the second switch 10 is closed, the first switch 10 is open and the second switch 10 is closed, and the first switch 10 is closed and the second switch 10 is open.

[0026] In some embodiments, each pair 100 of MEMS switches is electrically connected to an adjacent pair 100 of MEMS switches 10 at a central point 30. In the embodiment shown in FIG. 2, there are two central points 30a, 30b. In another embodiment where the number of pairs 100 of MEMS switches is different, the number of central points 30 may be different.

[0027] In some embodiments, the central point 30 is connected to a central point resistor 32. In the embodiment shown in FIG. 2, the first central point 30a is connected to the first central point resistor 32a.

[0028] In some embodiments, one or more of the central point resistors 32 are electrically connected to ground. In the exemplary embodiment shown in FIG. 2, both central point resistors 32a, 32b are electrically connected to ground. As another embodiment, the number of central point resistors electrically connected to ground may be different.

[0029] In some embodiments, such as the example shown in FIG. 2, each pair 100 of MEMS switches 10 includes: a first MEMS switch 10 (10a, 10c, 10e), and a second MEMS switch 10 (10b, 10d, 10f) electrically connected to the first MEMS switch 10 (10a, 10c, 10e) at an intermediate point 15 (15a, 15c, 15e), the first MEMS switch 10 and the second MEMS switch 10 being arranged in a back-to-back configuration; an input portion 17 (17a, 17b, 17c) electrically connected to the first MEMS switch 10; an output portion 18 (18a, 18b, 18c) electrically connected to the second MEMS switch 10; at least one input component 22 (22a, 22b, 22c) electrically connected from the input portion 17 to the intermediate point 15 via the first MEMS switch; and at least one output component 24 (24a, 24b, 24c) electrically connected from the intermediate point 15 to the output portion 18 via the second MEMS switch.

[0030] In some embodiments, the MEMS system 150 includes a system input portion and a system output portion. In some embodiments, the system input portion corresponds to the input portion 17 of the first pair 100 of MEMS switches 10 within the MEMS system 150. In some embodiments, the system output portion corresponds to the output portion 18 of the last pair 100 of MEMS switches 10 within the MEMS system 150.

[0031] In the exemplary embodiment shown in FIG. 2, the MEMS system 150 includes three pairs 100 (100a, 100b, 100c) of MEMS switches 10a - 10f. As a result, in this exemplary embodiment, the input portion 17a of the first pair 100a serves as the system input portion, and the output portion 18c of the third pair 100c serves as the system output portion.

[0032] In some embodiments, such as those shown in FIG. 2, the MEMS system 150 includes three pairs 100a - 100c of MEMS switches 10a - 10f. As another embodiment, the number of MEMS switches 10 included in the MEMS system 150 may be different.

[0033] In some embodiments, such as the example shown in FIG. 2, each pair 100 of MEMS switches 10 includes one input component 22a-22c electrically connected from the input section 17 to the intermediate point 15 via the first MEMS switch 10. As some embodiments, one or more of the MEMS switches 10 may include a different number of input components 22. In some embodiments, each input component 22 includes a passive element. As another embodiment, one or more of the input components may not include a passive element. In some embodiments, each input component includes a capacitor. As some embodiments, one or more of the input components 22 may not include a capacitor. In some embodiments, one or more of the input components 22 may include a resistor. In some embodiments, one or more of the input components 22 may include a resistor and a capacitor installed in parallel or in series.

[0034] In some embodiments, such as the example shown in FIG. 2, each pair 100 of MEMS switches 10 includes one output component 24. As another embodiment, one or more of the MEMS switches 10 may include a different number of output components 24. In some embodiments, such as those shown in FIG. 2, each output component 24 includes a passive element. As another embodiment, one or more of the output components 24 may not include a passive element. In some embodiments, such as those shown in FIG. 2, each output component 24 includes a capacitor. As another embodiment, one or more of the output components 24 may not include a capacitor. In another embodiment, one or more of the output components 24 may include a resistor. In another embodiment, one or more of the output components 24 may include a resistor and a capacitor installed in parallel or in series.

[0035] In some embodiments, one or more of the switches 10 include gate resistors 34 electrically connected to the gates 14. In some embodiments shown in FIG. 2 and the like, each of the switches 10a-10f includes a gate 14 and corresponding gate resistors 34a-34f.

[0036] In some embodiments shown in FIG. 2 and the like, each pair of MEMS switches 10a-10f of the pairs 100a-100c includes intermediate points 15a, 15b, 15c and corresponding at least one intermediate point resistor 16a, 16b, 16c.

[0037] In some embodiments shown in FIG. 2 and the like, each of the intermediate point resistors 16a, 16b, 16c may be connected to ground so as to prevent the intermediate point 15 from floating when the corresponding switch 10 is open. Such floating of the intermediate point 15 is important to avoid because it can lead to damage to the MEMS switch 10 by unspecified charges during operation. Note that when the intermediate point resistors 16a, 16b, 16c are grounded, the maximum input voltage is V SO will be limited.

[0038] If floating of at least one of the intermediate points 15a, 15b, 15c is allowed when the switch is off and a path from the at least one intermediate point 15 to ground is provided before operation, the MEMS system 150 can be made to correspond to an input voltage (Vin) higher than V SO while ensuring operation when a specified "operating" control voltage is applied to the gate.

[0039] In some embodiments, the MEMS system 150 includes at least one mode control switch 120 electrically connected to the pairs of MEMS switches 100. In the embodiment shown in FIG. 2, each pair 100a-100c of the MEMS switches 10a-10f is electrically connected to the corresponding mode control switches 120a-120c.

[0040] In some embodiments, one or more of the mode control switches 120 include MEMS switches. In the embodiment shown in FIG. 2, each of the mode control switches 120a-120c includes a MEMS switch. Each of the mode control switches 120a-120c shown in FIG. 2 has a beam portion 122 and gates 124 (124a-124c) as described in connection with FIGS. 1A-1C.

[0041] In some embodiments, one or more of the mode control switches 120 have a gate 124 and a mode control resistor 126 electrically connected to the gate 124. In the embodiment shown in FIG. 2, each of the mode control switches 120 has gates 124a-124c and mode control resistors 126a-126c electrically connected to the corresponding gates 124a-124c.

[0042] In some embodiments, the output of at least one mode control switch 120 is electrically connected to a bias resistor 128. In the embodiment shown in FIG. 2, the outputs of each of the mode control switches 120a-120c are electrically connected to bias resistors 128a-128c. Each bias resistor is also connected to gate control nodes 19a, 19b, 19c. For example, bias resistor 128a is connected to gate control 19a, and when switch 120a is actuated, a path is provided from gate 14a through resistor 34a, resistor 128a, and switch 120a to ground.

[0043] When the mode control switches 120a-120c are open (non-operating), the midpoints 15a-15c of all of the MEMS switch pairs 100a-100c are floating, and because the input voltage is distributed between the input component 22 and the output component 24, the MEMS system 150 can withstand an input voltage that exceeds V SO When the mode switches 120a-120c close, the MEMS switches 10a-10f function as a combination of typical MEMS switches (low loss, high linearity, but not capable of handling input voltages that exceed the standoff voltage).

[0044] FIG. 3 shows an overview of an exemplary embodiment of a MEMS system 150 in FIG. 2 in which each input component 22a - 22c includes a capacitor and each output component 24a - 24c includes a capacitor according to aspects of the inventive concept. It should be understood that the capacitance values of components 22a, 22b, 22c, 24a, 24b, 24c may all be equal, or the capacitance values of each component may be different, and any combination of the capacitance values of components 22a, 22b, 22c, 24a, 24b, 24c may be possible. In another embodiment, the number of capacitors included in each input component 22 is different. In some embodiments, one or more of the input components 22 may not include a capacitor. In another embodiment, one or more of the input components 22 may include a resistor. In another embodiment, one or more of the input components 22 may include a resistor and a capacitor installed in series or in parallel.

[0045] In another embodiment, the number of capacitors included in each output component 24 is different. In some embodiments, one or more of the output components 24 may not include a capacitor. In another embodiment, one or more of the output components 24 may include a resistor. In another embodiment, one or more of the output components 24 may include a resistor and a capacitor.

[0046] FIG. 4 is a diagram showing an overview of another embodiment of the MEMS system 150 in FIG. 2, in which each input component 22a-22c includes a capacitor and each output component 24a-24c includes a capacitor according to an aspect of the inventive concept. In some embodiments shown in FIG. 4 and the like, the capacitance magnitudes of the input component 22 and the output component 24 are set to a ratio of 4:2:1:1:2:4. In this embodiment, the capacitance of the first input component 22a is four times the capacitance of the second input component 22b. In this embodiment, the capacitance of the first output component 24a is twice the capacitance of the second output component 24b. In this embodiment, the capacitance of the second input component 22b is the same as the capacitance of the second output component 24b. In this embodiment, the capacitance of the third input component 22c is twice the capacitance of the second input component 22b. In this embodiment, the capacitance of the third output component 24c is four times the capacitance of the second output component 24b. As another embodiment, the capacitance ratio between these capacitors may be different. Due to such a relationship of the capacitance values of the above capacitors, the influence of the phase delay between the switches is suppressed. That is, any capacitance value that suppresses the influence of the phase delay between the switches falls within the scope of the inventive concept described herein.

[0047] In another embodiment in which each input component and each output component includes a resistor, the ratio of the corresponding resistance values may be adjusted to a setting of 4:2:1:1:2:4.

[0048] In another embodiment in which each input component and each output component includes a resistor and a capacitor, the ratio of the corresponding capacitances between the capacitors may be adjusted to a setting of 4:2:1:1:2:4.

[0049] In another embodiment in which each input component and each output component includes a resistor and a capacitor, the ratio of the corresponding resistance values between the resistors may be adjusted to a setting of 4:2:1:1:2:4.

[0050] Although the exemplary embodiments have been specifically illustrated and described, those skilled in the art will understand that various changes may be made to the form and details without departing from the scope of the embodiments encompassed by the appended claims.

Claims

1. a microelectromechanical system (MEMS) device, the MEMS device handling an input voltage higher than a standoff voltage of a MEMS switch within the MEMS device; At least one pair of MEMS switches; each pair of MEMS switches comprising: a first MEMS switch and a second MEMS switch electrically connected to the first MEMS switch at an intermediate point, the first MEMS switch and the second MEMS switch being arranged in a back-to-back configuration; an input electrically connected to the first MEMS switch; an output section electrically connected to the second MEMS switch; at least one input component electrically connected from the input to the intermediate point via the first MEMS switch; and at least one output component electrically connected from the intermediate point to the output via the second MEMS switch; 1. A MEMS device comprising:

2. The MEMS device of claim 1 , wherein one or more of the at least one input component and the at least one output component comprises a passive element.

3. The MEMS device of claim 1 , wherein each of the at least one input component and the at least one output component comprises a passive element.

4. The MEMS device of claim 1 , wherein one or more of the at least one input component and the at least one output component comprises a capacitor.

5. The MEMS device of claim 1 , wherein each of the at least one input component and the at least one output component comprises a capacitor.

6. 2. The MEMS device of claim 1 , wherein a capacitance of a first input component is four times the capacitance of a second input component, a capacitance of a first output component is twice the capacitance of a second output component, a capacitance of the second input component is the same as the capacitance of the second output component, a capacitance of a third input component is twice the capacitance of the second input component, and a capacitance of the third output component is four times the capacitance of the second output component.

7. The MEMS device of claim 1 , wherein one or more of the at least one input component and the at least one output component comprises a resistor.

8. The MEMS device of claim 1 , wherein each of the at least one input component and the at least one output component comprises a resistor.

9. The MEMS device of claim 1 , wherein one or more of the at least one input component and the at least one output component comprises a resistor and a capacitor.

10. The MEMS device of claim 1 , wherein each of the at least one input component and the at least one output component comprises a resistor and a capacitor.

11. The MEMS device of claim 1 , wherein two or more pairs of the MEMS switches are electrically connected in series.

12. 12. The MEMS device of claim 11, wherein three pairs of MEMS switches are electrically connected in series.

13. The MEMS device of claim 1 , wherein one or more of the at least one pair of MEMS switches is electrically connected to a mode control switch.

14. The MEMS device of claim 1 , wherein each of the at least one pair of MEMS switches is electrically connected to a mode control switch.

15. 14. The MEMS device of claim 13, wherein in a first configuration, the mode control switch is open and each of the at least one pair of MEMS switches is not electrically connected to ground, and wherein in a second configuration, the mode control switch is closed and each of the at least one pair of MEMS switches is electrically connected to ground.

16. 1. A method for handling an input voltage higher than a standoff voltage of a microelectromechanical systems (MEMS) device, comprising: providing the MEMS device comprising at least a pair of MEMS switches; each pair of MEMS switches comprising: a first MEMS switch and a second MEMS switch electrically connected to the first MEMS switch at an intermediate point, the first MEMS switch and the second MEMS switch being arranged in a back-to-back configuration; an input electrically connected to the first MEMS switch; an output section electrically connected to the second MEMS switch; at least one input component electrically connected from the input to the intermediate point via the first MEMS switch; and at least one output component electrically connected from the intermediate point to the output via the second MEMS switch; the method further comprising: distributing the input voltage from the input of a first pair of MEMS switches to the output of a last pair of MEMS switches; A method comprising:

17. 17. The method of claim 16 further comprising: connecting the at least one pair of MEMS switches to a mode control switch; A method comprising:

18. 18. The method of claim 17 further comprising: Implementing (i) a first configuration in which the mode control switch is open and each of the at least one pair of MEMS switches is not electrically connected to ground, or (ii) a second configuration in which the mode control switch is closed and each of the at least one pair of MEMS switches is electrically connected to ground; A method comprising:

19. 17. The method of claim 16 further comprising: electrically connecting two or more pairs of MEMS switches in series; A method comprising:

20. a microelectromechanical system (MEMS) device, the MEMS device handling an input voltage higher than a standoff voltage of a MEMS switch in the MEMS system; two or more MEMS switches electrically connected in series from a device input to a device output; a component for each of the two or more MEMS switches, the components being attached via the MEMS switches such that the components are connected in series from the device input to the device output and such that the input voltage is distributed between the components; A MEMS device comprising:

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