MEMS switch
By introducing holes into the anchors of the MEMS switch and utilizing coplanar waveguide technology, the problems of difficulty in galvanic isolation and high insertion loss at high frequencies are solved, and better isolation performance and lower insertion loss are achieved.
Patent Information
- Application Number
- CN202380059755.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Priority Date
- 2022-08-31
- Filing Date
- 2023-08-30
- Publication Date
- 2025-03-28
AI Technical Summary
Existing microelectromechanical system (MEMS) switches are difficult to achieve effective galvanic isolation at high frequencies, and the insertion loss is high.
The MEMS switch is designed using coplanar waveguide technology to reduce parasitic capacitance by introducing holes into the anchor and controlling the position of the crossbar with the gate to enable opening and closing of the current path.
The isolation performance of MEMS switches is significantly improved at high frequencies, reducing insertion loss while maintaining lower insertion loss.
Smart Images
Figure CN119731872A_ABST
Abstract
Description
[0001] The present specification relates to a micro-electromechanical system (MEMS) switch implemented with a coplanar waveguide. Background Art
[0002] Micro-electromechanical systems (MEMS) describe a manufacturing technology used to create micro-scale integrated devices or systems that combine mechanical and electrical components. These devices and systems are able to sense, control, and actuate at the micro-scale, and generate effects at the macro-scale.
[0003] A coplanar waveguide is a type of electrical planar transmission line. In some instances, coplanar waveguides are manufactured using printed circuit board technology and are used to transmit microwave frequency signals. Additionally or alternatively, on a smaller scale, coplanar waveguide transmission lines are also built into monolithic microwave integrated circuits (MIMICs). Typically, a coplanar waveguide is formed by an intermediate metal strip that is separated from a ground plane by two narrow gaps. Summary of the invention
[0004] A first example relates to a microelectromechanical system (MEMS) switch implemented with a coplanar waveguide. The MEMS switch includes an input terminal and an output terminal spaced apart from the input terminal. The MEMS switch also includes a crossbar extending between the input terminal and the output terminal of the MEMS switch. The crossbar includes a first edge and a second edge coupled to a gate of the MEMS switch. The crossbar includes a third edge near the input terminal, the first edge including a first set of finger contacts near a first corner of the crossbar and a second set of finger contacts near a second corner of the crossbar. The crossbar also includes a fourth edge near the output terminal, the fourth edge being opposite to the third edge. The MEMS switch includes a first anchor coupled to the input terminal. The first anchor has a first section extending from a region near the input terminal to a region overlying the first set of finger contacts of the crossbar. The first anchor has a second section spaced apart from the first section by a pore in the first anchor, the second section extending from a region near the input terminal to a region overlying the second set of finger contacts of the crossbar. A second anchor of the MEMS switch waveguide is coupled to the output terminal of the MEMS switch and the second edge of the crossbar.
[0005] A second example relates to a MEMS switch including an input terminal. The input terminal is coupled to an anchor having an aperture separating a first section of the anchor from a second section of the anchor. The MEMS switch also includes an output terminal spaced apart from the input terminal, and a crossbar coupled to the output terminal, and a gate, the crossbar extending from a region proximate the output terminal to a region proximate the input terminal. The crossbar is configured to contact the anchor in response to assertion of a control signal at the gate of the MEMS switch to establish a current path between the input terminal and the output terminal. The crossbar is also configured to disconnect from the anchor in response to deassertion of the control signal at the gate to galvanically isolate the input terminal from the output terminal.
[0006] A third example relates to a system including a single-pole double-throw (SPDT) switch. The system includes a MEMS switch having a first anchor, a first crossbar, a first gate, a first input terminal, and a first output terminal, wherein the first anchor has a first aperture between a first segment of the first anchor and a second segment of the first anchor, and the first input terminal is coupled to the first anchor. The first crossbar is configured to contact the first anchor in response to assertion of a first control signal at the first gate to establish a first current path between the first input terminal and the first output terminal. The first crossbar is also configured to disconnect from the first anchor in response to de-assertion of the first control signal at the first gate to galvanically isolate the first input terminal from the first output terminal. The system further includes a second MEMS switch, the second MEMS switch having a second anchor, a second crossbar, a second gate, a second input terminal, and a second output terminal, wherein the second anchor has a second aperture between the first segment of the second anchor and the second segment of the second anchor, and the second input terminal is coupled to the second anchor. The second crossbar is configured to contact the second anchor to establish a second current path between the second input terminal and the second output terminal in response to assertion of the second control signal at the second gate. The second crossbar is also configured to disconnect from the second anchor to galvanically isolate the second input terminal from the second output terminal in response to deassertion of the second control signal at the second gate. The system additionally includes a receiver coupled to the first output terminal, a transmitter coupled to the second input terminal. The system further includes an antenna coupled to the first input terminal and the second output terminal, and a controller configured to provide the first control signal and the second control signal. BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Figure 1A A top view of a micro-electromechanical system (MEMS) switch is shown.
[0008] Figure 1B A cross-sectional side view of a MEMS switch is shown.
[0009] Figure 2 A heat map is shown characterizing the surface current of the anchor of a MEMS switch.
[0010] Figure 3 Shown is a graph plotting insertion loss and isolation of a MEMS switch.
[0011] Figure 4 A block diagram of a radio frequency (RF) transceiver employing a single pole double throw (SPDT) switch implemented using a MEMS switch is shown. DETAILED DESCRIPTION
[0012] The present specification relates to a microelectromechanical system (MEMS) switch implemented with a coplanar waveguide. The coplanar waveguide of the MEMS switch includes an input terminal and an output terminal. The input terminal is configured to be coupled to a signal source, and the output terminal is configured to be coupled to a load. In the present specification, the term "coupled / couples" means an indirect or direct connection. As an example, the input terminal is coupled to a radio frequency (RF) transmitter (e.g., a signal source) and the output terminal is coupled to an antenna (e.g., a load). In some such examples, the MEMS switch is a first MEMS switch that operates in conjunction with a second MEMS switch to form a single-pole double-throw (SPDT) switch, wherein the input terminal of the second MEMS switch is coupled to an antenna (e.g., a signal source) and the output terminal of the second MEMS switch is coupled to an RF receiver (e.g., a load).
[0013] The output terminal of the MEMS switch is spaced apart from the input terminal, and the crossbar extends in a region between the input terminal and the output terminal of the coplanar waveguide. In some examples, the crossbar is formed of an aluminum mesh or other conductive material. The crossbar includes a first edge and a second edge coupled to a gate of the MEMS switch. The crossbar has a third edge near the input terminal. The third edge includes a first set of finger contacts near a first corner of the crossbar and a second set of finger contacts near a second corner of the crossbar. The crossbar also has a fourth edge near the output terminal.
[0014] The first anchor is coupled to the input terminal. The second anchor is coupled to the output terminal of the coplanar waveguide and the second edge of the crossbar. The first anchor has a first section and a second section, the first section extending from a region near the input terminal to a region of a first group of finger contacts overlying the crossbar, and the second section is spaced apart from the first section, the second section extending from a region near the input terminal to a region of a second group of finger contacts overlying the crossbar. In addition, the first anchor has a dovetail-shaped (e.g., trapezoidal) aperture that separates the first section of the first anchor from the second section. Accordingly, the first section and the second section extend from the input terminal toward the third edge of the crossbar at complementary angles (e.g., opposite angles).
[0015] The MEMS switch is normally open and electrically controllable. More specifically, the state of the MEMS switch can be controlled using a control signal provided to the gate of the MEMS switch. In some instances, the control signal is provided by a controller (e.g., a microcontroller). In other instances, other devices provide the control signal. The MEMS switch is a normally open switch. In the off state, the input terminal and the output terminal of the MEMS switch are galvanically isolated. Assertion of the control signal (e.g., a high logic state) applies a bias voltage (e.g., about 40 volts (V) or higher) to the gate of the MEMS switch. The bias voltage moves the crossbar so that the first and second groups of finger-shaped contacts contact the first and second segments of the first anchor, thereby establishing a current path between the input terminal and the output terminal.
[0016] As described herein, a first anchor of a MEMS switch includes an aperture (e.g., having a dovetail shape) that separates a first section from a second section. This aperture reduces the surface area of the first anchor overlying the crossbar. In fact, the ends of the first section and the second section (which also include finger-shaped contacts) overlie the crossbar. Therefore, the inclusion of the first aperture reduces the parasitic capacitance between the first anchor and the crossbar, thereby improving the isolation between the input terminal and the output terminal during the time interval when the MEMS switch is in an open state. This isolation degrades as a function of frequency. However, the inclusion of the aperture suppresses this degradation, such that at frequencies of about 40 gigahertz (GHz) or more, the inclusion of the aperture improves the isolation by about 1 decibel (dB) or more. In addition, analysis of the surface current (Jsurf) on the first anchor during the interval when the MEMS switch is in a closed state reveals that most of the current flows along the periphery of the first anchor (regardless of whether the first anchor includes an aperture). Therefore, the inclusion of the aperture does not significantly affect the insertion loss of the MEMS switch. More specifically, at a higher frequency of 40 GHz, the inclusion of the aperture adds approximately 0.06 dB of additional insertion loss. Thus, for a relatively small increase in insertion loss (e.g., approximately 0.6 dB), a significant improvement in isolation of the MEMS switch (e.g., approximately 1 dB or more) is achieved by including the aperture.
[0017] Figure 1A and 1B A diagram of a MEMS switch 100 implemented with a coplanar waveguide 104 is shown. More specifically, Figure 1A A top view of the MEMS switch 100 is shown, and Figure 1B A cross-sectional side view of a MEMS switch 100 is shown. The MEMS switch 100 is a normally open type and is electrically controllable. The MEMS switch 100 may be implemented as, for example, an integrated circuit (IC) package. A coplanar waveguide 104 is formed in a groove 108 of a substrate 112. The substrate 112 includes a first return conductor 116 and a second return conductor 120 located near the groove 108.
[0018] The coplanar waveguide 104 includes an input terminal 124 and an output terminal 128. The input terminal 124 is configured to be coupled to a signal source, such as a transmitter or an antenna. The output terminal 128 is configured to be coupled to a load, such as a receiver or an antenna. The input terminal 124 and the output terminal 128 are spaced apart from each other.
[0019] The crossbar 132 is located in the area between the input terminal 124 and the output terminal 128. The crossbar 132 is formed of a mesh of a conductive material such as aluminum. The crossbar 132 has a rectangular shape with a first edge 136, a second edge 140, a third edge 144, and a fourth edge 148. The first edge 136 is close to the input terminal 124, and the second edge 140 opposite to the first edge 136 is close to the output terminal 128. The third edge 144 and the fourth edge 148 are opposite to each other and extend between the input terminal 124 and the output terminal 128. A first group of finger contacts 152 is formed at the corners of the first edge 136 and the third edge 144 of the crossbar 132. A second group of finger contacts 156 is formed at the corners of the first edge 136 and the fourth edge 148. In some examples, there are four (4) or more finger contacts in the first group of finger contacts 152 and the second group of finger contacts 156. In other examples, there are more or fewer finger contacts in the first set of finger contacts 152 and the second set of finger contacts 156 .
[0020] The input terminal 124 includes a through hole 160 that couples the input terminal 124 to a first anchor 164. The output terminal 128 also includes a through hole 168 that couples the output terminal 128 to a second anchor 172. The second anchor 172 is coupled to the second edge 140 of the crossbar 132. In addition, the second anchor 172 has a parallelogram shape that tapers from the output terminal 128 toward the second edge 140 of the crossbar 132.
[0021] The first anchor 164 has a first section 176 and a second section 180. An aperture 182 in the first anchor 164 separates the first section 176 from the second section 180. The first section 176 of the first anchor 164 extends from the input terminal 124 to a region overhanging the first set of finger contacts 152 of the crossbar 132 at a first angle. Similarly, the second section 180 extends from the input terminal 124 to a region overhanging the second set of finger contacts 156 at a second angle, and the second angle is complementary (opposite) to the first angle. Accordingly, in the example shown, the aperture 182 has a dovetail shape. In addition, the first section 176 includes a third set of finger contacts 184 overhanging the first set of finger contacts 152 of the crossbar 132, and the second section 180 includes a fourth set of finger contacts 186 overhanging the second set of finger contacts 156. In some examples, there are equal numbers of finger contacts in the first set of finger contacts 152 , the second set of finger contacts 156 , the third set of finger contacts 184 , and the fourth set of finger contacts 186 .
[0022] The third edge 144 and the fourth edge 148 of the crossbar 132 are coupled to a gate 190 of the MEMS switch 100. The gate 190 has two (2) terminals. Applying a bias voltage (e.g., about 40 volts (V) or greater) across the gate 190 causes the crossbar 132 to move in the direction indicated by the arrow 192. Removing the bias voltage causes the crossbar 132 to move in the direction indicated by the arrow 194 to decouple the crossbar 132 from the first anchor 164. In other words, applying the bias voltage applied to the gate 190 causes the crossbar 132 to move from the first position to the second position. The input terminal 124 and the output terminal 128 are galvanically isolated in the first position, and provide a current path between the input terminal 124 and the output terminal 128 in the second position, so that the MEMS switch 100 is in an open state in the first position, and the MEMS switch 100 is in a closed state in the second position.
[0023] In operation, the MEMS switch 100 is a normally open switch such that the MEMS switch 100 is in an open state in the absence of a bias voltage applied across the gate 190. In the open state, the first set of finger contacts 152 and the second set of finger contacts 156 of the crossbar 132 are spaced apart and galvanically isolated from the third set of finger contacts 184 and the fourth set of finger contacts 186 of the first segment 176 and the second segment 180 of the first anchor 164, respectively. Therefore, during the time interval when the MEMS switch 100 is in the open state, there is no current path between the input terminal 124 and the output terminal 128.
[0024] In contrast, during the time intervals when the via voltage is applied across the gate 190, the MEMS switch 100 is in a closed state. More specifically, as described herein, applying a bias voltage to the gate 190 causes the crossbar 132 to move in the direction indicated by arrow 192. Moving the crossbar 132 in the direction indicated by arrow 192 causes the first set of finger contacts 156 of the crossbar 132 to contact the third set of finger contacts 184 of the first segment 176 of the first anchor 164, and causes the second set of finger contacts 156 to contact the fourth set of finger contacts 186 of the second segment 180. Accordingly, applying a bias voltage across the gate 190 causes the first anchor 164 to contact the crossbar 132 to provide a current path between the input terminal 124 and the output terminal 128 of the MEMS switch 100.
[0025] The inclusion of the aperture 182 suppresses parasitic capacitance between the crossbar 132 and the first anchor 164 during intervals when the MEMS switch 100 is in the off state. For example, the aperture 182 reduces the surface area between the first anchor 164 and a region of the crossbar 132 proximate the first edge 136 of the crossbar 132. Reducing this surface area reduces parasitic capacitance between the crossbar 132 and the first anchor 164 in the off state.
[0026] Figure 2 Shown for MEMS switches (eg Figure 1A and 1B The first thermal map 200 implements a baseline anchor 204 (eg, using conventional methods), such as a first thermal map 200 and a second thermal map 220 of an anchor of a MEMS switch 100). Figure 1A and 1B The first anchor 164 is omitted from the aperture 182. The baseline anchor 204 is adjacent to the crossbar 212 (e.g., Figure 1A and 1B In contrast, the second thermal map 220 implements a modified anchor 224, such as Figure 1A and 1B The modified anchor 224 includes a first segment 232 (e.g., Figure 1A and 1B The first segment 176 and the second segment 236 (e.g., Figure 1A and 1B The second section 180) has a pore 228 (e.g., Figure 1A and 1B The modified anchor 224 is located near the crossbar 240 (e.g., Figure 1A and 1B The edge of the cross bar 132).
[0027] The first thermal map 200 represents the surface current density (Jsurf) in amperes per meter (A / m) of the baseline anchor 204 in which the MEMS switch is in a closed state. The first thermal map 200 shows that the periphery of the baseline anchor 204 has the largest surface current density when the aperture 182 is omitted. In contrast, the interior region 208 of the baseline anchor 204 represented by the first thermal map 200 has a relatively low surface current density.
[0028] The second heat map 220 characterizes the surface current density (Jsurf) in A / m of the modified anchor 224 including the pores 228. As indicated, the first segment 232 and the second segment 236 have relatively high surface current density. Comparing the first heat map 200 with the second heat map 220, the inclusion of the pores 228 (in the modified anchor 224 of the second heat map 220) does not greatly affect the total surface current density. Accordingly, because the surface current density is lower in the inner region 208 of the baseline anchor 204 corresponding to the first heat map 200, removing the inner region 208 to form the modified anchor 224 with the pores 228 has a relatively small effect on the resistance (which corresponds to the insertion loss in the closed state) in the MEMS switch using the modified anchor 224. For example, there are multiple metal layers in the MEMS switch using the baseline anchor 204 or the modified anchor 224, which produce a parasitic parallel plate capacitance effect. For example, due to the inclusion of aperture 228, the capacitance between crossbar 212 and baseline anchor 204 (in the disconnected state) is greater than the capacitance between crossbar 240 and modified anchor 224 (in the disconnected state).
[0029] Figure 3 A first bar graph 300 is shown, which plots a graph having a baseline anchor (e.g., Figure 2 A MEMS switch having a baseline anchor 204) and a MEMS switch having a modified anchor (e.g., Figure 2 The modified anchor 224 and / or Figure 1A and 1B The insertion loss of the MEMS switch of the first anchor 164 is measured in decibels (dB). In the first bar graph 300, it is assumed that the MEMS switch is in a closed state and the current is flowing at the input terminal (e.g., Figure 1A and 1B The input terminal 124) and the output terminal (for example, Figure 1A and 1B The first bar graph 300 contains the insertion loss for a 20 gigahertz (GHz) input signal and a 40 GHz input signal.
[0030] As shown in the first bar graph 300, the pores (e.g. Figure 2 The pores 228 and / or Figure 1A and 1B The pores 182 ) induce an additional insertion loss of approximately 0.03 dB at 20 GHz (e.g., 0.7 dB for the baseline anchor compared to 0.73 dB for the modified anchor) and an additional insertion loss of approximately 0.06 dB at 40 GHz (e.g., 0.86 dB for the baseline anchor compared to 0.92 dB for the modified anchor).
[0031] Figure 3 Also shown is a second bar graph 320 that plots the isolation, in dB, of a MEMS switch with a baseline anchor and a MEMS switch with a modified anchor. In the second bar graph 320, it is assumed that the MEMS switch is in an open state and current is prevented from flowing between the input terminal and the output terminal. The second bar graph 320 includes isolation for an input signal of 20 GHz and an input signal of 40 GHz.
[0032] As shown in the second bar graph 320, the inclusion of apertures in the modified anchor improves isolation by about 1.59 dB at 20 GHz (e.g., 22.65 dB for the baseline anchor compared to 24.24 dB for the modified anchor) and about 1.44 dB at 40 GHz (e.g., 16.82 dB for the baseline anchor compared to 18.26 dB for the modified anchor). As shown in the second bar graph 320, as frequency increases, isolation degrades. However, employing the modified anchor suppresses this degradation.
[0033] Accordingly, the first bar graph 300 and the second bar graph 320 show that the isolation is improved by about 1.59 dB at the expense of about 0.03 dB insertion loss at 20 GHz. In addition, the first bar graph 300 and the second bar graph 320 show that the isolation is improved by 1.44 dB at the expense of about 0.06 dB insertion loss at 40 GHz. Therefore, at both 20 GHz and 40 GHz, the isolation of the MEMS switch is improved at the expense of almost negligible insertion loss.
[0034] Return to reference Figure 1A and 1B ,like Figure 2-3 As shown, during the time interval when the MEMS switch 100 is in the off state, the MEMS switch 100 provides a relatively low insertion loss (e.g., about 0.7 dB at 20 GHz and about 0.86 dB at 40 GHz). In addition, during the time interval when the MEMS switch 100 is in the off state, the MEMS switch 100 provides a relatively high isolation (e.g., 22.65 dB at 20 GHz and about 16.82 dB at 40 GHz).
[0035] Figure 44 is a block diagram of a system 400 that employs a single-pole double-throw (SPDT) switch 404. In some examples, the SPDT switch 404 is implemented on an integrated circuit (IC) package. The SPDT switch 404 includes two MEMS switches, namely, a first MEMS switch 408 (MEMS switch 1) and a second MEMS switch 412 (MEMS switch 2). The first MEMS switch 408 and the second MEMS switch 412 are implemented as Figure 1A and 1B Therefore, the first MEMS switch 408 and the second MEMS switch 412 are electrically controllable normally open switches.
[0036] In the example shown, the system 400 can be used to implement a radio frequency (RF) transceiver including an RF receiver 416 and an RF transmitter 420 in communication with an antenna 424 (e.g., more generally, a load). However, the SPDT switch 404 can be used in almost any system where high isolation is required. In some examples, the RF receiver 416 is configured to receive an RF signal having a frequency of about 50 GHz to about 80 GHz from the antenna 424. Similarly, the RF transmitter 420 is configured to send a signal having a frequency of about 50 GHz to about 80 GHz to the antenna 424. In other examples, other frequencies can be used.
[0037] In the example shown, the antenna 424 is coupled to the input terminal 425 of the first MEMS switch 408, and the RF receiver 416 is coupled to the output terminal 426 of the first MEMS switch 408. In addition, the RF transmitter 420 is coupled to the input terminal 428 of the second MEMS switch 412, and the antenna 424 is coupled to the output terminal 429 of the second MEMS switch 412.
[0038] The SPDT switch 404 has two modes of operation, namely, a receive mode and a transmit mode. A controller 430 (e.g., a microcontroller) controls the mode of operation of the SPDT switch 404. In some instances, the controller 430 is implemented in an IC package that communicates with the SPDT switch 404. In other instances, the controller 430 is integrated with the SPDT switch 404. The controller 430 includes embedded instructions for controlling the state of the SPDT switch 404. More specifically, the controller 430 provides a first control signal 432 that controls the state of the first MEMS switch 408 to a gate 434 of the first MEMS switch 408. The assertion of the first control signal 432 across the gate (e.g., Figure 1A and 1B40V or more DC voltage) to transition the first MEMS switch 408 from the open state to the closed state. The de-assertion of the first control signal 432 (e.g., a low logic state) removes the bias voltage and transitions the first MEMS switch 408 to the open state. Similarly, the controller 430 provides a second control signal 436 to the gate 438 of the second MEMS switch 412 that controls the state of the second MEMS switch 412. The assertion of the second control signal 436 across the gate (e.g., Figure 1A and 1B The gate 190 of the MEMS switch 412 is provided with a bias voltage (e.g., a DC voltage of about 40V or greater) to transition the second MEMS switch 412 from the open state to the closed state. The de-assertion of the second control signal 436 removes the bias voltage and transitions the second MEMS switch 412 from the closed state to the open state. The first control signal 432 and the second control signal 436 are complementary signals such that during the time interval when the first control signal 432 is asserted, the second control signal 436 is de-asserted, and vice versa.
[0039] The SPDT switch 404 is configured such that in the receive mode, the first control signal 432 is asserted and the second control signal 436 is de-asserted, so that the first MEMS switch 408 is in a closed state and the second MEMS switch 412 is in an open state. In addition, the SPDT switch 404 is configured such that in the transmit mode, the first control signal 432 is de-asserted and the second control signal 436 is asserted.
[0040] In the receive mode, the RF signal received by the antenna 424 flows from the antenna 424 through the first MEMS switch 408 (in a closed state) along the receive path 440 and flows to the RF receiver 416. In addition, in the receive mode, the second MEMS switch 412 is in an open state so that current does not flow through the second MEMS switch 412. In the transmit mode, the RF signal provided from the RF transmitter 420 flows from the RF transmitter 420 through the second MEMS switch 412 (in a closed state) along the transmit path 444 and flows to the antenna 424. In addition, in the transmit mode, the first MEMS switch 408 is in an open state so that current does not flow through the first MEMS switch 408.
[0041] In operation, because the SPDT switch 404 employs the first MEMS switch 408 and the second MEMS switch 412, high isolation between the RF receiver 416 and the RF transmitter 420 is achieved. More specifically, during the time interval when the SPDT switch 404 is in the receive mode such that the receive path 440 is active, the received RF signal is prevented from reaching the RF transmitter 420, which prevents loss of gain of the MEMS switch 100. In addition, during the time interval when the SPDT switch 404 is in the transmit mode such that the transmit path 444 is active, the signal provided by the RF transmitter 420 is prevented from flowing to the RF receiver 416, thereby avoiding corruption of the measurement of the transmitted signal. In addition, as Figure 3 As shown in the second bar graph 320 of FIG. 1 , increasing the frequency of the transmitted and received signals degrades the isolation of the first MEMS switch 408 and the second MEMS switch 412, resulting in an improvement of about 1 dB to about 2 dB (by including Figure 1A and 1B The pores 182 provided herewith provide a significant improvement in performance.
[0042] In this specification, unless otherwise stated, "about," "approximately," or "substantially" preceding a parameter means within + / - 10% of the parameter. Modifications in the described embodiments are possible, and other embodiments are possible, within the scope of the claims.
Claims
1. A micro-electromechanical system (MEMS) switch implemented with a coplanar waveguide, the MEMS switch comprising: Input terminal; an output terminal spaced apart from the input terminal; A crossbar extending between the input terminal and the output terminal, the crossbar comprising: coupled to a first edge and a second edge of a gate of the MEMS switch; a third edge proximate the input terminal, the first edge comprising a first set of finger contacts proximate a first corner of the crossbar and a second set of finger contacts proximate a second corner of the crossbar; and a fourth edge close to the output terminal, the fourth edge being opposite to the third edge; A first anchor, coupled to the input terminal, the first anchor comprising: a first segment extending from a region proximate the input terminal to a region overlying the first set of finger contacts of the crossbar; and a second segment spaced apart from the first segment by an aperture in the first anchor, the second segment extending from the region proximate the input terminal to a region of the second set of finger contacts overlying the crossbar; and A second anchor is coupled to the output terminal and the second edge of the crossbar.
2. The MEMS switch of claim 1 , wherein the crossbar is configured to move from a first position to a second position in response to a bias voltage at the gate, the MEMS switch having an open state in the first position to galvanically isolate the input terminal from the output terminal, and the MEMS switch having a closed state in the second position to establish a current path between the input terminal and the output terminal.
3. The MEMS switch of claim 2, wherein the MEMS switch has an isolation of about 24 decibels (dB) or greater between the input terminal and the output terminal for an input signal having a frequency of about 20 gigahertz.
4. The MEMS switch of claim 2, wherein the MEMS switch has an isolation of about 18 decibels (dB) or greater between the input terminal and the output terminal for an input signal having a frequency of about 40 gigahertz.
5. The MEMS switch of claim 2 , wherein an end of the first segment of the first anchor includes a third set of finger contacts and an end of the second segment of the first anchor includes a fourth set of finger contacts, and in the second position, the first set of finger contacts of the crossbar contacts the third set of finger contacts and the second set of finger contacts of the crossbar contacts the fourth set of finger contacts.
6. The MEMS switch of claim 5, wherein in the first position, the first set of finger contacts of the crossbar are spaced apart from the third set of finger contacts of the first segment, and the second set of finger contacts of the crossbar are spaced apart from the fourth set of finger contacts of the second segment. 7 . The MEMS switch of claim 1 , wherein the first segment and the second segment extend at opposite angles from the input terminal and toward the first edge of the crossbar. The MEMS switch of claim 1 , wherein the crossbar is formed from an aluminum mesh.
9. The MEMS switch of claim 1, wherein the MEMS switch is implemented on an integrated circuit (IC) package.
10. A micro-electromechanical system (MEMS) switch, comprising: an input terminal coupled to an anchor having an aperture separating a first segment of the anchor from a second segment of the anchor; an output terminal spaced apart from the input terminal; as well as a crossbar coupled to the output terminal and the gate, the crossbar extending from a region near the output terminal to a region near the input terminal; wherein the crossbar is configured to: contacting the anchor to establish a current path between the input terminal and the output terminal in response to assertion of a control signal at a gate of the MEMS switch; as well as Disconnecting from the anchor to galvanically isolate the input terminal from the output terminal in response to de-assertion of the control signal at the gate.
11. The MEMS switch of claim 10, wherein the crossbar is configured to: moving an edge of the crossbar to contact the first and second segments of the anchor in response to assertion of the control signal at the gate; and The edge of the crossbar is disconnected from the first and second segments of the anchor in response to de-assertion of the control signal at the gate. 12 . The MEMS switch of claim 11 , wherein the aperture has a dovetail shape such that the first segment and the second segment extend at opposite angles from the input terminal and toward the edge of the crossbar.
13. The MEMS switch of claim 10, wherein the MEMS switch is configured to apply a bias voltage of approximately 40 volts or more at the gate when the control signal is asserted at the gate.
14. The MEMS switch of claim 10, wherein the MEMS switch is configured to have an isolation of approximately 18 decibels (dB) or greater between the input terminal and the output terminal for an input signal applied to the input terminal at a frequency of approximately 40 gigahertz during a time interval in which the control signal is de-asserted.
15. The MEMS switch of claim 10, wherein the crossbar is formed from an aluminum mesh.
16. The MEMS switch of claim 10, wherein the MEMS switch is implemented on an integrated circuit (IC) package.
17. A system comprising: A single-pole double-throw (SPDT) switch comprising: a first microelectromechanical system (MEMS) switch having a first anchor, a first crossbar, a first gate, a first input terminal, and a first output terminal, wherein the first anchor has a first aperture between a first segment of the first anchor and a second segment of the first anchor, the first input terminal is coupled to the first anchor, and the first crossbar is configured to: contact the first anchor to establish a first current path between the first input terminal and the first output terminal in response to assertion of a first control signal at the first gate; and disconnect from the first anchor to galvanically isolate the first input terminal from the first output terminal in response to deassertion of the first control signal at the first gate; and a second MEMS switch having a second anchor, a second crossbar, a second gate, a second input terminal, and a second output terminal, wherein the second anchor has a second aperture between a first segment of the second anchor and a second segment of the second anchor, the second input terminal is coupled to the second anchor, and the second crossbar is configured to: contact the second anchor to establish a second current path between the second input terminal and the second output terminal in response to assertion of a second control signal at the second gate; and disconnect from the second anchor to galvanically isolate the second input terminal from the second output terminal in response to deassertion of the second control signal at the second gate; a receiver coupled to the first output terminal; a transmitter coupled to the second input terminal; an antenna coupled to the first input terminal and the second output terminal; and A controller is configured to provide the first control signal and the second control signal.
18. The system of claim 17, wherein the first crossbar is configured to: move an edge of the first crossbar to contact the first and second segments of the first anchor in response to assertion of the first control signal at the first gate; and disconnect the edge of the first crossbar from the first and second segments of the first anchor in response to de-assertion of the first control signal.
19. The system of claim 17, wherein the first MEMS switch is configured to apply a bias voltage of approximately 40 volts or more at the first gate when the first control signal is asserted at the first gate.
20. The system of claim 17, wherein the first MEMS switch is configured to have an isolation of approximately 18 decibels (dB) or greater between the first input terminal and the first output terminal for an input signal applied to the first input terminal at a frequency of approximately 40 gigahertz during a time interval in which the first control signal is de-asserted.