Terahertz wave band parallel MEMS switch

Abstract

The invention discloses a parallel MEMS switch of a terahertz wave band, and belongs to the field of radio frequency front-end devices. The antenna is composed of a first-layer metal patch, a middle-layer dielectric plate, a second-layer metal patch, a high-resistance bias line, a dielectric film, a metal pier and a third-layer metal patch which are stacked from bottom to top. Wherein the first layer of metal patch is an integral metal ground; the middle dielectric plate is an integral dielectric layer; the second layer of metal patch comprises a coplanar waveguide signal ground, a coplanar waveguide signal line, a direct current bias electrode and a switch driving electrode; and the third layer of metal patch comprises a switch metal beam and a CPW closed bridge. The lower driving electrode of the switch is covered with a dielectric film with a larger area, the middle section of the CPW signal ground is provided with a section of lifting bridge, and the direct current bias line is wired through the bridge and connects the lower electrode of the switch to the direct current bias electrode.

Description

Technical Field

[0001] The present invention relates to a parallel MEMS switch operating in the terahertz band, which is mainly used in phased arrays and reconfigurable antennas in the terahertz band, and belongs to the field of radio frequency front-end devices. Background Art

[0002] Terahertz MEMS switches are RF MEMS devices. Because they are designed based on transmission lines, they have low loss characteristics in high frequency bands and are widely used in RF communication links. Traditional RF switches mostly use PIN diodes and MOS tubes, which are used as components of phase shifters, reconfigurable antennas, phased arrays, electromagnetic metasurfaces and other devices, serving in the fields of mobile gadgets, satellite communications and airborne radar. For a long time, research and application of RF switches have been concentrated on frequency bands below 100 GHz, including WIFI and 5G applications. Most MEMS switch research also focuses on relatively low frequency bands such as millimeter waves. In 2022, researchers from North University of China proposed a single-pole, seven-throw MEMS switch based on a "M"-shaped power divider, which operates in the L-Ka band; in 2023, Munira et al. from the University of Malta proposed a lateral displacement mechanical contact MEMS switch that operates in the microwave frequency band; in 2022, Sofia et al. from the California Institute of Technology proposed a MEMS non-contact rotary terahertz waveguide switch operating at 500-750GHz, which innovatively solved the impact of static friction and other problems on the signal, but its structure is not convenient for integrated processing with microstrip devices.

[0003] The sixth generation of mobile communication technology is deployed in the terahertz field, and the losses of devices such as PIN diodes and MOS tubes become increasingly difficult to ignore as the operating frequency band increases. In this frequency band, MEMS switches have obvious performance advantages over the above-mentioned traditional RF switches. Summary of the invention

[0004] In view of this, the present invention designs a parallel MEMS switch operating in the terahertz band, which can meet the requirements of low loss in the terahertz band. The designed switch achieves the characteristics of low insertion loss, high isolation, broadband operation, simple structure, easy processing, and low cost.

[0005] The present invention adopts the following technical solutions to achieve the above technical effects:

[0006] A parallel MEMS switch in the terahertz band includes a first layer of metal patches, a middle layer of dielectric plates, a second layer of metal patches and high-resistance bias lines, a dielectric film and metal bridge piers, a third layer of metal patches,

[0007] The first layer of metal patch is a rectangular metal ground (1);

[0008] The intermediate dielectric plate is a rectangular dielectric layer (2);

[0009] The second layer of metal patch includes a ring-shaped coplanar waveguide signal ground (3), a dumbbell-shaped coplanar waveguide signal line (4), a square DC bias electrode and a rectangular switch drive electrode; the high-resistance bias line includes a positive voltage DC bias line (7) and a 0V DC bias line (8);

[0010] The dumbbell-shaped coplanar waveguide signal line (4) and the rectangular switch drive electrode are both located in the ring-shaped coplanar waveguide signal ground, wherein two rectangular switch drive electrodes are provided, respectively located on both sides of the waist of the dumbbell-shaped coplanar waveguide signal line (4); the square DC bias electrode includes a positive DC plate and a 0V DC plate;

[0011] A slot is provided in the middle of the annular coplanar waveguide signal ground (3), a positive voltage DC bias line passes through the slot and connects two rectangular switch drive electrodes to the positive DC plate; a 0V DC bias line (8) connects the annular coplanar waveguide signal ground (3) and the 0V DC plate;

[0012] The dielectric film includes two rectangular dielectric films, and the rectangular dielectric films are respectively placed on the upper surfaces of the corresponding rectangular switch drive electrodes; the metal bridge piers include three groups of rectangular bridge piers, and the three groups of rectangular bridge piers are all placed on the upper surface of the ring-shaped coplanar waveguide signal ground (3);

[0013] The third layer of metal patch includes a switch metal beam (15) and two CPW closed bridges, wherein the two CPW closed bridges are located above the slot through two corresponding sets of rectangular bridge piers; the switch metal beam includes a wing-shaped single-layer metal structure (18) and a circular contact pair (19); the wing-shaped single-layer metal structure is suspended above the annular coplanar waveguide signal ground (3), and is connected in parallel to the annular coplanar waveguide signal ground (3) through rectangular bridge piers on both sides of the rectangular switch drive electrode; the circular contact pair is located on the lower surface of the middle position of the wing-shaped single-layer metal structure.

[0014] Furthermore, a rectangular retaining groove for the switch driving electrode is provided on the inner side of the ring-shaped coplanar waveguide signal ground (3), and the retaining groove is directly opposite to the middle position of the dumbbell-shaped coplanar waveguide signal line (4); and the lifting bridge is located on one side of the retaining groove.

[0015] Furthermore, the bottom surface of the rectangular dielectric film is coplanar with the bottom surface of the rectangular bridge pier, and the thickness of the rectangular dielectric film is lower than the thickness of the rectangular bridge pier.

[0016] Furthermore: the switch metal beam is connected to the ring-shaped coplanar waveguide signal ground via the rectangular bridge pier connected thereto as a relay, and there is no dielectric layer between the circular contact pair and the dumbbell-shaped coplanar waveguide signal line.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] a) Low insertion loss can be achieved in the terahertz frequency band;

[0019] b) It has broadband characteristics and can work well in 50Ghz-250GHz;

[0020] c) High isolation between switch states;

[0021] d) Simple structure, easy manufacturing, and high production integration. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is the front view of the first layer of patch and dielectric of the parallel MEMS switch;

[0023] Figure 2 This is the front view of the second layer patch and high resistance line of the parallel MEMS switch;

[0024] Figure 3 It is a front view of the dielectric film and metal bridge pier of the parallel MEMS switch;

[0025] Figure 4 This is the front view of the third layer patch of the parallel MEMS switch;

[0026] Figure 5 It is a side view of the five-layer overall structure of the parallel MEMS switch;

[0027] Figure 6 are the insertion loss and isolation of the parallel MEMS switch.

[0028] In the figure: 1, rectangular metal ground, 2, rectangular dielectric layer, 3, coplanar waveguide signal ground, 4, coplanar waveguide signal line, 5, positive DC plate, 6, 0V DC bias line, 7, positive voltage DC bias line, 8, 0V DC bias line, 9, 10, rectangular switch drive electrode, 11, 12, dielectric film, 13, rectangular bridge pier (corresponding to switch metal beam), 14, rectangular bridge pier (corresponding to CPW closed bridge), 15, switch metal beam, 16, 17, CPW closed bridge, 19, circular contact pair. DETAILED DESCRIPTION

[0029] Below, the present invention is further described in conjunction with the accompanying drawings.

[0030] The following is combined with Figure 1-6 The specific implementation modes of the present invention are further described in detail with reference to the accompanying drawings and examples.

[0031] Attach Figure 2 , 3, 4 as an example, it consists of three layers. Among them, the first layer of structure on the medium is the second layer of switch patch, which is composed of coplanar waveguide signal ground 3, coplanar waveguide signal line 4, DC bias electrodes 5, 6, DC bias lines 7, 8, switch drive electrodes 9, 10; the second layer of structure on the medium is dielectric film 11, 12 and metal bridge piers 13, 14; the third layer of structure on the medium is switch metal beam 15 and CPW closed beams 16, 17.

[0032] The specific structure is described as follows: a raised bridge is set in the middle section of the CPW (coplanar waveguide) signal ground for routing the DC bias line; a MEMS metal beam is connected in parallel in the middle section of the CPW, and the metal beam is suspended in the air and connected to the CPW signal ground with a metal bridge pier.

[0033] The lower switch electrode, i.e., the positive bias electrodes 9 and 10, are located in the gap of the CPW and are symmetrically distributed on both sides with the CPW signal line 4 as the central axis. The upper surfaces of the positive bias electrodes 9 and 10 are covered with a slightly larger dielectric film to prevent the upper switch electrode from contacting and adhering to the lower electrode.

[0034] The lower electrode is connected to the positive DC plate through a high-resistance bias line. The switch metal beam as a whole can be regarded as a driving electrode, and the CPW signal ground is connected to the 0V DC plate through a high-resistance bias line. There is a pair of circular metal contacts on the lower surface of the metal beam. The normal switch is in the on state. When a positive DC voltage is applied to the positive plate, an electrostatic field is generated between the upper and lower electrodes, causing the metal beam to deform and pull down. The electric contact pair contacts the CPW signal line, blocking the RF signal and putting the switch in the off state. When the positive voltage is removed, the switch beam rebounds, causing the switch to return to the on state.

[0035] The two signal ports before and after the CPW signal line both have an equivalent impedance of 50 ohms. Adjusting the length of the CPW signal line will affect the impedance, thereby changing the electrical characteristics of the RF switch, such as insertion loss, return loss, and isolation.

[0036] In order to reduce losses, all metal materials used in the switch structure are made of gold, the dielectric layer uses quartz glass, the dielectric film uses silicon nitride, and the high-resistance line uses tantalum nitride.

[0037] For the terahertz parallel MEMS switch, a set of size combinations is selected here to illustrate the embodiment (the following data unit is micrometer um):

[0038] when Figure 2 The dimensions of the structure are:

[0039] Size 26 = 220, size 27 = 80, size 28 = 10, size 29 = 64, size 30 = 20, size 31 = 36, size 32 = 16, size 33 = 80, size 34 = 20, size 35 = 100, size 36 = 20, size 37 = 394, size 38 = 463, size 39 = 345;

[0040] when Figure 3 The dimensions of the structure are:

[0041] Size 40 = 5, size 41 = 20, size 42 = 60;

[0042] when Figure 4 The dimensions of the structure are:

[0043] Size 43 = 30, size 44 = 60, size 45 = 190, size 46 = 100, size R1 = 3;

[0044] when Figure 5 The dimensions of the structure are:

[0045] Size 20 = 1, size 21 = 100, size 22 = 1, size 23 = 1, size 24 = 0.2, size 25 = 0.5;

[0046] Figure 1 The length of the middle rectangular metal ground and dielectric layer is 1060 and the width is 720;

[0047] Under normal conditions, no voltage is applied to the positive plate. At this time, the insertion loss of the terahertz MEMS parallel switch is Figure 6 Middle curve 1; when a suitable positive voltage is applied to the positive plate, an electric field force is generated between the upper and lower electrodes, causing the switch metal beam to pull down, the contact to contact the CPW signal line, and the switch is in the off state. At this time, the isolation degree of the terahertz MEMS parallel switch is Figure 6 Middle curve 2, so the on-off state conversion of the switch can be achieved by controlling the DC bias voltage.

[0048] It should be understood that the above description of the specific implementation methods of this patent is only an exemplary description listed to facilitate ordinary technicians in the field to understand the patent scheme, and does not imply that the scope of protection of this patent is limited to these individual examples. Ordinary technicians in this field can fully understand the technical scheme of this patent and, without any creative work, obtain more specific implementation methods by combining technical features, replacing some technical features, adding more technical features, etc. to the examples listed in this patent. All these specific implementation methods are within the scope of the claims of this patent. Therefore, these new specific implementation methods should also be within the scope of protection of this patent.

[0049] In addition, for the purpose of simplifying the description, this patent may not list some common specific implementation schemes, which are naturally conceivable to ordinary technicians in this field after understanding the technical solution of this patent. Obviously, these solutions should also be included in the scope of protection of this patent.

Claims

1. A parallel MEMS switch in the terahertz band, comprising a first layer of metal patches, a middle layer of dielectric plates, a second layer of metal patches and high-resistance bias lines, a dielectric film and metal bridge piers, and a third layer of metal patches stacked from bottom to top, characterized in that: The first layer of metal patch is a rectangular metal ground (1); The intermediate dielectric plate is a rectangular dielectric layer (2); The second layer of metal patch includes a ring-shaped coplanar waveguide signal ground (3), a dumbbell-shaped coplanar waveguide signal line (4), a square DC bias electrode and a rectangular switch drive electrode; the high-resistance bias line includes a positive voltage DC bias line (7) and a 0V DC bias line (8); The dumbbell-shaped coplanar waveguide signal line (4) and the rectangular switch drive electrode are both located in the ring-shaped coplanar waveguide signal ground, wherein two rectangular switch drive electrodes are provided, respectively located on both sides of the waist of the dumbbell-shaped coplanar waveguide signal line (4); the square DC bias electrode includes a positive DC plate and a 0V DC plate; A slot is provided in the middle of the annular coplanar waveguide signal ground (3), a positive voltage DC bias line passes through the slot and connects two rectangular switch drive electrodes to the positive DC plate; a 0V DC bias line (8) connects the annular coplanar waveguide signal ground (3) and the 0V DC plate; The dielectric film includes two rectangular dielectric films, and the rectangular dielectric films are respectively placed on the upper surfaces of the corresponding rectangular switch drive electrodes; the metal bridge piers include three groups of rectangular bridge piers, and the three groups of rectangular bridge piers are all placed on the upper surface of the ring-shaped coplanar waveguide signal ground (3); The third layer of metal patch includes a switch metal beam (15) and two CPW closed bridges, wherein the two CPW closed bridges are located above the slot through two corresponding sets of rectangular bridge piers; the switch metal beam includes a wing-shaped single-layer metal structure (18) and a circular contact pair (19); the wing-shaped single-layer metal structure is suspended above the annular coplanar waveguide signal ground (3), and is connected in parallel to the annular coplanar waveguide signal ground (3) through rectangular bridge piers on both sides of the rectangular switch drive electrode; the circular contact pair is located on the lower surface of the middle position of the wing-shaped single-layer metal structure.

2. The terahertz-band parallel MEMS switch according to claim 1, characterized in that: A rectangular retaining groove for the switch driving electrode is provided on the inner side of the annular coplanar waveguide signal ground (3), and the retaining groove is directly opposite to the middle position of the dumbbell-shaped coplanar waveguide signal line (4); and the lifting bridge is located on one side of the retaining groove.

3. The terahertz band parallel MEMS switch according to claim 1, characterized in that: The bottom surface of the rectangular dielectric film is coplanar with the bottom surface of the rectangular bridge pier, and the thickness of the rectangular dielectric film is lower than the thickness of the rectangular bridge pier.

4. A terahertz band parallel MEMS switch according to claim 1, characterized in that: The switch metal beam is connected to the ring-shaped coplanar waveguide signal ground via a rectangular bridge pier connected thereto as a relay, and there is no dielectric layer between the circular contact pair and the dumbbell-shaped coplanar waveguide signal line.

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