WO2020206585A1

WO2020206585A1 - Capacitive rf-mems switch

Info

Publication number: WO2020206585A1
Application number: PCT/CN2019/081720
Authority: WO
Inventors: 姜梅; 熊文涛
Original assignee: 深圳大学
Priority date: 2019-04-08
Filing date: 2019-04-08
Publication date: 2020-10-15

Abstract

Disclosed is a capacitive RF-MEMS switch. The switch comprises an insulating plate, first to third microstrip lines, an insulating dielectric, N anchor points, and a switch piece. The switch piece comprises a movable metal film and N elastic fixed beams. The first to third microstrip lines are sequentially disposed on the insulating plate. The insulating dielectric is placed on the second microstrip line. The N anchor points are disposed on a microstrip line different from the second microstrip line. One end of the N elastic fixed beams of the switch piece is respectively connected to the movable metal film, and the other end of the switch piece is connected to the anchor points. The elastic fixed beams in the present invention have low elastic coefficients so that a pull-down voltage of the switch is decreased, thereby obtaining a high switching capacitance ratio and a high radio frequency turn-off property. Accordingly, the speed of the switch is fast. At the same time, decreasing the elastic coefficient of the switch can decrease a driving voltage thereof. On the other hand, a novel elastic fixed beam structure is used for the switch, which can reduce the switch area compared with the conventional long fixed beam.

Description

A Capacitive RF-MEMS Switch Technical Field

The present invention relates to a switch, particularly a capacitive RF-MEMS switch, which belongs to the field of electronic technology. Background technique

With the advent of the 5G information era, in the communications field, especially in the Internet of Things, satellite communications and mobile communications, there is an urgent need for new devices with low power consumption, ultra-miniaturization and planar structure that can be integrated with signal processing circuits, such as switch.

Compared with traditional PIN diode (PIN Diode) switches or field effect transistor (Field Effect Transistor, FET) switches, RF MEMS (Radio Frequency Micro Electro Mechanical System) switches have many advantages: close to zero power consumption, high isolation , Low insertion loss, low cost, etc. However, even if the RF MEMS switch has so many advantages, it still has many disadvantages, including excessively high driving voltage, slow switching speed, and large switching area. technical problem

The invention provides a low driving voltage, fast switching speed and small switching area.

RF MEMS switch. Technical solutions

1

Replacement page (Rule 26) The present invention provides a capacitive RF-MEMS switch. The switch includes an insulating plate, first to third microstrip lines, an insulating medium, N anchor points, and a switch sheet. The switch sheet includes a movable metal film and N elastic fixed supports The shape of the elastically fixed beam is M n-shaped connected together; N and M are positive integers;

The first to third microstrip lines are arranged on the insulating board in order, the insulating medium is covered on the second microstrip line, and the N anchor points are arranged on the microstrip line different from the second microstrip line;

One end of the N elastic fixed beams of the switch piece is respectively connected with the movable metal film, and the other end is connected with the anchor point.

Optionally, the thickness of the switch sheet is lum.

Optionally, N anchor points are set on the first microstrip line, or N anchor points are set on the third microstrip line, or N anchor points are set on the first microstrip line and the third microstrip line, respectively on.

Optionally, the insulating medium is silicon nitride.

Optionally, the width of the elastically fixed beam is 5 μm.

Optionally, the width of the movable metal film is 80 μm. Beneficial effect

The present invention provides a capacitive RF-MEMS switch. The switch includes an insulating plate, first to third microstrip lines, an insulating medium, N anchor points, and a switch sheet, wherein the switch sheet includes a movable metal film and N Elastically fixed beams, the shape of the elastically fixed beams is M n-shaped connected together; N and M are positive integers, the first to third microstrip lines are sequentially arranged on the insulating plate, and the insulating medium is covered on the second On the microstrip line, N anchor points are set on the microstrip line different from the second microstrip line, and one end of the N elastic fixed beams of the switch piece is connected with the movable metal film respectively (Article 26 of the Rules) The other end is connected to the anchor point. In the present invention, the elastic fixed beam has a lower elastic coefficient, which can reduce the pull-down voltage of the switch, thereby obtaining a high switching capacitance ratio and high radio frequency turn-off performance, thereby making the switching speed fast; The coefficient can reduce the driving voltage of the switch. On the other hand, the switch provided by the present invention adopts a new elastic fixed-supported beam structure, which can reduce the switch area compared with the traditional longer fixed-supported beam. Description of the drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only These are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

FIG. 1 is a schematic diagram of a first structure of a capacitive RF-MEMS switch provided by an embodiment of the present invention;

2 is a schematic diagram of a first structure of a switch chip in a switch provided by an embodiment of the present invention; FIG. 3 is a schematic diagram of a second structure of a switch chip in a switch provided by an embodiment of the present invention; The second schematic diagram of the RF-MEMS switch;

FIG. 5 is a schematic diagram of the first deformation of the capacitive RF-MEMS switch provided by the embodiment of the present invention;

FIG. 6 is a schematic diagram of the second deformation of the capacitive RF-MEMS switch provided by the embodiment of the present invention;

3

Replacement page (Rule 26) FIG. 7 is a schematic diagram of the overall displacement of the capacitive RF-MEMS switch provided by an embodiment of the present invention when it is in the "down" state at a driving voltage of 2V;

FIG. 8 is a schematic diagram of the change of the capacitance value of the capacitive RF-MEMS switch provided by an embodiment of the present invention under a driving voltage of 2V;

Fig. 9 is a time-displacement diagram of a capacitive RF-MEMS switch provided by an embodiment of the present invention;

Fig. 10 is a diagram of the relationship between the driving voltage and the displacement loaded by the capacitive RF-MEMS switch provided by an embodiment of the present invention. The best mode of the invention

In order to make the objectives, features, and advantages of the present invention more obvious and understandable, the technical solutions in the embodiments of the present invention will be described clearly and completely in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the description is The embodiments are only a part of the embodiments of the present invention, but not all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work shall fall within the protection scope of the present invention.

The present invention provides a capacitive RF-MEMS switch. Referring to FIG. 1, the switch includes an insulating plate 1, a first microstrip line 2, a second microstrip line 3, a third microstrip line 4, an insulating medium 5, and N There are two anchor points 6 and the switch piece 7. The switch piece 7 includes a movable metal film 71 and N elastic fixed beams 72. It should be understood that the shape of the elastic fixed beams 72 is M n-shaped connected together, see As shown in Figure 2, where N and M are positive integers.

The connection relationship of each component in the capacitive RF-MEMS switch can be replaced with Figure 1 (Article 26 of the Rules) View:

The first microstrip line 2, the second microstrip line 3, and the third microstrip line 4 are arranged on the insulating plate 1 in order, the insulating medium 5 is covered on the second microstrip line 3, and N anchor points 6 are arranged on A microstrip line different from the second microstrip line 3;

One end of the N elastic fixed beams 72 of the switch sheet 7 is connected to the movable metal film 71, and the other end is connected to the anchor point 6.

This embodiment also provides an example of a switch sheet, the specific structure of which can be seen in Figure 3, and the dimensions in Figure 3 can be seen in the following table:

What needs to be understood is that the insulating medium is attached to the transmission line, and its main function is to avoid direct contact between the upper electrode and the transmission line, to achieve DC isolation between the two, and to prevent adhesion and improve isolation.

The insulation board is FR-4, which is a kind of epoxy glass cloth laminate. According to different purposes, the industry is generally called: FR-4 epoxy glass cloth (Epoxy Glass Cloth), insulation board, epoxy board, epoxy Resin board, brominated epoxy resin board, FR-4, glass fiber board, glass fiber board, FR-4 reinforcement board, FPC reinforcement board, flexible circuit board reinforcement board, FR-4 epoxy resin board, flame retardant Insulation board, FR-4 laminated board, epoxy board, FR-4 light board, FR-4 fiberglass board, epoxy glass cloth board, epoxy glass cloth laminate, circuit board drilling pad. Replacement page (Rule 26) Main technical features and applications: Stable electrical insulation performance, good flatness, smooth surface, no pits, thickness tolerance standards, suitable for high-performance electronic insulation requirements products, such as FPC reinforcement board, PCB drilling pad, glass Fiber meson, potentiometer carbon film printed glass fiber board, precision star gear (wafer grinding), precision test plate, electrical (electrical) equipment insulation stay spacer, insulation backing board, transformer insulation board, motor insulation, grinding gear, Electronic switch insulation board, etc.

In some examples, the microstrip line is a Coplanar Waveguide (CPW).

When no voltage is applied to the switch, the switch capacitor Cup is very small, as shown in the following formula:

In the formula, g _Q is the initial distance of the air gap between the movable metal plate and the insulating medium;

A is the intersection area between the movable metal plate and the insulating medium;

t _d is the thickness of the insulating dielectric film;

^ Is the relative dielectric constant of the insulating dielectric film material.

At this time, the microwave signal will pass through the transmission line almost without attenuation, and the switch will be in the "up" state, as shown in Figures 1 and 4.

When a voltage is applied to the switch, the generated electrostatic force causes the switch to deform and pull the movable metal plate to move to the transmission line, so that the air gap in the middle will change, thereby changing the capacitance. When the voltage value reaches the pull-down voltage, the movable metal plate is in close contact with the insulating medium, ignoring the edge effect, and the switched capacitor is: Replacement page (Regulation 26)

In this state, the capacitance value increases, so that high-frequency microwave signals are coupled to the ground line, almost no signal passes through the transmission line, and the switch is in the "down" state, as shown in Figs. 5 and 6.

It should be understood that in some examples, the thickness of the switch sheet is 1 μm; the insulating medium is silicon nitride; the width of the elastic fixed beam is 5 μm; and the width of the movable metal film is 80 μm.

In some other examples, N anchor points are set on the first microstrip line, or N anchor points are set on the third microstrip line, or N anchor points are set on the first microstrip line and the third microstrip line. Microstrip line.

It should be understood that in traditional RF-MEMS switches, to reduce the pull-down voltage or maintain a reduced pull-down voltage, a longer fixed-supported beam is generally used. As a result, a large switching area is caused. The impact is the increase in production costs. The capacitive RF-MEMS switch provided by the present invention adopts a new fixed-supported beam structure, which reduces the pull-down voltage by reducing the elastic coefficient of the switch, and has a smaller switch area, which can reach 23695 (175x135) u m2.

Please refer to the attached drawings:

Figure 7 shows the overall position of the switch when it is in the "down" state under the 2V driving voltage;

Figure 8 shows the change of the capacitance value of the switch under the 2V driving voltage.

7

Replacement page (Rule 26) The capacitance ratio is 135.5:1;

Figure 9 shows the switching time vs. displacement diagram, which shows that the switching time is 12.35ms; Figure 10 shows the relationship between the driving voltage applied to the switch and the displacement, and the pull-down voltage of the switch is 1.9V.

This embodiment provides a capacitive RF-MEMS switch. The switch includes an insulating plate, first to third microstrip lines, an insulating medium, N anchor points, and a switch sheet, where the switch sheet includes a movable metal film and N elastically fixed beams, the shape of the elastically fixed beams is M n-shaped connected together; N and M are positive integers, the first to third microstrip lines are sequentially arranged on the insulating board, and the insulating medium is covered On the second microstrip line, N anchor points are arranged on a microstrip line different from the second microstrip line, one end of the N elastic fixed beams of the switch piece is connected to the movable metal film, and the other end is connected to the anchor point connection. The elastic fixed beam in the present invention has a lower elastic coefficient, which can reduce the pull-down voltage of the switch, thereby obtaining a high switching capacitance ratio and high radio frequency turn-off performance, thereby making the switching speed fast; on the other hand, reduction reduces the flexibility of the switch The coefficient can reduce the driving voltage of the switch. On the other hand, the switch provided by the present invention adopts a new elastic fixed-supported beam structure, which can reduce the switch area compared with the traditional longer fixed-supported beam.

In the foregoing embodiments, the description of each embodiment has its own focus. For parts that are not described in detail in an embodiment, reference may be made to the related descriptions of other embodiments. At the same time, the sequence numbers of the foregoing embodiments of the present invention are only for description. Representing the advantages and disadvantages of the embodiments, under the enlightenment of the present invention, those of ordinary skill in the art can make many forms without departing from the purpose of the present invention and the scope of protection of the claims, which are all protected by the present invention within.

8

Replacement page (Rule 26)

Claims

[Claim 1] A capacitive RF-MEMS switch, characterized in that, the switch includes an insulating plate, first to third microstrip lines, an insulating medium, N anchor points, and a switch sheet, and the switch sheet includes The movable metal film and N elastically fixed beams, wherein the shape of the elastically fixed beams is M n-shaped connected together; the N and M are positive integers;

The first to third microstrip lines are arranged on the insulating plate in order, the insulating medium is overlaid on the second microstrip line, and the N anchor points are arranged different from the second Microstrip line of microstrip line;

One ends of the N elastic fixed beams of the switch sheet are respectively connected with the movable metal film, and the other end is connected with an anchor point.

[Claim 2] The switch of claim 1, wherein the thickness of the switch sheet is 1 pm.

[Claim 3] The switch of claim 1, wherein the N anchor points are set on the first microstrip line, or the N anchor points are set on the third microstrip line Or the N anchor points are respectively set on the first microstrip line and the third microstrip line.

[Claim 4] The switch of claim 1, wherein the insulating medium is silicon nitride.

[Claim 5] The switch of claim 1, wherein the width of the elastic fixed beam is 5^

[Claim 6] The switch of claim 1, wherein the width of the movable metal film is 8

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