CN102243940B

CN102243940B - Buckling radio frequency micro switch by using folded beams

Info

Publication number: CN102243940B
Application number: CN 201110075734
Authority: CN
Inventors: 田文超; 阮红芳; 杨银堂; 曹艳荣
Original assignee: Xidian University
Current assignee: Xidian University
Priority date: 2011-03-28
Filing date: 2011-03-28
Publication date: 2013-09-25
Anticipated expiration: 2031-03-28
Also published as: CN102243940A

Abstract

The invention discloses a buckling radio frequency micro switch by using folded beams and mainly solves the problems of high driving voltage, long response time, high loss and the like of the conventional switch. The buckling radio frequency micro switch comprises an adjusting electrode pair (31 and 32), a fixed engine base (33), a driving electrode pair (34 and 35) and an outer framework (39), wherein a micro beam (36) and the folded beams (38) are fixed on the inner wall of the outer framework (39); the folded beams (38) have a plurality of rectangular bent structures and the micro beam (36) has a longitudinal and transverse bending and buckling deformation structure; the folded beams (38) are positioned at both ends of the micro beam (36), and the folded beams (38) and the micro beam (36) have an integrated structure; guide mechanisms (37) are arranged at both ends of the fixed engine base (33) and both ends of the outer framework (39); and the adjusting electrode pair (31 and 32) has a comb teeth type structure and is symmetric up and down. The buckling radio frequency micro switch has the advantages of low voltage, high frequency response, high isolation degree and low loss and can be used in radio frequency transceiver circuits, microwave integrated circuits, radar and antenna T/R components and radio frequency dual-station circuits.

Description

Folding beam flexing radio frequency microswitch

Technical field

The invention belongs to technical field of electronic devices, particularly radio frequency microswitch can be used for fields such as microwave integrated circuit, radio-frequency (RF) transmit-receive circuit and radar antenna T/R assembly.

Technical background

The flexing radio frequency microswitch, be to be processed by micro mechanical technology, based on folding beam bending with combined axial and lateral load theory, break through the traditional concept of the unidirectional loading of radio frequency microswitch, utilize elastic energy release and stiffness variation and the kick characteristic that show of folding beam in bending deformation, change elastic force into actuating force, realize the purpose of radio frequency microswitch high-isolation, low-loss, low-voltage and high frequency response.It has characteristics such as volume is little, reliability is high, simple in structure, therefore in fields such as radio-frequency (RF) transmit-receive circuit, microwave integrated circuit, radar antenna T/R assembly and radio frequency duplicate circuitry, has tight demand.

MEMS key lab of Southeast China University was in [the analysis of RF mems switch pick-up voltage in 2008, Dong Qiaohua, Liao Xiaoping, yellow Qingan County, Huang Jianqiu, key lab of the MEMS Ministry of Education of Southeast China University, the semiconductor journal, the 29th the 1st phase of volume, in January, 2008,163-169] the power-actuated radio frequency microswitch of the fixed static in two ends that proposes, as shown in Figure 1.Wherein little beam 11 is fixed by anchoring point 12 and is suspended from ground plate 13 and signal plate 14 tops, and external circuits is connected on little beam 11 and the signal plate 14.When

little beam

11 and 14 of signal plates were added with voltage, little beam 11 moved down under electrostatic force and with signal plate 14 contacts, thereby realized the closure between external circuits.There is following problem in this radio-frequency (RF) switch:

1) owing to the high voltage that needs to add 33V between little beam 11 and signal plate 14, thereby there is the danger of ablating in switch.

2) space is too little between little beam 11 and signal plate, causes the radio-frequency (RF) switch isolation too low.

California university San Diego branch school was at [Rashed Mahameed in 2010, Gabriel M.Rebeiz, Electrical and Computer Engineering Department, University of California at San Diego, A High-Power Temperature-Stable Electrostatic RF MEMS Capacitive Switch Based on a Thermal Buckle-Beam Design, JOURNAL OF MICROELECTROMECHANICAL SYSTEMS, VOL.19, NO.4,2010,816-826] in proposed a kind of static and driven thermal buckling type high power RF switch, as shown in Figure 2.The anchor point 23 of this radio-frequency (RF) switch is fixed on the solid point 25, and top crown 21 is connected on the anchor point 23 by little beam 22.Top crown 21 is connected external circuits with bottom crown 24.When external voltage acts on little beam 22, little beam 22 expanded by heating bending deformations, top crown 21 moves down, with bottom crown 24 contacts, external circuits conducting, switch closure.

Though this structure has improved the isolation of radio-frequency (RF) switch, there are the following problems again:

1) driving voltage is too high, reaches 40V.

2) response time long, switching frequency is low excessively.

Summary of the invention

The objective of the invention is to overcome the deficiency of above-mentioned prior art, a kind of folding beam flexing radio frequency microswitch is provided, to reduce driving voltage, improve response frequency.

For achieving the above object, micro switch of the present invention comprises: regulate electrode pair, fixedly support, drive electrode to and outer frame, wherein: be consolidated with little beam on the inwall of outer frame and roll over beam; Fixedly the two ends of support are provided with guiding mechanism, are used for swinging of the little beam of restriction; Regulate electrode pair and adopt broach shape structure.

Described little beam and folding beam are structure as a whole, and the folding beam is positioned at the two ends of little beam.This folding beam adopts a plurality of rectangular bend structures, to reduce to roll over the rigidity of beam; This little beam adopts bending with combined axial and lateral load bending deformation structure, drives to realize the low pressure large deformation.

The present invention has following advantage:

1) the present invention is owing to the inwall at outer frame is consolidated with little beam and folding beam, the axial overall length L ' of little beam and folding beam is 101: 100 with the ratio of the inwall length L of outer frame, make little beam and folding beam obtain axial compression flexing potential energy in advance, therefore reduced driving voltage;

2) the present invention adopts broach shape structure owing to regulate electrode pair, can regulate electrode voltage by adjusting, and makes little beam reach Euler critical load and be in " little curved balance " state before distortion, thereby reduces driving voltage;

3) the present invention reducing to roll over the rigidity of beam, thereby reduces driving voltage because the folding beam adopts a plurality of rectangular bend structures, improves response frequency;

4) the present invention breaks through the traditional concept of unidirectional loading owing to adopt little beam bending with combined axial and lateral load bending deformation structure, has reduced driving voltage and deformation time, realizes that the large deformation of micro switch low pressure drives, improves response frequency;

5) the present invention has limited swinging of little beam owing to be provided with guiding mechanism at the fixing two ends of support, thereby guarantees that the distortion of folding beam is symmetrical;

6) micro switch of the present invention is with respect to existing other micro switch, and number of components is few, and all adopts silicon materials, and cost is low, is easy to processing and realizes.

Description of drawings

Fig. 1 is the fixed radio frequency microswitch structure chart in existing two ends;

Fig. 2 drives flexing type radio frequency microswitch structure chart for existing constant temperature static;

Fig. 3 rolls over beam flexing radio frequency microswitch structure chart for the present invention.

Embodiment

With reference to Fig. 3, micro switch of the present invention mainly by

regulate electrode pair

31 and 32, fixedly support 33, drive electrode to 34 and 35, detecting electrode to 38 and 39, little beam 36, roll over beam 38, guiding mechanism 37 and outer frame 39 and form, total is symmetry up and down, and material adopts silicon materials.

Little beam 36 and folding beam 38 are structure as a whole, and roll over the two ends that beam 38 is positioned at little beam 36, and two ends folding beam 38 all adopts a plurality of rectangular bend structures, and symmetrical up and down, to reduce to roll over the rigidity of beam.Little beam 36 and folding beam 38 are cemented in by the pressure welding mode on the inwall of outer frame 39, and little beam 36 adopts bending with combined axial and lateral load bending deformation structure, drive to realize the low pressure large deformation.Axial overall length L ' by the little beam of appropriate design 36 and folding beam 38 is 101: 100 with the ratio of outer frame 39 inwall length L, makes little beam 36 and folding beam 38 obtain axial compression power in advance.Regulate

electrode pair

31 and 32 and adopt broach shape structure, be fixed on little beam 36, and symmetrical up and down.This is regulated electrode pair 31 and links to each other with outside regulating circuit by the pressure welding mode with 32, adjusting by outside regulating circuit, enforcement is to little beam 36 two ends Synchronization Control, make little beam 36 and folding beam 38 reach Euler critical load, keep " little curved balance " state, avoid little beam 36 to be in loaded state for a long time simultaneously, reduce little beam risk of breakage, prolong the useful life of micro switch.

Guiding mechanism 37 is fixed on the two ends of fixing support 33 and outer frame 39, is used for swinging of the little beam 36 of restriction, guarantees folding beam 38 bending deformation symmetries, avoids the secondary bending deformation to take place.Drive electrode is that golden film by fixedly support right side, 33 middle part and little beam 36 left-hand face deposition forms to 34 and 35, and this drive electrode links to each other with outside regulating circuit by the pressure welding mode with 35 to 34.Apply driving voltage at drive electrode to 34 and 35, realize little beam 36 bending with combined axial and lateral load bending deformations thereby produce cross force.The present invention breaks through the traditional concept of the unidirectional loading of present micro switch, utilizes energy release and the stiffness variation of little beam and the combined deformation of folding beam to show " kick " characteristic, and the axial potential energy of storage is discharged fast, changes elastic force into actuating force.Outer frame 39 middle part left-hand face deposit golden film as fixed test electrode 40, and little beam 36 right sides deposit golden film as movable detecting electrode 41.When little beam 36 reaches Euler critical load with folding beam 38, keep " little curved balance " state, apply driving voltage at drive electrode to 34 and 35, thereby produce cross force and realize little beam 36 bending with combined axial and lateral load flexing large deformation, movable detecting electrode 41 is contacted with fixed test electrode 40, finish detecting electrode and external circuits turn-on power loss, thereby realize radio frequency microswitch high-isolation, low-loss, high-frequency and low driving voltage requirement.

Operation principle of the present invention is as follows:

Under non operating state, regulating

electrode pair

31 and 32 both end voltage is 0, and drive electrode is 0 to 34 and 35 both end voltage, and little beam 36 is in linear state, and the folding beam 38 that is cemented on the outer frame 39 is subjected to axial prefabricating load.Because last lower guide mechanism 37 is spacing, guarantees that little beam 36 is in the vertical line state, micro switch remains open state, shown in Fig. 3 solid line.

In working order down, regulate the both end voltage of

electrode pair

31 and 32 by outside regulating circuit, make little beam 36 axial loads reach Euler's load critical value, little beam 36 is in " little curved balance " state, apply driving voltage by external drive circuit at

drive electrode

34 and 35 two ends again, because little beam 36 has been in " little curved balance " state, the electric field force that this moment, very little driving voltage produced, just cause little beam 36 to produce flexing large deformation fast to the right, movable detecting electrode 41 is contacted with fixed test electrode 40, micro switch is in closure state, realizes the connection of external testing circuit, shown in Fig. 3 dotted line.

Claims

1. roll over beam flexing radio frequency microswitch for one kind, comprise: regulate electrode pair (31,32), fixedly support (33), drive electrode to (34,35) and outer frame (39), it is characterized in that: fixedly support (33) is provided with guiding mechanism (37) with the two ends of outer frame (39), is used for swinging of the little beam of restriction; Be consolidated with little beam (36) and folding beam (38) on the inwall of outer frame (39), this little beam (36) and folding beam (38) are structure as a whole, and folding beam (38) is positioned at the two ends of little beam (36); Regulate electrode pair (31,32) and adopt broach shape structure, be fixed on little beam (36), and symmetrical up and down;

Described folding beam (38) adopts a plurality of rectangular bend structures, and to reduce to roll over the rigidity of beam, little beam (36) adopts bending with combined axial and lateral load bending deformation structure, drives to realize the low pressure large deformation; The axial overall length L ' of little beam (36) and folding beam (38), with the ratio of the inwall length L of outer frame (39) be 101:100 so that little beam (36) and folding beam (38) are cemented in outer frame (39) inwall by pressure welding, acquisition axial compression power.

2. radio frequency microswitch according to claim 1, it is characterized in that the left side of little beam (36) and fixedly the right lateral surface of support (33) all be deposited with golden membranous layer, two golden membranous layers form drive electrode (34,35), and this drive electrode links to each other with external drive circuit by the pressure welding mode.

3. radio frequency microswitch according to claim 1 is characterized in that fixedly support (33), outer frame (39), little beam (36) and folding beam (38) are silicon materials.

4. radio frequency microswitch according to claim 1 is characterized in that regulating electrode pair (31,32) and links to each other with outside regulating circuit by the pressure welding mode, and Synchronization Control, guarantees that little beam (36) keeps " little curved balance " state.