CN100495811C

CN100495811C - Ferroelectric phase shifter

Info

Publication number: CN100495811C
Application number: CNB200510102551XA
Authority: CN
Inventors: 李翡; 张雪强; 孟庆端; 何豫生; 何艾生; 李春光; 黎红
Original assignee: Institute of Physics of CAS
Current assignee: Institute of Physics of CAS
Priority date: 2005-09-12
Filing date: 2005-09-12
Publication date: 2009-06-03
Anticipated expiration: 2025-09-12
Also published as: CN1738097A

Abstract

The invention discloses a ferro-electricity phase shifter, which using strontium titanate barium (BST) ferro-electricity film and the coplane reflection configuration. It mainly comprises two parts: a variable interdigital capacitor and a impedance matching circuit. Wherein, the variable interdigital capacitor is reached by ferro-electricity material whose capacity can be serially adjusted by external voltage, and whose size can be adjusted according to different designs; the impedance matching circuit is reached by four exponent's quarter-wave, whose size and exponent number can be adjusted by design. Compared to same product, said invention has the advantages of simple design, better versatility, and it can be adjusted only several size for variable demands.

Description

Ferroelectric phase shifter

Technical field

The invention belongs to the microwave engineering field, relate to a kind of phase shifter, particularly relate to a kind of ferroelectric phase shifter.

Background technology

Development along with satellite television, the satellite mobile communication technology has wide practical use on civilian project, more importantly be because the new and high technology weapons are widely used in war, the satellite mobile communication technology that integrates mobile communication technology and communication technology of satellite, becoming the new topic of developing that each military power is competitively studied under the modern war condition, is the significant problem that is related to national security.

The key issue of satellite mobile communication is the problem that will solve Satellite Tracking in the moving process, and phased array antenna is a kind of good solution.In phased array antenna, phase shifter plays an important role as primary element.Change the phase difference value △ of adjacent antenna with phase shifter, just can make phase array antenna beam carry out electric scanning and antenna needn't rotate in the space.For the performance that improves phase array with reduce cost, make it obtain extensive use, seek low-loss and cheaply microwave phase shifter become an instant significant problem.

At present, most of phased array antenna systems all use ferrite phase shifter and semiconductor PIN diode phase shifter.But the ferrite phase shifter response speed is slow, and is not suitable for requiring the phased array antenna of fast beam scanning, and this phase shifter costs an arm and a leg, volume is big, quality is heavy, thereby has limited its application; The response speed of semiconductor phase shifter is fast, volume is little, but bigger at centimeter wave and millimeter-wave frequency scope internal loss, power handling capability is limited.

The performance of phase shifter not only depends on selected material, and structural design is also very important.Because improving constantly of integrated level, device size structurally requires miniaturization more, complanation, filming; Require little Insertion Loss on the performance, have the certain power capacity, also to satisfy in addition cost low, commercial requirement such as can produce in batches.

Summary of the invention

At the problem and the requirement of above-mentioned existence, purpose of the present invention just provides a kind of low-loss, low cost, and can use the ferroelectric phase shifter of voltage-regulation.

For achieving the above object, a kind of ferroelectric phase shifter of the present invention comprises variable interdigital capacitor and impedance matching circuit, and wherein variable interdigital capacitor utilizes ferroelectric material to realize.

Further, described ferroelectric material is barium strontium titanate Ba _1-xSr _xTiO ₃Ferroelectric thin film.

Further, described impedance matching circuit is the quarter-wave impedance conversion line at least two rank.

Further, described variable interdigital capacitor and impedance matching circuit adopt the coplane reflection electric circuit, realize phase shift by measuring reflection coefficient.

Further, described barium strontium titanate Ba _1-xSr _xTiO ₃The backing material of ferroelectric thin film is magnesium oxide or lanthanum aluminate.

Further, described barium strontium titanate Ba _1-xSr _xTiO ₃The conductive of ferroelectric thin film is noble metal or superconductor.

Further, described impedance matching circuit is the quarter-wave impedance conversion line of quadravalence.

Compared with prior art, the present invention is simple in structure, and highly versatile for different performance requirements, only need change indivedual sizes and just can realize; Can realize significantly phase-shift phase; Phase-shift phase can be adjustable continuously with applied voltage; Energy loss is little; Need not other bias circuit, circuit itself just can be realized the bias voltage requirement; The circuit volume is little, and electricity is controlled; Reduced of the influence of the even property of uneven film thickness to circuit performance.

Description of drawings

Fig. 1 is the structural representation of ferroelectric phase shifter of the present invention;

Fig. 2 is the schematic diagram of the whole coplane catoptric arrangement of ferroelectric phase shifter of the present invention;

Fig. 3 is the structural representation of the adjustment interdigital capacitor among Fig. 2;

Fig. 4 is the structural representation of the adjustment impedance matching circuit among Fig. 2;

Fig. 5 is the corresponding reflex response curve of impedance matching circuit;

Fig. 6 is a ferroelectric phase shifter overall calculation machine simulation result of the present invention;

Fig. 7 is the structural representation of the interdigital capacitor of embodiment 2;

Fig. 8 is the structural representation of the impedance matching circuit of embodiment 2.

Embodiment

Ferroelectric phase shifter of the present invention mainly is made of two parts: a part is variable interdigital capacitor, and another part is an impedance matching circuit, and two parts adopt the coplane catoptric arrangement, and wherein variable interdigital capacitor utilizes ferroelectric material to realize.Barium strontium titanate is a kind of ferroelectric material, and its dielectric constant can change with extra electric field, by its adjustable device that makes good application prospects is arranged.As shown in Figure 1, ferroelectric material is one deck barium strontium titanate 2 of growing on magnesium oxide or lanthanum aluminate substrate 3 earlier, plates conductive layer 1 more thereon, and conductive layer 1 can be gold or noble metals such as copper or platinum, also can be superconductor.At conductive layer 1, on can utilize photoetching process, processing generates various figures.As shown in Figure 2, two parts of ferroelectric phase shifter adopt the coplane catoptric arrangement, and wherein, coplane is meant mainly and adopts single face conductive layer 1 that figure all is created on same plane---on the conductive layer 3; Reflection is meant by measuring reflection coefficient, compares under different bias voltages the variation of reflection coefficient phase, thereby the purpose of realization phase shift.Fig. 3 is the structural representation that A partly adjusts the amplification of interdigital capacitor among Fig. 2, as shown in the figure, utilize the ferroelectric material dielectric constant to realize variable interdigital capacitor with the character that extra electric field changes, its capacitance is adjustable continuously with applied voltage, and its concrete structure size can be adjusted according to different designing requirements.Fig. 4 is the structural representation of the amplification of the adjustment impedance matching circuit of B part among Fig. 2, as shown in the figure, utilize the coupling between the impedance of quatrter-wavelength line realization different characteristic, its concrete structure size can be adjusted according to different requirements with exponent number, be at least secondary, select quadravalence usually for use.

When ferroelectric phase shifter uses bst thin film as ferroelectric material, because the dielectric constant of BST material can change with the change of applied voltage, therefore the electric adjustable device that utilizes its this character to make, has the big and fast advantage of switching speed of adjustable extent, and owing to be voltage control, so energy loss is little.

When the integral body of ferroelectric phase shifter adopts the coplane catoptric arrangement, have lot of advantages: (1) bias circuit is simple, as shown in Figure 2: this ferroelectric phase shifter need not other bias circuit, applying bias one termination signal input and output side 5, other end connection circuit equivalence ground plane 4.Simplify design greatly, reduced cost; (2) adopt this structure, can realize the requirement of circuit easily, reduced the realization difficulty of ground connection, reduced unnecessary process procedure for ground connection; (3) adopt this structure,, can also significantly reduce because the even harmful effect that causes of uneven film thickness because electromagnetic wave mainly is distributed in the surface of material; (4) can significantly reduce device volume, satisfy the requirement of device miniaturization.

Realize variable interdigital capacitor when ferroelectric phase shifter utilizes ferroelectric material, its capacitance is adjustable continuously with applied voltage.The interdigital capacitor design easily, and is simple in structure, is convenient to realize with the coplane circuit; In addition, interdigital capacitor is compared with plane capacitance, has reduced the harmful effect of parasitic capacitance.

Ferroelectric phase shifter is to utilize quarter-wave impedance conversion line to realize impedance matching, and the minimum second order impedance conversion line of selecting for use is selected quadravalence impedance conversion line usually for use, adopts this structure, and (1) can realize significantly phase shift; (2) can make device under different operating states, Insertion Loss is consistent as far as possible, reaches the purpose of improving the Insertion Loss performance, as shown in Figure 5, this figure is a computer artificial result, characterizes the frequency characteristic of impedance matching circuit, and the impedance matching circuit service behaviour is good as we know from the figure; (3) can simplified design, for the designing requirement of different phase-shift phases, it is motionless that the other parts circuit keeps, and only needs to adjust this part-structure and just can realize.

Below in conjunction with the drawings and specific embodiments the present invention is done description further:

The centre frequency of the work of embodiment 1 ferroelectric phase shifter is 5GHZ

Shown in Fig. 1-2, at first to ferroelectric thin film plating single face metal film, this ferroelectric thin film is the ε that is earlier at dielectric constant _rThe substrate 3 of MgO medium on growth one deck BST ferroelectric thin film 2, and then one deck conductive layer 1 gold medal film of growing thereon, and it is measured obtain required physical parameter.According to designing requirement, the MgO medium of selecting for use, its DIELECTRIC CONSTANT _r=9.60, adjust interdigital capacitor size partly, finally determine dimension of picture, as shown in Figure 3: a=10 micron, b=290 micron, c=100 micron.

According to designing requirement, adjust the size of impedance matching circuit part, in the present embodiment, the centre frequency of work is 5GHZ, realizes 200 ° phase shift.Final determine dimension of picture, its structure as shown in Figure 4: d=1300 micron, e=400 micron, the f=700 micron, g=900 micron, h=1260 micron, the corresponding reflex response curve of impedance matching circuit as shown in Figure 5, the impedance matching circuit service behaviour is good as can be known by curve among the figure.

Utilize the whole phase shifter of sonnet EM simulator emulation, its result as shown in Figure 6, wherein " Δ " line is that reflection is with the variation relation of frequency under the normal state, and " o " line is the variation relation that reflects bias state under with frequency, and " X " line is that phase shift under the two condition is with the variation relation of frequency.The ferroelectric thin film dielectric constant is respectively 300,600 under two operating states, and as seen from the figure, its Insertion Loss when centre frequency equates to be-0.7db, and phase shifts is (180+63) °, has satisfied designing requirement.The centre frequency of the work of embodiment 2 ferroelectric phase shifters is 3GHZ.

At first to ferroelectric thin film plating single face metal film, this ferroelectric thin film is the ε that is earlier at dielectric constant _rThe substrate of MgO medium on growth one deck BST ferroelectric thin film, and then the layer of metal film of growing thereon, and it is measured obtain required physical parameter.

According to designing requirement, the MgO medium of selecting for use, its DIELECTRIC CONSTANT _r=9.6, adjust interdigital capacitor size partly, finally determine figure, structure is as shown in Figure 7.

According to designing requirement, adjust the size of impedance matching circuit part, finally determine figure, structure is as shown in Figure 8.

Claims

1, a kind of ferroelectric phase shifter is characterized in that, comprises variable interdigital capacitor and impedance matching circuit, and wherein variable interdigital capacitor utilizes ferroelectric material to realize, impedance matching circuit adopts the coplanar structure circuit, and phase shifter integral body is single port reflection-type device; Realize phase shift by measuring reflection coefficient; Applying bias one termination signal input and output side, another section connection circuit equivalence ground plane.

2, ferroelectric phase shifter according to claim 1 is characterized in that, described ferroelectric material is barium strontium titanate Ba _1-xSr _xTiO ₃Ferroelectric thin film.

3, ferroelectric phase shifter according to claim 1 is characterized in that, described impedance matching circuit is the quarter-wave impedance conversion line at least two rank.

4, ferroelectric phase shifter according to claim 2 is characterized in that, described barium strontium titanate Ba _1-xSr _xTiO ₃The backing material of ferroelectric thin film is magnesium oxide or lanthanum aluminate.

5, ferroelectric phase shifter according to claim 2 is characterized in that, described barium strontium titanate Ba _1-xSr _xTiO ₃The conductive of ferroelectric thin film is noble metal or superconductor.

6, ferroelectric phase shifter according to claim 3 is characterized in that, described impedance matching circuit is the quarter-wave impedance conversion line of quadravalence.