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Superconductive appliance based on multi-element structure from josephson junctions. RU patent 2483392.

IPC classes for russian patent Superconductive appliance based on multi-element structure from josephson junctions. RU patent 2483392. (RU 2483392):

H01L39/22 - Devices comprising a junction of dissimilar materials, e.g. Josephson-effect devices

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Superconductive appliance comprises the next main elements: a chip comprising a SKIF-structure and a matching circuit board designed to set an input electromagnetic signal into a resonant circuit of the SKIF-structure on the chip and output signal pickup with the help of a microstrip line and its transfer to an output coaxial slot. The SKIF-structure arranged inside the loop of input electromagnet signal setting has a high amplification ratio and high linearity of voltage response to a magnetic component of an electromagnet signal in the frequency band of 0.1-10 GHz and dimensions of Josephson junctions (JJ), which satisfy the condition, at which the operation mode is provided, characterised by Fraunhofer dependence of critical current from magnetic field penetrating the JJ.

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FIELD: measurement equipment.

SUBSTANCE: superconductive appliance comprises the next main elements: a chip comprising a SKIF-structure and a matching circuit board designed to set an input electromagnetic signal into a resonant circuit of the SKIF-structure on the chip and output signal pickup with the help of a microstrip line and its transfer to an output coaxial slot. The SKIF-structure arranged inside the loop of input electromagnet signal setting has a high amplification ratio and high linearity of voltage response to a magnetic component of an electromagnet signal in the frequency band of 0.1-10 GHz and dimensions of Josephson junctions (JJ), which satisfy the condition, at which the operation mode is provided, characterised by Fraunhofer dependence of critical current from magnetic field penetrating the JJ.

EFFECT: higher amplification ratio and high linearity of voltage response at a magnetic component of an electromagnet signal of a superconductive appliance in a frequency band of 0,1-10 GHz, optimised isolation between an input and an output for prevention of input signal feedthrough to a device output, increased sensitivity of a device due to optimised communication along a magnetic field between an input line and a SKIF-structure, increased noise immunity of a device.

2 cl, 4 dwg

The invention relates to devices and can be used in the measuring technique, radio technical and information systems operating at low temperatures, to strengthen the weak signal of the microwave range, and as a detector of weak magnetic fields.

Known superconducting magnetometer on the basis of Josephson junctions (DP), implemented on a parallel chain of superconducting quantum interferometers (Squids) variable area (SKIF-structure) (patent WO 0125805, Schopohl et al., 12.04.2001; patent WO 2004114463, Oppenlaender J. et al., 29.12.2004). Due to the interference of responses areas form response voltage of the applied magnetic fields of such SKIF-structure has one big least in zero magnetic field.

The disadvantage of this is the low value of the output impedance, which complicates the use of parallel SKIF-patterns for high-frequency devices. High-frequency devices on the basis of parallel SKIF-structures do not provide the necessary linearity of the signal gain and fail to achieve large-signal on the output.

Known high-frequency amplifier, consisting of PD (patent RU 2353051 C2, 06.06.2007) based on linear chains of DC Squids with increased gain coefficient and high linearity response pressure on magnetic component of the electromagnetic signal within the range of 1-10 GHz (prototype of the proposed technical solution).

Device prototype is a broadband superconducting microwave amplifier contains the input element intended for the filing of the microwave signal and convert it to the magnetic flux affecting the Daisy chain tubular Squids; source DC offset, which is a means of job regime magnetic field offset, the inductive connected way to each of Squids the chain Squids. This consecutive chain of Squids, educated segment connects to the target item thus, to get the total change in voltage. These input and output elements are in the form of a superconducting strip line transmission.

The main disadvantages of the prototype are:

1) decreasing the amplitude of the voltage-field characteristics, and hence gain a result of suppression of the dependence of the critical current on the applied magnetic field due to the penetration of a magnetic field in the DP, which was not taken into account when modeling amplifier design;

2) the imperfect isolation of input and output due to the design of electromagnetic connection implemented on the basis of parallel bars two-wire lines, which leads to the presence of nonzero mutual induction;

3) is not optimal connection to the magnetic field of the input line with the SKIF structure due to the rapid field when going beyond the two-wire lines: field of parallel wires are deducted outside the wire, which reduces the mutual induction input circuit loops and Squids;

4) the expected broadband the response difficult to implement in the presence of restrictions on the size of the SKIF-patterns - prototype must have a size greater than or about the length of a wave, as it is based on the absorption of traveling wave upon wave attenuation contribution active elements will fall, otherwise coordination is possible due to the damping resistors, causing the inevitable absorption (a significant part) of the signal.

Analysis of the level of technology, including prototype, shows that the General lack of structures devices, made on the basis of low-temperature metal and Coulomb superconductors and implemented on the basis of regular chains Squids and irregular SKIF-structures is a noticeable decrease in the amplitude of a voltage-field characteristics because of dispersion parameters PD and influence inductances Squids.

Purpose the invention is:

1) increased gain and provide high linearity response pressure on magnetic component of the electromagnetic signal superconducting device in the frequency range of 0.1 to 10 GHz on the basis of the SKIF, the structure of the DP, which tend inevitably existing variation of parameters;

2) optimization of isolation between input and output to prevent the infiltration of the input signal on the output device;

3) increasing the sensitivity of the device due to optimization due to the magnetic field between the input line and SKIF-structure;

4) improving the noise immunity device.

This goal is achieved by the fact that superconducting device on the basis of multi-elemental structure of Josephson junctions, containing a chip ( substrate), which includes a line to specify the input of the electromagnetic signal in the form of a superconducting strip transmission line is intended for submission of a microwave signal and convert it into a magnetic flux, and structure of superconducting Josephson junctions (DP), consisting of a series connection of a superconducting tubular quantum interferometers (Squids), having square, representing a superconducting quantum interference filter (SKIF-structure), having increased the amplification coefficient and high linearity response pressure on magnetic component of the electromagnetic signal in the frequency range of 0.1 to 10 GHz, and the output element, made in the form of a superconducting strip line transfer, according to the invention, contains a matching charge, designed to specify the input of the electromagnetic signal in the resonant circuit SKIF-structures on a chip and removal of the output signal of the microstrip line and passing it on output coaxial connector, on one side of the coordinating Board placed input and output microstrip lines, and on the other side of the card is resonator, made in the form of u-shaped slit line length, l/2, dimensions DP included in superconducting structure satisfy the condition: w<4λ J , where w is the width of the DP, l J - penetration depth of the magnetic field, the proposed solution is based on resonance in the loop input line to specify the input of the electromagnetic signal, the SKIF-structure is located inside the loop input line not having damping elements, as the superconductor is used rare-earth connection cuprates General formula ReBa 2 Cu 3 O 7-x , where Re - rare-earth metal and a weak correlation was established border.

This goal is achieved by the fact that decides Board is made of a laminate and bilateral metallization, thickness t and dielectric permeability of a material laminate selected ensuring the estimated value of a wave resistance of microwave lines.

The nature of the invention is illustrated by drawings:

figure 1 - equivalent electrical circuit of invention instrument for the case of its use for the strengthening of the microwave signal, where a 1 ...a n - square Squids included in structure of the PD; I B DC offsets; I RF - high-current, which flows through the line job the input signal is converted to magnetic flux in the contours of the SKIF structure; C1 and C2 - capacity trimming capacitors;

figure 2 - matching Plata, where (1) - input line (2) - u-shaped slot resonator (3) - supply microstrip lines, (4) - output line, (5) chip with SKIF-structure;

figure 3 - V voltage dependence of the magnetic flux f in SKIF-structure; ΔV - the maximal amplitude characteristics, f 0 - quantum of magnetic flux f In - flow of displacement corresponding to the operating point, the f i - registered external magnetic flux equal to the work of the recorded current I, i , passing through the line to specify the input signal on a chip, and mutual induction M i between this line and the SKIF structure, V 0 - response SKIF-structure of the registered external magnetic flux;

figure 4 - the family of voltage-current characteristics (VCC) SKIF-patterns at various values of the applied magnetic field.

The device is a superconducting device that contains: (i) chip, which includes a line to specify the input of the electromagnetic signal in the form of a superconducting strip line transmission of the microwave signal and superconducting the structure of the DP, located inside the loop input line and consisting of the serial connection Squids with square, representing SKIF-structure, having increased the amplification coefficient and high linearity response pressure on magnetic component of the electromagnetic signal within the range of 0.1 to 10 GHz, (ii) matching charge, designed to specify the input of the electromagnetic signal in the resonant circuit SKIF-structures on a chip and removal of the output signal of the microstrip line and send it to the output coaxial connector. Across the line job is also possible supply DC offset to set the working point. The linear dimensions of the DP included in superconducting structure, must satisfy the condition: w<4λ J , where w is the linear size of the width of the thin film DP crossing border, l J - penetration depth of the magnetic field. This ensures mode multiple patterns determined by the penetration of a magnetic field in the PD, which is characterized by -dependent (type sin(x)/x) of the critical current on the applied magnetic field.

The proposed technical solution consists of the following main elements: chip, the equivalent circuit diagram of which is shown in figure 1, and matching charge, the image of which is presented in figure 2. Matching card designed to specify the input of the electromagnetic signal in the resonant circuit SKIF-structure located on a chip. On the Board there is a transition from the coaxial connector on line, and then transition to the ring resonator in the gap which can be enabled with the line job SKIF-patterns. The Board is made of a laminate and bilateral plating thickness t=1,0 mm and dielectric permeability ceramic insulator e=9,2 selected from the conditions meet the approval of impedances SKIF-structure and wave resistance of microstrip lines on coordinating Board, using the known relations for strip transmission lines. Input (1) and output (4) microstrip lines are on one side of a double-sided Board. On the other side of the card is resonator, made in the form of u-shaped slit line (2), excited by crossing its input microstrip line (1). The open end of the microstrip line (1) forms quarter-wave train, which provides short circuit mode in the plane crossing slit line. Slot resonator (2) half-wave length is and not lossless. Due antiphased excitation of two microstrip line (3) at the point of their accession to the chip (5) currents in them . After conversion (gain) signal SKIF-structure of the signal from the chip removed with the help of a microstrip line and fed to the output coaxial connector. The isolation of input and output Board optimized so that the field of the input signal and the output current does not interact in force balanced design signal circuits.

The voltage on the SKIF is guaranteed job displacement current I (B . High frequency RF current I flowing through the loop to specify the input signal, creates in every magnetic flux Δ k =M k I RF , where M k - factor of mutual induction between the k-th (area a k , k=1...n) and a line to specify the input signal. The value of containers C1, C2 and inductance line to specify the input signal L 0 is determined from the condition of resonance f RF =1/(2π Radic(C1+C2)*L 0 ) to ensure the greatest amplitude of a current in a line connected to a microwave circuit reference signal on the baseboard to which to connect a chip with SKIF-structure. When using capacitors possible to realize the coordination with the SKIF structure in the bandwidth of 200 MHz (centre frequency of 1.5 GHz) with loss of 1.2 dB.

The proposed construction of a chip containing SKIF-structure, can be configured in a wide range of frequencies on the strip, a component of the order of 20-30% from the Central frequency over a compromise combination of compactness and resonance properties of the input chain, which makes it more noise. The proposed solution is based on resonance in the loop input line assignment and SKIF-structure is located inside the loop input line job, not having damping elements, which means the minimum possible level of signal losses.

The proposed device operates as follows.

Figure 3 shows a mechanism of conversion of the input stream f i V output voltage, V 0 at the fixed value of a constant magnetic flux f In . Input stream f i =M i QV V(Z i +R (i ), where M i - mutual inductance between loop job input and SKIF-structure, Q - q of the input-resonant circuit Z i - input impedance SKIF-patterns. Output voltage, V 0 can be determined from the expression V 0 =V f f i , where V, f =C V/C f i - the transfer function of the SKIF structure, which is determined by the maximum span output voltage ΔV, which is proportional to using a particle induced characteristic voltage V C APS and quantum of magnetic flux f 0 .

The maximum possible link to the magnetic field (sensitivity) is due to two factors: firstly, due to the premises of the SKIF patterns in share button between the strip lines, secondly, due to resonance increase the signal current in the input circuit, located on the coordinating Board.

In this configuration SKIF-structure devices when volt-field characteristics mainly determined dependence of the critical current of individual APS. The contribution to the magnitude of the transformation of the magnetic field in the voltage provided by circulating currents, and induced magnetic flux. Input induces shielding currents in superconducting loops of each of the elements of the SKIF patterns. Current in the loop, induced by an external magnetic field, is converted in the current circulating in the DP. This transformation allows to provide the required magnetic coupling DP and input circuit, which, in turn, increases the gain of the microwave signal.

The increase in dynamic range can be obtained through the use of a serial or parallel chains of Squids. However, the spread of technology parameters PD (I C and R N ) doesn't allow to reach efficiently combine responses from all Squids in the chain. This problem can be solved by applying multiple patterns of Squids with square superconducting loops, so-called superconducting quantum interference filters (Scythians) serial or parallel types. The basis of the generation of the response Scythian laid precisely condition square Squids. Dynamic range of both parallel and sequential multi-elemental structure increases with number N Squids in proportion to the

. In the sequential structure of the Squids increases the amplitude of the output signal and output impedance. This increase dynamic range is achieved without tracking the feedback circuit.

Side modulation on the current-field dependence of suppressed with increasing numbers N Squids in the chain due to the interference of the responses of the individual Squids with different areas (with different periods modulation response)that also results in smooth slopes of the main peak response SKIF-patterns.

Figure 4 shows VACH family SKIF-the structure consisting of N=20 sequentially included Squids, measured at 15 fixed values of the applied magnetic field. Because they are scattered critical currents DP spikes, voltage, which are due to the transition in the resistive state of the Squids in the structure of the increase in bias current (B . As you increase the applied magnetic field WAH becomes smoother.

As a superconducting material is used, the connection of rare earth cuprates with the General formula ReBa 2 Cu 3 O 7-x , where Re - rare-earth metal. Among the Coulomb superconducting DP highest reproducibility of parameters have bicrystal transitions that are formed by contact of two single-crystal parts of the film, crystallographic axes are mutually deployed at an angle of 45°>θ>20oC, and border has the property of weak connection.

All elements of the chip can be performed using photolithography and located on a single insulating substrate. The technology for producing such structures known, so in the present description is not given. Connection of the chip and coordinating Board is ensured by the well-known method metal wires.

Thus, the technical result of the proposed device consists of increasing the gain and ensuring high linearity response pressure on magnetic component of the electromagnetic signal SKIF-structure, optimization isolation between input and output matching cards, increasing the sensitivity of the device due to optimize communications in applied magnetic field between the input line and SKIF-structure, increase the noise immunity of the device.

1. Superconducting device on the basis of multi-elemental structure of Josephson junctions, containing a chip ( substrate), which includes a line to specify the input of the electromagnetic signal in the form of superconducting strip transmission line is intended for submission of a microwave signal and convert it to the magnetic flux and structure of superconducting Josephson junctions (DP), consisting of a series connection of a superconducting tubular quantum interferometers (Squids), having square, representing a superconducting quantum interference filter (SKIF-structure), having increased the amplification coefficient and high linearity response pressure on magnetic component of the electromagnetic signal in the frequency range of 0.1 to 10 GHz, and output element, made in the form of a superconducting strip line transmission, notable for containing matching charge, designed to specify the input of the electromagnetic signal in the resonant circuit SKIF-structures on a chip and removal of the output signal of the microstrip line and transfer the output coaxial connector, on one side of the coordinating Board placed input and output microstrip lines, and on the other side of the card is resonator, made in the form of u-shaped slit line length, l/2, dimensions DP included in superconducting structure, satisfy the condition: w<4λ J , where w is the width of the DP, l J - penetration depth of the magnetic field, the SKIF, the structure is located inside the loop input line to specify the input of the electromagnetic signal with no damping elements, as superconductor used rare-earth connection cuprates General formula ReBa 2 Cu 3 O 7-x , where Re - rare-earth metal and a weak correlation was established border.

2. Superconducting device according to claim 1, characterized in that decides Board is made of a laminate and bilateral metallization, thickness t and dielectric permeability of a material laminate selected ensuring the estimated value of a wave resistance of microwave lines.