EP1844499B1 - Use of superconductor components in thin layers as variable inductance and devices including said components and corresponding control method - Google Patents

Abstract

Use, as a component with variable inductance which is a function of the current passing through it, of an inductive superconductive component having at least two terminals and comprising at least one line segment working with said terminals and integrating at least one of these terminals, this line segment constituting a conductive or superconductive layer within a stack of films alternately superconductive and insulating.

Description

The present invention relates to a use of a thin-film superconductor component as variable inductance. It also relates to devices performing such use, as well as a method of controlling the inductance of such a component.

This invention is in the field of superconductive electrical and electronic components for the electrical engineering or electronics, telephony, antennas and high frequency components sectors. These components are useful in particular for medical imaging, radar and defense electronics, mobile telephony, as well as television or satellite communication.

The production of superconductive inductive components in thin layers is generally carried out by deposition of a superconductive film, generally by vacuum methods such as sputtering or pulsed laser ablation, and then by lithographic photo-etching of one or more turns. In this technique the dimension of the device increases with the value of its inductance.

A practical example of embodiment consists of a coil comprising 5 turns whose external diameter is 15 mm, with tracks of 0.4 mm width spaced 0.3 mm having an inductance of 2.12 μH, which is described in the thesis dissertation supported by Jean-Christophe Ginefri on December 16, 1999 at the University of Paris XI and entitled "Superconducting miniature surface antenna for 1.5 Tesla NMR imaging".

• la surface occupée par chaque composant inductif est importante. Par exemple, le composant décrit au paragraphe précédent occupe une surface de plus de 700mm² :

• si le composant est intégré dans un circuit, il est souvent nécessaire de raccorder l'extrémité de la spire intérieure à une ligne supraconductrice.

The technique described above has two main disadvantages:

• the area occupied by each inductive component is important. For example, the component described in the previous paragraph occupies an area of more than 700mm ² :

• if the component is integrated in a circuit, it is often necessary to connect the end of the inner coil to a superconducting line.

1. a) le dépôt et la gravure d'un film isolant,
2. b) le dépôt et la gravure sur cet isolant d'un deuxième film supraconducteur présentant des propriétés similaires à celles du premier film. Cette dernière étape est particulièrement délicate car il est nécessaire de réaliser une reprise d'épitaxie, technique qui est difficilement maîtrisable. Il existe d'autres procédés permettant de déposer une bobine en couches minces, mais ils présentent des difficultés de réalisation identiques à celles décrites ici.

This involves a complex process involving after the deposition and etching of the turns:

1. a) depositing and etching an insulating film,
2. b) depositing and etching on this insulator a second superconducting film having properties similar to those of the first film. This last step is particularly delicate because it is necessary to carry out a recovery of epitaxy, a technique that is difficult to control. There are other methods for depositing a coil in thin layers, but they have difficulties of realization identical to those described here.

On the other hand, these techniques do not make it possible to obtain inductive components whose inductance characteristics are easily adjustable once they are implanted in a circuit or an electrical or electronic device.

However it may be very useful to have inductive components whose inductance can be adjusted after implantation, for example to perform a calibration, measurement, adjustment or adjustment within an apparatus including such components.

Devices or methods known for this often use adjustment or adjustment of this inductance by changing the geometry by mechanical action. This is for example to adjust or adjust the position of a ferrite core in the core of a coil as in the patent US 4,558,295 , or a metal electrode between two dielectric parts as described in the patent US 6,556,415 in the case of a resonant circuit. It can also be a displacement of contact on a conductive track forming a meander deposited in a thin layer, as taught by the patent application. US 2002/01 90835 .

It is also possible to selectively associate, by electrical or electronic connection, a certain number of known inductance sub-components, as proposed by the patent. US 5,872,489 , which has obvious limits, for example in terms of number of values obtained and complexity of implementation.

Another method is proposed by the patent US 5,426,409 which consists of controlling the degree of saturation with a variable current magnetic core of a coil. When the constraints and the frequencies concerned allow it, it is also possible to adjust a frequency variation inductance on a semiconductor material (MESFET GaAs technology, described in the patent US 6,211,753 ). This type of solution is however not applicable in all cases, and is not always miniaturizable beyond a certain limit.

With the known solutions, the components obtained may be subject to wear. Often, they impose a significant amount of space. They also have limitations in terms of frequency ranges and / or usable performance. In addition, they are often difficult to integrate in circuits manufactured industrially and low cost.

An object of the present invention is to overcome all or part of these disadvantages.

In the French patent application No. 03 09212 of July 28, 2003 , the authors of the present invention propose a method of producing an inductive superconductive component in thin layers, good performance in inductance value as in miniaturization and integration.

This inductive superconductive component has at least two terminals and comprises at least one line segment integrating at least one of these terminals, this line segment constituting a conductive or superconducting layer within a stack of alternately superconductive and insulating films.

More particularly, this line segment may consist of a superconducting line passing through the component and on which this stack is deposited.

During the development and testing of this type of component, under certain conditions, the inventors have observed an inductive behavior whose inductance varies when the intensity of a current flowing through this component varies.

The present invention proposes to use, as variable-inductance component as a function of the current flowing through it, an inductive superconductive component having at least two terminals and comprising at least one line segment integrating at least one of these terminals. line segment constituting a conductive or superconducting layer within an impalement of alternately superconductive and insulating films.

In the same spirit, the invention proposes an electronic device comprising at least one such inductive superconducting inductor variable component depending on the current flowing therethrough, said superconducting inductive component having at least two terminals and comprising at least one line segment integrating at least one of these terminals, this line segment constituting a conductive or superconductive layer within a stack of alternately superconductive and insulating films.

According to a first embodiment, the invention proposes such a use in which the inductance value of the superconductive inductive component is modified or controlled by current control means acting on a direct current which passes through said component.

The invention proposes in particular a method for controlling the inductance of a superconductive inductive component, this superconductive inductive component having at least two terminals and comprising at least one line segment integrating at least one of these terminals, this line segment. constituting a conductive or superconductive layer within a stack of alternately superconductive and insulating films, this component being subjected to a voltage or an alternating current, this method comprising an injection of a substantially continuous control current in superposition of the alternating current passing through said superconductive inductive component.

In this embodiment, a device according to the invention comprises at least one superconductive inductive component which is crossed by an alternating current. This device further comprises means for controlling or modifying the inductance value of said superconductive inductive component, these means acting on the intensity of a direct current passing through said superconductive inductive component and superimposed on the alternating current.

In such a device, the superconductive inductive component can be used in an electronic circuit performing a frequency filtering, at least one characteristic of which is modified by modifying the inductance of said superconducting inductive component.

The superconductive inductive component can also be used within an electronic circuit producing a delay line, at least one of which is modified by modifying the inductance of said superconducting inductive component.

More particularly, the superconductive inductive component may be used in an electronic circuit producing an antenna manufactured from a thin superconducting film, at least one characteristic of this antenna being controlled or modified by modifying the inductance of said inductive component superconductor.

The invention also proposes a phase shift radar device comprising a plurality of antennas each comprising at least one electronic circuit including a delay line, this delay line being arranged so that each of said antennas transmits or receives a signal whose phase is shifted relative to that of the neighboring antennas, this arrangement being controlled by modifying the inductance of said superconductive inductive component.

In addition, in many applications it may be useful to have a treatment modifying certain characteristics of one or more waves involving an alternating current, in particular to treat a component of this wave when this component represents a carrier signal. information.

Another object of the invention is then to use these variations of inductance to perform new electronic treatments or to perform new electronic treatments that were made in the state of the art very differently or with other types of components.

According to a second embodiment, the invention also proposes such a use in which the superconductive inductive component is subjected to a voltage or a wave current. constituting at least one wave, to which it reacts with an inductive behavior varying within the same period of this wave, this variation producing a modification of at least one characteristic of this wave.

In this embodiment, a device according to the invention comprises at least one such superconducting inductive component which is subjected to a voltage or an undulatory current constituting at least one wave, to which said component reacts with a varying inductive behavior within the same period of this wave, this variation producing a modification of at least one characteristic of this wave.

More particularly, the invention proposes such a use for producing a frequency mixer, as well as a device implementing this use.

• d'une part à une onde d'entrée comprenant au moins une première composante constituant un signal, dit signal d'entrée, à une première fréquence, dite fréquence haute, et
• d'autre part à une onde régulière à une fréquence d'oscillation proche de la fréquence haute.

Within this mixer, at least one such superconducting inductive component is subjected:

• on the one hand to an input wave comprising at least a first component constituting a signal, called an input signal, at a first frequency, referred to as the high frequency, and
• on the other hand, to a regular wave at an oscillation frequency close to the high frequency.

The inductive behavior of said superconductive inductive component then produces an output wave comprising at least a second undulatory component according to a second frequency, called low frequency, approximately equal to the high frequency less the oscillation frequency, said second component constituting an output signal depending on the input signal.

According to a feature, such a mixer comprises at least one superconductive inductive component mounted in parallel with an oscillator component.

According to another particularity, such a mixer comprises at least one oscillator component in parallel as well as a serial superconducting inductive component mounted downstream and at the output of which is connected at least one capacitive and inductive assembly producing a low-pass filtered.

The invention also proposes a system for receiving an electromagnetic radio transmission signal comprising such a mixer.

In the same spirit, the invention also proposes such a use for producing a frequency modulator, as well as a device implementing this use.

• d'une part à une onde d'entrée comprenant au moins une première composante constituant un signal d'entrée à une première fréquence, dite fréquence basse, et
• d'autre part à une onde régulière à une fréquence d'oscillation.

Within this modulator, at least one such superconducting inductive component is subjected:

• on the one hand to an input wave comprising at least a first component constituting an input signal at a first frequency, called a low frequency, and
• on the other hand to a regular wave at an oscillation frequency.

The inductive behavior of said superconductive inductive component then produces an output wave comprising at least a second wave component according to a second frequency, referred to as the high frequency, approximately equal to the sum of the low frequency and the oscillation frequency, said second component constituting a output signal dependent on the input signal.

According to a feature, such a modulator comprises at least one oscillator component in parallel and a superconducting inductive component in series mounted downstream and at the output of which is connected at least one capacitive and inductive assembly producing a high-pass filter.

The invention then proposes a system for transmitting a signal. electromagnetic transmission system comprising such a modulator.

Thus, the invention provides an audiovisual broadcasting system or communication or satellite using at least one of these devices.

• la figure 1 est un schéma d'un empilement E de couches alternativement supraconductrices C₁ et isolantes C₂ déposées sur un substrat S de façon à réaliser un composant inductif ;
• la figure 2A est une vue de dessus d'une ligne supraconductrice LS comportant un composant inductif constitué de films alternativement supraconducteurs C1 et isolants C2 ;
• la figure 2B est une vue en coupe d'une ligne supraconductrice LS comportant un composant inductif E constitué de films alternativement supraconducteurs C1 et isolants C2 ;
• la figure 3A est une photographie du motif utilisé pour les tests montrant l'emplacement des entrées de courant I1 et I2, les plots de mesure V1 et V2 de la différence de potentiel aux bornes d'un pont recevant un composant inductif en couches minces, ainsi que l'emplacement de celui-ci ;
• la figure 3B représente le masque de photolithogravure utilisé pour réaliser le motif de test de la figure3A ;
• La figure 4 est un schéma du dispositif de mesure utilisé pour

caractériser un composant inductif supraconducteur selon l'invention ;

• la figure 5 illustre une différence de potentiel mesurée entre les plots V1 et V2 (traits pleins) lorsqu'un courant (pointillés) en dents de scie à la fréquence de 1000 Hz circule dans l'échantillon ;
• la figure 6 représente une comparaison des différences de potentiel mesurées entre les plots V1 et V2 lorsque deux courants en dents de scie de même amplitude Imax =10 microampères mais de fréquences différentes circulent dans l'échantillon ;
• la figure 7 illustre une ligne de retard implémentant un composant inductif supraconducteur selon l'invention
• la figure 8 illustre un schéma de principe d'une antenne à décalage de phase utilisant de telles lignes à retard ;
• la figure 9 est une courbe représentant la valeur de la différence de potentiel mesurée entre les plots V1 et V2 en fonction de l'intensité circulant entre les plots I1 et I2, au cours d'une période d'un courant alternatif I_AC à une fréquence de 2 kHz ;
• la figure 10 est une courbe représentant la valeur de la différence de potentiel mesurée entre les plots V1 et V2 en fonction du temps, lorsqu'un courant alternatif I_AC en dents de scie (pointillés) à la fréquence de 10 kHz circule dans l'échantillon, dans le cas où un courant continu I_DC circule également dans l'échantillon, et pour des intensités de ce courant continu I_DC valant respectivement 0 A, 5 µA, et 10 µA.
• la figure 11 illustre des valeurs d'inductance selon la fréquence et pour différentes intensités de ce courant continu I_DC valant respectivement 0 A (points carrés), 5 µA (cercles), 10 µA (triangles montants) et -10 µA (triangles descendants) ;
• la figure 12 est un schéma de principe d'un filtre passe-haut accordable selon l'invention ;
• la figure 13 est un schéma de principe d'un filtre passe-bas accordable selon l'invention
• la figure 14 est un schéma de principe d'un mélangeur hétérodyne selon l'art antérieur, utilisant une diode ;
• les figures 15 et 16 sont des schémas de principe de mélangeurs hétérodynes selon l'invention ;
• les figures 17 et 18 sont des schémas de principe de modulateurs selon l'art antérieur, à base de diodes et respectivement de transistors ;
• la figure 19 est un schéma de principe d'un modulateur selon l'invention.

Other advantages and characteristics of the invention will appear on examining the detailed description of non-limiting embodiments, and the appended drawings in which:

• the figure 1 is a diagram of a stack E of alternately superconducting layers C ₁ and insulating layers C ₂ deposited on a substrate S so as to produce an inductive component;
• the Figure 2A is a top view of a superconducting line LS comprising an inductive component consisting of alternately superconductive C1 and insulating C2 films;
• the Figure 2B is a sectional view of a superconducting line LS comprising an inductive component E consisting of alternately superconductive C1 and insulating films C2;
• the figure 3A is a photograph of the pattern used for the tests showing the location of the current inputs I1 and I2, the measurement pads V1 and V2 of the potential difference across a bridge receiving an inductive thin-film component, and the location of it;
• the figure 3B represents the photolithographic mask used to make the test pattern of the figure3A ;
• The figure 4 is a diagram of the measuring device used to

characterize a superconductive inductive component according to the invention;

• the figure 5 illustrates a potential difference measured between the pads V1 and V2 (solid lines) when a current (dotted) sawtooth at the frequency of 1000 Hz flows in the sample;
• the figure 6 represents a comparison of the potential differences measured between the pads V1 and V2 when two sawtooth currents of the same amplitude Imax = 10 microamperes but of different frequencies circulating in the sample;
• the figure 7 illustrates a delay line implementing a superconductive inductive component according to the invention
• the figure 8 illustrates a block diagram of a phase shift antenna using such delay lines;
• the figure 9 is a curve representing the value of the potential difference measured between the pads V1 and V2 as a function of the intensity flowing between the pads I 1 and I 2, during a period of an _AC current I _AC at a frequency of 2 kHz;
• the figure 10 is a curve representing the value of the potential difference measured between the pads V1 and V2 as a function of time, when an alternating current I _AC sawtooth (dotted) at the frequency of 10 kHz flows in the sample, in the case where a DC current I _DC also circulates in the sample, and for intensities of this direct current I _DC respectively worth 0 A, 5 μA, and 10 μA.
• the figure 11 illustrates inductance values according to the frequency and for different intensities of this DC current I _DC respectively 0 A (square points), 5 μA (circles), 10 μA (rising triangles) and -10 μA (descending triangles);
• the figure 12 is a block diagram of a tunable high-pass filter according to the invention;
• the figure 13 is a schematic diagram of a tunable low-pass filter according to the invention
• the figure 14 is a block diagram of a heterodyne mixer according to the prior art, using a diode;
• the Figures 15 and 16 are schematic diagrams of heterodyne mixers according to the invention;
• the Figures 17 and 18 are schematic diagrams of modulators according to the prior art, based on diodes and respectively on transistors;
• the figure 19 is a block diagram of a modulator according to the invention.

The principle used in the component and its production method according to the invention comprises a stack E of thin films, or thin layers, alternately superconducting C1 and insulating C2, deposited on a substrate S, with reference to FIG. figure 1 , or on a superconducting line LS. It is important for C2 films to be insulative and to control any growth defects that may put two adjacent superconducting films in direct contact. This stack makes it possible to obtain particularly efficient components, inter alia because of a very high inductance value with respect to their size.

Within the inductive behavior of this component when it receives an IAC current or an alternating or transient voltage, the principle consists in obtaining a modification of this inductive behavior by passing it through a determined continuous current IDC.

By controlling the value of this direct current IDC, it is then possible to control the inductance value obtained for this component.

It is thus possible to produce components having an inductance of the desired value, or an inductance that can be controlled according to the needs.

It is also possible to make components whose inductance value can be modified by the passage of a current to be detected or measured, or by one or more physico-chemical quantities to be detected causing a variation of such a current.

In a preferred embodiment of the invention, the first deposited film for making the stack E is insulating as indicated on FIG. figure 1 .

The integration of inductive components in a superconducting circuit can be carried out in the manner indicated on the Figures 2A and 2B using thin film deposition techniques well known to those skilled in the art, for example laser ablation, radio frequency sputtering, vacuum evaporation, chemical vapor deposition and generally any deposit technique for obtaining thin layers.

It should be noted that in this particular version of the method according to the invention corresponding to the Figures 2A and 2B , a superconductive film L1 deposited on a substrate S, once etched, constitutes a superconducting line LS on which the inductive stack E will be placed.

In a particular embodiment of the invention provided in a non-limiting manner, the materials chosen are compounds YBa ₂ Cu ₃ O ₇ -δ for superconductive films and LaAlO ₃ for insulating films. The thicknesses are 10 nm (10 ^-8 m) for superconducting films and 4 nm (4.10 ^-9 m) for insulating films. 14 pairs of films have been deposited.

After deposition, the films were etched to obtain the pattern shown on the figure 3A in which one distinguishes the metallized contacts I1, I2 which make it possible to bring the current in the sample and those which make it possible to measure the voltages V1 and V2 at the terminals of the central element, called bridge, of the pattern. As an indication and not limitation, the size of the bridge is 10 microns x 20 microns. The modification of the value of the inductance can however also be obtained with patterns of the same shape but of different dimensions or with patterns of different shape from that shown in the figures.

The measuring device used to characterize the samples of superconductive inductive components according to the invention, represented in FIG. figure 4 , comprises a generator GBF creating a variable current in time I (t) which passes through the resistor R and the sample Ech via the contacts I1 and I2. The potential difference across the resistor R is amplified by a differential amplifier AI and sent to an input. YI oscilloscope Osc. It makes it possible to know the intensity I (t) of the current passing through the sample. The potential difference at the terminals of the sample is taken at V1 and V2, amplified by the amplifier Av and sent to the input Yv of oscilloscope Osc.

The figure 5 shows the signals collected in YI and Yv when the sample is at a temperature of 37 K. In the present case, the sample was placed in a helium cryogenerator but any process making it possible to obtain a temperature below the critical temperature of the sample studied is suitable.

The generator delivers a sawtooth current at the frequency of 1000 Hz. The value of the current I (t) has been directly reported. It is observed that the potential difference V (t) between V1 and V2 has the form of slots, which indicates that V (t) is proportional to the derivative with respect to the time of I (t). This characteristic indicates that the sample behaves well as an inductive component. We reported on the figure 6 the V (t) signals measured at 700 Hz and 2 kHz for a peak current value equal to 10 μA in both cases. In this figure, the solid line corresponds to the voltage recorded for a current at the frequency F = 700 Hz and the dashed line to that recorded for a current at the frequency F = 2000 Hz.

It is observed that the ratio of the amplitude of the signals obtained is in the ratio of the applied frequencies, which again is typical of an inductive component.

Results presented on the figure 6 it is deduced that the inductance of the component produced according to the invention is equal to 535 μH ± 10 μH. The components tested did not all have such a high inductance but values of the order of a few tens of microhenry were commonly obtained with components of identical shape to that presented here.

On the figure 9 it is found that the absolute value of the voltage V between the pads V1 and V2 decreases when the intensity of the current IAC increases in absolute value. This decrease corresponds to a reduction of the inductance of the test device when the current IAC increases in intensity within one of its periods.

On the figure 10 , is shown the value of the potential difference V measured between the pads V1 and V2, during a period of the sawtooth alternating current IAC at a frequency of 10 kHz, and in the superconducting state. This potential difference V is represented on three different curves obtained by passing or not the test device by a continuous current IDC.

A first of these curves represents the situation with IDC = 0, ie with a purely alternating current, and represents an inductive behavior of the test device. In this same figure and for the same device tested, a second curve for this voltage V is obtained. with a superimposed current IDC = 5 μA (microamperes); which can be considered as continuous with respect to the frequency of the alternating current IAC. This second curve then indicates a lower inductance than the curve obtained with alternating current alone. With a larger superimposed DC current, equal to IDC = 10 μA (microamperes), a third curve for this voltage V indicates an inductance of the same device tested even lower than the first and second curves.

The figure 11 represents a measurement of the inductance of the test device over a frequency range between 100 Hz and 10 kHz, for superimposed continuous DCI values taking the values of 0.5μA, + 10μA, and -10μA (microamperes) . Over all of this frequency range, it is found that the value of the inductance decreases when the DC current IDC increases in intensity, and in both directions of this current IDC. More particularly in the frequency range where the inductance is substantially constant, ie between 1 and 10 kHz, this inductance is a decreasing function of the intensity of this superimposed continuous current IDC.

The invention thus provides an inductive component with variable inductance as a function of current flows through it.

By passing such an inductive superconductive component through a controlled direct current IDC, the value of the inductance with which this component reacts to a corresponding alternating signal can be controlled.

The invention thus provides an adjustable or tunable inductive component by controlling a current flowing through it.

In addition, when the component is crossed by an alternating current, the instantaneous intensity flowing through it varies during each period. As indicated by the figure 9 the inductance of the component also varies during each period.

In particular, when this alternating current corresponds to a wave carrying or including one or more signals, this variation of inductance within a period then produces an alternating voltage across the component which represents a modified version of the signal carried by this current. alternative. For conventional inductive behavior, this voltage produced would be the time derivative of the current flowing through the component. In this case, the voltage produced is a modified image of this derivative, and therefore represents a modified version of the input signal. Thus, the invention also provides an inductive modification or signal processing component.

The superconducting inductive components obtained by the method according to the invention can find applications in the fields of electrical engineering or electronics, telephony, antennas and passive high frequency components, in particular for medical imaging. as well as radar and defense electronics.

In a first example of application, superconductive inductive components are implemented in antenna systems. Thus, in a number of cases, for example in medical magnetic resonance imaging (MRI) surface, using tuned antennas. It is then possible to make an agreement of an antenna by adjusting the inductance of one or more of the inductive components that it comprises. An important parameter in the efficiency of the antenna is the overvoltage coefficient which is proportional to its inductance. A superconducting antenna makes it possible to increase this coefficient because its ohmic resistance is very weak. It is conceivable to obtain a new increase in the overvoltage coefficient by including in the antenna circuit a device of the type of those described here.

A particularly favorable case will be that where the antenna itself is made from a thin superconducting film.

In another exemplary application, superconductive inductive components are implemented in delay lines. Delay lines are in common use in all areas of electronics. The simplest form that a delay line can take is represented on the figure 7 .

The presence in the circuit of the inductance L and the capacitor C causes a phase difference between the voltage V and the current I. An example of use is that of the phase shift radars which make it possible to explore the surrounding space with a fixed antenna system. A schematic diagram for such a system is reported on the figure 8 . In this device the main line carrying the current 1 is coupled to the different antennas. Each of these includes in its circuit a delay line. As a result, each antenna transmits or receives a signal whose phase is offset from that of the neighboring antennas. By varying this phase shift the direction of the emitted radiation is changed. In defense electronics, we have long studied the introduction of superconducting components in electronic circuits, particularly for radar and more generally countermeasures. The presence of high inductance components, small in size and whose manufacturing uses processes similar to those used for the rest of the circuit would be an important innovation in this area.

In such applications, the component according to the invention, because it is tunable in use, can be advantageously used to modify the characteristics or the behavior of a device in which it is included. This makes it possible, for example, to modify or calibrate the characteristics of a composite and / or active antenna, by global adjustment or differentiated inductance within the delay lines of the individual antennas that compose it.

The setting possibilities of such individual or composite antennas including tunable inductive superconducting component according to the invention can also allow significant advances in the field of medical imaging. For example for MRI imaging, the use of such antennas could make it possible to produce images with different values of the applied magnetic field. This would provide an additional degree of freedom to optimize the quality of the images obtained.

Such powerful and easily integrable inductive components can also be used generically in most general electronics applications, in particular to perform filtering functions of all types, for example high-pass, low-pass or pass-through. bandaged. It is then possible to produce highly integrated and / or miniaturized filters.

The use of a component according to the invention makes it possible to integrate an inductance of significant value in a circuit of small size.

As illustrated in figures 12 and 13 for high-pass and low-pass filters, it is then possible to adjustably filter an input voltage V _in to obtain an output voltage V _out , using a variable inductance L _v according to the invention. As illustrated in this example, the use of inductive components according to the invention makes it possible to realize in integrated circuits filters having only capacitors and inductances, which are not very dissipative compared to filters constructed with capacitors. and resistances.

By using the inductance variations within an undulatory period, the component according to the invention can also be used advantageously to produce a type of electronic device called a mixer, and used in particular in heterodyne detection.

Mixers are widely used to process a wave at a certain frequency f1, for example 12 GHz, using an oscillator producing a frequency wave f0, for example 10 GHz, so as to obtain a wave at a frequency f2 = f1-f0 carrying a signal to be detected. Typically, such a mixer is used in the vicinity of a receiving antenna to decode 12 GHz signals received from a direct television satellite, and draw a signal at a frequency of 2 GHz which will be sent by coaxial cable to a demodulator.

In the state of the art, the mixers are typically made using discrete components which are causes of cost and fragility encumbrance, or using non-linear components, for example diodes, which have certain disadvantages, such as a significant dissipation of energy or the fact of requiring a high signal level.

The figure 14 thus illustrates a schematic diagram of such a diode mixer.

For example, the figure 15 represents a block diagram of a variable inductive component according to the invention, used to perform a mixer function in a simple way. The current to be detected 11 of frequency f1, with the current i0 coming from a local oscillator at the frequency f0, is sent on a variable inductance component Lv1. according to the invention. The value of the inductance of the component according to the invention Lv1 then depends on the current received, according to a function of the magnitude i1 + i0. More particularly under certain conditions, for example over certain frequency ranges, this function can be written in the form of a relation comprising a coefficient a that can be determined by different types of measurements, for example similar to those illustrated in FIG. Figures 9 and 10 . Such a relation can then be written in the following form: $${\mathrm{The}}_{\mathrm{v}}\mathrm{=}{\mathrm{The}}_{\mathrm{0}}\mathrm{-}\mathrm{\alpha }\mathrm{.}\left({\mathrm{i}}_{\mathrm{1}}\mathrm{+}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="imgf0003.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{0}}\right)$$

In which L0 is the inductance value of the component when the DC superimposed current I _DC is zero.

In particular, when the amplitude of the local current i0 coming from the oscillator is much greater, this relation corresponds to a following relation of form: $${\mathrm{The}}_{\mathrm{v}}\mathrm{=}{\mathrm{The}}_{\mathrm{0}}\mathrm{-}\mathrm{\alpha }\mathrm{.}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="imgf0003.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{0}}$$

où φ est la phase du signal du signal d'entrée par rapport à celui de l'oscillateur. Cette relation indique que le composant inductif variable selon l'invention se comporte bien comme un mélangeur.Under these conditions, if the input signal is sinusoidal, the output voltage V contains a component Vf2 waving at the frequency f2 = f1-f0 and depending on the input signal. This frequency component f1-f0 then has the following form: $${\mathrm{vf}}_{\mathrm{2}}\mathrm{=}\mathrm{\pi }\mathrm{.}\mathrm{\alpha }\mathrm{.}{\mathrm{<figure-callout\; id="0"\; label="i"\; filenames="imgf0003.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{0}}\mathrm{.}{\mathrm{<figure-callout\; id="1"\; label="i"\; filenames="imgf0009.png"\; state="\{\{state\}\}">i</figure-callout>}}_{\mathrm{1}}\mathrm{.}\sin \left[\mathrm{2}\mathrm{\pi }\mathrm{(}{\mathrm{f}}_{\mathrm{0}}\mathrm{-}{\mathrm{f}}_{\mathrm{1}}\mathrm{)}\mathrm{t}\mathrm{+}\mathrm{\phi }\right]$$

where φ is the phase of the signal of the input signal relative to that of the oscillator. This relationship indicates that the variable inductive component according to the invention behaves well as a mixer.

The figure 16 is a block diagram of a mixer using a variable inductor according to the invention for extracting a signal at a frequency f2, from a signal S1 at a frequency f1 and using a wave at the frequency f0 resulting from a osc oscillator and close to f1, with f2 = f1-f0. This operation can be used, for example, to obtain a signal S2 by extracting it from the signal S1 coming, for example, from a reception antenna. Compared to the diagram of the figure 15 , the schema of the figure 16 further comprises a capacitor C and an inductance LA, constituting a low-pass filter, at the output of variable inductance. The presence of this filter makes it possible to isolate the signal S2 at the frequency f2 = f1-f0, and may be useful or even necessary to integrate this type of mixer into a signal processing device.

The tunable inductive component according to the invention can also be advantageously used to produce a device including a modulator. A modulator is typically used to obtain a signal at a high frequency f1 from a signal component S2 at a relatively low frequency f2 by adding a wave at a frequency f0 close to f1.

The state of the art knows modulators typically made using discrete components that are causes of cost and fragility clutter, or using integrated non-linear components, which have certain drawbacks, such as for example some dissipation. energy. The Figures 17 and 18 thus represent diagrams of the principle of modulators respectively made using diodes ( fig.17 ) and using transistors ( fig.18 ).

The figure 19 illustrates a block diagram of a mixer using a variable inductor according to the invention for mixing a signal at a frequency f2 with a wave at the frequency f0 from an oscillator Osc, usable for example to encode a signal S2 before transmission. More particularly in the case where the frequency f 0 is significantly greater than the frequency f 2, the variable inductance L v 2 mixes into a signal which is then filtered by the high-pass circuit constituted by the inductance L _A and the capacitor C This filtering then lets pass only the wave component Vf1 of frequency f1, with f1 = f2 + f0.

In the examples described, the inductances that are not specified as variable or controlled can of course also be made in the form of a superconductive inductive component, so as to homogenize the device obtained and maintain or improve the gains of the invention, for example in terms of cost, reliability, performance or bulk.

In all these examples, as in other embodiments not described here, the current control according to the invention in particular makes it possible to drive a greater part of functions and adjustments in a fully electronic manner. Such control then allows greater flexibility in the design of the devices concerned, but also to provide new features and performance compared to the state of the art.

Similarly, the production of these components in the form of thin superconducting layers allows for greater miniaturization as well as integration on a much larger scale. This makes it possible to design less dissipative systems, multiply the components, and improve the power and / or reduce the size. Integration also improves the reliability and reproducibility of such devices, and reduces manufacturing costs.

Of course, the invention is not limited to the examples that have just been described and many adjustments can be made to these examples without departing from the scope of the invention. Thus, the number of respectively insulating and superconductive films is not limited to the examples described. Moreover, the dimensions of the superconductive inductive components as well as their surfaces can evolve according to the specific applications of these components. In addition, the respectively superconductive and insulating films can be made from other compounds than those proposed in the example described, provided that these compounds satisfy the physical conditions required for the applications.

Claims (21)

1. Use, as a component with variable inductance which is a function of the current passing through it, of an inductive superconductive component having at least two terminals and comprising at least one line segment working with said terminals and integrating at least one of these terminals, this line segment constituting a conductive or superconductive layer within a stack (E) of films alternately superconductive (C1) and insulating (C2).
2. Use according to claim 1, wherein the value of the inductance of the superconductive inductive component is modified or controlled by current control means acting on a direct current which passes through said component.
3. Use according to claim 1, wherein the superconductive inductive component is subjected to an undulating voltage or current constituting at least one wave, to which it reacts with an inductive behaviour varying within a single period of this wave, this variation producing a modification of at least one characteristic of this wave.
4. Use according to one of claims 1 or 3 to produce a frequency mixer, in which the superconductive inductive component (L_v1 Fig. 15, 16) is subjected on the one hand to an input wave comprising at least one first component constituting a signal, termed input signal (S1), at a first frequency, termed high frequency (f₁), and on the other hand to a regular wave at an oscillation frequency (f₀) close to the high frequency (f₁), the inductive behaviour of said superconductive inductive component (L_v1) producing an output wave comprising at least one second wave component at a second frequency, termed low frequency (f₂), approximately equalling the high frequency reduced by the oscillation frequency, said second component constituting an output signal (S2) dependent on the input signal (S1).
5. Use according to one of claims 1 or 3 to produce a frequency modulator, wherein the superconductive inductive component (L_v2 Fig. 19) is subjected on the one hand to an input wave comprising at least one first component constituting an input signal (S2), at a first frequency, termed low frequency (f₂), and on the other hand to a regular wave at an oscillation frequency (f₀), the inductive behaviour of said superconductive inductive component (L_v2) producing an output wave comprising at least one second wave component at a second frequency, termed high frequency (f₁), approximately equalling the sum of the low frequency and the oscillation frequency, said second component constituting an output signal (S1) dependent on the input signal (S2).
6. Electronic device comprising at least one superconductive inductive component with variable inductance which is a function of the current passing through it, said superconductive inductive component having at least two terminals and comprising at least one fine segment working with said terminals and integrating at least one of these terminals, this line segment constituting a conductive or superconductive layer within a stack (E) of alternately superconductive (C1) and insulating (C2) films.
7. Device according to claim 6, wherein an alternating current passes through the superconductive inductive component and wherein the device also comprises means for controlling or modifying the value of the inductance of said superconductive inductive component, these means acting on the intensity of a direct current passing through said superconductive inductive component and being superimposed on the alternating current.
8. Device according to either of claims 6 and 7, wherein the superconductive inductive component is used in an electronic circuit producing a frequency filtering, at least one characteristic of which is modified by modification of the inductance of said superconductive inductive component.
9. Device according to either of claims 6 and 7, wherein the superconductive inductive component is used in an electronic circuit producing a delay line, at least one characteristic of which is modified by modification of the inductance of said superconductive inductive component.
10. Device according to one of claims 6 to 9, wherein the superconductive inductive component is used in an electronic circuit producing an antenna made from a superconductive thin film, at least one characteristic of this antenna being controlled or modified by modification of the inductance of said superconductive inductive component.
11. Device according to claim 10, used in a phase shift radar comprising a plurality of antennae, each comprising an electronic circuit including at least one delay line, this delay line being arranged such that each of said antennae transmits or receives a signal the phase of which is shifted relative to that of the neighbouring antennae, this configuration being controlled by modification of the inductance of said superconductive inductive component.
12. Device according to claim 6, wherein a current constituting at least one wave passes through this superconductive inductive component, to which said component reacts with an inductive behaviour varying within a single period of this wave, this variation producing a modification of at least one characteristic of this wave.
13. Device according to one of claims 6 or 12, wherein this superconductive inductive component (L_v1 Fig. 15, 16) is subjected on the one hand to an input wave comprising at least one first component constituting a signal, termed input signal (S1), at a first frequency, termed high frequency (f₁), and on the other hand to a regular wave at an oscillation frequency (f₀) close to the high frequency (f₁), the inductive behaviour of said superconductive inductive component (L_v1) producing an output wave comprising at least one second wave component at a second frequency, termed low frequency (f₂), approximately equalling the high frequency reduced by the oscillation frequency, said second component constituting an output signal (S2) dependent on the input signal (S1).
14. Device according to claim 13, characterized in that it produces a mixer and comprises at least one superconductive inductive component (L_v1, Fig. 15) mounted in parallel with an oscillator component (Osc).
15. Device according to one of claims 13 or 14, characterized in that it produces a mixer and comprises at least one oscillator component (Osc) in parallel, as well as a superconductive inductive component (L_v1, Fig. 16) in series mounted downstream and to the output of which is connected at least one capacitive and inductive assembly producing a low pass filter.
16. Device according to one of claims 6 or 12 to 15, used in a system for receiving a Hertzian transmission of an electromagnetic signal.
17. Device according to one of claims 6 or 12, wherein the superconductive inductive component (L_v2 Fig. 19) is subjected on the one hand to an input wave comprising at least one first component constituting an input signal (S2), at a first frequency, termed low frequency (f₂), and on the other hand to a regular wave at an oscillation frequency (f₀), the inductive behaviour of said superconductive inductive component (L_v2) producing an output wave comprising at least one second wave component at a second frequency, termed high frequency (f₁), approximately equalling the sum of the low frequency and the oscillation frequency, said second component constituting an output signal (S1) dependent on the input signal (S2).
18. Device according to claim 17, characterized in that it produces a modulator and comprises at least one oscillator component (Osc) in parallel, as well as a superconductive inductive component (L_v2, Fig. 19) in series mounted downstream and to the output of which is connected at least one capacitive and inductive assembly producing a high pass filter.
19. Device according to one of claims 6, 12, 17 or 18, characterized in that it is used in a system for transmitting a Hertzian transmission of an electromagnetic signal.
20. Device according to one of claims 6 to 19, used in an audiovisual broadcasting system, or a communication system, or a satellite system.
21. Method for controlling the inductance of a superconductive inductive component, this superconductive inductive component having at least two terminals and comprising at least one line segment working with said terminals and integrating at least one of these terminals, this line segment constituting a conductive or superconductive layer within a stack (E) of alternately superconductive (C1) and insulating (C2) films, this component being subjected to an alternating voltage or current, this method comprising an injection of an approximately continuous control current, with superposition of the alternating current passing through said superconductive inductive component.

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