EP3077833A1

EP3077833A1 - Analog spectrum analyser

Info

Publication number: EP3077833A1
Application number: EP14806643.4A
Authority: EP
Inventors: Julien KERMORVANT; Paolo Bortolotti; Bruno Marcilhac; Jean-Claude Mage; Vincent Cros
Original assignee: Centre National de la Recherche Scientifique CNRS; Thales SA
Current assignee: Centre National de la Recherche Scientifique CNRS; Thales SA
Priority date: 2013-12-04
Filing date: 2014-12-04
Publication date: 2016-10-12
Also published as: WO2015082618A1; FR3014205A1; US20160305994A1; US10408867B2; FR3014205B1

Abstract

The invention relates to a spectrum analyser for a signal I_RF comprising a plurality of frequencies f_i characterised by comprising N entities (20_n) each made up of a structure formed by a stack of magnetic and non-magnetic layers having in at least one of the magnetic layers a magnetic configuration in the shape of a vortex, the excitation modes of the magnetic configuration being suitable for detecting the frequencies contained in an incident signal in real time, each entity having a first lower electrode (21_n) and a second upper electrode (22_n), a voltage-measuring device (6_a) suitable for measuring an electric voltage showing the presence of a frequency f_k in the analysed signal I_RF, the device (6_a) being connected to the lower electrode (21_n) and to the upper electrode (22_n), a measurement-processing device (7) suitable for determining the value of the frequencies f_k in the signal l_RF, and a line (53) carrying the signal to be analysed to each of the entities.

Description

ANALOG SPECTRUM ANALYZER

The subject of the invention relates to an integrated spectral analyzer of radiofrequency signals. In particular, it makes it possible to know instantaneously or almost instantaneously the frequencies present in an _RF signal. The analyzer can be used to determine the availability or occupancy of a frequency or band of frequencies over a given frequency spectrum. The invention applies for example for frequency ranges ranging from a few tens of MHz up to a few GHz.

The applicant's current radiocommunication and spectrum control protocols increasingly require real-time knowledge of the state of occupancy of the frequency bands, in order to effectively manage the allocation of frequency bands for users and in case of unauthorized presence to locate it. There are currently several techniques for performing spectral analysis of a radio frequency signal.

One way to do this is to perform multichannel spectral analysis using filter banks. This technique has the particular disadvantage of being complex to implement on broad bands. A second way of proceeding is to perform an analog spectral analysis by bank of delay lines. In this case, digital counting and standard delay line systems operate only in single frequency. The combination of the two systems can be considered but generates complexity and difficulty in mastering the concept. A third alternative is to perform a multi-tap delay line analog spectral analysis. Finally, it is also known to use a technique known as the Anglo-Saxon "Spectral Hole Burning" which requires cryogenics and requires the use of bulky and expensive heavy equipment. Other techniques developed more recently are based on magnetic stack structures (for example spin valves or tunneling metal junctions) whose electrical resistance varies thanks to a grinding effect when applying a radio frequency wave. This characteristic variation is used to perform real-time detection and / or spectral analysis of a given frequency range. These magnetic structures are in the form of a multilayer stack manufactured in the form of nano pillars, in the following "junction". Four representative examples of magnetic structures applied to frequency detection are detailed in patent applications: WO2006101040, US20130099339, US20080180085 and EP2515130.

Despite their performance, the magnetic devices proposed by the prior art only allow frequency detection above 1 GHz and with a modest resolution due to the resonance mode used (resonance mode related to a quasi-uniform magnetization). In addition, the proposed devices are not compatible with instant broadband spectral analysis. Indeed, to cover wide bands with a single detection element, it is necessary to apply a variable magnetic field or a variable electric current over a wide range, the detection then being carried out by scanning in a non-instantaneous manner. In order to eliminate this limitation, it is proposed in the US Pat. No. 20090140733 to network several junctions. However to operate the device requires the application of a different magnetic field on each loot. This field is then applied via a structure of "YOKE" type known to those skilled in the art, making the realization extremely complex. In addition, one of the major interests of this technology, which is the extreme compactness, is seen quite reduced.

In order to simultaneously address the broadband characteristic, instantaneity, compactness and detection capacity below 1 GHz, the idea of the present invention is a new approach that relies on the use of a network of magnetic structures presenting a specific resonance mode, associated with a non-uniform magnetic configuration. In the case of a vortex magnetization, this resonance mode is the "gyrotropic mode of the vortex core", at most simply "vortex mode" which makes it possible to associate the oscillation frequency of a magnetic structure with its geometry .

The subject of the invention relates to a spectrum analyzer of an RF signal comprising several frequencies f, characterized in that it comprises N entities each consisting of a structure formed of a stack of magnetic and non-magnetic layers, having in at least one of the magnetic layers a vortex-shaped magnetic configuration, the excitation modes of said magnetic configuration being adapted to detect in real time the frequencies contained in an incident signal, each entity having a first lower electrode and a second upper electrode, a device adapted to measure a voltage representative of the presence of a frequency f _k in the analyzed signal _RF, the voltage measuring device being connected to the lower electrode and to the upper electrode, a device measurement processing adapted to determine the value of the frequencies fk present in the signal I RF, a line bringing the sig to analyze at each of the entities.

According to an alternative embodiment, the spectrum analyzer is characterized in that the said entities are arranged in parallel, a transmission line bringing the signal to be analyzed to a _RF divider adapted to divide the RF power of the signal to be analyzed and distributing the signal over N transmission sub-lines, each sub-line being connected to a connection circuit connecting the upper electrode to the voltage measuring device adapted to measure the value V _n of the voltage between the lower electrode and the upper electrode, the lower electrode being connected to a mass point common to all the entities and to the voltage measuring device.

According to another variant embodiment, said entities are arranged in series, the first entity is connected to the voltage measuring device and to the injection circuit via a connection circuit, the electrode upper is connected to the connecting circuit by means of connecting wire, the lower electrode is connected to the voltage measuring device by means of connection wires, a transmission line brings the _RF signal to the first connection circuit, a point node on the connection line enables the polarization and measurement circuit to be connected to the lower electrode and to a connection circuit of a next entity, the entity being connected to the voltage measuring device by means of a connection circuit at its upper electrode and a line having a nodal point at its lower electrode, the nodal point being connected with the connecting circuit of the next entity, this up to the last entity.

According to another variant embodiment, the analyzer is characterized in that the entities are arranged in parallel, the upper electrode being connected to the voltage measuring device adapted to measure the value of the voltage V _n between the lower electrode and the upper electrode, the lower electrode being connected to a mass point common to all the entities, a radiating magnetic line for inductively coupling the _RF signal to the detector at each of the entities.

According to an alternative embodiment, the voltage measuring device also consists of N lines making it possible to inject a direct current l _n between the nodal points respectively connected to the lower electrode and to the upper electrode of the entity and allowing to vary the frequency that the entities are able to detect by measuring the value of the voltage V _n between the lower electrode and the upper electrode, the node is connected via a first connection wire to a first inductor , connected in turn connected to a second lead wire via the lead wire, a second node is connected via a second lead wire to a second inductor in turn connected to the lead wire via another lead wire.

The voltage measuring device may also consist of a current source connected by a main connection to a device division adapted to divide the current and distribute it over N sub-lines connections, each sub-line is connected to a node.

The entities are, for example, pillar-shaped devices having a structure selected from the following list:

A stack consisting of: a lower electrode, a synthetic multilayer of SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, an active layer containing a magnetic vortex and a top electrode,

A stack consisting of a lower electrode, a magnetic multilayer of the SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, an active layer containing a magnetic vortex, a second non-magnetic intermediate layer, a perpendicular magnetic polarizer and a top electrode,

A stack consisting of: a lower electrode, a first active layer containing a magnetic vortex, a magnetic intermediate layer, a second active layer containing a vortex and an upper electrode, and

A stack comprising: a lower electrode, a synthetic multilayer of the SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, a first active layer containing a magnetic vortex, and a second non-magnetic intermediate layer; , a second active layer containing a magnetic vortex and a top electrode.

The analyzer may comprise a voltmeter for measuring the voltage V _n at the terminals of each entity and the processing device is, for example, made up of N comparators of the values V _n at a threshold value.

An entity can have an ellipsoidal, square or rectangular shape.

The spectrum analyzer may comprise several entities or circular junctions having different and variable diameters between 50 nm to 1 μηι to adjust the frequency over a range of frequencies typically between 30 MHz and 2GHz.

According to an alternative embodiment, the entities have a structure or an operating mode adapted to produce a magnetic configuration corresponding to a magnetic vortex without a core also called C-state.

Other characteristics and advantages of the method and of the device according to the invention will appear better on reading the following description of an exemplary embodiment given by way of illustration and in no way limiting attached to the figures which represent:

FIGS. 1A and 1B, a junction illustration used to implement the invention,

FIG. 2, a first device diagram according to the invention for which the elements are arranged in parallel with direct electrical coupling by a transmission line,

FIG. 3, a second example of a device for which the elements are arranged in series with direct electrical coupling by transmission line,

FIG. 4, a third example for which the elements are excited by magnetic coupling by means of an inductive line, and

FIG. 5, an exemplary embodiment for the device for polarization and measurement.

Before giving some examples of embodiment of spectrum analysis device according to the invention, a reminder on the elements used to detect the frequencies present in a frequency spectrum will be given.

FIGS. 1A and 1B show an example of a basic brick for the implementation of the invention: a spintronic device having a vortex configuration, ie, "vortex junction". This junction is constructed from a cylindrical stack of at least two ferromagnetic thin layers 1, 2 separated by an intermediate layer 3 (can be metallic or insulating). For simplicity, consider a circular cylinder. Without departing from the scope of the invention, it is possible to use other shapes, for example an elliptical cylinder. For at least one of the two magnetic layers, called the "active layer" corresponding to the upper layer 1 of FIG. 1, the ground state or remanent magnetic configuration is characterized by a non-uniform magnetization, for example a "vortex configuration" or a "C-state" configuration, known to those skilled in the art. A detailed description of the magnetic vortex and also the terminology used for this field are described in the patent application WO201307797. The thickness of the active layer is denoted h and its diameter Φ. In a first configuration the second magnetic layer, lower layer 2, is called "trapped" and is characterized by a uniform magnetization.

The materials envisaged for producing the magnetic layers 1 and 2 may be, for example, Fe iron, cobalt Co, nickel Ni, alloys comprising at least one of these elements (CoFeB for example) and also Heusler alloys. . The thickness of each layer can vary between 0.5 and 40 nm.

Regarding now the intermediate layer, it is possible to envisage, for example, insulating materials such as MgO with a thickness of about 1 nm or metal layers such as Au gold or Cu copper, or Ruthenium Ru whose thicknesses may vary. from 1 to 10 nm.

Each layer may consist of a stack of sub-layers in order to improve the magnetic characteristics of the object under consideration. For example, the trapped layer may be a so-called synthetic antiferromagnetic layer (known by the acronym "SAF"), ie, formed by a stack of an antiferromagnetic layer of IrMn or PtMn of 10 nm, for example, a layer of ferromagnetic materials in direct contact with the antiferromagnetic layer, 2.5 nm of CoFeB for example, and a last magnetic layer, for example 3 nm of CoFeB, separated by a layer of non-magnetic materials, 0.85 nm of Ru, for example.

It is furthermore possible to improve the magnetoresistive properties of the tunnel barrier defined by the intermediate layer by inserting magnetic sub-layers such as CoFe of about 1 nm between the intermediate layer and the active layer.

This junction also comprises on each of its faces, so-called electrical contact layers (upper and lower electrodes), not shown in FIG. 1, making it possible to electrically connect the junction to a source of current at the voltage in order to circulate a current. electrons through the junction and / or to a device for measuring the voltage such as a voltmeter or an ammeter.

The analyzer structure may include a plurality of pillar-shaped entities (20 _n ) having a structure selected from the following list:

A stack consisting of: a lower electrode, a synthetic multilayer of the SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, an active layer containing a magnetic vortex and a top electrode,

A stack consisting of a lower electrode, a magnetic multilayer of SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, an active layer containing a magnetic vortex, a second non-magnetic intermediate layer, a perpendicular magnetic polarizer and a top electrode;

A stack consisting of: a lower electrode, a synthetic multilayer of the SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, a first layer; magnetic vortex containing active material, a second nonmagnetic intermediate layer, a second active layer containing a magnetic vortex and a top electrode.

An example, in no way limiting, of materials that can be used to produce the electrodes may be as follows: the upper electrode is formed by 7 nm of Ta, 6 nm of Ru, 5 nm of Cr and 200 nm of Au, the electrode lower is formed of 3 nm Ta and 2 nm Ru. The electrodes are obtained by several steps of micro / nanomanufacture according to a technique known to those skilled in the art and described for example in the patent application US20080150643.

An important geometric parameter for defining the radiofrequency properties of the junction is its diameter; it may vary, for example, between a few tens of nanometers and a few microns, while the total thickness may be of the order of a few tens of nanometers. In general, all the layers of the junction (except the electrodes) have the same diameter Φ as that of the active layer. However, there may be variants in which the diameter of the junction is not constant over its entire height.

Typically the junction is deposited on a substrate, for example of SiO ₂ type.

If no external force acts on the active layer, the vortex is stable in its equilibrium position (usually at the center of the disk, Fig. 1 A). If a spin-polarized electric current is injected through the junction, thanks to the spin-transfer phenomenon, the magnetic vortex core can be gyrated around its equilibrium position (Figure 1B). The frequency of gyration is determined by the geometrical parameters and the materials used. For example, if one considers a circular layer of NiFe with a diameter of 500 nm and a thickness of 5 nm, the frequency of gyration will be of the order of 140 MHz. By magneto-resistive effect, this vortex magnetization dynamics is converted into an oscillation of the electrical voltage across the junction with a frequency characteristic, called "natural frequency of the junction", which depends on the thickness / diameter ratio (h / Φ) of the active layer. This dependence of the oscillation frequency on the ratio (h / Φ) is typical of the vortex mode.

When an RF I RF signal is injected whose frequency is close to the natural frequency of the system (i.e. in the order of the linewidth of the resonance signal), there is a modification of the voltage V _dc across the junction. More directly, the electrical resistance of the junction typically changes when the frequency of the injected RF signal is close to the natural frequency of the junction. This variation of voltage (or resistance) is the discriminator for detecting the signal and the frequencies of the RF signal.

Different junction structures may be envisaged within the scope of the invention.

A first structure, called "1 Vortex Standard" consists of the following stack: a lower electrode; SAF; an intermediate layer of MgO; an active layer; an upper electrode.

A second structure, called "1 Vortex Hybrid" includes, for example, a lower electrode, SAF, an intermediate layer of MgO, an active layer; a few nm of Cu; a perpendicular polarizer formed by a succession of sub-layers: for example [Co0.2 / Ni0.5] * 1 0; an upper electrode.

A third structure, called "2 Vortex hybrid" is composed of a lower electrode, SAF; an intermediate layer of MgO; a first active layer; a few nm of Cu; a second active layer; of an upper electrode.

A fourth structure, referred to as "2 standard Vortex" is composed of a lower electrode, a first active layer; intermediate layer of MgO; a second active layer; of an upper electrode. By way of illustrative and in no way limiting example, a network of circular junctions whose diameter varies from 50 nm to 1 m makes it possible to adjust the frequency over a range of approximately 2 GHz to 30 MHz.

The resonance frequency IR of the junction is also dependent on two other parameters, namely the intensity of the direct current flowing through the piller and the perpendicular component of the magnetic field possibly applied to the latter. It is therefore possible to make a very precise adjustment of the frequency by playing on these two parameters. For example, if one of these external parameters is scanned, the frequency resolution of the detector can be improved; in addition, with this scan it is possible to extract additional information: the amplitude of the RF signal. However, this information is obtained at the cost of the loss of the "real time" character of the detection.

FIG. 2 illustrates a first example of a device according to the invention. The device comprises N junctions or entities 20 _n connected in parallel on which a signal to be analyzed by _RF direct electrical coupling is injected. Each junction 20 _n is characterized by a specific structure, for example, that described in Figure 1 or one of the four structures described above, with a diameter Φ _η and a thickness h _n of the active layer. To this junction structure is associated a resonance frequency fr _n . All the junctions are deposited on a substrate 4.

The lower electrode 21 _n of a junction 20 _n is connected via a transmission line 42 _n to a mass point 41 common to all the junctions and, via a connection wire 24 _η, to a measuring device 6a adapted to measure a voltage value. The current that will be distributed at each junction may be continuous or alternating type. The upper electrode 22 _n of the junction 20 _n is connected via a connection wire 23 _n to a connection circuit 3 _n which separates the alternating side (AC injection circuit 5 connected via a connection wire 25 _n. ) and the continuous side (measurement device 6a connected via a connection wire 26 _n ).

The connection circuit 3 _n comprises, for example: A connection wire 33 _n which connects a junction point 30 _n to the node to the upper electrode 22 _n of the junction 20 _n via a connection wire 23 _n ,

A connection wire 36 _n which connects the node 30 _n to the device 6a for measuring voltage via the connection wire 26 _n ,

A connection wire 31 _n connecting the node 30 _n to a first side 34 _n of a capacitance 34 _n ,

A connection wire 35 _n connecting the second side 34 _n2 of the capacitance 34 _n to the AC injection circuit 5 via the connection wire 25 _n .

In the AC injection circuit 5, a main transmission line 53 causes the RF signal I to be analyzed 52 to a dividing device 54 or "splitter", which may be an active or passive element. The splitter 54 divides the RF power of the signal to be analyzed, and distributes the I RF signal over N sub-transmission lines, 55 _n . Each sub-line 55 _n is connected to the connection circuit 3 _n via the connection wire 25 _n. In this way, the _RF signal to be analyzed 52 is injected on each junction 20 _n, via each of the sub-lines.

The voltage measurement device 6a makes it possible to measure the voltage V _n measured between the lower electrode and the upper electrode of each junction (sub-circuit 6 _a ). It can also be used to inject DC direct current (sub-circuit _6b ). This voltage measuring device is connected to the lower electrode 21 _n via the connection wire 24 _n and to the connection circuit 3 _n via the connection wire 26 _n . Two inductances (67 _n i and 67 _n 2) prevent the passage of alternating current in the voltage measuring device 6a.

The sub-circuit _6a consists of N measuring devices 68 _n each adapted to measure the voltage V _n across each junction, e.g., a voltmeter. The voltage V _n is measured between two nodal points 60 _n i and 60 _n ₂ respectively connected to the lower electrode and to the upper electrode of the junction. According to a first example, the sub-circuit 6b consists of a parallel arrangement of several polarization lines 69 _n each delivering a particular current intensity I _n between the two nodes 60 _n i and 60 _n 2 connected respectively to the lower electrode (21 _n ) and the upper electrode (22 _n ) of the entity 20 _n , and making it possible to vary the frequency that the entities (20 _n ) are capable of detecting through the measurement of the value of the voltage V _n between the lower electrode (21 _n ) and the upper electrode (22 _n) The first node 60 _n i is connected via a first connection wire 61 _n i to a first inductor 67 _n i that is connected at the connection wire 24 _n via the connection wire 64 _n , the second node 60 _n 2 is connected via a second connection wire 61 _P 2 to a second inductor 67 _{n2 which} is connected to the connection wire 26 _n via the wire connection 66 _n .

It is also possible to have a single common polarization line and to adjust the current I _n individually by adding an active or passive element in series between the main polarization line and the junction _n . In this second sub-circuit version 6b (see Fig. 5) a main lead wire 63 brings the current _C to a splitter 69 or splitter, which may be an active or passive element. The splitter 69 divides the current l _dc 62 and distributes it over N 65 _n connection wires. Each sub-line 65 _n is connected to the node 61 _n via an element Z _n . Element Z _n can be active in the passive (diodes, resistance, etc.). 60 nodes _n i and 60n2 are connected to the inductors 67 and 67 _n _n2 in the same manner of the previous example.

The voltage measuring sub-circuit 6 _a is itself connected to a device 7 for processing the values. The device 7 may be a comparator of the voltage values measured for each junction with respect to one or more reference values, threshold values, in order to determine whether a frequency fk corresponding to the resonant frequency of the junction 20 _n is present in the signal being analyzed. The presence of a frequency f _k of the analyzed signal _RF can be memorized in writing and stored in a memory and / or displayed on a screen 8. Another way to proceed for the device 7 is to use a set of digital analog converters.

All working independently and having very small dimensions, in the range of hundreds of nanometers, a massive paralleling of these unit detection entities or junctions allows in a very small volume to achieve an instantaneous analog spectrum analyzer function. an _RF signal. The resonance frequency band of each junction [f ₀ -Af, f ₀ + Δί] is adjusted by adjusting the thickness / diameter ratio (h / Φ) of the active layer. The diameter Φ _η is, for example, adjusted so that the resonant frequencies juxtapose and thus create a frequency detection network without holes for analyzing a signal. In this way, it is possible to detect the frequencies present in an RF signal.

The frequency analyzer device according to the invention will act in the following manner, when an _RF signal to be analyzed containing, for example, three frequencies, f-ι,,, is coupled to the device, only the junctions having the appropriate structure. to resonate on these three frequencies will resound around f-ι,, so as to simultaneously give the information that the spectrum is occupied around these three frequencies.

In this first example (junctions connected in parallel by direct electrical coupling) the number of sub-lines 55 _n is equal to the numbers of the junctions. This approach makes it easier to control the impedance adaptation of the network but at the expense of the sensitivity since the incident power is divided into several sub-lines. It is for example used in the case where one seeks to detect frequencies with few channels and also high power.

Another way of proceeding is to consider junctions connected in series. Figure 3 shows an alternative embodiment where the entities or junctions are connected in series. This arrangement allows a relative good control of sensitivity to the detriment of the ability to adapt impedance.

In this embodiment, each junction 20 _n of the network is connected to the connection circuit 3 _n identically to that described in FIG. 2, that is to say, the upper electrode 22 _n is connected to the connection circuit 3 _n via the connection wire 23 _n . Similarly, the voltage measurement circuit 6a is connected to the connection circuit 3 _n via wire connection 26 _n. By cons, the lower electrode 21 _n is connected in a different manner, as will be described below. The purpose of this embodiment is to connect the junctions in series. The AC injection circuit 5 is thus simplified. A main transmission line 53 brings the _RF signal 52 directly to the connection circuit of the first junction 3i via the connection wire 25-i. Each junction, in this example, is electrically separated from the other junctions. For a series connection each junction 20 _n is connected to the next junction 20 _{n +} i. For each junction there is a node 27 _n which makes it possible to connect the voltage measurement circuit 6a (via the connection wire 24 _n ), the lower electrode of the pillar 21 _n (via the connection wire 28 _n ), and the connection circuit 3 _{n +} i of the successive junction 20 _{n +} i (via the connection wire 25 _{n +} 1). In this way, the signal to be analyzed or the _RF alternating current is injected in series in abutment, while a direct current I _n is applied to each pillar and the voltage V _n is measured separately.

FIG. 4 schematizes another possible variant embodiment for the device according to the invention. In this case, the _RF signal to be analyzed 52 is conveyed by a radiating magnetic coupling line 53. This alternating current I RF generates an alternating field which, by inductive coupling, will act on each junction. The amplitude of the alternating signal felt by the junction 20 _n depends on the distance between the line 53 and the junction itself. Typical values are of the order of a few hundred nanometers. The line may be below or adjacent to the junction depending on the type of junction considered. As in the first embodiment (see Figure 2), the electrode The bottom 21 _n of a junction 20 _n is connected via a transmission line 42 _n to a ground point 41 common to all the junctions and via a connecting wire 24 _n to the voltage measuring device 6a. In contrast, the upper electrode 22 _n is connected directly to the voltage measuring device 6a via the connection wire 23 _n. The voltage measuring device 6a, and consequently the value processing device 7 and the screen 8 with all their variants, are identical to those described in the first variant embodiment (see FIGS. 2 and 5).

Parallel reading of a network of magnetic junctions makes it possible to obtain instantaneous information of a range of frequencies present in an incident radiofrequency signal. By using nano-objects in the form of a nano-sized cylindrical magnetic stack in which the resonance frequencies can be induced to effect detection, the dimensions of the device are extremely small.

Claims

claims

1 - Spectrum analyzer of an _RF signal comprising several frequencies f, characterized in that it comprises N entities (20 _n ) each consisting of a structure formed of a stack of magnetic and non-magnetic layers having in at least one of the magnetic layers a vortex-shaped magnetic configuration, the excitation modes of the magnetic configuration being adapted to detect in real time the frequencies contained in an incident signal, each entity having a first lower electrode (21 _n ) and a second upper electrode (22 _n ), a voltage measuring device (6a) adapted to measure an electrical voltage representative of the presence of a frequency f _k in the analyzed signal I RF _, the device (6a) being connected to the electrode lower (21 _n ) and the upper electrode (22 _n ), a device (7) for processing measurements adapted to determine the value of the frequencies f _k present in the signal _RF , a line (53) bringing the signal to be analyzed to each of the entities.

2 - spectrum analyzer according to claim 1 characterized in that said entities (20 _n ) are arranged in parallel, a transmission line (53) causing the signal to analyze the _RF up to a divider (54) adapted to divide the RF power of the signal to be analyzed and to distribute the signal on N sub-transmission lines (55 _n ), each sub-line being connected to a connection circuit (3 _n ) connecting the upper electrode (22 _n ) to the device ( 6) adapted to measure the value V _n of the voltage between the lower electrode (21 _n ) and the upper electrode (22 _n ), the lower electrode (21 _n ) being connected to a mass point (41) common to all entities (20 _n ) and to the voltage measuring device (6a).

3 - spectrum analyzer according to claim 2 characterized in that the connection circuit (3 _n ) connected to an entity (20 _n ) comprises: a lead wire (33 _n ) which connects a junction point (30 _n ) to the upper electrode (22 _n ) of said entity via a lead wire 23 _n , a lead wire (36 _n ) which connects the point connecting (30 _n ) to the voltage measuring device (6a) via the connecting wire (26 _n ), a connecting wire (31 _n ) connecting the junction point (30 _n ) to the first wall (34 _n ) a capacity (34 _n ),

a connection wire (35 _n ) connecting the second wall (34 _N 2) of the capacitance (34 _n ) to a connection wire (25 _n ) supplying the signal to be analyzed. 4 - spectrum analyzer according to claim 1 characterized in that said entities (20 _n ) are arranged in series, the first entity (20i) is connected to the device (6a) and the injection circuit (5) via a circuit of connection (3i), the upper electrode is connected to the connecting circuit (3i) by means of connecting wire (23i), the lower electrode (21) is connected to the device (6a) by means of connection wires (24). -i _, 28-i), a transmission line (53) supplies the RF signal to the first connection circuit (3-i), a node (27-i) located on the connection line (24 _; i) allows the connection of the device (6a) to the lower electrode and to a connection circuit (3 _n ) of a next entity (20 _n ), the entity (20 _n ) being connected to the polarization device and measurement by means of a connecting circuit (3 _n ) at its upper electrode and by a line having a nodal point (27 _n ) at its lower electrode ee, the nodal point (27 _n ) being in connection with the circuit (3 _{n +} i) connecting the next entity (20 _{n +} i), this up to the last entity (20N).

5 - spectrum analyzer according to claim 4 characterized in that a connection circuit (3 _n ) comprises:

A connection wire (33 _n ) which connects a junction point (30 _n ) to the upper electrode (22 _n ) of said entity via a connection wire 23 _n , a connecting wire (36 _n ) which connects the junction point (30 _n ) to the voltage measuring device (6a) via the connection wire (26 _n ), A connection wire (31 _n ) connecting the junction point (30 _n ) to the first wall (34 _n ) of a capacitance (34 _n ),

A connection wire (35 _n ) connecting the second wall (34 _n2 ) of the capacitance (34 _n ) to a connection wire (25 _n ),

6 - Analyzer according to claim 1 characterized in that the entities are arranged in parallel, the upper electrode (22 _n ) being connected to the voltage measuring device (6a) adapted to measure the value of the voltage V _n between the lower electrode (21 _n ) and the upper electrode (22 _n ), the lower electrode (21 _n ) being connected to a mass point (41) common to all the entities (20 _n ), a radiating magnetic line (53). ) for inductively coupling the _RF signal to the detector at each of the entities. 7 - Analyzer according to one of claims 1 to 6 characterized in that the device (6a) is also constituted by N polarization lines 69 _n adapted to inject a direct current l _n between two nodal points (60 _n i, 60 _n 2) respectively connected to the lower electrode (21 _n ) and to the upper electrode (22 _n ) of the entity (20 _n ) and adapted to vary the frequency that the entities (20 _n ) are capable of detecting at the by measuring the value of the voltage V _n between the lower electrode (21 _n ) and the upper electrode (22 _n ), the first node (60 _n i) is connected via the first connection wire (61 _n). i) at a first inductance (67 _n i) connected to the connection wire (24 _n ) via the connecting wire (64 _n ), the second node (60 _n 2) is connected via the second connecting wire (61 _P 2) to a second inductor (67 _n2 ) in turn connected to the connection wire (26 _n ) via the connecting wire (66 _n ).

8 - Analyzer according to one of claims 1 to 6 characterized in that the device (6a) consists of a current source (62) connected by a main connection (63) to a dividing device (69) adapted to divide the current (I _d c) and distribute it over N sub-lines connections (65 _n ), each sub-line (65 _n ) is connected to a node (60 _n 2) -

9 - spectrum analyzer according to one of claims 1 to 6 characterized in that the entities (20 _n ) are pillar-shaped devices having a structure selected from the following list:

A stack consisting of: a lower electrode, a magnetic multilayer of the SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, an active layer containing a magnetic vortex, a second non-magnetic intermediate layer, a perpendicular magnetic polarizer and a top electrode,

A stack comprising: a lower electrode, a synthetic multilayer of the SyntheticAntiFerromagnet (SAF) type, a non-magnetic intermediate layer, a first active layer containing a magnetic vortex, and a second non-magnetic intermediate layer; , a second active layer containing a magnetic vortex and a top electrode

10 - spectrum analyzer according to one of claims 1 to 9 characterized in that the measuring device (68 _n ) is a voltmeter for measuring the voltage V _n at the terminals of each entity (20 _n ) and the processing device ( 7) consists of N comparators (71 _n ) of the values V _n at a threshold value. 1 - Spectrum analyzer according to one of claims 1 to 10 characterized in that an entity has an ellipsoidal shape, square or rectangular.

12 - Spectrum analyzer according to one of claims 1 to 1 1 characterized in that it comprises several entities or circular junctions having different diameters and variables between 50nm to 1 m in order to adjust the frequency over a range of frequencies included between 30 MHz and 2 GHz ..

13 - Spectrum analyzer according to one of the preceding claims, characterized in that the entities have a structure adapted to produce a magnetic configuration corresponding to a magnetic vortex without heart type C-state.