FR3119956A1

FR3119956A1 - Transimpedance amplifier

Info

Publication number: FR3119956A1
Application number: FR2101610A
Authority: FR
Inventors: Frédéric Broyde; Evelyne Clavelier
Original assignee: Tekcem SAS
Current assignee: Excem Fr
Priority date: 2021-02-18
Filing date: 2021-02-18
Publication date: 2022-08-19
Also published as: WO2022175755A1

Abstract

L’invention concerne un amplificateur à transimpédance, par exemple un amplificateur à transimpédance d’une antenne active comportant un cadre ou un cadre blindé. Un amplificateur à transimpédance selon l’invention comporte : un accès d’entrée (1) ayant une première borne (11) et une seconde borne (12) ; un premier dispositif d’amplification (21) comportant au moins un transistor ; un deuxième dispositif d’amplification (22) comportant au moins un transistor ; un troisième dispositif d’amplification (23) comportant au moins un transistor ; un quatrième dispositif d’amplification (24) comportant au moins un transistor ; un premier condensateur (31) ; un deuxième condensateur (32) ; un premier amplificateur différentiel (41) pour créer une première commande en boucle fermée ; un second amplificateur différentiel (42) pour créer une deuxième commande en boucle fermée ; un amplificateur de puissance (6) ; un accès de sortie (7) ayant une première borne (71) et une seconde borne (72) ; et une résistance (5) pour créer une rétroaction. Figure pour l’abrégé : Figure 1.The invention relates to a transimpedance amplifier, for example a transimpedance amplifier of an active antenna comprising a frame or a shielded frame. A transimpedance amplifier according to the invention comprises: an input port (1) having a first terminal (11) and a second terminal (12); a first amplifying device (21) comprising at least one transistor; a second amplifying device (22) comprising at least one transistor; a third amplifying device (23) comprising at least one transistor; a fourth amplifying device (24) including at least one transistor; a first capacitor (31); a second capacitor (32); a first differential amplifier (41) for creating a first closed-loop control; a second differential amplifier (42) for creating a second closed loop drive; a power amplifier (6); an output port (7) having a first terminal (71) and a second terminal (72); and a resistor (5) to create feedback. Figure for abstract: Figure 1.

Description

Transimpedance amplifier

DOMAINE TECHNIQUE DE L’INVENTIONTECHNICAL FIELD OF THE INVENTION

L’invention concerne un amplificateur à transimpédance, par exemple un amplificateur à transimpédance d’une antenne active comportant un cadre ou un cadre blindé.The invention relates to a transimpedance amplifier, for example a transimpedance amplifier of an active antenna comprising a frame or a shielded frame.

ÉTAT DE LA TECHNIQUE ANTÉRIEUREPRIOR ART

Dans la suite, “couplé” fait toujours référence à un couplage électrique. Lorsque ce terme est appliqué à deux entités telles que des bornes, des conducteurs, des noeuds, etc, “couplé” peut indiquer que les entités sont directement couplées, c’est-à-dire connectées (ou, de façon équivalente, en contact électrique) l’une avec l’autre, et/ou que les entités sont indirectement couplées, une interaction électrique différente du couplage direct existant dans ce cas entre les entités, par exemple à travers un ou plusieurs composants. Lorsque ce terme est appliqué à deux entités à plusieurs bornes, telles que des accès, des connecteurs, etc, “couplé” peut indiquer que les entités sont directement couplées, chaque borne d’une des entités étant dans ce cas directement couplée à une et une seule des bornes de l’autre entité, et/ou que les entités sont indirectement couplées, une interaction électrique différente du couplage direct existant dans ce cas entre les bornes des entités, par exemple à travers un ou plusieurs composants. Dans la suite, en accord avec la théorie des circuits, un accès a exactement deux bornes.In the following, “coupled” always refers to an electrical coupling. When this term is applied to two entities such as terminals, conductors, nodes, etc., “coupled” can indicate that the entities are directly coupled, i.e. connected (or, equivalently, in contact electrical) with each other, and/or that the entities are indirectly coupled, an electrical interaction different from the direct coupling existing in this case between the entities, for example through one or more components. When this term is applied to two entities with several terminals, such as accesses, connectors, etc, “coupled” can indicate that the entities are directly coupled, each terminal of one of the entities being in this case directly coupled to one and only one of the terminals of the other entity, and/or that the entities are indirectly coupled, an electrical interaction different from the direct coupling existing in this case between the terminals of the entities, for example through one or more components. In the sequel, in accordance with circuit theory, an access has exactly two terminals.

Les antennes de type “cadre” (appelées “loop antennas” en anglais) et de type “cadre blindé” (appelées “shielded loop antennas” en anglais) sont bien connues des spécialistes. Elles sont utilisées pour la réception radio appliquée aux mesures de champs électromagnétiques, à la radiogoniométrie et aux communications radio. Des caractéristiques et limitations de ces antennes pour ces utilisations sont expliquées dans l’article de F. Broydé et E. Clavelier intitulé “Contribution to the Theory of Planar Wire Loop Antennas Used for Reception”, publié dans la revueIEEE Transactions on Antennas and Propagation, vol. 68, no. 3, en Mars 2020. En particulier, cet article explique dans quelle mesure il est possible de considérer que ces antennes mesurent une composante d’un champ magnétique incident, c’est-à-dire une composante magnétique d’un champ électromagnétique incident. Comme indiqué dans cet article et dans le paragraphe 5-4 du chapitre 5 du livre de R.C. Johnson intitulé “Antenna Engineering Handbook, 3rd Edition”, publié par McGraw-Hill en 1993, le blindage d’un cadre blindé fonctionne typiquement comme un cadre. Les cadres blindés utilisés pour la réception radio donnent de meilleurs résultats que les cadres non blindés, car ils ne sont pas affectés par un courant de mode commun circulant sur le câble reliant l’antenne à un appareil de mesure ou un récepteur radio, induit par un champ électromagnétique incident reçu en tant que signal, ou par des perturbations électromagnétiques.Antennas of the “frame” type (called “loop antennas” in English) and of the “shielded frame” type (called “shielded loop antennas” in English) are well known to specialists. They are used for radio reception applied to electromagnetic field measurements, direction finding and radio communications. Characteristics and limitations of these antennas for these uses are explained in the article by F. Broydé and E. Clavelier entitled “Contribution to the Theory of Planar Wire Loop Antennas Used for Reception”, published in the journal IEEE Transactions on Antennas and Propagation , flight. 68, no. 3, in March 2020. In particular, this article explains to what extent it is possible to consider that these antennas measure a component of an incident magnetic field, that is to say a magnetic component of an incident electromagnetic field. As noted in this article and in paragraph 5-4 of Chapter 5 of RC Johnson's Antenna Engineering Handbook, 3rd Edition, published by McGraw-Hill in 1993, the shielding of an armored frame typically functions as a frame. . Shielded frames used for radio reception give better results than unshielded frames because they are not affected by a common mode current flowing on the cable connecting the antenna to a measuring device or a radio receiver, induced by an incident electromagnetic field received as a signal, or by electromagnetic disturbances.

On appelle facteur d’antenne (en anglais: antenna factor) un module d’un rapport d’une intensité d’un champ incident (exprimée en V/m pour un champ électrique ou en A/m pour un champ magnétique) sur une tension développée par une antenne aux bornes d’une impédance spécifiée. Pour les mesures de champs électromagnétiques, on préfère souvent, quand c’est possible, utiliser une antenne présentant un facteur d’antenne sensiblement indépendant de la fréquence, sur une large bande de fréquence. Le spécialiste sait que ce résultat peut être obtenu, dans une bande de fréquence connue, la bande de fréquence connue ayant une borne supérieure, la borne supérieure correspondant à une longueur d’onde dans le vide, en utilisant, pour la réception radio, une antenne active de l’état de l’art antérieur comportant :One calls antenna factor (in English: antenna factor) a module of a ratio of an intensity of an incident field (expressed in V/m for an electric field or in A/m for a magnetic field) on a voltage developed by an antenna across a specified impedance. For electromagnetic field measurements, it is often preferred, when possible, to use an antenna with an antenna factor that is substantially independent of frequency, over a wide frequency band. The specialist knows that this result can be obtained, in a known frequency band, the known frequency band having an upper limit, the upper limit corresponding to a wavelength in vacuum, by using, for radio reception, a active antenna of the state of the prior art comprising:

a passive antenna, the passive antenna being a single-spiral frame or a shielded single-spiral frame, the passive antenna being small compared to said wavelength in vacuum, the passive antenna having a port, an impedance presented by this port being called “passive antenna impedance”;
an amplifier, the port of the passive antenna being coupled to an input of the amplifier, the input of the amplifier having an impedance called "input impedance of the amplifier", a module of the impedance d the input of the amplifier being, at any frequency in the known frequency band, much smaller than a module of the impedance of the passive antenna, an output voltage of the amplifier being, at a given frequency in the known frequency band, equal to the product of an input current of the amplifier and a transimpedance, a module of the transimpedance being substantially independent of the given frequency.

Le spécialiste sait qu’un amplificateur convenable pourrait en principe être un amplificateur à transimpédance (en anglais: transimpedance amplifier) ou un amplificateur à transrésistance (en anglais: transresistance amplifier) similaires à ceux discutés dans le paragraphe 8.11 du livre de P. Horowitz et W. Hill intitulé “The Art of Electronics, Third Edition”, publié par Cambridge University Press en 2015, ou à ceux qui sont utilisés dans la demande internationale numéro PCT/DE2006/000415 (WO 2006/097071) intitulée “Active reception antenna system”.The specialist knows that a suitable amplifier could in principle be a transimpedance amplifier or a transresistance amplifier similar to those discussed in paragraph 8.11 of the book by P. Horowitz and W. Hill entitled “The Art of Electronics, Third Edition”, published by Cambridge University Press in 2015, or those used in international application number PCT/DE2006/000415 (WO 2006/097071) entitled “Active reception antenna system ”.

Un tel amplificateur à transimpédance classique, prévu pour procurer une transimpédance connue dans une bande de fréquence connue, comporte :Such a conventional transimpedance amplifier, provided to provide a known transimpedance in a known frequency band, comprises:

an input port having a first terminal and a second terminal, the second terminal of the input port being directly coupled to a reference conductor;
an operational amplifier, the first terminal of the input port being directly coupled to an inverting input terminal of the operational amplifier, a non-inverting input terminal of the operational amplifier being coupled to the reference conductor; And
one or more means for creating feedback, the feedback determining the known transimpedance in the known frequency band, the feedback reducing a modulus of an impedance presented by the input port in the known frequency band.

Typiquement, les dits un ou plusieurs moyens pour créer une rétroaction comportent une résistance ayant deux bornes, une borne de cette résistance étant directement couplée à une borne de sortie de l’amplificateur opérationnel, l’autre borne de cette résistance étant directement couplée à la borne d’entrée inverseuse de l’amplificateur opérationnel. Souvent, les dits un ou plusieurs moyens pour créer une rétroaction comportent aussi un condensateur de faible valeur connecté en parallèle avec la résistance.Typically, said one or more means for creating feedback comprises a resistor having two terminals, one terminal of this resistor being directly coupled to an output terminal of the operational amplifier, the other terminal of this resistor being directly coupled to the inverting input terminal of the operational amplifier. Often said one or more means for creating feedback also includes a low value capacitor connected in parallel with the resistor.

Un tel amplificateur à transimpédance classique pose malheureusement deux problèmes quand il est utilisé dans l’antenne active considérée ci-dessus, pour une bande de fréquence connue qui est la bande 9 kHz à 30 MHz : premièrement, l’accès d’entrée d’un tel amplificateur à transimpédance ne peut pas être directement couplé à l’antenne passive, car la rétroaction devient, aux basses fréquences et à la fréquence nulle, trop faible pour procurer une polarisation convenable de l’amplificateur opérationnel (en notant qu’un couplage indirect à l’antenne passive, à travers un condensateur, n’est pas une bonne option dans cette bande de fréquence connue) ; et, deuxièmement, un tel amplificateur à transimpédance est beaucoup plus bruyant que nécessaire, parce qu’il n’est pas optimisé pour l’impédance de l’antenne passive.Such a conventional transimpedance amplifier unfortunately poses two problems when it is used in the active antenna considered above, for a known frequency band which is the 9 kHz to 30 MHz band: firstly, the input port of such a transimpedance amplifier cannot be directly coupled to the passive antenna, because the feedback becomes, at low frequencies and at zero frequency, too weak to provide a suitable biasing of the operational amplifier (noting that a coupling passive antenna, through a capacitor, is not a good option in this known frequency band); and, secondly, such a transimpedance amplifier is much noisier than necessary, because it is not optimized for the impedance of the passive antenna.

Ainsi, pour une antenne passive qui est un cadre monospire ou un cadre blindé monospire, petit devant la longueur d’onde dans le vide correspondant à la borne supérieure de la bande de fréquence connue, l’état de l’art antérieur ne divulgue pas un amplificateur tel que : un module de l’impédance d’entrée de l’amplificateur soit, à toute fréquence dans la bande de fréquence connue, beaucoup plus petit qu’un module de l’impédance de l’antenne passive ; un module de la transimpédance de l’amplificateur soit sensiblement indépendant de la fréquence, dans la bande de fréquence connue ; l’accès d’entrée de l’amplificateur puisse être directement couplé à l’antenne passive ; et l’amplificateur produise un très faible bruit dans la bande de fréquence connue, lorsque son accès d’entrée est directement couplé à l’antenne passive.Thus, for a passive antenna which is a single-spiral frame or a shielded single-spiral frame, small compared to the wavelength in vacuum corresponding to the upper limit of the known frequency band, the state of the prior art does not disclose an amplifier such that: a module of the input impedance of the amplifier is, at any frequency in the known frequency band, much smaller than a module of the impedance of the passive antenna; an amplifier transimpedance modulus is substantially independent of frequency, within the known frequency band; the amplifier input port can be directly coupled to the passive antenna; and the amplifier produces very low noise in the known frequency band, when its input port is directly coupled to the passive antenna.

L’invention a pour objet un amplificateur à transimpédance, dépourvu des limitations mentionnées ci-dessus des techniques connues.The subject of the invention is a transimpedance amplifier, devoid of the aforementioned limitations of known techniques.

Une base d’un transistor bipolaire est une électrode qui peut être utilisée pour contrôler un courant de collecteur du transistor et un courant d’émetteur du transistor. Ainsi, dans le brevet des États-Unis d’Amérique numéro 3851235 intitulé “Bridge circuit for controlling a direct current motor”, une base d’un transistor bipolaire est appelée “control electrode”, c’est-à-dire “électrode de contrôle” en français. Une grille d’un transistor à effet de champ (la grille est parfois appelée “porte” par certains auteurs) est une électrode qui peut être utilisée pour contrôler un courant de drain du transistor et un courant de source du transistor. Ainsi, dans le brevet des États-Unis d’Amérique numéro 5426382 intitulé “Complementary logic recovered energy circuit”, une grille d’un transistor à effet de champ est appelée “control electrode”, c’est-à-dire “électrode de contrôle” en français.A base of a bipolar transistor is an electrode that can be used to control a transistor's collector current and a transistor's emitter current. Thus, in the patent of the United States of America number 3851235 entitled “Bridge circuit for controlling a direct current motor”, a base of a bipolar transistor is called “control electrode”, that is to say “electrode of control” in French. A gate of a field-effect transistor (the gate is sometimes called a “gate” by some authors) is an electrode that can be used to control a transistor drain current and a transistor source current. Thus, in the patent of the United States of America number 5426382 entitled “Complementary logic recovered energy circuit”, a gate of a transistor with field effect is called “control electrode”, that is to say “electrode of control” in French.

Dans la suite, “électrode de contrôle” signifie soit une base d’un transistor bipolaire, soit une grille d’un transistor à effet de champ. C’est aussi le cas dans le brevet des États-Unis d’Amérique numéro 4754233 intitulé “Low noise ultra high frequency amplifier having automatic gain control”, et dans le brevet des États-Unis d’Amérique numéro 5617056 intitulé “Base current compensation circuit”.In the following, "control electrode" means either a base of a bipolar transistor or a gate of a field-effect transistor. This is also the case in United States patent number 4754233 entitled “Low noise ultra high frequency amplifier having automatic gain control”, and in United States patent number 5617056 entitled “Base current compensation circuit".

Dans la suite, en accord avec le “IEC multilingual dictionary of electricity” édité par leBureau Central de la Commission Electrotechnique Internationaleen 1983, “commande en boucle fermée” (traduction littérale de l’expression “closed-loop control” de la langue anglaise), synonyme de “commande en chaîne fermée” et de “asservissement”, signifie une commande où l’action sur le système commandé est rendue dépendante d’une mesure de la grandeur commandée.In the following, in accordance with the “IEC multilingual dictionary of electricity” published by the Central Office of the International Electrotechnical Commission in 1983, “closed-loop control” (literal translation of the expression “closed-loop control” of the language English), synonym of “closed chain control” and “servo control”, means a control where the action on the controlled system is made dependent on a measurement of the controlled quantity.

Un amplificateur selon l’invention est un amplificateur procurant une transimpédance dans une bande de fréquence connue, l’amplificateur comportant :An amplifier according to the invention is an amplifier providing transimpedance in a known frequency band, the amplifier comprising:

an input port having a first terminal and a second terminal, the second terminal being directly coupled to a reference conductor;
a first amplifying device comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being positive, a current leaving the second terminal and a current entering the third terminal being positive and controlled by a voltage between the first terminal and the second terminal, the second terminal being coupled to the first terminal of the input port;
a second amplifying device comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being negative, a current leaving the second terminal and a current entering the third terminal being negative and controlled by a voltage between the first terminal and the second terminal, the second terminal being coupled to the first terminal of the input port;
a third amplifying device comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being negative, a current leaving the second terminal and a current entering the third terminal being negative and controlled by a voltage between the first terminal and the second terminal, the first terminal being coupled to the third terminal of the first amplification device;
a fourth amplifying device comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being positive, a current out of the second terminal and a current in the third terminal being positive and controlled by a voltage between the first terminal and the second terminal, the first terminal being coupled to the third terminal of the second amplifying device, the third terminal being coupled to the third terminal of the third amplifying device;
a first capacitor having a first terminal and a second terminal, the first terminal being coupled to the first terminal of the first amplifier device, the second terminal being coupled to the reference conductor;
a second capacitor having a first terminal and a second terminal, the first terminal being coupled to the first terminal of the second amplifying device, the second terminal being coupled to the reference conductor;
one or more means, including a first differential amplifier comprising at least two transistors, for creating a first closed-loop control in which a controlled quantity is a bias voltage between the third terminal of the third amplifying device and the reference conductor, a output of the first differential amplifier being in a first case coupled to the first terminal of the first amplification device, or in a second case coupled to the first terminal of the second amplification device;
one or more means, including a second differential amplifier comprising at least two transistors, for creating a second closed-loop control in which a controlled quantity is in said first case a bias voltage between the third terminal of the second amplifier device and the conductor reference, or in said second case a bias voltage between the third terminal of the first amplifying device and the reference conductor, an output of the second differential amplifier being in said first case coupled to the first terminal of the second amplifying device , or in said second case coupled to the first terminal of the first amplifying device; And
one or more means for creating feedback, the feedback determining the transimpedance in the known frequency band, the feedback reducing a modulus of an impedance presented by the input port in the known frequency band.

Le spécialiste comprend que, dans la phrase précédente : “tension” signifie une différence de potentiel ; et “tension de polarisation”, qui peut aussi être appelée “tension de repos”, désigne une tension continue en l’absence de signal appliqué à l’accès d’entrée de l’amplificateur selon l’invention.The specialist understands that, in the preceding sentence: “voltage” means a potential difference; and "bias voltage", which can also be called "quiescent voltage", denotes a DC voltage in the absence of a signal applied to the input port of the amplifier according to the invention.

Le spécialiste comprend que ladite rétroaction est telle que l’amplificateur selon l’invention est un amplificateur à transimpédance.The specialist understands that said feedback is such that the amplifier according to the invention is a transimpedance amplifier.

D’autres avantages et caractéristiques ressortiront plus clairement de la description qui va suivre de modes particuliers de réalisation de l'invention, donnés à titre d'exemples non limitatifs, et représentés dans les dessins annexés sur lesquels :Other advantages and characteristics will emerge more clearly from the following description of particular embodiments of the invention, given by way of non-limiting examples, and represented in the appended drawings in which:

- la est un schéma-bloc d’un amplificateur à transimpédance selon l’invention (premier mode de réalisation) ;- there is a block diagram of a transimpedance amplifier according to the invention (first embodiment);

- la est un schéma-bloc d’un amplificateur à transimpédance selon l’invention (deuxième mode de réalisation) ;- there is a block diagram of a transimpedance amplifier according to the invention (second embodiment);

- la est une première partie d’un schéma d’un amplificateur à transimpédance selon l’invention (troisième mode de réalisation) ; et- there is a first part of a diagram of a transimpedance amplifier according to the invention (third embodiment); And

- la est une seconde partie du schéma d’un amplificateur à transimpédance selon l’invention (troisième mode de réalisation).- there is a second part of the diagram of a transimpedance amplifier according to the invention (third embodiment).

EXPOSÉ DÉTAILLÉ DE CERTAINS MODES DE RÉALISATIONDETAILED DISCUSSION OF CERTAIN EMBODIMENTS

Premier mode de réalisation. First embodiment .

Au titre d’un premier mode de réalisation d’un dispositif selon l’invention, donné à titre d’exemple non limitatif, nous avons représenté sur la le schéma-bloc d’un amplificateur à transimpédance pour une bande de fréquence connue, l’amplificateur à transimpédance comportant :As a first embodiment of a device according to the invention, given by way of non-limiting example, we have represented on the the block diagram of a transimpedance amplifier for a known frequency band, the transimpedance amplifier comprising:

an input port (1) having a first terminal (11) and a second terminal (12), the second terminal of the input port being directly coupled to a reference (ground) conductor;
a first amplifying device (21) comprising a first terminal, a second terminal, a third terminal and at least one transistor, the first terminal of the first amplifying device being directly coupled to a control electrode of the at least one transistor of the first amplifying device, the first amplifying device being such that, if a voltage between the third terminal of the first amplifying device and the second terminal of the first amplifying device is greater than a given positive voltage, then a current coming out of the second terminal of the first amplifying device and a current entering the third terminal of the first amplifying device are positive or zero, and mainly depend on a voltage between the first terminal of the first amplifying device and the second terminal of the first amplifying device, the second terminal of the first amplifying device being coupled to the first terminal of entrance access;
a second amplifying device (22) comprising a first terminal, a second terminal, a third terminal and at least one transistor, the first terminal of the second amplifying device being directly coupled to a control electrode of the at least one transistor of the second amplifying device, the second amplifying device being such that, if a voltage between the third terminal of the second amplifying device and the second terminal of the second amplifying device is lower than a given negative voltage, then a current coming out of the second terminal of the second amplifying device and a current entering the third terminal of the second amplifying device are negative or zero, and mainly depend on a voltage between the first terminal of the second amplifying device and the second terminal of the second amplifying device, the second terminal of the second amplifying device being coupled to the first e entry access terminal;
a third amplifying device (23) comprising a first terminal, a second terminal, a third terminal and at least one transistor, the first terminal of the third amplifying device being directly coupled to a control electrode of the at least one transistor of the third amplifying device, the third amplifying device being such that, if a voltage between the third terminal of the third amplifying device and the second terminal of the third amplifying device is lower than the given negative voltage, then a current coming out of the second terminal of the third amplifying device and a current entering the third terminal of the third amplifying device are negative or zero, and mainly depend on a voltage between the first terminal of the third amplifying device and the second terminal of the third amplifying device, the first terminal of the third amplifying device being coupled to the third terminal of the first amplification device;
a fourth amplifying device (24) comprising a first terminal, a second terminal, a third terminal and at least one transistor, the first terminal of the fourth amplifying device being directly coupled to a control electrode of the at least one transistor of the fourth amplifying device, the fourth amplifying device being such that, if a voltage between the third terminal of the fourth amplifying device and the second terminal of the fourth amplifying device is greater than the given positive voltage, then a current outgoing from the second terminal of the fourth amplifying device and a current entering the third terminal of the fourth amplifying device are positive or zero, and mainly depend on a voltage between the first terminal of the fourth amplifying device and the second terminal of the fourth amplifying device, the first terminal of the fourth amplifying device being coupled to the third terminal of the second amplifying device, the third terminal of the fourth amplifying device being directly coupled to the third terminal of the third amplifying device;
a first capacitor (31) having a first terminal and a second terminal, the first terminal of the first amplifying device being coupled to the first terminal of the first capacitor, the second terminal of the first capacitor being coupled to the reference conductor;
a second capacitor (32) having a first terminal and a second terminal, the first terminal of the second amplifying device being coupled to the first terminal of the second capacitor, the second terminal of the second capacitor being coupled to the reference conductor;
one or more means, including a first differential amplifier (41) having at least two transistors, for creating a first closed-loop control in which a controlled quantity is a bias voltage between the third terminal of the third amplifying device and the conductor of reference, an output of the first differential amplifier being coupled to the first terminal of the first amplification device;
one or more means, including a second differential amplifier (42) having at least two transistors, for creating a second closed-loop control in which a controlled quantity is a bias voltage between the third terminal of the second amplifier device and the conductor of reference, an output of the second differential amplifier being coupled to the first terminal of the second amplification device;
a power amplifier (6) having, in the known frequency band, a voltage gain greater than 8/10 and less than 1, and an input impedance which is much greater than its output impedance, an input of the power amplifier being coupled to the third terminal of the third amplifying device and to the third terminal of the fourth amplifying device;
an output port (7) having a first terminal (71) and a second terminal (72), the first terminal of the output port being directly coupled to an output of the power amplifier, the second terminal of the output port being directly coupled to the reference conductor;
a resistor (5) for creating a feedback, the feedback determining, in the known frequency band, a transimpedance of the transimpedance amplifier, the feedback reducing a modulus of an impedance presented by the input port in the band of known frequency;
a positive supply line (91), a voltage between the positive supply line and the reference conductor being made positive and stable by a supply which is not shown in Figure 1; And
a negative supply line (92), a voltage between the negative supply line and the reference conductor being made negative and stable by said supply.

Le spécialiste comprend que, dans la phrase précédente, “tension de polarisation”, qui peut aussi être appelée “tension de repos”, désigne une tension continue en l’absence de signal appliqué à l’accès d’entrée de l’amplificateur à transimpédance.The specialist understands that, in the preceding sentence, “bias voltage”, which can also be called “quiescent voltage”, means a DC voltage in the absence of a signal applied to the input port of the amplifier at transimpedance.

La première commande en boucle fermée et la deuxième commande en boucle fermée sont configurées pour être telles que :The first closed loop command and the second closed loop command are configured to be such that:

the voltage between the third terminal of the first amplifying device and the second terminal of the first amplifying device is greater than the given positive voltage;
the current leaving the second terminal of the first amplifying device and the current entering the third terminal of the first amplifying device are positive and controlled by a voltage between the first terminal of the first amplifying device and the second terminal of the first amplification device;
the voltage between the third terminal of the second amplifying device and the second terminal of the second amplifying device is lower than the given negative voltage;
the current leaving the second terminal of the second amplifying device and the current entering the third terminal of the second amplifying device are negative and controlled by a voltage between the first terminal of the second amplifying device and the second terminal of the second amplification device;
the voltage between the third terminal of the third amplifying device and the second terminal of the third amplifying device is lower than the given negative voltage;
the current leaving the second terminal of the third amplifying device and the current entering the third terminal of the third amplifying device are negative and controlled by a voltage between the first terminal of the third amplifying device and the second terminal of the third amplification device;
the voltage between the third terminal of the fourth amplifying device and the second terminal of the fourth amplifying device is greater than the given positive voltage; And
the current leaving the second terminal of the fourth amplifying device and the current entering the third terminal of the fourth amplifying device are positive and controlled by a voltage between the first terminal of the fourth amplifying device and the second terminal of the fourth amplification device.

Par exemple, il est possible que le premier dispositif d’amplification soit un transistor bipolaire NPN ayant une base, un émetteur et un collecteur, la première borne du premier dispositif d’amplification étant la base du transistor bipolaire NPN, la deuxième borne du premier dispositif d’amplification étant l’émetteur du transistor bipolaire NPN, la troisième borne du premier dispositif d’amplification étant le collecteur du transistor bipolaire NPN ; et que le deuxième dispositif d’amplification soit un transistor bipolaire PNP ayant une base, un émetteur et un collecteur, la première borne du deuxième dispositif d’amplification étant la base du transistor bipolaire PNP, la deuxième borne du deuxième dispositif d’amplification étant l’émetteur du transistor bipolaire PNP, la troisième borne du deuxième dispositif d’amplification étant le collecteur du transistor bipolaire PNP. Dans ce cas, le spécialiste comprend que le premier dispositif d’amplification est un transistor NPN utilisé dans un circuit base commune, et que le deuxième dispositif d’amplification est un transistor PNP utilisé dans un circuit base commune.For example, it is possible that the first amplifying device is an NPN bipolar transistor having a base, an emitter and a collector, the first terminal of the first amplifying device being the base of the NPN bipolar transistor, the second terminal of the first amplification device being the emitter of the NPN bipolar transistor, the third terminal of the first amplification device being the collector of the NPN bipolar transistor; and that the second amplifying device is a PNP bipolar transistor having a base, an emitter and a collector, the first terminal of the second amplifying device being the base of the PNP bipolar transistor, the second terminal of the second amplifying device being the emitter of the PNP bipolar transistor, the third terminal of the second amplification device being the collector of the PNP bipolar transistor. In this case, the specialist understands that the first amplifying device is an NPN transistor used in a common base circuit, and that the second amplifying device is a PNP transistor used in a common base circuit.

Par exemple, il est possible que le troisième dispositif d’amplification soit un transistor bipolaire PNP ayant une base, un émetteur et un collecteur, la première borne du troisième dispositif d’amplification étant la base du transistor bipolaire PNP, la deuxième borne du troisième dispositif d’amplification étant l’émetteur du transistor bipolaire PNP, la troisième borne du troisième dispositif d’amplification étant le collecteur du transistor bipolaire PNP ; et que le quatrième dispositif d’amplification soit un transistor bipolaire NPN ayant une base, un émetteur et un collecteur, la première borne du quatrième dispositif d’amplification étant la base du transistor bipolaire NPN, la deuxième borne du quatrième dispositif d’amplification étant l’émetteur du transistor bipolaire NPN, la troisième borne du quatrième dispositif d’amplification étant le collecteur du transistor bipolaire NPN. Dans ce cas, le spécialiste comprend que le troisième dispositif d’amplification est un transistor PNP utilisé dans un circuit émetteur commun (avec dégénération d’émetteur), et que le quatrième dispositif d’amplification est un transistor NPN utilisé dans un circuit émetteur commun (avec dégénération d’émetteur).For example, it is possible that the third amplifying device is a PNP bipolar transistor having a base, an emitter and a collector, the first terminal of the third amplifying device being the base of the PNP bipolar transistor, the second terminal of the third amplification device being the emitter of the PNP bipolar transistor, the third terminal of the third amplification device being the collector of the PNP bipolar transistor; and that the fourth amplifying device is an NPN bipolar transistor having a base, an emitter and a collector, the first terminal of the fourth amplifying device being the base of the NPN bipolar transistor, the second terminal of the fourth amplifying device being the emitter of the NPN bipolar transistor, the third terminal of the fourth amplifying device being the collector of the NPN bipolar transistor. In this case, the specialist understands that the third amplifying device is a PNP transistor used in a common-emitter circuit (with emitter degeneration), and that the fourth amplifying device is an NPN transistor used in a common-emitter circuit (with emitter degeneration).

Par exemple, si le premier dispositif d’amplification et le quatrième dispositif d’amplification sont des transistors NPN, la tension positive donnée peut être égale à un volt. Par exemple, si le deuxième dispositif d’amplification et le troisième dispositif d’amplification sont des transistors PNP, la tension négative donnée peut être égale à moins un volt.For example, if the first amplifying device and the fourth amplifying device are NPN transistors, the given positive voltage can be one volt. For example, if the second amplifying device and the third amplifying device are PNP transistors, the given negative voltage can be equal to minus one volt.

Par exemple, il est possible qu’au moins un des dits transistors bipolaires NPN soit remplacé par un circuit ayant un comportement similaire, par exemple une paire Darlington NPN, ou deux transistors NPN utilisés dans un circuit cascode. Par exemple, il est possible qu’au moins un des dits transistors bipolaires PNP soit remplacé par un circuit ayant un comportement similaire, par exemple une paire Darlington PNP, ou deux transistors PNP utilisés dans un circuit cascode.For example, it is possible that at least one of said NPN bipolar transistors is replaced by a circuit having a similar behavior, for example an NPN Darlington pair, or two NPN transistors used in a cascode circuit. For example, it is possible that at least one of the said PNP bipolar transistors is replaced by a circuit having a similar behavior, for example a Darlington PNP pair, or two PNP transistors used in a cascode circuit.

Le spécialiste comprend que, si l’accès d’entrée de l’amplificateur à transimpédance est directement couplé à une antenne passive qui est un cadre monospire ou un cadre blindé monospire, petit devant une longueur d’onde dans le vide correspondant à une borne supérieure de la bande de fréquence connue, la rétroaction créée par la résistance (5) est négative dans la bande de fréquence connue, et appropriée pour : déterminer, dans la bande de fréquence connue, la transimpédance de l’amplificateur à transimpédance, un module de la transimpédance de l’amplificateur à transimpédance étant sensiblement indépendant de la fréquence, dans la bande de fréquence connue ; et réduire, dans la bande de fréquence connue, un module d’une impédance d’entrée de l’amplificateur à transimpédance, le module de l’impédance d’entrée de l’amplificateur à transimpédance étant, à toute fréquence dans la bande de fréquence connue, beaucoup plus petit qu’un module de l’impédance de l’antenne passive. Toutefois, la rétroaction créée par la résistance (5) est, aux basses fréquences et à la fréquence nulle, trop faible pour procurer une polarisation convenable du troisième dispositif d’amplification et du quatrième dispositif d’amplification. Le spécialiste comprend que ce n’est pas un problème, parce que : la première commande en boucle fermée est telle que la tension de polarisation entre la troisième borne du troisième dispositif d’amplification et le conducteur de référence est voisine de zéro volt, par exemple zéro volt plus ou moins dix millivolts ; et la deuxième commande en boucle fermée est telle que la tension de polarisation entre la troisième borne du deuxième dispositif d’amplification et le conducteur de référence est voisine d’une tension voulue appliquée à une borne d’entrée inverseuse du second amplificateur différentiel. Ainsi, le premier dispositif d’amplification, le deuxième dispositif d’amplification, le troisième dispositif d’amplification et le quatrième dispositif d’amplification sont convenablement polarisés.The specialist understands that, if the input port of the transimpedance amplifier is directly coupled to a passive antenna which is a single-spiral frame or a shielded single-spiral frame, small compared to a wavelength in vacuum corresponding to a terminal upper part of the known frequency band, the feedback created by the resistor (5) is negative in the known frequency band, and suitable for: determining, in the known frequency band, the transimpedance of the transimpedance amplifier, a module the transimpedance of the transimpedance amplifier being substantially independent of frequency, in the known frequency band; and reducing, in the known frequency band, a modulus of an input impedance of the transimpedance amplifier, the modulus of the input impedance of the transimpedance amplifier being, at any frequency in the band of known frequency, much smaller than a passive antenna impedance module. However, the feedback created by the resistor (5) is, at low frequencies and at zero frequency, too weak to provide suitable biasing of the third amplifying device and the fourth amplifying device. The specialist understands that this is not a problem, because: the first closed-loop control is such that the bias voltage between the third terminal of the third amplification device and the reference conductor is close to zero volts, for example zero volts plus or minus ten millivolts; and the second closed-loop control is such that the bias voltage between the third terminal of the second amplifier device and the reference conductor is close to a desired voltage applied to an inverting input terminal of the second differential amplifier. Thus, the first amplifying device, the second amplifying device, the third amplifying device and the fourth amplifying device are suitably biased.

Si le premier dispositif d’amplification et le quatrième dispositif d’amplification sont chacun un transistor NPN à faible bruit bien choisi, et si le deuxième dispositif d’amplification et le troisième dispositif d’amplification sont chacun un transistor PNP à faible bruit bien choisi, alors l’amplificateur à transimpédance produit un très faible bruit dans la bande de fréquence connue, lorsque son accès d’entrée est directement couplé à l’antenne passive, parce que les deux circuits base commune sont, du point de vue du bruit produit, optimisés pour l’impédance de l’antenne passive.If the first amplifying device and the fourth amplifying device are each a well-chosen low-noise NPN transistor, and if the second amplifying device and the third amplifying device are each a well-chosen low-noise PNP transistor , then the transimpedance amplifier produces very low noise in the known frequency band, when its input port is directly coupled to the passive antenna, because the two common base circuits are, from the point of view of the noise produced , optimized for the impedance of the passive antenna.

Ainsi, pour une antenne passive qui est un cadre monospire ou un cadre blindé monospire, petit devant une longueur d’onde dans le vide correspondant à une borne supérieure de la bande de fréquence connue, l’amplificateur à transimpédance est tel que : un module de l’impédance d’entrée de l’amplificateur à transimpédance est, à toute fréquence dans la bande de fréquence connue, beaucoup plus petit qu’un module de l’impédance de l’antenne passive ; un module de la transimpédance de l’amplificateur à transimpédance est sensiblement indépendant de la fréquence, dans la bande de fréquence connue ; l’accès d’entrée de l’amplificateur à transimpédance peut être directement couplé à l’antenne passive ; et l’amplificateur à transimpédance produit un très faible bruit dans la bande de fréquence connue, lorsque son accès d’entrée est directement couplé à l’antenne passive. Par conséquent, l’amplificateur à transimpédance est une solution aux deux problèmes expliqués ci-dessus dans la section sur l’état de la technique antérieure.Thus, for a passive antenna which is a monospiral frame or a shielded monospiral frame, small compared to a wavelength in vacuum corresponding to an upper limit of the known frequency band, the transimpedance amplifier is such that: a module of the input impedance of the transimpedance amplifier is, at any frequency in the known frequency band, much smaller than a module of the impedance of the passive antenna; a module of the transimpedance of the transimpedance amplifier is substantially independent of frequency, in the known frequency band; the input port of the transimpedance amplifier can be directly coupled to the passive antenna; and the transimpedance amplifier produces very low noise in the known frequency band, when its input port is directly coupled to the passive antenna. Therefore, the transimpedance amplifier is a solution to the two problems explained above in the prior art section.

Deuxième mode de réalisation. Second embodiment .

Au titre d’un deuxième mode de réalisation d’un dispositif selon l’invention, donné à titre d’exemple non limitatif, nous avons représenté sur la le schéma-bloc d’un amplificateur à transimpédance pour une bande de fréquence connue, l’amplificateur à transimpédance comportant :As a second embodiment of a device according to the invention, given by way of non-limiting example, we have represented on the the block diagram of a transimpedance amplifier for a known frequency band, the transimpedance amplifier comprising:

an input port (1) having a first terminal (11) and a second terminal (12), the second terminal of the input port being directly coupled to a reference conductor;
a first amplifying device (21) having a transistor, a first terminal, a second terminal and a third terminal, the first terminal of the first amplifying device being directly coupled to a control electrode of the transistor of the first amplifying device , a voltage between the third terminal of the first amplifying device and the second terminal of the first amplifying device being greater than a given positive voltage, a current leaving the second terminal of the first amplifying device and a current entering the third terminal of the first amplifying device being positive and controlled by a voltage between the first terminal of the first amplifying device and the second terminal of the first amplifying device, the second terminal of the first amplifying device being coupled to the first entrance access terminal;
a second amplifying device (22) having a transistor, a first terminal, a second terminal and a third terminal, the first terminal of the second amplifying device being directly coupled to a control electrode of the transistor of the second amplifying device , a voltage between the third terminal of the second amplifying device and the second terminal of the second amplifying device being lower than a given negative voltage, a current leaving the second terminal of the second amplifying device and a current entering the third terminal of the second amplifying device being negative and controlled by a voltage between the first terminal of the second amplifying device and the second terminal of the second amplifying device, the second terminal of the second amplifying device being coupled to the first entrance access terminal;
a third amplifying device (23) comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal of the third amplifying device being directly coupled to a control electrode of the transistor of the third amplifying device , a voltage between the third terminal of the third amplifying device and the second terminal of the third amplifying device being lower than the given negative voltage, a current leaving the second terminal of the third amplifying device and a current entering the third terminal of the third amplifying device being negative and controlled by a voltage between the first terminal of the third amplifying device and the second terminal of the third amplifying device, the first terminal of the third amplifying device being coupled to the third terminal of the first amplification device;
a fourth amplifying device (24) having a transistor, a first terminal, a second terminal and a third terminal, the first terminal of the fourth amplifying device being directly coupled to a control electrode of the transistor of the fourth amplifying device , a voltage between the third terminal of the fourth amplifying device and the second terminal of the fourth amplifying device being higher than the given positive voltage, a current leaving the second terminal of the fourth amplifying device and a current entering the third terminal of the fourth amplifying device being positive and controlled by a voltage between the first terminal of the fourth amplifying device and the second terminal of the fourth amplifying device, the first terminal of the fourth amplifying device being coupled to the third terminal of the second amplifying device, the third terminal of the fourth amplifying device amplification being coupled to the third terminal of the third amplification device;
a first capacitor (31) having a first terminal and a second terminal, the first terminal of the first amplifying device being coupled to the first terminal of the first capacitor, the second terminal of the first capacitor being coupled to the reference conductor;
a second capacitor (32) having a first terminal and a second terminal, the first terminal of the second amplifying device being coupled to the first terminal of the second capacitor, the second terminal of the second capacitor being coupled to the reference conductor;
one or more means, including a first differential amplifier (41), for creating a first closed-loop control in which a controlled quantity is a bias voltage between the third terminal of the third amplifier device and the reference conductor, an output of the first differential amplifier being coupled to the first terminal of the second amplifying device, the first differential amplifier being a two-transistor differential amplifier;
one or more means, including a second differential amplifier (42), for creating a second closed-loop control in which a controlled quantity is a bias voltage between the third terminal of the first amplifier device and the reference conductor, an output of the second differential amplifier being coupled to the first terminal of the first amplifying device, the second differential amplifier being a two-transistor differential amplifier;
a power amplifier (6) having, in the known frequency band, a voltage gain greater than 9/10 and less than 11/10, and an input impedance which is much greater than its output impedance, a input of the power amplifier being coupled to the third terminal of the third amplifying device and the third terminal of the fourth amplifying device;
an output port (7) having a first terminal (71) and a second terminal (72), the first terminal of the output port being directly coupled to an output of the power amplifier, the second terminal of the output port being directly coupled to the reference conductor;
one or more means for creating feedback, said one or more means for creating feedback including a resistor (5), the feedback determining, in the known frequency band, a transimpedance of the transimpedance amplifier, the feedback reducing a modulates an impedance presented by the input port in the known frequency band;
a positive supply line (91), a voltage between the positive supply line and the reference conductor being made positive and stable by a first battery which is not shown in Figure 2; And
a negative supply line (92), a voltage between the negative supply line and the reference conductor being made negative and stable by a second battery which is not shown in Figure 2.

Par exemple, il est possible que le premier dispositif d’amplification soit un transistor à effet de champ à canal N ayant une grille, une source et un drain, la première borne du premier dispositif d’amplification étant la grille du transistor à effet de champ à canal N, la deuxième borne du premier dispositif d’amplification étant la source du transistor à effet de champ à canal N, la troisième borne du premier dispositif d’amplification étant le drain du transistor à effet de champ à canal N ; et que le deuxième dispositif d’amplification soit un transistor à effet de champ à canal P ayant une grille, une source et un drain, la première borne du deuxième dispositif d’amplification étant la grille du transistor à effet de champ à canal P, la deuxième borne du deuxième dispositif d’amplification étant la source du transistor à effet de champ à canal P, la troisième borne du deuxième dispositif d’amplification étant le drain du transistor à effet de champ à canal P. Dans ce cas, le spécialiste comprend que le premier dispositif d’amplification est un transistor à canal N utilisé dans un circuit grille commune, et que le deuxième dispositif d’amplification est un transistor à canal P utilisé dans un circuit grille commune.For example, it is possible for the first amplifier device to be an N-channel field effect transistor having a gate, a source and a drain, the first terminal of the first amplifier device being the gate of the field effect transistor. N-channel field, the second terminal of the first amplifying device being the source of the N-channel field-effect transistor, the third terminal of the first amplifying device being the drain of the N-channel field-effect transistor; and the second amplifying device is a P-channel field-effect transistor having a gate, a source and a drain, the first terminal of the second amplifying device being the gate of the P-channel field-effect transistor, the second terminal of the second amplifying device being the source of the P-channel field-effect transistor, the third terminal of the second amplifying device being the drain of the P-channel field-effect transistor. In this case, the specialist understands that the first amplifying device is an N-channel transistor used in a common-gate circuit, and the second amplifying device is a P-channel transistor used in a common-gate circuit.

Par exemple, il est possible que le troisième dispositif d’amplification soit un transistor à effet de champ à canal P ayant une grille, une source et un drain, la première borne du troisième dispositif d’amplification étant la grille du transistor à effet de champ à canal P, la deuxième borne du troisième dispositif d’amplification étant la source du transistor à effet de champ à canal P, la troisième borne du troisième dispositif d’amplification étant le drain du transistor à effet de champ à canal P ; et que le quatrième dispositif d’amplification soit un transistor à effet de champ à canal N ayant une grille, une source et un drain, la première borne du quatrième dispositif d’amplification étant la grille du transistor à effet de champ à canal N, la deuxième borne du quatrième dispositif d’amplification étant la source du transistor à effet de champ à canal N, la troisième borne du quatrième dispositif d’amplification étant le drain du transistor à effet de champ à canal N. Dans ce cas, le spécialiste comprend que le troisième dispositif d’amplification est un transistor à canal P utilisé dans un circuit source commune (avec dégénération de source), et que le quatrième dispositif d’amplification est un transistor à canal N utilisé dans un circuit source commune (avec dégénération de source).For example, it is possible for the third amplifying device to be a P-channel field effect transistor having a gate, a source and a drain, the first terminal of the third amplifying device being the gate of the P-channel field effect transistor. P-channel field, the second terminal of the third amplifying device being the source of the P-channel field-effect transistor, the third terminal of the third amplifying device being the drain of the P-channel field-effect transistor; and the fourth amplifier device is an N-channel field effect transistor having a gate, a source and a drain, the first terminal of the fourth amplifier device being the gate of the N-channel field effect transistor, the second terminal of the fourth amplifying device being the source of the N-channel field-effect transistor, the third terminal of the fourth amplifying device being the drain of the N-channel field-effect transistor. In this case, the specialist understands that the third amplifying device is a P-channel transistor used in a common-source circuit (with source degeneration), and that the fourth amplifying device is an N-channel transistor used in a common-source circuit (with source degeneration source).

Par exemple, si le premier dispositif d’amplification et le quatrième dispositif d’amplification sont des transistors à canal N, la tension positive donnée peut être égale à deux volts. Par exemple, si le deuxième dispositif d’amplification et le troisième dispositif d’amplification sont des transistors à canal P, la tension négative donnée peut être égale à moins deux volts.For example, if the first amplifying device and the fourth amplifying device are N-channel transistors, the positive voltage given can be two volts. For example, if the second amplifying device and the third amplifying device are P-channel transistors, the given negative voltage can be equal to minus two volts.

Par exemple, il est possible qu’au moins un des dits transistors à effet de champ à canal N soit remplacé par un circuit ayant un comportement similaire, par exemple deux transistors à canal N utilisés dans un circuit cascode, ou par un composant ayant un comportement similaire, par exemple un MOSFET à double grille à canal N. Par exemple, il est possible qu’au moins un des dits transistors à effet de champ à canal P soit remplacé par un circuit ayant un comportement similaire, par exemple deux transistors à canal P utilisés dans un circuit cascode, ou par un composant ayant un comportement similaire, par exemple un MOSFET à double grille à canal P.For example, it is possible that at least one of said N-channel field-effect transistors is replaced by a circuit having a similar behavior, for example two N-channel transistors used in a cascode circuit, or by a component having a similar behavior, for example an N-channel double-gate MOSFET. For example, it is possible that at least one of said P-channel field-effect transistors is replaced by a circuit having a similar behavior, for example two transistors with P-channel used in a cascode circuit, or by a component having a similar behavior, for example a P-channel dual-gate MOSFET.

Ladite transimpédance de l’amplificateur à transimpédance est une transimpédance entre l’accès d’entrée et l’accès de sortie. Le spécialiste comprend que, si l’accès d’entrée de l’amplificateur à transimpédance est directement couplé à une antenne passive qui est un cadre monospire ou un cadre blindé monospire, petit devant une longueur d’onde dans le vide correspondant à une borne supérieure de la bande de fréquence connue, la rétroaction créée par la résistance (5) est négative dans la bande de fréquence connue, et appropriée pour : déterminer, dans la bande de fréquence connue, la transimpédance de l’amplificateur à transimpédance, un module de la transimpédance de l’amplificateur à transimpédance étant sensiblement indépendant de la fréquence, dans la bande de fréquence connue ; et réduire, dans la bande de fréquence connue, un module d’une impédance d’entrée de l’amplificateur à transimpédance, le module de l’impédance d’entrée de l’amplificateur à transimpédance étant, à toute fréquence dans la bande de fréquence connue, beaucoup plus petit qu’un module de l’impédance de l’antenne passive. Toutefois, la rétroaction créée par la résistance (5) est, aux basses fréquences et à la fréquence nulle, trop faible pour procurer une polarisation convenable du troisième dispositif d’amplification et du quatrième dispositif d’amplification. Le spécialiste comprend que ce n’est pas un problème, parce que : la première commande en boucle fermée est telle que la tension de polarisation entre la troisième borne du troisième dispositif d’amplification et le conducteur de référence est voisine de zéro volt ; et la deuxième commande en boucle fermée est telle que la tension de polarisation entre la troisième borne du premier dispositif d’amplification et le conducteur de référence est voisine d’une tension voulue appliquée à une borne d’entrée inverseuse du second amplificateur différentiel. Ainsi, le premier dispositif d’amplification, le deuxième dispositif d’amplification, le troisième dispositif d’amplification et le quatrième dispositif d’amplification sont convenablement polarisés.Said transimpedance of the transimpedance amplifier is a transimpedance between the input port and the output port. The specialist understands that, if the input port of the transimpedance amplifier is directly coupled to a passive antenna which is a single-spiral frame or a shielded single-spiral frame, small compared to a wavelength in vacuum corresponding to a terminal upper part of the known frequency band, the feedback created by the resistor (5) is negative in the known frequency band, and suitable for: determining, in the known frequency band, the transimpedance of the transimpedance amplifier, a module the transimpedance of the transimpedance amplifier being substantially independent of frequency, in the known frequency band; and reducing, in the known frequency band, a modulus of an input impedance of the transimpedance amplifier, the modulus of the input impedance of the transimpedance amplifier being, at any frequency in the band of known frequency, much smaller than a passive antenna impedance module. However, the feedback created by the resistor (5) is, at low frequencies and at zero frequency, too weak to provide suitable biasing of the third amplifying device and the fourth amplifying device. The specialist understands that this is not a problem, because: the first closed-loop control is such that the bias voltage between the third terminal of the third amplification device and the reference conductor is close to zero volts; and the second closed-loop control is such that the bias voltage between the third terminal of the first amplifier device and the reference conductor is close to a desired voltage applied to an inverting input terminal of the second differential amplifier. Thus, the first amplifying device, the second amplifying device, the third amplifying device and the fourth amplifying device are suitably biased.

Les dits un ou plusieurs moyens pour créer une rétroaction pourraient aussi comporter, en plus de la résistance (5), d’autres moyens, par exemple un condensateur connecté en parallèle avec la résistance (5). Le spécialiste comprend que ceci peut parfois être utile, par exemple pour améliorer une marge de phase de cette rétroaction, et/ou pour rendre le module de la transimpédance de l’amplificateur à transimpédance plus indépendant de la fréquence, dans la bande de fréquence connue.Said one or more means for creating a feedback could also comprise, in addition to the resistor (5), other means, for example a capacitor connected in parallel with the resistor (5). The specialist understands that this can sometimes be useful, for example to improve a phase margin of this feedback, and/or to make the modulus of the transimpedance of the transimpedance amplifier more independent of frequency, in the known frequency band .

Si le premier dispositif d’amplification et le quatrième dispositif d’amplification sont chacun un transistor à canal N à faible bruit bien choisi, et si le deuxième dispositif d’amplification et le troisième dispositif d’amplification sont chacun un transistor à canal P à faible bruit bien choisi, alors l’amplificateur à transimpédance produit un très faible bruit dans la bande de fréquence connue, lorsque son accès d’entrée est directement couplé à l’antenne passive, parce que les deux circuits grille commune sont, du point de vue du bruit produit, optimisés pour l’impédance de l’antenne passive.If the first amplifying device and the fourth amplifying device are each a well-chosen low-noise N-channel transistor, and if the second amplifying device and the third amplifying device are each a low-noise P-channel transistor well-chosen low noise, then the transimpedance amplifier produces very low noise in the known frequency band, when its input port is directly coupled to the passive antenna, because the two common gate circuits are, from the point of view of the noise produced, optimized for the impedance of the passive antenna.

Troisième mode de réalisation. Third embodiment .

Au titre d’un troisième mode de réalisation d’un dispositif selon l’invention, donné à titre d’exemple non limitatif, nous avons représenté sur la et la un schéma simplifié d’un amplificateur selon l’invention procurant une transimpédance dans une bande de fréquence connue, la bande de fréquence connue étant la bande 9 kHz à 30 MHz, l’amplificateur comportant :As a third embodiment of a device according to the invention, given by way of non-limiting example, we have represented on the and the a simplified diagram of an amplifier according to the invention providing transimpedance in a known frequency band, the known frequency band being the 9 kHz to 30 MHz band, the amplifier comprising:

an input port (1) having a first terminal (11) and a second terminal (12), the second terminal being directly coupled to a reference conductor;
a first amplifying device (21) comprising an NPN transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a base of the NPN transistor, the second terminal being directly coupled to an emitter of the transistor NPN, the third terminal being directly coupled to a collector of the NPN transistor, the second terminal being coupled to the first terminal of the input port;
a second amplifier device (22) comprising a PNP transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a base of the PNP transistor, the second terminal being directly coupled to an emitter of the transistor PNP, the third terminal being directly coupled to a collector of the PNP transistor, the second terminal being coupled to the first terminal of the input port;
a third amplifying device (23) comprising a PNP transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a base of the PNP transistor, the second terminal being directly coupled to an emitter of the transistor PNP, the third terminal being directly coupled to a collector of the PNP transistor, the first terminal being coupled to the third terminal of the first amplification device;
a fourth amplifying device (24) comprising an NPN transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a base of the NPN transistor, the second terminal being directly coupled to an emitter of the transistor NPN, the third terminal being directly coupled to a collector of the NPN transistor, the first terminal being coupled to the third terminal of the second amplification device, the third terminal being coupled to the third terminal of the third amplification device;
a first capacitor (31) having a first terminal and a second terminal, the first terminal being coupled to the first terminal of the first amplifying device, the second terminal being coupled to the reference conductor;
a second capacitor (32) having a first terminal and a second terminal, the first terminal being coupled to the first terminal of the second amplifier device, the second terminal being coupled to the reference conductor;
one or more means including a first differential amplifier comprising two NPN transistors (4101) (4102) and a resistor (4103), for creating a first closed loop control in which a controlled quantity is a bias voltage between the third terminal of the third amplifier device and the reference conductor, an output of the first differential amplifier being coupled to the first terminal of the first amplifier device;
one or more means including a second differential amplifier comprising two PNP transistors (4201) (4202) and a resistor (4203), for creating a second closed loop control in which a controlled quantity is a bias voltage between the third terminal of the second amplifier device and the reference conductor, an output of the second differential amplifier being coupled to the first terminal of the second amplifier device;
one or more means for creating feedback, the one or more means for creating feedback comprising three resistors (51) (52) (53), the feedback determining the transimpedance in the known frequency band;
an output port (7) having a first terminal (71) and a second terminal (72), the second terminal of the output port being directly coupled to the reference conductor;
a positive feed line (91), a voltage between the positive feed line and the reference conductor being positive and stable; And
a negative feed line (92), a voltage between the negative feed line and the reference conductor being negative and stable.

La et la comportent chacune trois symboles de continuation, un couplage direct existant entre symboles de continuation contenant la même lettre. Ainsi, les deux symboles de continuation contenant la lettre A (93) sont connectés l’un à l’autre, les deux symboles de continuation contenant la lettre B (94) sont connectés l’un à l’autre, et les deux symboles de continuation contenant la lettre C (95) sont connectés l’un à l’autre.There and the each have three continuation symbols, a direct coupling existing between continuation symbols containing the same letter. Thus, the two continuation symbols containing the letter A (93) are connected to each other, the two continuation symbols containing the letter B (94) are connected to each other, and the two symbols continuation containing the letter C (95) are connected to each other.

Le spécialiste voit que le circuit représenté sur la est un amplificateur de puissance ayant, dans la bande de fréquence connue, un gain en tension inférieur ou égal à 1, et une impédance d’entrée qui est bien plus grande que son impédance de sortie, la première borne de l’accès de sortie étant directement couplée à une borne de sortie de l’amplificateur de puissance, une borne d’entrée de l’amplificateur de puissance étant couplée à la troisième borne du troisième dispositif d’amplification et à la troisième borne du quatrième dispositif d’amplification.The specialist sees that the circuit represented on the is a power amplifier having, in the known frequency band, a voltage gain less than or equal to 1, and an input impedance which is much greater than its output impedance, the first terminal of the output port being directly coupled to an output terminal of the power amplifier, an input terminal of the power amplifier being coupled to the third terminal of the third amplifying device and to the third terminal of the fourth amplifying device.

Le spécialiste voit que les dits un ou plusieurs moyens incluant un premier amplificateur différentiel comportant deux transistors NPN (4101) (4102) et une résistance (4103), pour créer une première commande en boucle fermée, incluent aussi deux résistances (8101) (8102), un condensateur (8103), et ledit amplificateur de puissance. Dans ledit amplificateur de puissance, deux résistances (8104) (8105) sont utilisées pour capter, au noeud correspondant aux deux symboles de continuation contenant la lettre C (95), un potentiel très proche d’un potentiel de la troisième borne du troisième dispositif d’amplification. Le spécialiste comprend donc qu’une tension de polarisation entre la troisième borne du troisième dispositif d’amplification et le conducteur de référence est bien une grandeur commandée par la première commande en boucle fermée.The specialist sees that said one or more means including a first differential amplifier comprising two NPN transistors (4101) (4102) and a resistor (4103), for creating a first closed loop control, also include two resistors (8101) (8102 ), a capacitor (8103), and said power amplifier. In said power amplifier, two resistors (8104) (8105) are used to pick up, at the node corresponding to the two continuation symbols containing the letter C (95), a potential very close to a potential of the third terminal of the third device of amplification. The specialist therefore understands that a bias voltage between the third terminal of the third amplification device and the reference conductor is indeed a quantity controlled by the first closed-loop control.

Le spécialiste voit que les dits un ou plusieurs moyens incluant un second amplificateur différentiel comportant deux transistors PNP (4201) (4202) et une résistance (4203), pour créer une deuxième commande en boucle fermée, incluent aussi deux résistances (8201) (8202), et un condensateur (8203). La résistance (8201) est utilisée pour capter, à la deuxième borne du quatrième dispositif d’amplification, un potentiel présentant une différence presque constante avec un potentiel de la troisième borne du deuxième dispositif d’amplification. Le spécialiste comprend donc qu’une tension de polarisation entre la troisième borne du deuxième dispositif d’amplification et le conducteur de référence est bien une grandeur commandée par la deuxième commande en boucle fermée.The specialist sees that said one or more means including a second differential amplifier comprising two PNP transistors (4201) (4202) and a resistor (4203), for creating a second closed loop control, also include two resistors (8201) (8202 ), and a capacitor (8203). The resistor (8201) is used to pick up, at the second terminal of the fourth amplifying device, a potential having an almost constant difference with a potential of the third terminal of the second amplifying device. The specialist therefore understands that a bias voltage between the third terminal of the second amplification device and the reference conductor is indeed a quantity controlled by the second closed-loop control.

Le spécialiste comprend que ladite transimpédance est mesurée entre l’accès d’entrée et l’accès de sortie. Le spécialiste comprend comment ladite rétroaction détermine la transimpédance dans la bande de fréquence connue. A n’importe quelle fréquence dans la bande de fréquence connue, la rétroaction est telle qu’un module de la transimpédance est voisin de 257 ohms.The specialist understands that said transimpedance is measured between the input port and the output port. The specialist understands how said feedback determines the transimpedance in the known frequency band. At any frequency within the known frequency band, the feedback is such that one modulus of the transimpedance is close to 257 ohms.

A 1 MHz, un module d’une impédance présentée par l’accès d’entrée est d’environ 78 milliohms, mais si ladite rétroaction est enlevée en enlevant la résistance (51), le module de l’impédance présentée par l’accès d’entrée est d’environ 2 ohms. Par conséquent, nous pouvons dire que la rétroaction réduit un module d’une impédance présentée par l’accès d’entrée dans la bande de fréquence connue.At 1 MHz, a module of an impedance presented by the input port is approximately 78 milliohms, but if said feedback is removed by removing the resistor (51), the module of the impedance presented by the port input is approximately 2 ohms. Hence, we can say that the feedback reduces a module of an impedance presented by the input port in the known frequency band.

Le spécialiste comprend que, si l’accès d’entrée de l’amplificateur selon l’invention est directement couplé à un accès d’une antenne passive qui est un cadre monospire ou un cadre blindé monospire, petit devant une longueur d’onde dans le vide correspondant à une borne supérieure de la bande de fréquence connue, la rétroaction créée par les trois résistances (51), (52) et (53) est négative dans la bande de fréquence connue, et appropriée pour : déterminer, à toute fréquence dans la bande de fréquence connue, la transimpédance de l’amplificateur selon l’invention, un module de la transimpédance de l’amplificateur selon l’invention étant sensiblement indépendant de la fréquence, dans la bande de fréquence connue ; et réduire, à certaines fréquences dans la bande de fréquence connue, un module d’une impédance d’entrée de l’amplificateur selon l’invention, le module de l’impédance d’entrée de l’amplificateur selon l’invention étant, à toute fréquence dans la bande de fréquence connue, beaucoup plus petit qu’un module de l’impédance de l’antenne passive. Toutefois, la rétroaction créée par les trois résistances (51), (52) et (53) est, aux basses fréquences et à la fréquence nulle, trop faible pour procurer une polarisation convenable du troisième dispositif d’amplification et du quatrième dispositif d’amplification. Le spécialiste comprend que ce n’est pas un problème, parce que : la première commande en boucle fermée est telle que la tension de polarisation entre la troisième borne du troisième dispositif d’amplification et le conducteur de référence est voisine de zéro volt, par exemple zéro volt plus ou moins dix millivolts ; et la deuxième commande en boucle fermée est telle que la tension de polarisation entre la troisième borne du deuxième dispositif d’amplification et le conducteur de référence est voisine d’une tension voulue déterminée par les résistances (8201) et (8202), et par la tension entre la ligne d’alimentation positive et le conducteur de référence. Ainsi, le premier dispositif d’amplification, le deuxième dispositif d’amplification, le troisième dispositif d’amplification et le quatrième dispositif d’amplification sont convenablement polarisés.The specialist understands that, if the input port of the amplifier according to the invention is directly coupled to a port of a passive antenna which is a single-spiral frame or a single-spiral shielded frame, small compared to a wavelength in the vacuum corresponding to an upper limit of the known frequency band, the feedback created by the three resistors (51), (52) and (53) is negative in the known frequency band, and suitable for: determining, at any frequency in the known frequency band, the transimpedance of the amplifier according to the invention, a module of the transimpedance of the amplifier according to the invention being substantially independent of the frequency, in the known frequency band; and reducing, at certain frequencies in the known frequency band, a module of an input impedance of the amplifier according to the invention, the module of the input impedance of the amplifier according to the invention being, at any frequency in the known frequency band, much smaller than a passive antenna impedance module. However, the feedback created by the three resistors (51), (52) and (53) is, at low frequencies and at zero frequency, too weak to provide suitable biasing of the third amplifier device and the fourth amplifier device. amplification. The specialist understands that this is not a problem, because: the first closed-loop control is such that the bias voltage between the third terminal of the third amplification device and the reference conductor is close to zero volts, for example zero volts plus or minus ten millivolts; and the second closed-loop control is such that the bias voltage between the third terminal of the second amplification device and the reference conductor is close to a desired voltage determined by the resistors (8201) and (8202), and by the voltage between the positive supply line and the reference conductor. Thus, the first amplifying device, the second amplifying device, the third amplifying device and the fourth amplifying device are suitably biased.

Les dits un ou plusieurs moyens pour créer une rétroaction pourraient aussi comporter, en plus des trois résistances (51), (52) et (53), d’autres moyens, par exemple un condensateur connecté en parallèle avec la résistance (51). Le spécialiste comprend que ceci peut parfois être utile, par exemple pour améliorer une marge de phase de cette rétroaction, et/ou pour rendre le module de la transimpédance de l’amplificateur selon l’invention plus indépendant de la fréquence, dans la bande de fréquence connue.Said one or more means for creating a feedback could also comprise, in addition to the three resistors (51), (52) and (53), other means, for example a capacitor connected in parallel with the resistor (51). The specialist understands that this can sometimes be useful, for example to improve a phase margin of this feedback, and/or to make the module of the transimpedance of the amplifier according to the invention more independent of the frequency, in the band of known frequency.

Si le premier dispositif d’amplification et le quatrième dispositif d’amplification sont chacun un transistor NPN à faible bruit bien choisi, et si le deuxième dispositif d’amplification et le troisième dispositif d’amplification sont chacun un transistor PNP à faible bruit bien choisi, alors l’amplificateur selon l’invention produit un très faible bruit dans la bande de fréquence connue, lorsque son accès d’entrée est directement couplé à l’accès de l’antenne passive, parce que les circuits base commune comportant le premier dispositif d’amplification et le deuxième dispositif d’amplification sont, du point de vue du bruit produit, optimisés pour l’impédance de l’antenne passive.If the first amplifying device and the fourth amplifying device are each a well-chosen low-noise NPN transistor, and if the second amplifying device and the third amplifying device are each a well-chosen low-noise PNP transistor , then the amplifier according to the invention produces very low noise in the known frequency band, when its input port is directly coupled to the port of the passive antenna, because the common base circuits comprising the first device amplification and the second amplification device are, from the point of view of the noise produced, optimized for the impedance of the passive antenna.

Ainsi, pour une antenne passive qui est un cadre monospire ou un cadre blindé monospire, petit devant une longueur d’onde dans le vide correspondant à une borne supérieure de la bande de fréquence connue, l’amplificateur selon l’invention est tel que : un module de l’impédance d’entrée de l’amplificateur selon l’invention est, à toute fréquence dans la bande de fréquence connue, beaucoup plus petit qu’un module de l’impédance de l’antenne passive ; un module de la transimpédance de l’amplificateur selon l’invention est sensiblement indépendant de la fréquence, dans la bande de fréquence connue ; l’accès d’entrée de l’amplificateur selon l’invention peut être directement couplé à l’accès de l’antenne passive ; et l’amplificateur selon l’invention produit un très faible bruit dans la bande de fréquence connue, lorsque son accès d’entrée est directement couplé à l’accès de l’antenne passive. Par conséquent, l’amplificateur selon l’invention est une solution aux deux problèmes expliqués ci-dessus dans la section sur l’état de la technique antérieure.Thus, for a passive antenna which is a single-spiral frame or a shielded single-spiral frame, small compared to a wavelength in vacuum corresponding to an upper limit of the known frequency band, the amplifier according to the invention is such that: a module of the input impedance of the amplifier according to the invention is, at any frequency in the known frequency band, much smaller than a module of the impedance of the passive antenna; a module of the transimpedance of the amplifier according to the invention is substantially independent of the frequency, in the known frequency band; the input port of the amplifier according to the invention can be directly coupled to the port of the passive antenna; and the amplifier according to the invention produces very low noise in the known frequency band, when its input port is directly coupled to the port of the passive antenna. Therefore, the amplifier according to the invention is a solution to the two problems explained above in the section on the state of the prior art.

INDICATIONS SUR LES APPLICATIONS INDUSTRIELLESINDUSTRIAL APPLICATION INDICATIONS

L’amplificateur selon l’invention est adapté pour être utilisé dans une antenne active comportant un cadre monospire ou un cadre blindé monospire. L’amplificateur selon l’invention est aussi adapté pour être utilisé dans l’antenne active divulguée dans la demande de brevet français numéro FR2002047 du 28 février 2020, intitulée “Antenne active comportant un cadre blindé”, et pour être utilisé dans l’antenne active divulguée dans la demande de brevet français numéro FR2004969 du 18 mai 2020, intitulée “Antenne active incluant un cadre blindé”. De telles antennes actives comportant l’amplificateur selon l’invention sont particulièrement adaptées aux mesures de champs électromagnétiques, et à la radiogoniométrie.The amplifier according to the invention is suitable for use in an active antenna comprising a single-spiral frame or a shielded single-spiral frame. The amplifier according to the invention is also suitable for use in the active antenna disclosed in French patent application number FR2002047 of February 28, 2020, entitled “Active antenna comprising a shielded frame”, and for use in the antenna antenna disclosed in French patent application number FR2004969 of May 18, 2020, entitled “Active antenna including an armored frame”. Such active antennas comprising the amplifier according to the invention are particularly suitable for measurements of electromagnetic fields, and for direction finding.

Claims

Amplifier providing transimpedance in a known frequency band, the amplifier comprising:

an input port (1) having a first terminal (11) and a second terminal (12), the second terminal being directly coupled to a reference conductor;
a first amplifying device (21) comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being positive, a current leaving the second terminal and a current entering the third terminal being positive and controlled by a voltage between the first terminal and the second terminal, the second terminal being coupled to the first terminal of the input port;
a second amplifying device (22) comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being negative, a current leaving the second terminal and a current entering the third terminal being negative and controlled by a voltage between the first terminal and the second terminal, the second terminal being coupled to the first terminal of the input port;
a third amplifying device (23) comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being negative, a current leaving the second terminal and a current entering the third terminal being negative and controlled by a voltage between the first terminal and the second terminal, the first terminal being coupled to the third terminal of the first amplification device;
a fourth amplifier device (24) comprising a transistor, a first terminal, a second terminal and a third terminal, the first terminal being directly coupled to a control electrode of the transistor, a voltage between the third terminal and the second terminal being positive, a current leaving the second terminal and a current entering the third terminal being positive and controlled by a voltage between the first terminal and the second terminal, the first terminal being coupled to the third terminal of the second amplifying device, the third terminal being coupled to the third terminal of the third amplifying device;
a first capacitor (31) having a first terminal and a second terminal, the first terminal being coupled to the first terminal of the first amplifying device, the second terminal being coupled to the reference conductor;
a second capacitor (32) having a first terminal and a second terminal, the first terminal being coupled to the first terminal of the second amplifier device, the second terminal being coupled to the reference conductor;
one or more means, including a first differential amplifier (41) having at least two transistors, for creating a first closed-loop control in which a controlled quantity is a bias voltage between the third terminal of the third amplifying device and the conductor of reference, an output of the first differential amplifier being in a first case coupled to the first terminal of the first amplification device, or in a second case coupled to the first terminal of the second amplification device;
one or more means, including a second differential amplifier (42) comprising at least two transistors, for creating a second closed-loop control in which a controlled quantity is in said first case a bias voltage between the third terminal of the second amplifier device and the reference conductor, or in said second case a bias voltage between the third terminal of the first amplifying device and the reference conductor, an output of the second differential amplifier being in said first case coupled to the first terminal of the second device amplification, or in said second case coupled to the first terminal of the first amplification device; And
one or more means for creating feedback, the feedback determining the transimpedance in the known frequency band, the feedback reducing a modulus of an impedance presented by the input port in the known frequency band.

An amplifier according to claim 1, further comprising a power amplifier (6), an input terminal of the power amplifier being coupled to the third terminal of the third amplifier device and to the third terminal of the fourth amplifier device. amplification.

An amplifier according to claim 1, further comprising an output port (7) having a first terminal (71) and a second terminal (72), the second terminal of the output port being directly coupled to the reference conductor, said transimpedance being measured between the input port and the output port.

An amplifier according to claims 2 and 3, wherein the first terminal of the output port is directly coupled to an output terminal of the power amplifier.

Amplifier according to any one of Claims 2 or 4, in which the power amplifier has, in the known frequency band, a voltage gain less than or equal to 1.

An amplifier according to any one of claims 1 to 5, wherein the first amplifying device is an NPN bipolar transistor having a base, an emitter and a collector, the first terminal of the first amplifying device being the base of the bipolar transistor NPN, the second terminal of the first amplifying device being the emitter of the NPN bipolar transistor, the third terminal of the first amplifying device being the collector of the NPN bipolar transistor; and wherein the second amplifying device is a PNP bipolar transistor having a base, an emitter and a collector, the first terminal of the second amplifying device being the base of the PNP bipolar transistor, the second terminal of the second amplifying device being the emitter of the PNP bipolar transistor, the third terminal of the second amplifying device being the collector of the PNP bipolar transistor.

An amplifier according to any one of claims 1 to 5, wherein the first amplifying device is an N-channel field effect transistor having a gate, a source and a drain, the first terminal of the first amplifying device being the gate of the N-channel field effect transistor, the second terminal of the first amplifier device being the source of the N-channel field effect transistor, the third terminal of the first amplifier device being the drain of the effect transistor N-channel field; and wherein the second amplifying device is a P-channel field effect transistor having a gate, a source and a drain, the first terminal of the second amplifying device being the gate of the P-channel field effect transistor , the second terminal of the second amplifying device being the source of the P-channel field-effect transistor, the third terminal of the second amplifying device being the drain of the P-channel field-effect transistor.

An amplifier according to any one of claims 1 to 7, wherein the third amplifying device is a PNP bipolar transistor having a base, an emitter and a collector, the first terminal of the third amplifying device being the base of the bipolar transistor PNP, the second terminal of the third amplifying device being the emitter of the PNP bipolar transistor, the third terminal of the third amplifying device being the collector of the PNP bipolar transistor; and wherein the fourth amplifying device is an NPN bipolar transistor having a base, an emitter and a collector, the first terminal of the fourth amplifying device being the base of the NPN bipolar transistor, the second terminal of the fourth amplifying device being the emitter of the NPN bipolar transistor, the third terminal of the fourth amplifying device being the collector of the NPN bipolar transistor.

An amplifier according to any one of claims 1 to 7, wherein the third amplifying device is a P-channel field effect transistor having a gate, a source and a drain, the first terminal of the third amplifying device being the gate of the P-channel field effect transistor, the second terminal of the third amplifying device being the source of the P-channel field effect transistor, the third terminal of the third amplifying device being the drain of the effect transistor P-channel field; and wherein the fourth amplifier device is an N-channel field effect transistor having a gate, a source and a drain, the first terminal of the fourth amplifier device being the gate of the N-channel field effect transistor , the second terminal of the fourth amplifier device being the source of the N-channel field effect transistor, the third terminal of the fourth amplifier device being the drain of the N-channel field effect transistor.