FR2963140A1 - Contactless microcircuit device e.g. microcircuit module, for microcircuit card, has unit referencing potentials with respect to reference potential, where unit is effective at supply frequency and ineffective at communication frequency - Google Patents

Abstract

The device (16) has a near field communication antenna (32) generating voltage between terminals of a microcircuit (14) by an electromagnetic coupling with an external terminal (100). A unit references potentials with respect to predetermined reference potential. The potentials referencing unit is effective at supply frequency and ineffective at communication frequency, where the communication frequency is defined by ISO 14. The microcircuit and the antenna form a part of an oscillating assembly (35).

Description

The present invention relates to the technical field of non-contact type electronic devices comprising an antenna for establishing a near-field communication with an external terminal. Such devices are generally portable and are able to exchange data with the external terminal by electromagnetic coupling. The invention also applies to any type of portable or pocket electronic devices incorporating such an antenna, such as a USB key, an RFID (acronym for "Radio Frequency IDentity"), a smart card, etc. . The invention applies more particularly, but not exclusively, to microcircuit cards provided with an antenna, such as so-called non-contact cards making it possible to establish a contactless communication at a predefined communication frequency, such as, for example, the frequency 13 , 56 MHz 20 defined by the ISO 14 443 standard, with an external terminal. It also applies to so-called hybrid or dual cards, making it possible to establish, in addition to contactless communication, contact communication via an interface of external contacts able to come into contact with a suitable reader. In general, the device is devoid of autonomous power. To function, it comprises for example an oscillating circuit, formed in particular by the near-field communication antenna and a microcircuit connected to the antenna, capable of being coupled magnetically with an oscillating circuit of the external terminal. To exchange data with the external terminal, the oscillating circuit of the device is generally tuned to a frequency, so-called

communication frequency, corresponding to a frequency of reception and transmission of data by the terminal. The microcircuit comprises for example a variable component allowing adjustment of the resonant frequency of the oscillating circuit of the device to the communication frequency. For example, the communication frequency is the frequency of 13.56 MHz defined by ISO 14 443. There is a constant need to reduce the dimensions of the antenna to facilitate its integration on reduced media, such as for example a SIM card in ID-000 format.

However, reducing the size of the antenna often has the consequence of significantly degrading the performance of the device, particularly in terms of range, that is to say maximum distance for communication between the device and the external terminal. It is known from the state of the art, in particular document FR 2 938 095, to incorporate an antenna gain amplifier into a support incorporating the antenna to compensate for a possible decrease in the performance of the antenna related to the antenna. the reduction of the useful surface of the latter. In this document, the antenna gain amplifier is in the form of a ground plane. In order to function, the antenna gain amplifier is arranged next to the antenna, outside the external contour of the antenna. As a result, the assembly comprising the antenna and the antenna gain amplifier is relatively bulky and that the space gained by reducing the size of the antenna is lost in favor of the gain amplifier. The invention aims in particular to provide a microcircuit device comprising a near field communication antenna in which the performance of the antenna are improved with simple means and space-saving. For this purpose, the subject of the invention is a microcircuit device comprising a near-field communication antenna capable of generating

a voltage between the first and second terminals of the microcircuit by electromagnetic coupling with an external terminal, for feeding the microcircuit to a supply frequency and the data exchange between the microcircuit and the terminal at a communication frequency, characterized in that, the voltage being defined by the difference between first and second electrical potentials respectively of the first and second terminals, the device comprises means for referencing the first and second potentials with respect to a predetermined reference potential configured to be effective at least at the power frequency and ineffective at least at the communication frequency. The invention makes it possible to improve the performance of the antenna with a completely different approach than that conventionally proposed in the state of the art. The invention is essentially based on the distinction between the operation of the microcircuit at the communication frequency and the operation of the microcircuit at another frequency, called the supply frequency. The invention thus proposes to reduce the noise disturbing the supply voltage of the microcircuit by means of a stabilization of the electrical potentials at the supply frequency with respect to a reference potential. When the microcircuit is unpowered, that is to say out of reach of the magnetic field of the terminal, the oscillating circuit of the device is tuned with respect to the supply frequency and is then detuned with respect to the communication frequency.

By entering the magnetic field of the terminal, the oscillating circuit of the device resonates with the supply frequency and generates a voltage across the microcircuit allowing the activation of the latter. The microcircuit thus powered will be able to tune the resonant frequency to the communication frequency thus allowing data exchange at this same frequency. Thanks to the invention, by stabilizing the input electrical potentials of the microcircuit at the supply frequency, it is possible to improve

substantially the performance of the antenna including allowing a significant increase in the reading distance, by noise reduction. Thus, to exchange data with an external terminal via the antenna, the voltage generated between the input terminals at the communication frequency is electrically isolated from the reference terminal. It is desirable that the potentials are not stabilized at the communication frequency because this would have the effect of degrading very significantly the quality of the data exchange, or even make it virtually impossible any data exchange. Indeed, the microcircuit receives and transmits data according to the back-modulation principle, for example by varying an internal load connected between the two input terminals, and the stabilization of the potentials at its two terminals would have the effect of disrupt this dynamic voltage at the input terminals of the microcircuit which is essential for optimal data exchange. In addition, the referencing means may be in the form of an electronic circuit which can be easily arranged near the antenna in a small space unlike the gain amplifiers of the antenna operating by magnetic coupling with the terminal .

In a preferred embodiment, the referencing means comprise a member adapted to electrically connect, at the supply frequency, a point of the antenna to a reference terminal carried at a ground potential of the device and to electrically isolate the communication frequency the point of the reference terminal.

The stabilization of the electrical potentials is thus achieved by referencing the supply voltage of the microcircuit to the supply frequency with respect to a potential of the device. This amounts to forming a differential signal supply source of the microcircuit, at the supply frequency.

In other words, the referencing means and the antenna form a differential signal supply source at least at the frequency

power supply and a floating power source at least at the communication frequency. In a preferred embodiment of the invention, the member comprises a parallel resonance type filter centered on the communication frequency.

The filter makes it possible to passively block the electrical signals oscillating at the communication frequency and let the electrical signals pass at the other frequencies, and in particular at the supply frequency. The stabilization circuit thus operates for a large number of power frequencies without requiring adaptation of the filter.

Preferably, the filter comprises a coil and a capacitor connected in parallel. In a preferred embodiment, the device comprises a body made of a dielectric material and the capacitor comprises two armatures arranged vis-à-vis one another in the body.

Preferably, the support body, the armatures of the capacitor are formed by depositing a metallic material on each side of the support or on each side of a layer or a stack of layers forming the support. Such an arrangement of the capacitor is particularly well suited to applications in which the support is thin. Preferably, the coil is formed by a winding of electrically conductive turns and / or a CMS component. In a particular embodiment, the device comprises a support delimiting first and second opposite faces, one of the faces carrying the antenna and the other of the faces carrying the coil. In a preferred embodiment, the coil is formed by a winding of electrically conductive turns and or a CMS component. Preferably, the device comprises a support delimiting first and second opposite faces, one of the faces carries the antenna and the other of the faces carries the coil. Such an arrangement is particularly advantageous in devices with high spatial constraints.

In a preferred embodiment, the point of the antenna is positioned on the antenna so that the voltage defined by the difference between the first potential and the ground potential on the one hand and the voltage defined by the difference between the second potential and the mass potential on the other hand are substantially balanced. Such an arrangement makes it possible to optimize the performance of the device. Indeed, it is desirable for the differential signal supply source thus obtained to produce impedances as close as possible between the first input terminal and the reference terminal on the one hand, and between the second input terminal and the reference terminal on the other hand. In addition, it is also desirable for the differential signal supply source to produce opposite instantaneous voltages between the first terminal and the reference terminal on the one hand and the second terminal and the reference terminal on the other hand.

The power source is in this case called balanced or symmetrical which further improves the performance of the device. Preferably, the point of the antenna is positioned equidistant from two ends of the antenna respectively connected to the first and second terminals of the microcircuit.

This makes it possible to obtain in a simple manner a symmetrical differential signal supply source in the case where the antenna itself has a symmetrical configuration. In a preferred embodiment, the reference terminal is a third terminal of the microcircuit and the reference terminal is brought to a ground potential of the microcircuit. For example, the microcircuit comprises a plurality of connection terminals including the two input terminals. It also preferably comprises a third terminal which is a reference terminal of all the internal circuits of the microcircuit. Preferably, the terminal transmits and / or receives data at the communication frequency, the frequency being for example that defined by the ISO 14 443 standard at 13.56 MHz.

Preferably, the microcircuit and the antenna forming at least a portion of a first oscillating circuit of the device, the supply frequency corresponds to a resonance frequency of this first circuit when the microcircuit is unpowered.

In the example described, the device comprises an interface of external contacts in accordance with the ISO 7816 standard of microcircuit cards and the reference terminal is electrically connected to the contact C5. In a preferred embodiment, the device is a microcircuit module, the module comprising a support carrying the antenna, the microcircuit and the stabilization means. The invention also relates to a microcircuit card comprising a body provided with a receiving cavity of a microcircuit module, characterized in that the module is according to the invention. Other features and advantages of the invention will become apparent in the light of the description which follows, made with reference to the accompanying drawings, in which: FIG. 1 represents a top view of a microcircuit card according to the invention; Figure 2 shows a sectional view of the map of Figure 1 along the line 2-2; FIG. 3 represents a view from above of a microcircuit module of the card of FIG. 1; FIG. 4 represents a view from below of the microcircuit module of the card of FIG. 1; FIGS. 5 to 7 show electrical diagrams of the electronic circuits carried by the microcircuit module of FIGS. 1 to 3. FIG. 1 shows a microcircuit device according to the invention. This device is designated by the general reference 10.

In the example described in this application, the microcircuit device 10 is a microcircuit card. Alternatively, the device can be

a page of a passport such as the cover of the passport or a self-adhesive label such as a "sticker". As shown in Figure 1, the device 10 comprises a body 12 in the general form of a card delimiting first 12A and second 12B opposite faces. In this embodiment, this body 12 delimits the external dimensions of the card 10. In this example and preferably, the dimensions of the card 10 are defined by the ID-1 format of the ISO 7816 standard which is the conventionally used format. for bank cards of dimensions 86 mm by 54 mm. Of course, other card formats may also be used. Preferably, the card body 12 is shaped by lamination, that is to say by forming, for example by means of a press and in a hot lamination operation, a stack of layers or sheets. laminates made for example of thermoplastic material. For example, in this embodiment, the body 12 comprises a stack of at least three layers: a central layer forming a data printing layer interposed between two transparent outer layers. Alternatively, the body may be shaped by molding, for example plastic. In a conventional manner, the device 10 comprises a microcircuit 14 able to exchange, process and / or store data. In a preferred embodiment, the body 12 comprises a microcircuit module 16 incorporating the microcircuit 14. Preferably, all the electronic circuits of the device 10 is integrated in a single chip 14 or microcircuit. In the example described, the module 16 comprises a support 18 carrying the microcircuit 14. Thus, as illustrated in FIG. 2, the support 18 defines first 18A and second 18B opposite faces, referred to respectively as the outer face and the inner face, the outer face 18A being turned towards the outside of the card 10. The support 18 is, for example, made of fiber

epoxy type of glass, polyester or paper and has a thickness for example between one hundred and two hundred micrometers. In addition, in this example, as illustrated in FIG. 2, the body 12 comprises a housing 20 of the module 16.

The cavity 20 comprises for example a deep central zone 22 provided with a bottom 24 for housing the microcircuit 14 and an elevated peripheral zone 26 with respect to the central zone 22 delimiting a step 28 with the bottom 24. This peripheral zone 26 comprises a bearing surface raised relative to the bottom of the cavity 20 on which the edges of the support 18 of the module 16 rest. Such a cavity 20 is generally obtained by machining, typically by milling or counterboring in two operations: a large countersink to form the peripheral zone 26 corresponding to the depth of the step, a small countersink to form the deeper central zone 24. In order to communicate with an external terminal, the card 10 comprises, for example, an external interface 30 of contact pads electrically connected to the microcircuit 14 This interface 30 makes it possible to establish contact communication with the card 10, for example when the card 10 is inserted into a card. adapted card reader. This interface 30 comprises for example a series of metal pads of electrical contacts, in accordance with a predefined standard microcircuit card. For example, the contact pads are in accordance with ISO 7816. In this embodiment, the contact pads of the interface 30 correspond to the contacts C1, C2, C3, C5, C6, C7 of ISO 7816. The interface 30 of the card 10 is preferably made of a layer of metallic material such as copper but may also be made, alternatively, by screen printing conductive ink of the epoxy type loaded with silver particles or or by screen printing an electrically conductive polymer. Preferably, the ranges are electrically connected to the microcircuit 14 by electrically conductive wires (not

shown) such as for example gold son through via formed in the support 18 of the module 16, themselves connected to electrically conductive tracks links extending on the inner face 18B of the support 18. These tracks n ' have not been shown in Figure 4.

In this embodiment, the card 10 is of dual type, that is to say it comprises both a contactless interface capable of establishing a near-field communication with an external terminal and a suitable contact interface. to establish a communication with another external terminal by contact. However, in a variant, the card 10 may only be of the non-contact type. In this case, the card 10 is preferably devoid of the interface of external contacts 30. For this purpose, for the establishment of a communication without contact with an external terminal 100, such as an external reader, the device 10 still includes a near field communication antenna 32.

The antenna 32 is, in this embodiment, formed by a winding of electrically conductive turns of increasing circumferences. Preferably, the antenna 32 is arranged in the microcircuit module 16. For example, the antenna 32 extends on the face 18B carrying the microcircuit 14. Preferably and in this embodiment, the antenna 32 is extends around the periphery of the module support 18. The antenna 32 is in this example spirally wound around the microcircuit 14. The module support 16 has for example a generally rectangular shape and the antenna 32 runs along the periphery of the support 18 In the example illustrated in the figures, the support 18 has a generally oblong shape. In Figure 4, there is shown only two turns of the antenna 32 for reasons of simplicity. However, the antenna 32 may comprise a larger number of turns and the overall shape of the turns may vary depending on the geometry of the support 18 carrying the antenna 32.

Preferably, the antenna 32 comprises first 32A and second 32B ends respectively connected to first 14A and

second 14B input terminals of the microcircuit 14. These input terminals 14A, 14B are formed for example by connection pads of the microcircuit 14. More specifically, the antenna 32 is able to generate a voltage between the first 14A and second 14B input terminals by electromagnetic coupling with an external terminal 100. The voltage thus generated is defined in particular by the difference between first and second electrical potentials respectively of the first 14A and second 14B terminals. Thus, VA will denote the first electrical potential of the first terminal 14A and VB the second electric potential of the second terminal 14B.

In the example described, the magnetic field emitted by the external terminal 100 supplies the energy intended to supply the microcircuit 14 at a supply frequency f1 and serves as a support for the exchange of data between the microcircuit 14 and the microcircuit 14. terminal 100 at a communication frequency f2. FIG. 5 shows an electrical diagram of a data exchange system comprising the terminal 100 and the electronic device 10. As illustrated in FIG. 5, the external terminal 100 comprises a first oscillating circuit 102 formed by an inductor L1 in series with a resistor R1 forming the antenna 104 of the terminal 100. The circuit 102 also comprises two capacitors Cal and Cal 'forming impedance matching means 106 of the inductance L1. The circuit 102 is for example powered by an electrical source 108, such as an electrical distribution network. On the side of the card 10, the near-field communication antenna 32 has been schematized by an inductance L2 and a resistor R2. The microcircuit 14 also comprises a variable component 34 such as for example a variable capacity capacitor C2 mounted between the two input terminals. This capacitor C2 forms with the inductor L2 a second parallel oscillating circuit 35 for sensing the magnetic field generated by the first oscillating circuit 102 of the external terminal 100.

The terminal 100 transmits and / or receives data preferably at the communication frequency which corresponds, for example, to the resonant frequency of the oscillating circuit of the terminal 100. In general, and preferably, the resonant circuit L2, C2 of the electronic device 10 is adapted to be tuned to the resonant frequency of the oscillating circuit L1, C1 of the external terminal 100 by adjusting the capacitance of the capacitor C2. The resonant frequency of the first circuit 102 is generally 13.56 megahertz in accordance with the ISO 14443 standard. Furthermore, in order to allow data exchange, the microcircuit 14 comprises a load retro-modulation stage comprising a resistor. modulation R3 connected in series to a switch K3 (for example a transistor) and a resistor R4 connected in parallel with this branch. The resistor R4 corresponds in this example to the charge of the microcircuit 14.

Opening and closing the switch K3 according to the modulation introduced by the data to be transmitted at a retro-modulation frequency alternately switches the charging impedance of the card 10 from R3 to R4. The retro-modulation frequency has, for example, in accordance with the standard in force, a value of 847 kilohertz. This retro-modulation is for example based on a type of BPSK (acronym for "Binary Phase Shift Keying"). According to the invention, the communication frequency f2 and the supply frequency f1 of the microcircuit 14 are distinct. In this embodiment, the supply frequency f1 is defined as a resonant frequency of the electronic device 10 in an inactive mode of the microcircuit 14 (or standby mode), that is to say when the device is located off scope of the external terminal 100 and its magnetic field and is thus unpowered. This resonance frequency depends for example on electrical and physical parameters of the card 10 or the module 16 such as, for example, the dimensions of the antenna (width, length), the internal circuits of the microcircuit, etc. In this example, this resonance frequency is set to about sixteen megahertz.

According to the invention, the device 10 further comprises means 40 for referencing the first potential VAs and second VBs with respect to a predetermined reference potential, configured to be effective at least at the f1 and ineffective power frequency at least at the communication frequency f2. For example, the first and second potentials VA and VB are stabilized at least at the supply frequency f1 whereas they are said to be floating at the communication frequency f2. Preferably, and as illustrated in FIG. 5, the stabilization means 40 comprise a member 42 able to electrically connect the supply frequency f1 to a point of the antenna 321 to the reference terminal 14M and to electrically isolate it from the communication frequency f2 is the point 321 of the reference terminal 14M. This reference terminal 14M generates, for example, the predetermined reference potential VM. Preferably, the reference potential is fixed. In this example, reference terminal 14M is a third terminal of microcircuit 14. For example, reference terminal 14M is electrically connected to contact C5 as illustrated in FIG. potential of all the electronic circuits of the microcircuit 14. In a preferred embodiment, the member 42 comprises a filter 44 of the parallel resonance type, also referred to as the "plug circuit", and centered on the frequency of communication f2. Conventionally and preferably, the filter 44 comprises a coil 46 and a capacitor 48 connected in parallel, as illustrated in FIG. 5. This filter 44 is preferably centered on the communication frequency f2, that is to say say on the frequency of 13.56 megahertz. In a manner known per se, a parallel resonance filter 44 has an infinite impedance at a predefined frequency and prevents the flow of current at this frequency. Thus, FIGS. 6 and 7 show equivalent electrical diagrams of the system at the supply frequency f1 (FIG. 6) and FIG.

communication frequency f2 (FIG. 7). Thus, at the communication frequency f2, the filter 44 behaves as an open switch while at the supply frequency f1 and for frequencies different from the communication frequency f2, the filter 44 behaves as a closed circuit connecting electrically the point 321 of the antenna 32 and the reference terminal 14M. Thus, the microcircuit 14 is powered at the supply frequency f1 in the mode that can be referred to as differential, that is to say that the supply voltage corresponds to the difference between the voltage between on the one hand terminal 14A and reference terminal 14M and secondly between terminal 14B and reference terminal 14M. Preferably, the point of the antenna 321 is positioned on the antenna 32 so that the voltage defined by the difference between the first potential VA and the reference potential VM on the one hand and the voltage defined by the difference between the second potential and the reference potential VM on the other hand is substantially balanced. For example, the point 321 of the antenna 32 is positioned equidistant from the two ends 32A, 32B of the antenna 32 respectively connected to the first 14A and second 14B terminals of the microcircuit 14.

This makes it possible to obtain optimum performance of the antenna circuit by substantially balancing the impedances between the point 321 of the antenna 32 and each of the input terminals 14A, 14B of the microcircuit 14. It is said that the input (of the microcircuit 14) is balanced (or symmetrical) for the frequency f1. This makes it possible to have opposite instantaneous voltages between the first terminal 14A and the reference terminal 14M on the one hand and between its second terminal 14B and the reference terminal 14M on the other hand. Preferably, and as illustrated in FIGS. 3 and 4, the capacitor 48 comprises two armatures 48A, 48B arranged facing each other in a dielectric region of the device 10.

In the embodiment illustrated in FIGS. 3 and 4, the capacitor 48 is carried by the support 18 of the module 16. For example, the

two armatures 48A, 48B extend in two substantially parallel planes of the support 18 of the module 16. Preferably, the first 48A and second 48B armatures of the capacitor 48 are formed by depositing a metallic material on each face of a layer or a stack of layers forming the support 18. The support 18 is for example made of an electrically insulating material having good dielectric properties. Many plastics known to those skilled in the art are suitable for this application. As illustrated in these figures, the armatures 48A, 48B extend for example vis-à-vis each other on the first 18A and second 18B faces of the support 18 and the support 18 forms the dielectric support . The first armature 48A extending on the face 18A is electrically connected to the point 321 of the antenna 32 by an electrically conductive track 50. The second armature 48B extending on the face 18B is electrically connected to the contact C5, itself electrically connected to the reference terminal 14M, via a via 52M formed in the support 18. Moreover, in the preferred embodiment of the invention, the coil 46 is preferably formed by a winding of electrically conductive turns. In the example illustrated in FIG. 3, the coil 46 is carried by the face 18A carrying the interface of external contacts 30. The coil 46 extends between the point 321 and the reference terminal 14M. In a variant not shown in the figures, the coil 46 is formed by a CMS component.

The principal aspects of the operation of the device of FIGS. 1 to 7 will now be described. Initially, the card 10 is out of reach of the magnetic field generated by the external terminal 100. A card holder 10 approaches, for example, the latter of the terminal 100. .

When the card 10, initially out of range of the magnetic field generated by the external terminal, is placed in the field

magnetic generated by the terminal 100, the circuit comprising the antenna 32 and the microcircuit 14 resonates at the supply frequency f1. As the potentials VA, VB are stabilized at this power supply frequency f1, the noise is reduced at this frequency which has the effect of increasing the reading distance or range. Once energized, the microcircuit 14 initially in standby or inactive mode, then goes into active mode and grants by adjusting the value of the capacity of the capacitor C2 its resonance frequency at the communication frequency f2.

Frequency selective electric potentials enhancement improves the performance of the antenna by reducing noise at the power frequency without disturbing the operation of the device at the communication frequency. It is understood that the embodiments which have just been described are not limiting and they can receive any desirable modification without departing from the scope of the invention. In particular, it would be consistent with the invention to incorporate the antenna and the microcircuit directly in a card body and not only in an electronic module. It would still be consistent with the invention to incorporate the antenna in the card body and the microcircuit in the electronic module.

Claims (17)

REVENDICATIONS1. Microcircuit device (16) comprising a near-field communication antenna (32) adapted to generate a voltage between first (14A) and second (14B) terminals of the microcircuit (14) by electromagnetic coupling with an external terminal (100), for supplying the microcircuit (14) to a supply frequency (fi) and exchanging data between the microcircuit (14) and the terminal (100) at a communication frequency (f2), characterized in that, the voltage being defined by the difference between first (VA) and second (VB) electrical potentials respectively of the first (14A) and second (14B) terminals, the device (16) comprises means (40) for referencing the first (VA) ) and second (VB) potentials with respect to a predetermined reference potential (VM) configured to be effective at least at the supply frequency (f1) and ineffective at least at the communication frequency (f2). 2. Device (16) according to the preceding claim, wherein the referencing means (40) comprise a member (42) capable of electrically connecting, at the supply frequency (fi), a point (321) of the antenna (32) to a reference terminal (14M) brought to the reference potential (VM) of the device (10) and to electrically isolate the point (321) of the reference terminal (14M) from the communication frequency (f2). 3. Device (16) according to the preceding claim, wherein the member (42) comprises a filter (44) of the parallel resonance type centered on the communication frequency (f2). 4. Device (16) according to the preceding claim, wherein the filter (44) comprises a coil (46) and a capacitor (48, 48A, 48B) connected in parallel. 5. Device (16) according to the preceding claim, comprising a body (18) made of a dielectric material, the capacitor (48) comprises two armatures (48A, 48B) arranged vis-à-vis one another in the body (18). 6. Device (16) according to the preceding claim, wherein, the support body (18), the armatures (48A, 48B) of the capacitor (48) are formed by depositing a metal material on each face (18A, 18B ) of the support (18) or on each side of a layer or stack of layers forming the support (18). 7. Device (16) according to any one of claims 4 to 6, wherein the coil (46) is formed by a winding electrically conductive turns and / or a CMS component. 8. Device (16) according to claim 4 to 7, comprising a support (18) delimiting first (18A) and second (18B) opposite faces, one (18B) of the faces carries the antenna (32) and the other (18A) faces carries the coil (46). 9. Device (16) according to any one of claims 2 to 8, wherein the point (321) of the antenna (32) is positioned on the antenna (32) so that the voltage defined by the difference between the first potential (VA) and the ground potential (VM) on the one hand and the voltage defined by the difference between the second potential (VB) and the ground potential (VM) on the other hand are substantially balanced. 10. Device (16) according to the preceding claim, wherein the point (321) of the antenna (32) is positioned equidistant from two ends (32A, 32B) of the antenna (32) respectively connected to the first (14A ) and second (14B) terminals of the microcircuit (14). 11. Device (16) according to any one of claims 2 to 10, wherein the reference terminal (14M) is a third terminal of the microcircuit (14) brought to a ground potential (VM) of the microcircuit (14). 12. Device (16) according to any one of claims 2 to 11, comprising an interface (30) of external contacts according to ISO 7816 microcircuit cards, wherein the reference terminal (14M) is electrically connected to contact C5. 13. Device (16) according to any preceding claim, wherein the terminal (100) transmits and / or receives data at the communication frequency (f2), the frequency (f2) being for example that defined by the ISO 14443 at 13.56 MHz. 14. Device (16) according to any preceding claim, wherein the microcircuit (14) and the antenna (32) form at least a portion of a first oscillating assembly (35) of the device (16), the supply frequency (fi) corresponds to the resonance frequency of this first set (35) when the microcircuit (14) is unpowered. Apparatus according to any one of the preceding claims, wherein the reference potential (VM) is substantially fixed. 16. Device (16) according to any one of the preceding claims, being a microcircuit module (16), the module (16) comprising a support (18) carrying the antenna (32), the microcircuit (14) and the stabilizing means (40). 17. Microcircuit card (10) comprising a body (12) provided with a cavity for receiving a microcircuit module, characterized in that the module (16) is according to the preceding claim.