Power supply of an electronic device

Abstract

Power supply of an electronic device The present description relates to an electronic device (100) comprising, at least: - an antenna (102) adapted to, at least, receive a radiofrequency signal; and - a control unit (101), in which, when the control unit (101) is switched off and the antenna (102) receives a radiofrequency signal, the antenna (102) provides a first voltage representative of said radiofrequency signal and supplies said control unit (101) with said voltage for the duration of the start-up of said control unit (101). Figure for the abstract: Fig. 1

Description

Title of the invention: Power supply for an electronic device Technical field

[0001] The present description relates generally to electronic circuits, devices and systems, and more particularly to electronic circuits, devices and systems equipped with an antenna adapted to, at least, receive a radiofrequency signal. The present description relates more specifically to the power supply of these electronic circuits, devices and systems. Prior art

[0002] The energy consumption of circuits, devices and systems is, nowadays, a major issue in most technical fields.

[0003] Many electronic circuits, devices and systems are adapted to adjust their energy consumption according to the operations they must implement. For this, many of them have different power supply modes, such as full power modes, low power modes or standby modes.

[0004] It would be desirable to be able to improve, at least in part, certain aspects of the power supply of electronic circuits, devices and systems. Summary of the invention

[0005] There is a need for electronic circuits, devices and systems that consume less power.

[0006] There is a need for less power consuming electronic devices suitable for receiving radio frequency waves.

[0007] There is a need for such electronic devices that consume less power during the implementation of a standby mode.

[0008] One embodiment overcomes all or part of the drawbacks of such known electronic devices.

[0009] One embodiment provides an electronic device comprising, at least: - an antenna adapted to, at least, receive a radiofrequency signal; and - a control unit, in which, when the control unit is switched off and the antenna receives a radiofrequency signal, the antenna provides a first voltage representative of said radiofrequency signal and supplies said control unit with said voltage for the duration of the start-up of said control unit.

[0010] Another embodiment provides a method of starting an electronic device comprising, at least: - an antenna suitable for, at least, receiving a radio frequency signal; and - a control unit, wherein, when the control unit is switched off and the antenna receives a radio frequency signal, the antenna provides a voltage representative of said radio frequency signal and supplies said control unit with said voltage for the duration of the start-up of said control unit.

[0011] According to one embodiment, the control unit is a processor, a microprocessor or a microcontroller.

[0012] According to one embodiment, when the start-up of said control unit is completed, the control unit is powered by a second voltage supplied by a power supply circuit of said electronic device.

[0013] According to one embodiment, the voltage representative of said radiofrequency signal is converted into a supply voltage by a conversion circuit.

[0014] According to one embodiment, the supply voltage is a direct voltage.

[0015] According to one embodiment, the conversion circuit comprises a diode bridge voltage rectifier.

[0016] According to one embodiment, when the control unit is not in use, it is turned off.

[0017] According to one embodiment, the startup of the central unit comprises the software startup of the central unit, and the startup of clock systems of the central unit, and communication of the central unit.

[0018] According to one embodiment, the device further comprises a selection circuit adapted to select a reference potential applied to the different elements of the device.

[0019] According to one embodiment, the selection circuit is adapted to select a first reference potential when the control unit is powered by the voltage representative of said radiofrequency signal, and is adapted to select a second reference potential when the control unit is powered by the power supply circuit.

[0020] According to one embodiment, the control unit is a monostable circuit.

[0021] According to one embodiment, the device further comprises a circuit adapted to the wireless communication.

[0022] According to one embodiment, said circuit adapted to wireless communication is adapted to near-field communication. Brief description of the drawings

[0023] These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments given without limitation in relation to the attached figures among which:

[0024] [Fig.l] represents, in a very schematic and simplified manner, an embodiment of an electronic device;

[0025] [Fig.2] represents a block diagram illustrating the operation of the embodiment of [Fig.l];

[0026] [Fig. 3] represents a more detailed exemplary embodiment of the embodiment of [Fig. 1]; and

[0027] [Fig.4] represents timing diagrams illustrating the operation of the exemplary embodiment of [Fig.3]. Description of the embodiments

[0028] The same elements have been designated by the same references in the different figures. In particular, the structural and / or functional elements common to the different embodiments may have the same references and may have identical structural, dimensional and material properties.

[0029] For the sake of clarity, only the steps and elements useful for understanding the embodiments described have been represented and are detailed. In particular, the computer protocols used to implement the embodiments described in the description are not described but are accessible to those skilled in the art in view of the indications present in the following description.

[0030] Unless otherwise specified, when referring to two elements connected to each other, this means directly connected without intermediate elements other than conductors, and when referring to two elements connected (in English "coupled") to each other, this means that these two elements can be connected or be connected by means of one or more other elements.

[0031] In the following description, when reference is made to absolute position qualifiers, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers, such as the terms "above", "below", "upper", "lower", etc., or to orientation qualifiers, such as the terms "horizontal", "vertical", etc., reference is made unless otherwise specified to the orientation of the figures.

[0032] Unless otherwise specified, the expressions "about", "approximately", "substantially", and "of the order of" mean to within 10%, preferably to within 5%.

[0033] [Fig.l] is a very schematic and simplified block diagram of an embodiment of an electronic device 100.

[0034] The electronic device 100 comprises a control unit 101 (PROC) adapted to implement different operations and functions of the electronic device 100. According to a preferred example, the control unit 101 is a processor, a microprocessor, or a microcontroller. According to a variant, the control unit 101 is a monostable circuit, or simply monostable in the remainder of the Description. Here, a monostable circuit is a circuit that provides an output voltage at a first level, for example at a low level, continuously, and which, upon receipt of a control pulse, modifies the value of its output voltage to a second level, for example a high level, for a determined duration, before changing its output voltage back to the first level.

[0035] The control unit 101 comprises at least one power supply terminal VCC on which the control unit 101 is adapted to receive a power supply voltage. The control unit 101 further comprises a reference terminal, not shown in [Fig.l], on which the control unit 101 is adapted to receive a reference voltage, for example ground. The control unit 101 further comprises several communication terminals allowing the control unit 101 to communicate with other elements of the device 100. These communication terminals are detailed below, as the other elements of the electronic device 100 are described.

[0036] The electronic device 100 further comprises an antenna 102 (ANT) adapted to receive, and, where appropriate, to transmit, radiofrequency signals. Here, a radiofrequency signal is a signal whose frequency is between 3 kHz and 300 GHz; these signals are commonly used for radiocommunication.

[0037] The antenna 102 comprises at least one output terminal ANT-IO adapted to provide a voltage representative of a radiofrequency signal received by the antenna 102. The output terminal ANT-IO may in practice be composed of two electrical nodes providing potentials whose difference is the voltage representative of the radiofrequency signal received by the antenna 102.

[0038] The electronic device 100 further comprises, optionally, a wireless communication circuit 103 (RFID). According to one example, the circuit 103 may be a circuit adapted to radio frequency or radio identification (RFID) wireless communication, or more particularly, to near field wireless communication (NFC). The circuit 103 comprises at least one RFID-IO input terminal connected, for example connected, to the ANT-IO output terminal of the antenna 102, and at least one RFID-COMM communication terminal connected to an RFID-COMM2 communication terminal of the control unit 101. According to one example, the circuit 103 communicates with the control unit 101 using an electronic bus of the I2C (Inter-Integrated Circuit) type. According to one example, the circuit 103 does not need to be powered, the reception of the voltage supplied by the antenna 102 is sufficient for its operation.According to a variant, the circuit 103 has a power supply terminal.

[0039] The electronic device 100 further comprises, optionally, one or more circuits 104 for implementing applications of the device 100. A single circuit 104 is shown in [Fig.l]. The circuit 104 may be a measuring circuit, a sensor, a display circuit, an encryption circuit, etc. Each circuit 104 comprises at least one supply terminal VCCAPP on which the circuit 104 is adapted to receive a supply voltage. Each circuit 104 further comprises a reference terminal, not shown in [Fig.l], on which the circuit 104 is adapted to receive a reference voltage, for example ground. Each circuit 104 further comprises an APP-COMM communication terminal connected, for example connected, to an APP-COMM2 communication terminal of the control unit 101.

[0040] The electronic device 100 further comprises means for supplying the control unit 101 and the circuit(s) 104. These supply means comprise a supply circuit 105, a conversion circuit 106, and a selection means 107.

[0041] The power supply circuit 105 is adapted to power the elements of the electronic device 100. More particularly, the power supply circuit 105 is adapted to supply one or more different power supply voltages to the elements. In [Fig.l], the circuit 105 is adapted to supply a first power supply voltage to the control unit 101, and a second power supply voltage to the circuit 104. The power supply circuit 105 may also be adapted to communicate with the control unit 101, and may thus comprise at least one communication terminal ALIM-COMM connected, for example connected, to a communication terminal ALIM-COMM2 of the control unit 101. According to another embodiment, the power supply circuit 105 does not communicate with the control unit 101.

[0042] The conversion circuit 106 is adapted to convert the voltage representative of a radiofrequency signal received by the antenna 102 into a voltage adapted to power the control unit 101. According to one example, the voltage adapted to power the control unit 101 is a rectified alternating voltage, or even a direct voltage. The conversion circuit 106 comprises an input terminal CONV-IN receiving the output voltage from the antenna 102, and an output terminal CONV-OUT providing the voltage adapted to power the control unit 101.

[0043] The selection means 107 allows the control unit 101 to choose a power source. In particular, the selection means 107 allows the control unit to choose whether its power supply terminal VCC receives a power supply voltage from the power supply circuit 105, or a power supply voltage from the conversion circuit 106. According to one example, the selection means 107 is a selector controlled by the control unit 101. According to another example, the selection means 107 is internal to the control unit 101.

[0044] According to one embodiment, the control unit 101 is adapted to implement implements several operating modes. In a first operating mode, or an active mode, the control unit 101 operates at full power and is adapted to control all the elements of the electronic device 100. In a second operating mode, a standby mode, or a low power mode, the control unit 101 is switched off, and can be started at any time if the antenna 102 receives a radio frequency signal. In other words, during a standby mode the control unit does not receive a supply voltage. The power supply method implemented upon receipt of a radio frequency signal by the antenna 102 is described in relation to [Fig.2].

[0045] [Fig.2] is a block diagram illustrating a method of powering the control unit 101 of the device 100 described in relation to [Fig.l], when the control unit is in a standby mode, and the antenna 102 receives a radio frequency signal.

[0046] At the start of the powering method, the control unit 101 is in an initial state 201, represented by an "OFF" block, in which the control unit 101 is switched off, i.e., is not powered. For its part, the antenna 102 is also in an initial state 202, represented by a "NO RF" block, in which the antenna 102 does not yet receive a radiofrequency signal. It can also be said that, during states 201 and 202, the electronic device 100 is in a standby mode. No function of the electronic device 100 is implemented. According to one example, the power supply circuit 105 is functional but is not used when the control unit 101 is switched off.

[0047] At a state 203, represented by an "RF" block, subsequent to the initial state 202, the antenna 102 receives a radiofrequency signal. The antenna 102 converts this signal into a voltage representative of said radiofrequency signal. This voltage is transmitted to the conversion circuit 106 which then produces a supply voltage suitable for powering the control unit 101. This voltage can, furthermore, be sent to the wireless communication circuit 103 which processes this voltage, for example to power the circuit 103.

[0048] According to one embodiment, once the conversion circuit 106 produces a supply voltage, and since the control unit 101 is switched off, the selection means 107 supplies the supply voltage of the conversion circuit 106 to the supply terminal VCC of the control unit 101.

[0049] The control unit 101 then enters a startup state 204, represented by a "BOOT" block. During state 204, the control unit performs all the operations necessary for its startup, such as a software startup, and the startup of its internal circuits and components, the startup of the power supply circuit 105, but also, optionally, the startup of the other elements of the electronic device 100, such as that of the application circuit(s) 104. More particularly, the operations necessary for starting the control unit include, starting its internal clocks, its communication units, starting its internal software or program, etc.

[0050] Once the start-up of the control unit 101 is complete, the control unit 101 moves to a state 205, represented by an "ACTIVE" block, in which the control unit 101 is in an active mode. The selection means 107 no longer provides the supply voltage from the conversion circuit 106, but provides a supply voltage from the supply circuit 105 which is now started.

[0051] In other words, during its start-up phase, the control unit 101 is powered by the conversion circuit 106, and once its start-up phase is complete, the control unit 101 is powered by the power supply circuit 105.

[0052] The control unit 101 remains in active mode as long as necessary, regardless of whether the antenna 102 receives a radio frequency signal or not. If the antenna 102 no longer receives a radio frequency signal, the control unit 101 chooses whether to continue to be in active mode or to switch to standby mode.

[0053] An advantage of this embodiment is that, during a standby mode, the control unit 101 does not consume energy since it is not powered and therefore switched off. Indeed, electronic devices generally have a low consumption mode in which they consume less energy than in their active consumption mode. During this low consumption mode, the control unit remains "on alert" to be able to process a radiofrequency signal, or more generally any event that could cause it to start up, and for this it needs to always be powered, but generally with a lower power. This is not the case with the device 100.

[0054] [Fig. 3] is an electrical diagram, partially in block form, of an exemplary embodiment of an electronic device 300 of the type of the electronic device 100 described in relation to [Fig. 1].

[0055] Like the electronic device 100, the electronic device 300 comprises: - a control unit 301 (PROC) of the type of the control unit 101 of [Fig.l]; - an antenna 302 (ANT) of the type of antenna 102 of [Fig.l]; - an optional wireless communication circuit 303 (RFID), of the type of the wireless communication circuit 103 of [Fig.l]; - one or more optional circuits 304 (APP) for implementing the application of the device 300, of the type of the circuit(s) 104 of [Fig.l]; - a power supply circuit 305 (ALIM), of the type of power supply circuit 105 of [Fig.l]; - a conversion circuit 306 (CONV), of the type of the conversion circuit 106 of [Fig.l]; and - a selection means 307, of the type of the selection means 107 of [Fig.l].

[0056] In [Fig.3], the control unit 301 comprises: - a VCC supply terminal connected, for example connected, to the selection means 307 and receiving a VCC supply potential; - a GND terminal on which the control unit 301 receives a reference potential GND, for example, ground; - three communication terminals ALIM-C0MM2, APP-COMM2 and RFID-COMM2 connected, for example connected, respectively to the power supply circuit 305, to the circuit 306, and to the circuit 303; - a reset terminal N_RST for controlling a start or a restart, or a reset, of the control unit 101.

[0057] The antenna 302 comprises two terminals ANT-IO1 and ANT-IO2 each providing a potential. The difference in the potentials of the terminals ANT-IO1 and ANT-IO2 is a voltage VANT representative of a radiofrequency signal received by the antenna 302.

[0058] The wireless communication circuit 303 comprises two terminals RFID-IO1 and RFID-IO2 connected, for example connected, respectively to the terminals ANT-IO1 and ANT-IO2 of the antenna 302. The circuit 303 further comprises a terminal RFIDGND receiving a reference potential, for example ground, and an RFID-COMM communication terminal connected, for example connected, to the terminal RFID-COMM2 of the control unit 101.

[0059] In [Fig.3], the application implementation circuit 304 comprises: - an APP-COMM communication terminal connected, for example, to the APP-COMM2 communication terminal of the control unit 301; - a supply terminal VCCAPP receiving a supply potential VCCAPP from the supply circuit 305; and - an APPGND terminal receiving a reference potential, for example ground.

[0060] In [Fig.3], the power supply circuit 305 comprises: - a VCC supply terminal providing the VCC supply potential; - a VCCAPP supply terminal providing the VCCAPP supply potential; - an ALIMGND terminal receiving a reference potential, for example ground; and - an ALIM-COMM communication terminal connected, for example connected, to the ALIM-C0MM2 communication terminal of the control unit 302.

[0061] According to one example, the supply potentials VCC and VCCAPP are identical.

[0062] In the example of [Fig. 3], the conversion circuit 306 comprises: - two input terminals CONV-IN1 and CONV-IN2 connected, for example, respectively, to terminals ANT-I01 and ANT-I02 of antenna 302; - a CONV-OUT output terminal providing a VCC-ANT supply potential; and - a terminal providing a GND-ANT reference potential.

[0063] According to an exemplary embodiment, the circuit 306 comprises three elements coupled in parallel between the terminals CONV-OUT and CONV-GND. The circuit 306 comprises, more particularly, a voltage rectifier diode bridge receiving the voltage VANT as input, and providing as output the supply voltage being the difference between the potential VCC-ANT and the potential GND-ANT corresponding to the rectified voltage VCCANT. The diode bridge is composed of four diodes D1, D2, D3 and D4. According to an example, the anode of the diode D1 is connected, preferably connected, to the terminal CONV-IN1, and the cathode of the diode D1 is connected, preferably connected, to the terminal CONV-OUT. The anode of the diode D2 is connected, preferably connected, to the terminal CONV-OUT, and the cathode of the diode D2 is connected, preferably connected to the terminal CONV-IN2.The anode of diode D3 is connected, preferably connected, to terminal CONV-IN2, and the cathode of diode D3 is connected, preferably connected, to terminal CONV-GND. The anode of diode D4 is connected, preferably connected, to terminal CONV-GND, and the cathode of diode D4 is connected, preferably connected, to terminal CONV-IN1. Circuit 306 further comprises a diode D-CONV, for example a Zener diode, the anode of which is connected, preferably connected, to terminal CONV-GND, and the cathode of which is connected, preferably connected, to terminal CONV-OUT. Circuit 306 further comprises a capacitor C-CONV, a first electrode of which is connected, preferably connected, to terminal CONV-GND, and the second electrode of which is connected, preferably connected, to terminal CONV-OUT.

[0064] The electronic device 300 further comprises an RC type circuit for protecting the reset terminal N-RST of the control unit 301. This circuit comprises a resistor R-RST and a capacitor C-RST. A first terminal of the resistor R-RST is connected, preferably connected, to the terminal CONV-OUT of the conversion circuit 306, and a second terminal of the resistor R-RST is connected, preferably connected, to the terminal N-RST of the control unit 301. A first electrode of the capacitor C-RST is connected, preferably connected, to the terminal N-RST of the control unit 301, and a second electrode of the capacitor C-RST receives a reference potential GND-PERM.

[0065] The electronic device 300 further comprises a GND-SELECT selection circuit adapted to select the reference potential applied to the different elements of the device 300. Indeed, as the main power source of the device 300, and more particularly of the control unit 301, is modifiable, the reference potential is also modifiable. The GND-SELECT selection circuit comprises a input node A connected to the terminals GND of the control unit 301, APPGND of the circuit 304, ALIM-GND of the circuit 305, and RFID-GND of the circuit 303. The selection circuit GND-SELECT is adapted to provide either the reference potential GND-ANT provided by the conversion circuit 306 on its terminal CONV-GND, or the reference potential GND-PERM.

[0066] The GND-SELECT selection circuit comprises an INT-GND switch, for example an N-channel MOS transistor. A MOS transistor is an insulated gate field effect transistor, more commonly called a MOSFET (Metal Oxide Semiconductor Field Effect Transistor). The INT-GND switch comprises a first terminal, corresponding to a first conduction terminal of the transistor, connected, preferably connected, to node A, and a second terminal, corresponding to a second conduction terminal of the transistor, connected, preferably connected, to a node providing the reference potential GND-PERM. The control node of the INT-GND switch, corresponding to the gate of the transistor, is connected, preferably connected, to the SEL terminal of the control unit 301.

[0067] The GND-SELECT selection circuit further comprises a D-GND diode whose anode is connected, preferably connected, to node A, and whose cathode is connected, preferably connected, to terminal CONV-GND of the conversion circuit 306. According to an alternative embodiment, the D-GND diode can be replaced by a switch of the INT-GND switch type. According to another alternative embodiment, the D-GND diode can be replaced by a switch controlled by the presence or absence of a radiofrequency field.

[0068] When the control unit 301 is powered by the power supply circuit 305 then the switch INT-GND is conductive, and the node A provides the potential GND-PERM, otherwise the switch INT-GND is open, and the node A provides the potential CONV-GND.

[0069] The application of the feeding method described in relation to [Fig.2], is described in more detail for the device 300 in relation to [Fig.4].

[0070] [Fig. 4] illustrates voltage timing diagrams of the electronic device 300 during the power supply method described in relation to [Fig. 2]. In other words, these timing diagrams illustrate the transition of the control unit 301 from a standby mode where it is not powered to an active mode upon receipt of a radiofrequency signal by the antenna 302.

[0071] [Fig.4] illustrates, more particularly, the temporal evolution: - the output voltage VANT of the antenna 302; - a supply voltage VCC received by the control unit 301 on its supply terminal VCC; - of a voltage VN_RST being the difference between the potential at the terminal N-RST of the control unit 301 and the potential GND-PERM; and - a voltage VSEL being the difference between the potential at the SEL terminal of the control unit 301 and the potential GND-PERM.

[0072] At an initial instant t0, all voltages are in a low state, or reference state. In other words, the antenna 302 does not receive a radiofrequency signal, and the conversion circuit 306 does not receive a voltage to be converted. The start of the control unit 301 is not requested by its reset terminal N_RST since the control unit 301 is not powered. The selection circuit GND-SELECT selects the potential GND-PERM as being the reference potential of the elements of the device 100.

[0073] At a time t1, subsequent to time t0, the antenna 302 receives a radiofrequency signal. The voltage VANT then passes from its low state, corresponding to a difference of two substantially equal potentials, to an oscillating state representative of the radiofrequency signal received by the antenna 302. The conversion circuit 306 receives the voltage VANT and begins its conversion. For this, and up to a time t2, subsequent to time t1, the voltage VCC is the voltage VCCANT supplied by the conversion circuit 306 increases, for example, in a substantially linear manner.

[0074] At time t2, voltage VCC, and therefore voltage VCCANT, has reached its maximum amplitude, and is then equal to the rectified voltage VANT. Voltage VCCANT is then high enough to power control unit 301, and to increase voltage VN-RST at reset terminal N-RST of control unit 301.

[0075] At a time t3, subsequent to time t2, the voltage VN-RST is at a high level. In other words, the reset terminal N-RST of the control unit 301 is activated, and the control unit 301 can begin its startup.

[0076] At a time t4, subsequent to time t3, the control unit 301 has completed its startup. As described in relation to [Fig.2], the control unit 301 is then able to modify its power source for the power supply circuit 305. As the power source is modified, the selection circuit GND-SELECT modifies the reference potential of the elements of the device 300. For this, the control unit 301 sets the voltage VSEL to a high state, different from its low state.

[0077] At a time t5, subsequent to time t4, the voltage VCC is the voltage VCC-ALIM supplied by the power supply circuit 305. Thus from time t5, the voltage VCC is a stable voltage, or even a continuous voltage.

[0078] At a time t6, subsequent to time t5, the antenna 302 no longer receives a radiofrequency signal, and no longer supplies voltage. Thus, the voltage VANT returns to its low state. According to an exemplary embodiment, the control unit 301 here decides to continue operating and not to stop. The person skilled in the art could imagine different embodiments.

[0079] At a time t7, subsequent to time t6, the control unit 301 has completed the operations that it was to implement, and the device 300 can be switched off. All the elements of the device 300 are switched off, and the voltages VCC, VN-RST and VSEL are set back to their low state.

[0080] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these various embodiments and variations could be combined, and other variations will occur to those skilled in the art.

[0081] Finally, the practical implementation of the embodiments and variants described is within the reach of those skilled in the art from the functional indications given above.

Claims

Claims

1. Electronic device (100; 300) comprising, at least: - an antenna (102; 302) adapted to, at least, receive a radiofrequency signal; and - a control unit (101; 301), wherein, when the control unit (101; 301) is switched off and the antenna (102; 302) receives a radiofrequency signal, the antenna (102; 302) provides a first voltage (VANT) representative of said radiofrequency signal and supplies said control unit (101; 301) with said voltage (VANT) for the duration of the start-up of said control unit (101; 301), wherein when the start-up of said control unit (101; 301) is completed, the control unit (101; 301) is supplied with a second voltage (VCC-ALIM) provided by a power supply circuit (105; 305) of said electronic device (100; 300), wherein the voltage (VANT) representative of said radiofrequency signal is converted into a power supply voltage (VCC-ANT) by a conversion circuit (106;306), and wherein the starting of the central unit (101; 301) comprises the software starting of the central unit (101; 301), and the starting of clock systems of the central unit (101; 301), and communication of the central unit (101; 301).;

2. Device according to claim 1, wherein the control unit (101; 301) is a processor, a microprocessor or a microcontroller.

3. Device according to claim 1 or 2, wherein the supply voltage (VCC-ANT) is a direct voltage.

4. Device according to any one of claims 1 to 3, in which the conversion circuit (106; 306) comprises a voltage rectifier diode bridge.

5. Device according to any one of claims 1 to 4, wherein when the control unit (101; 301) is not in use, it is switched off.

6. Device according to any one of claims 1 to 5, in which the device (300) further comprises a selection circuit (GND-SELECT) adapted to select a reference potential applied to the different elements of the device (300).

7. A device according to claim 6, wherein the selection circuit (GND-SELECT) is adapted to select a first reference potential (GND-ANT) when the control unit (301) is supplied by the voltage (VANT) representative of said radiofrequency signal, and is adapted to select a second reference potential (GND-PERM) when the control unit (301) is supplied by the power supply circuit (305).

8. Device according to any one of claims 1 to 7, wherein the control unit (101; 301) is a monostable circuit.

9. Device according to any one of claims 1 to 8, wherein the device further comprises a circuit (103; 303) adapted for wireless communication.

10. Device according to claim 9, wherein said circuit (103; 303) adapted for wireless communication is adapted for near-field communication.

11. Method for starting an electronic device (100; 300) comprising, at least: - an antenna (102; 302) adapted to, at least, receive a radiofrequency signal; and - a control unit (101; 301), wherein, when the control unit (101; 301) is switched off and the antenna (102; 302) receives a radiofrequency signal, the antenna (102; 302) provides a voltage (VANT) representative of said radiofrequency signal and supplies said control unit (101; 301) with said voltage (VANT) for the duration of the start-up of said control unit (101; 301), wherein when the start-up of said control unit (101; 301) is completed, the control unit (101; 301) is supplied by a second voltage (VCC-ALIM) supplied by a power supply circuit (105; 305) of said electronic device (100;300), in which the voltage (VANT) representative of said radiofrequency signal is converted into a supply voltage (VCC-ANT) by a conversion circuit (106; 306), and in which the starting of the central unit (101; 301) comprises the software starting of the central unit (101; 301), and the starting of clock systems of the central unit (101; 301), and communication of the central unit (101; 301).;

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