Electronic device and method for electronic device

Abstract

Embodiments of the present disclosure relate to an optimized low power mode for an NFC / RFID system. The specification relates to an electronic device having an antenna configured to receive a radio frequency signal. The electronic device also includes a control unit. The control unit is turned off and the antenna receives the radio frequency signal. The antenna is configured to transmit a first voltage representing the radio frequency signal during startup of the control unit to power the control unit with the voltage.

Description

[0001] Priority claim

[0002] This application claims the benefit of French patent application No. 2111452, filed on October 28, 2021, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates generally to electronics and, in particular embodiments, to optimized low power modes for near field communication (NFC) and radio frequency identification (RFID) systems. Background Art

[0004] Energy consumption of circuits, devices and systems is currently a critical issue in most areas of technology.

[0005] Many electronic circuits, devices and systems are adapted to adjust their energy consumption according to the operations they must perform. For this purpose, many have power modes, such as full power, low power or standby mode.

[0006] It would be desirable to improve, at least in part, certain aspects of power supply for electronic circuits, devices, and systems. Summary of the Invention

[0007] Electronic circuits, devices, and systems that consume less energy are required.

[0008] There is a need for electronic devices suitable for receiving radio frequency waves that consume less energy.

[0009] There is a need for such electronic devices to consume less energy during implementation of a standby mode.

[0010] One embodiment overcomes all or some of the disadvantages of this known electronic device.

[0011] One embodiment provides an electronic device comprising at least an antenna adapted to receive at least a radio frequency signal; and a control unit, wherein when the control unit is turned off and the antenna receives a radio frequency signal, the antenna delivers a first voltage representing the radio frequency signal and utilizes the voltage to power the control unit during startup of the control unit.

[0012] Another embodiment provides a method for starting an electronic device, the method comprising at least: an antenna adapted to at least receive a radio frequency signal; and a control unit, wherein, when the control unit is turned off and the antenna receives a radio frequency signal, the antenna delivers a voltage representing the radio frequency signal and utilizes the voltage to power the control unit during startup of the control unit.

[0013] According to one embodiment, the control unit is a processor, a microprocessor or a microcontroller.

[0014] According to one embodiment, when the activation of the control unit is finished, the control unit is powered by the second voltage provided by the circuit for powering the electronic device.

[0015] According to an embodiment, the voltage representing the radio frequency signal is converted into the power supply voltage by a conversion circuit.

[0016] According to an embodiment, the supply voltage is a DC voltage.

[0017] According to an embodiment, the conversion circuit comprises a voltage-rectifying diode bridge.

[0018] According to one embodiment, when the control unit is not used it is switched off.

[0019] According to one embodiment, the startup of the control unit includes a soft startup of the control unit, a startup of a clock system of the control unit, and communication of the control unit.

[0020] According to an embodiment, the device further comprises a selection circuit adapted to select the reference potentials applied to different elements of the device.

[0021] According to one embodiment, the selection circuit is adapted to select the first reference potential when the control unit is powered by a voltage representing a radio frequency signal and the selection circuit is adapted to select the second reference potential when the power supply circuit supplies power to the control unit.

[0022] According to one embodiment, the control unit is a monostable circuit.

[0023] According to an embodiment, the device further comprises circuitry adapted for wireless communication.

[0024] According to an embodiment, the circuit adapted for wireless communication is adapted for near field communication. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a more complete understanding of the present disclosure and its advantages, reference is now made to the following description taken in conjunction with the accompanying drawings, in which:

[0026] Figure 1 is a schematic diagram of an electronic device of an embodiment;

[0027] Figure 2 is a flow chart of an embodiment operating method;

[0028] Figure 3 is a block diagram of an embodiment electronic device; and

[0029] Figure 4 is a timing diagram of the operation of the embodiment. DETAILED DESCRIPTION

[0030] In the various drawings, the same features are represented by the same reference numerals. In particular, common structural or functional features in various embodiments may have the same reference numerals and may be provided with the same structure, dimensions, and material properties.

[0031] For the sake of clarity, only the steps and elements that can be used to understand the embodiments described herein are described in detail. In particular, the computer protocols used to implement the embodiments described in the specification are not described, but the instructions present in the following description are accessible to those skilled in the art.

[0032] Unless otherwise specified, when two elements are referred to as being connected together, this means a direct connection without any intermediate elements other than conductors, and when two elements are referred to as being coupled together, this means the two elements may be connected or they may be coupled via one or more other elements.

[0033] In the following disclosure, unless otherwise stated, when absolute position qualifiers are mentioned, such as the terms "front", "back", "top", "bottom", "left", "right", etc., or relative position qualifiers are mentioned, such as the terms "upper", "lower", "upper", "lower", etc., or orientation qualifiers are mentioned, such as "horizontal", "vertical", etc., it refers to the orientation shown in the figures.

[0034] Unless otherwise indicated, the expressions "about," "approximately," "substantially," and "on the order of" mean within 10%, preferably within 5%.

[0035] Figure 1 is a very schematic and simplified block diagram of an embodiment of an electronic device 100 .

[0036] The electronic device 100 comprises a control unit 101 (PROC) adapted to implement the different operations and functions of the electronic device 100. According to one embodiment, the control unit 101 is a processor, a microprocessor or a microcontroller. In the remainder of the description, according to one embodiment, the control unit 101 is a monostable circuit or simply a monostable.

[0037] In one embodiment, the monostable circuit continuously delivers an output voltage at a first level (e.g., a low level), and upon receiving a control pulse, the monostable circuit modifies the value of its output voltage to a second level (e.g., a high level) for a determined time before changing its output voltage back to the first level.

[0038] 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 Figure 1The control unit 101 includes a reference terminal (not shown) at which the control unit 101 is adapted to receive a reference voltage, such as ground. The control unit 101 also includes a plurality of communication terminals that enable the control unit 101 to communicate with other components of the device 100. These communication terminals and other components of the electronic device 100 will be described in detail below.

[0039] The electronic device 100 comprises an antenna 102 (ANT) adapted to receive and transmit radio frequency signals. In an embodiment, radio frequency signals are signals having a frequency ranging from 3 kHz to 300 GHz; these signals are currently used for radio communications.

[0040] The antenna 102 comprises at least one output terminal ANT-IO adapted to deliver a voltage representative of a radio frequency signal received by the antenna 102. The output terminal ANT-IO may in fact be formed by two electrical nodes delivering potentials having a voltage difference representative of the radio frequency signal received by the antenna 102.

[0041] The electronic device 100 may also optionally include a wireless communication circuit 103 (RFID). According to an example, the circuit 103 may be a circuit suitable for wireless radio frequency communication or radio frequency identification (RFID), or more specifically, a circuit suitable for wireless near field communication (NFC). The circuit 103 includes at least one RFID-IO input terminal coupled to (e.g., connected to) the output terminal ANT-IO of the antenna 102, and at least one communication terminal RFID-COMM coupled to the communication terminal RFID-COMM2 of the control unit 101. According to one example, the circuit 103 communicates with the control unit 101 by using an electronic bus of the I2C (Inter-Integrated Circuit) type. According to one example, the circuit 103 does not need to be powered, and receiving the voltage delivered by the antenna 102 is sufficient for its operation. According to one variant, the circuit 103 has a power supply terminal.

[0042] The electronic device 100 may also optionally include one or more circuits 104 for implementing the application of the device 100 . Figure 1 A single circuit 104 is shown in FIG. The circuit 104 may be a measurement circuit, a sensor, a display circuit, a cryptographic circuit, etc. Each circuit 104 includes at least one power supply terminal VCCAPP, on which the circuit 104 is adapted to receive a power supply voltage. Each circuit 104 also includes Figure 1 Each circuit 104 further comprises a communication terminal APP-COMM coupled (eg connected) to a communication terminal APP-COMM2 of the control unit 101 .

[0043] The electronic device 100 further comprises means for supplying power to the control unit 101 and the circuit(s) 104. These power supply means comprise a power supply circuit 105, a conversion circuit 106 and a selection means 107.

[0044] The power supply circuit 105 is adapted to supply power to the components of the electronic device 100. More specifically, the power supply circuit 105 is adapted to deliver a power supply voltage or a plurality of different power supply voltages to the components. Figure 1 , circuit 105 is adapted to deliver a first supply voltage to control unit 101 and a second supply voltage to circuit 104. Power supply circuit 105 may also be adapted to communicate with control unit 101 and may therefore comprise at least one communication terminal ALIM-COMM coupled to (e.g. connected to) communication terminal ALIM-COMM2 of control unit 101. According to another embodiment, power supply circuit 105 does not communicate with control unit 101.

[0045] The conversion circuit 106 is adapted to convert a voltage representing a radio frequency signal received by the antenna 102 into a voltage suitable for the power control unit 101. According to one example, the voltage suitable for the power control unit 101 is a rectified AC voltage, or even a DC voltage. The conversion circuit 106 includes an input terminal CONV-IN for receiving the output voltage of the antenna 102 and an output terminal CONV-OUT for delivering a voltage suitable for the power control unit 101.

[0046] The selection device 107 enables the control unit 101 to select a power supply. In particular, the selection device 107 enables the control unit to select whether its power supply terminal VCC receives a power supply voltage originating from the power supply circuit 105 or a power supply voltage originating from the conversion circuit 106. According to one example, the selection device 107 is a selector controlled by the control unit 101. According to another example, the selection device 107 is internal to the control unit 101.

[0047] According to one embodiment, the control unit 101 is adapted to implement multiple operating modes. In a first operating mode or active mode, the control unit 101 operates at full power and is adapted to control all elements of the electronic device 100. In a second operating mode, standby mode or low power mode, the control unit 101 is switched off and can be switched on at any time if the antenna 102 receives a radio frequency signal. In other words, during the standby mode, the control unit does not receive a supply voltage. Figure 2 The power supply method implemented when a radio frequency signal is received via the antenna 102 is described.

[0048] Figure 2 FIG. 1 is a diagram showing a state in which the control unit is in standby mode and the antenna 102 receives a radio frequency signal. Figure 1 A block diagram of a method for powering the control unit 101 of the device 100 is described.

[0049] At the start of the power supply method, control unit 101 is in an initial state 201, as indicated by the "OFF" block, in which control unit 101 is off, i.e., not powered. Antenna 102 is also in an initial state 202, as indicated by the "NO RF" block, in which antenna 102 has not yet received a radio frequency signal. Alternatively, during states 201 and 202, electronic device 100 is in standby mode. None of the functions of electronic device 100 are implemented. According to one example, power supply circuit 105 is functional but unused when control unit 101 is off.

[0050] Following initial state 202, in state 203, shown in the "RF" box, antenna 102 receives a radio frequency signal. Antenna 102 converts the signal into a voltage representing the radio frequency signal. This voltage is transmitted to conversion circuit 106, which then generates a supply voltage suitable for power control unit 101. This voltage may also be transmitted to wireless communication circuit 103, which processes the voltage, for example, to provide power to circuit 103.

[0051] According to an embodiment, once the conversion circuit 106 generates the supply voltage, and since the control unit 101 is switched off, the selection device 107 delivers the supply voltage of the conversion circuit 106 to the power supply terminal VCC of the control unit 101 .

[0052] The control unit 101 then enters a startup state 204, represented by the box "BOOT". During state 204, the control unit performs all operations required for its startup, such as soft startup, startup of its internal circuits and components, startup of the power supply circuit 105, and optionally startup of other components of the electronic device 100, such as startup of the application circuit 104. More specifically, the operations required for the startup of the control unit include startup of its internal clock, startup of its communication unit, startup of its internal software or program, etc.

[0053] Once the start-up of the control unit 101 is complete, the control unit 101 switches to state 205, as shown in the box "ACTIVE", in which the control unit 101 is in active mode. The selection device 107 no longer delivers the supply voltage originating from the conversion circuit 106, but instead delivers the supply voltage originating from the power supply circuit 105, which is now activated.

[0054] In other words, during its startup phase, the control unit 101 is powered by the conversion circuit 106 , and once its startup phase is over, the control unit 101 is powered by the power supply circuit 105 .

[0055] The control unit 101 remains in active mode as long as necessary, regardless of whether the antenna 102 receives radio frequency signals. If the antenna 102 no longer receives radio frequency signals, the control unit 101 selects whether it continues in active mode or whether it switches to standby mode.

[0056] An advantage of this embodiment is that during standby mode, the control unit 101 consumes no energy, since it is not powered and is therefore switched off. In practice, electronic devices typically have a low-consumption mode in which they consume less energy than when they are in an active consumption mode. During this low-consumption mode, the control unit remains "on alert" to be able to process radio frequency signals, or more generally, any event that can cause it to activate, and for this purpose, it needs to be always powered, but generally at a lower power level. This is not the case with device 100.

[0057] Figure 3 It's about Figure 1 An electrical diagram, partially in block form, of an example of an embodiment of an electronic device 300 of the type described is provided.

[0058] Similar to the electronic device 100 , the electronic device 300 includes: Figure 1 A control unit 301 (PROC) of the type of control unit 101; Figure 1 Antenna 302 (ANT) of type antenna 102; Figure 1 Optional wireless communication circuit 303 (RFID) of the wireless communication circuit 103 type; implementation Figure 1 One or more optional circuits 304 (APP) for applications of the device 300 of the circuit 104 type; Figure 1 A power supply circuit 305 (ALIM) of the power supply circuit 105 type; Figure 1 A conversion circuit 306 (CONV) of the type of conversion circuit 106; and Figure 1 A selection device 307 of the same type as the selection device 107 .

[0059] exist Figure 3 In the embodiment, the control unit 301 includes: a power supply terminal VCC, which is coupled (for example, connected) to the selection device 307 and receives a power supply potential VCC; a terminal GND, on which the control unit 301 receives a reference potential GND, for example, ground; three communication terminals ALIM-COMM2, APP-COMM2 and RFID-COMM2, for example, respectively connected to the power supply circuit 305, the circuit 306 and the circuit 303; a reset terminal N_RST, which can control the startup, restart or reset of the control unit 101.

[0060] The antenna 302 includes two terminals ANT-IO1 and ANT-IO2, each of which provides a potential. The potential difference between the terminals ANT-IO1 and ANT-IO2 is a voltage VANT representing the radio frequency signal received by the antenna 302.

[0061] Wireless communication circuit 303 includes two terminals RFID-IO1 and RFID-IO2, which are connected, for example, to terminals ANT-IO1 and ANT-IO2, respectively, of antenna 302. Circuit 303 also includes a terminal RFIDGND that receives a reference potential (e.g., ground), and a communication terminal RFID-COMM that is coupled (e.g., connected) to terminal RFID-COMM2 of control unit 101.

[0062] exist Figure 3 , the circuit 304 for implementing the application includes: a communication terminal APP-COMM, which is coupled (connected) to a communication terminal APP-COMM2 of the control unit 301; a power terminal VCAPP, which receives a power potential VCCAPP from the power circuit 305; and a terminal APPGND, which receives a reference potential, such as ground.

[0063] exist Figure 3 In the embodiment, the power supply circuit 305 includes: a power supply terminal VCC transmitting a power supply potential VCC; a power supply terminal VCCAPP transmitting a power supply potential VCCAPP; a terminal ALIMGND receiving a reference potential, such as ground; and a communication terminal ALIM-COMM coupled to, for example, a communication terminal ALIM-COMM2 connected to the control unit 302.

[0064] According to one example, the supply potentials VCC and VCCAPP are identical.

[0065] exist Figure 3 In the example, the conversion circuit 306 includes two input terminals CONV-IN1 and CONV-IN2, which are respectively coupled (e.g., connected) to the terminals ANT-IO1 and ANT-IO2 of the antenna 302; an output terminal CONV-OUT, which delivers a power supply potential VCC-ANT; and a terminal for providing a reference potential GND-ANT.

[0066] According to an example embodiment, circuit 306 includes three elements coupled in parallel between terminals CONV-OUT and CONV-GND. More specifically, circuit 306 includes a voltage rectifier diode bridge that receives an input voltage VANT and delivers a supply voltage as an output, which is the difference between the potential VCC-ANT corresponding to the rectified voltage VCCANT and GND-ANT. The diode bridge is formed by four diodes D1, D2, D3, and D4. According to one example, the anode of diode D1 is coupled to, preferably connected to, terminal CONV-IN1, and the cathode of diode D1 is coupled to, preferably connected to, terminal CONV-OUT. The anode of diode D2 is coupled to, preferably connected to, terminal CONV-OUT, and the cathode of diode D2 is coupled to, preferably connected to, terminal CONV-IN2. The anode of diode D3 is coupled to, preferably connected to, terminal CONV-IN2, and the cathode of diode D3 is coupled to, preferably connected to, terminal CONV-GND. The anode of diode D34 is coupled, preferably connected, to terminal CONV-GND, while the cathode of diode D4 is coupled, preferably connected, to terminal CONV-IN1. Circuit 306 also includes a diode D-CONV, such as a Zener diode, having its anode coupled to (preferably connected to) terminal CONV-GND and its cathode coupled to (preferably connected to) terminal CONV-OUT. Circuit 306 also includes a capacitor C-CONV having a first electrode coupled to (preferably connected to) terminal CONV-GND and a second electrode coupled to (preferably connected to) terminal CONV-OUT.

[0067] Electronic device 300 also includes an RC-type circuit that protects reset terminal N-RST of control unit 301. This circuit includes a resistor R-RST and a capacitor C-RST. A first terminal of resistor R-RST is coupled (preferably connected) to terminal CONV-OUT of conversion circuit 306, and a second terminal of resistor R-RST is coupled (preferably connected) to terminal N-RST of control unit 301. A first electrode of capacitor C-RST is coupled (preferably connected) to terminal N-RST of control unit 301, and a second electrode of capacitor C-RST receives reference potential GND-PERM.

[0068] Electronic device 300 further includes a selection circuit GND-SELECT, which is adapted to select the reference potentials applied to the various components of device 300. In practice, since the main power supply of device 300, particularly that of control unit 301, is modifiable, so too are the reference potentials. Selection circuit GND-SELECT includes an input node A coupled to terminals GND of control unit 301, APPGND of circuit 304, ALIM-GND of circuit 305, and RFID-GND of circuit 303. Selection circuit GND-SELECT is adapted to transmit, at its terminal CONV-GND, either the reference potential GND-ANT delivered by conversion circuit 306 or the reference potential GND-PERM.

[0069] The selection circuit GND-SELECT includes a switch INT-GND, for example, an N-channel MOS transistor. MOS transistors are referred to as insulated-gate field-effect transistors, more commonly known as MOSFETs (metal-oxide-semiconductor field-effect transistors). The switch INT-GND includes a first terminal, corresponding to the first conduction terminal of the transistor, coupled (preferably connected) to node A; and a second terminal, corresponding to the second conduction terminal of the transistor, coupled (preferably connected) to a node that delivers a reference potential GND-PERM. The control node of the switch INT-GND, corresponding to the gate of the transistor, is coupled (preferably connected) to terminal SEL of the control unit 301.

[0070] The selection circuit GND-SELECT further comprises a diode D-GND, the anode of which is coupled (preferably connected) to the node A, and the cathode of which is coupled (preferably connected) to the terminal CONV-GND of the conversion circuit 306. According to an alternative embodiment, the diode D-GND can be replaced by a switch of the INT-GND type. According to another alternative embodiment, the diode D-GND can be replaced by a switch controlled by the presence or absence of an RF field.

[0071] When the control unit 301 is powered by the power circuit 305 , the switch INT-GND is turned on and the node A delivers the potential GND-PERM; otherwise, the switch INT-GND is turned off and the node A delivers the potential CONV-GND.

[0072] Combine Figure 4 Related device 300, further described in detail with Figure 2 Application of the power supply method described in the related text.

[0073] Figure 4 Shown in about Figure 2The timing diagrams show the voltages of the electronic device 300 during the power supply method described. In other words, these timing diagrams show the process of the control unit 301 switching from the non-powered standby mode to the active mode when the antenna 302 receives a radio frequency signal.

[0074] exist Figure 4 The temporal changes are shown more specifically in FIG: the timing changes of the output voltage VANT of the antenna 302; the timing changes of the power supply voltage VCC received by the control unit 301 at its power supply terminal VCC; the timing changes of the difference voltage VN_RST between the potential at the level of the terminal N-RST of the control unit 301 and the potential GND-PERM; and the timing changes of the difference voltage VSEL between the potential at the level of the terminal SEL of the control unit 301 and the potential GND-PERM.

[0075] At initial time t0, all voltages are in a low or reference state. In other words, antenna 302 receives no RF signal, and conversion circuit 306 receives no voltage to convert. Control unit 301 is not activated by its reset terminal N_RST because it is not powered. Selector circuit GND-SELECT selects potential GND-PERM as a reference potential for components in device 100.

[0076] At time t1, after time t0, antenna 302 receives an RF signal. Voltage VANT then switches from its low state, corresponding to the difference between two substantially equal potentials, to an oscillating state representing the RF signal received by antenna 302. Conversion circuit 306 receives voltage VANT and begins its conversion. For this purpose, and until time t2, after time t1, voltage VCC is delivered by conversion circuit 306 to voltage VCCANT, and increases, for example, substantially linearly.

[0077] At time t2 , voltage VCC and therefore voltage VCCANT have reached their maximum amplitude and are then equal to rectified voltage VANT. Voltage VCCANT is then high enough for power control unit 301 to cause voltage VN-RST at reset terminal N-RST of control unit 301 to increase.

[0078] At time t3 after 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 start its startup.

[0079] At time t4 after time t3, the control unit 301 ends its startup. Figure 2As described, the control unit 301 can then modify its power supply for the power supply circuit 305. Due to the modified power supply, the selection circuit GND-SELECT modifies the reference potential of the components of the device 300. To this end, the control unit 301 switches the voltage VSEL to a high state, which is different from its low state.

[0080] At time t5 after time t4, the voltage VCC is the voltage VCC-ALIM provided by the power supply circuit 305. Therefore, from time t5 onward, the voltage VCC is a stable voltage, or even a DC voltage.

[0081] At time t6, after time t5, antenna 302 no longer receives the RF signal and no longer delivers voltage. Therefore, voltage VANT switches back to its low state. According to one example embodiment, control unit 301 decides to continue operation without stopping. It would be within the purview of those skilled in the art to envision different embodiments.

[0082] At time t7, after time t6, control unit 301 has completed the operations it was supposed to perform, and device 300 can be turned off. All components of device 300 are stopped, and voltages VCC, VN-RST, and VSEL are set back to their low states.

[0083] Various embodiments and variations have been described. Those skilled in the art will appreciate that certain features of these various embodiments and variations may be combined, and those skilled in the art will recognize other variations.

[0084] Finally, based on the functional indications given above, the actual implementation of the described embodiments and variants is within the capabilities of a person skilled in the art.

Claims

1. An electronic device comprising: Control unit; as well as Antenna, configured as: receiving a radio frequency signal when the control unit is in an off state, and transmitting a first voltage to the control unit to power the control unit for the duration of a startup sequence of the control unit, the first voltage being representative of the radio frequency signal; a power supply circuit configured to generate a second voltage; A selection circuit is configured to: selecting a first reference potential in response to the control unit being powered by the first voltage; as well as A second reference potential is selected in response to the control unit being powered by the power supply circuit, the second reference potential being different from the first reference potential. 2 . The electronic device according to claim 1 , wherein the control unit is a processor, a microprocessor, or a microcontroller. 3 . The electronic device of claim 1 , wherein the control unit is configured to be powered by the second voltage from the power supply circuit after the startup sequence is completed. 4 . The electronic device according to claim 1 , wherein the electronic device further comprises a conversion circuit configured to convert the first voltage into a power supply voltage. The electronic device according to claim 4 , wherein the power supply voltage is a direct current (DC) voltage.

6. The electronic device of claim 4, wherein the conversion circuit comprises a voltage rectifying diode bridge. 7 . The electronic device according to claim 1 , wherein when the control unit is not used, the control unit is configured to be in an off state.

8. The electronic device of claim 1, wherein the startup sequence comprises: Soft start of the control unit, start of the clock system of the control unit, and start of the communication circuit of the control unit.

9. The electronic device according to claim 1, wherein the control unit is a monostable circuit.

10. The electronic device of claim 1, wherein the electronic device further comprises a communication circuit configured for wireless communication. The electronic device according to claim 10 , wherein the communication circuit is configured for near field communication (NFC).

12. A method for an electronic device, comprising: When the control unit of the electronic device is in a shut-down state, receiving a radio frequency signal through the antenna of the electronic device; transmitting a first voltage to the control unit via the antenna; powering the control unit with the first voltage for the duration of a startup sequence of the control unit, the first voltage representing the radio frequency signal; In response to the control unit being powered by the first voltage, selecting a first reference potential by a selection circuit of the electronic device; as well as In response to the control unit being powered by a power supply circuit of the electronic device, a second reference potential is selected by the selection circuit, the second reference potential being different from the first reference potential.

13. The method of claim 12, further comprising powering the control unit using a second voltage from a power supply circuit of the electronic device after the startup sequence is completed.

14. An electronic device comprising: an antenna configured to receive radio frequency signals; a power supply circuit configured to generate a power supply voltage; as well as a control unit configured to be switched on in a first mode and a second mode, wherein in the first mode the control unit is turned off when the antenna receives the radio frequency signal and is turned on in response to the antenna transmitting a first voltage representative of the radio frequency signal to the control unit to turn the control unit on during a start-up sequence of the control unit, and wherein in said second mode, after completion of said start-up sequence of said control unit, said control unit is switched on by said supply voltage from said power supply circuit; A selection circuit is configured to: selecting a first reference potential in response to the control unit being switched on in the first mode; as well as A second reference potential is selected in response to the control unit being switched on in the second mode, the second reference potential being different from the first reference potential.

15. The electronic device of claim 14, wherein the electronic device comprises a reference potential selected to be applied to a component of the electronic device.

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