Electronic device, wireless charger, and method of operating electronic device

Abstract

Embodiments of the present disclosure relate to quality factor estimation of an inductive element. The present disclosure relates to an apparatus comprising: an inductive element and a first capacitive element connected in series between a first node and a second node; a first MOS transistor connected between the first node and a third node configured to receive a reference potential, the second node being coupled to the third node directly or via a second MOS transistor; a second capacitive element connected between a fourth node and an interconnection node, the interconnection node being located between the first capacitive element and the inductive element; a current generator configured to provide an AC current to the fourth node; and a switch connected between the fourth node and the third node.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of European Patent Application No. 20305965.4, filed on August 31, 2020, which is incorporated herein by reference. Technical Field

[0003] This disclosure generally relates to electronic devices and methods, and more specifically to electronic devices and methods for supplying power to other devices using a wireless link, i.e., devices and methods for providing wireless power to another device. Background Technology

[0004] Electronic devices capable of wirelessly supplying power to another device are known. In such devices, an AC signal is supplied to the device's antenna, which then emits a magnetic field. This magnetic field is received by the device to be wirelessly powered, which then uses the power carried by the magnetic field to be powered. Summary of the Invention

[0005] There is a need to overcome at least some of the drawbacks of known devices configured to provide wireless power.

[0006] For example, there is a need for an electronic device in which the quality factor of the inductive element of the device's antenna can be estimated, which addresses at least some of the drawbacks of known devices suitable for providing wireless power.

[0007] For example, it is necessary to overcome at least some of the drawbacks of known methods for estimating the quality factor of the inductive element of an antenna, especially when such methods are implemented by a device that includes the antenna.

[0008] One embodiment addresses all or some of the known disadvantages of a known device configured to provide wireless power.

[0009] One embodiment provides an apparatus comprising: an inductor and a first capacitor (C) connected in series between a first node and a second node; a first metal-oxide-semiconductor (MOS) transistor connected between the first node and a third node configured to receive a reference potential, the second node being coupled directly to or via the second MOS transistor to the third node; a second capacitor connected between a fourth node and an interconnect node located between the first capacitor and the inductor; a current generator configured to supply alternating current (AC) to the fourth node; and a switch connected between the fourth node and the third node.

[0010] According to an embodiment, the value of the first capacitor element is at least 100 times higher than the value of the second capacitor element.

[0011] According to an embodiment, a current generator is connected between a fourth node and a fifth node configured to receive a power supply voltage.

[0012] According to an embodiment, the first transistor is part of a half-bridge connected between a third node and a sixth node configured to receive a power supply voltage.

[0013] According to an embodiment, the second transistor is part of another half-bridge connecting the third node and the sixth node.

[0014] According to the embodiment, the frequency of the generator is controllable.

[0015] According to an embodiment, the device includes circuitry configured to control the frequency of a generator such that the frequency of the generator is equal to the frequency of the voltage of the interconnect node.

[0016] According to an embodiment, the circuit includes a detector configured to provide a binary signal and switch the binary signal whenever the voltage of the interconnect node crosses a reference potential, wherein a generator is configured to switch AC current between high and low levels at each switch of the binary signal.

[0017] According to an embodiment, the device includes circuitry configured to measure the frequency of voltages at interconnect nodes.

[0018] According to an embodiment, the circuit configured to measure the frequency of the voltage of an interconnect node includes circuit configured to measure the frequency of a binary signal, such as a counter.

[0019] According to an embodiment, the device includes circuitry configured to measure the voltage of interconnect nodes.

[0020] According to an embodiment, the device includes a control circuit configured to couple a first node and a second node to a third node and to open the switch during the estimation phase of the quality factor of the inductor element, or otherwise close the switch.

[0021] One embodiment provides a wireless charger, including the disclosed device, wherein an inductive element and a first capacitive element form an antenna for the wireless charger.

[0022] One embodiment discloses a method implemented with a device or wireless charger, comprising: coupling a first node and a second node to a third node and opening a switch at the beginning of an estimation phase of the quality factor of an inductor element; measuring the voltage of the interconnect node during the implementation of the phase when the AC current has a frequency equal to the resonant frequency of the series connection of the inductor element and the first capacitor element; measuring the resonant frequency; and closing the switch at the end of the phase.

[0023] According to an embodiment, the method further includes estimating the quality factor of the inductor based on the measured voltage, the capacitance value of the first capacitor element, the value of the AC current, and the measured resonant frequency. Attached Figure Description

[0024] The foregoing features and advantages, as well as other features and advantages, will be described in detail below with reference to the accompanying drawings, which are given by way of illustration rather than limitation, of specific embodiments:

[0025] Figure 1 A device that provides wireless power to another device is illustrated schematically;

[0026] Figure 2 The illustration depicts an embodiment of a device suitable for providing wireless power to another device;

[0027] Figure 3 The diagram shows Figure 2 Alternative embodiments of the device; and

[0028] Figure 4 A more detailed illustration is provided. Figure 2 Example embodiments of the device. Detailed Implementation

[0029] Similar features have been indicated using similar reference numerals in the various figures. Specifically, structural and / or functional features common to the various embodiments may have the same reference numerals and may have the same structure, dimensions, and material properties.

[0030] For clarity, only operations and elements useful for understanding the embodiments described herein are illustrated and described in detail.

[0031] Unless otherwise indicated, when referring to two elements connected together, this means there is no direct connection with any intermediate element other than a conductor; and when referring to two elements coupled together, this means that the two elements can be connected or can be coupled via one or more other elements. Furthermore, when a component (such as a transistor, switch, inductor, or capacitor) has its first conductive terminal coupled (preferably connected) to a first node of two nodes and its second conductive terminal coupled (preferably connected) to a second node of two nodes, the component is referred to as being connected between the two nodes.

[0032] In the following disclosure, unless otherwise stated, the inductive element (and correspondingly the capacitive element) and the inductance value (and correspondingly the capacitance value) of the component will be indicated by the same reference numerals.

[0033] In the following disclosure, unless otherwise stated, when referring 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,” “higher,” “lower,” etc.) or orientation qualifiers (such as “horizontal,” “vertical,” etc.), reference is made to the orientation shown in the figures.

[0034] Unless otherwise indicated, the expressions “about,” “roughly,” “substantially,” and “approximately” indicate within 10%, and preferably within 5%.

[0035] Figure 1 The diagram schematically illustrates device 1, which provides wireless power 2 to another device 3. The wireless power is provided by... Figure 1 Arrow 2 in the image represents...

[0036] Device 1 (block TX) is designed to provide wireless power 2. Device 1 is, for example, a wireless charger.

[0037] Device 1 includes an inductive element L (typically an inductor, such as a coil or winding) and a capacitive element C (typically a capacitor) connected in series between two nodes 100 and 102. Node 100 is configured to receive an alternating current (AC) signal, typically an AC voltage. Node 102 is configured to receive a reference potential, typically ground (GND), and the AC voltage received by node 100 is referenced, for example, to the reference potential GND. Elements C and L form antenna 103 of device 1.

[0038] Device 3 includes an antenna 301, which includes an inductive element L', typically an inductor, such as a coil or winding.

[0039] When an AC signal is supplied to node 100 at a frequency equal to or approximately the resonant frequency of antenna 103, wireless power 2 is emitted by antenna 103 in the form of a magnetic field. When devices 1 and 3 are sufficiently close to each other, inductor element L' receives wireless power 2; in other words, inductor elements L and L' are coupled together and form a low-coupling transformer. Therefore, current flows through inductor element L' and a voltage exists across inductor element L', which allows power to be supplied to device 3.

[0040] When device 1 is emitting wireless power 2, any external conductive object placed within the magnetic field emitted by device 1 (i.e., any conductive object not configured to be wirelessly powered by wireless power 2) will heat up because the emitted magnetic field induces a Foucault current within the conductive object. The temperature of the conductive object can then exceed 80°C, for example, above 100°C. At such temperatures, the conductive object may harm the user of device 1 or may degrade device 1. For example, when device 1 includes a plastic casing, the plastic may melt due to the high temperature of the conductive object, especially if the conductive object is placed on the casing of device 1. As an example, the conductive object could be a metal coin or a metal key.

[0041] To avoid the problem described in the preceding paragraph, device 1 can be configured to detect whether an object placed in its transmitting magnetic field is a device to be wirelessly powered or a foreign conductive object before providing wireless power 2. If device 1 detects that the object in its magnetic field is a foreign conductive object, then device 1 does not provide wireless power 2.

[0042] One way device 1 can detect an external conductive object in its emitted magnetic field is by determining or evaluating the quality factor QfL of the inductor L. In essence, the quality factor QfL represents the ability of the inductor L to retain energy within it. When the external conductive object heats up due to the magnetic field emitted by device 1, it extracts energy from the inductor L, leading to a decrease in the quality factor QfL.

[0043] As an example, the Qi specification developed by the Wireless Power Consortium (WPC) requires this method of detecting the presence of foreign conductive objects in wireless power sources.

[0044] Components L and C form a resonant LC filter. When applied to the interconnect node 104 (i.e., Figure 1 When the excitation voltage on the inductor terminal opposite node 100 is at the resonant frequency f0 of the LC filter, the quality factor QfLC of the LC filter is then equal to the ratio between the oscillation amplitude of the voltage at the interconnect node 104 between components L and C and the amplitude equal to that excitation voltage.

[0045] The quality factor QfL(f0) of the inductor L of the LC filter at the resonant frequency f0 is actually equal to the quality factor QfLC of the LC filter.

[0046] However, it may be necessary to determine the quality factor QfL(f) of the inductor L at a given frequency f, which may differ from the resonant frequency f0 of the LC filter. For example, the Qi specification requires that the quality factor QfL(f) of the inductor L be determined at a frequency f equal to 100 kHz.

[0047] Furthermore, when evaluating the quality factor QfL(f) of inductor L, the voltage amplitude at interconnect node 104 can be high enough to wake up or activate device 3. Such wake-up of device 3 when evaluating the quality factor QfL(f) should be avoided. In fact, once device 3 is activated, it draws energy from inductor L to be wirelessly powered, causing a decrease in the quality factor QfL(f). Device 1, detecting this decrease, will consider a foreign conductive object in its emitted magnetic field and will then not supply wireless power 2 to device 3. Therefore, device 3 will not be wirelessly powered.

[0048] As an example, in the Qi specification, in order not to wake up devices to be wirelessly powered, the peak-to-peak voltage amplitude on node 104 should not exceed 1V.

[0049] Although this is in Figure 1 Not shown, but device 1 includes circuitry for supplying AC voltage to node 100 when device 1 wirelessly powers device 3. This circuitry is, for example, a half-bridge, comprising two metal-oxide-semiconductor (MOS) transistors connected in series between node 102 and a node configured to receive the power supply voltage. However, during the evaluation phase of the quality factor QfL(f), it is necessary to reduce or suppress the influence of this circuitry on the estimation of the quality factor QfL(f).

[0050] Furthermore, in order to shorten the time between the instant when device 3 enters the magnetic field emitted by device 1 and the instant when device 1 effectively supplies wireless power to device 3, it is necessary to shorten the duration of the stage for estimating the quality factor QfL(f) as much as possible. For example, the Qi specification requires that this final duration not exceed 3 seconds, which requires that the estimation of the quality factor QfL(f) of element L be completed in less than 3 seconds, for example, in less than 1 second. Such a duration is, for example, incompatible with the method of evaluating the quality factor QfL(f) by switching the frequency of the AC voltage applied to node 100 and measuring the corresponding voltage on node 104 until the measured voltage is at its maximum value such that the frequency of the applied voltage is the resonant frequency of antenna 103.

[0051] Figure 2 An embodiment of device 1' is illustrated, which is adapted to provide wireless power to another device, such as providing wireless power 2. Figure 1 Device 3.

[0052] like Figure 1 Device 1' includes an inductor L and a capacitor C forming an antenna 103 of device 1'. Components L and C are connected in series between node 200 and node 202.

[0053] MOS transistor T2 is connected between node 200 and node 204, which is configured to receive a reference potential (e.g., ground GND).

[0054] Preferably, transistor T2 is part of half-bridge 206. Half-bridge 206 is configured to provide an AC signal to node 200 when device 1' provides wireless power to another device. Half-bridge 206 is connected between node 204 and node 208 configured to receive a power supply voltage Vdd_bridge, which is, for example, a positive DC voltage referenced to the potential GND. As an example, the power supply voltage Vdd_bridge is in the range from 1V to 24V or higher. Figure 2 In the example, the half-bridge includes a transistor T2 and a MOS transistor T1 connected in series between nodes 204 and 208, with transistor T1 connected between nodes 200 and 208.

[0055] exist Figure 2 In one embodiment, node 202 is directly coupled (i.e., connected) to node 204.

[0056] A capacitor element C1 (e.g., a capacitor) is connected between node 210 and interconnect node 212, which is located between element L and C.

[0057] A current generator 214 is connected to node 210. More specifically, generator 214 is connected between node 210 and node 209, which is configured to receive a supply voltage Vdd, which is, for example, a positive DC voltage referenced to a potential GND. As an example, the supply voltage Vdd is in the range of 1.8V to 5V. Generator 214 is configured to provide an AC current I to node 210. The frequency of the AC current I is controllable; that is, the frequency of generator 214 is controllable.

[0058] Switch IT is connected between nodes 210 and 204.

[0059] The phase of estimating the quality factor QfL(f) implemented by device 1' will now be described.

[0060] At the start of this phase, device 1' is configured to disconnect switch IT. Switch IT remains disconnected throughout all phases of estimating the quality factor QfL(f). Device 1' includes, for example, control circuitry, such as a microcontroller configured to control switch IT.

[0061] Furthermore, at the start of the stage for estimating the quality factor QfL(f), device 1' is configured to control transistor T2 such that transistor T2 switches to its on state. When transistor T2 is on, transistor T1 is controlled to be off. Therefore, a reference potential GND is applied to node 200. Device 1' includes, for example, a control circuit configured to control transistors T1 and T2, such as the same control circuit as the control circuit for controlling switch IT.

[0062] Since the same reference potential GND is applied to both nodes 200 and 202, the resonant gain of the LC filter formed by elements L and C will be at its maximum value.

[0063] Then, generator 214 provides current I to node 212. When generator 214 provides AC current I to node 210, node 210 (and therefore capacitor element C1) is charged and discharged based on the polarity of current I. Therefore, the voltage V of node 212 oscillates. The charging and discharging of capacitor element C1 has no effect on the quality factor QfL(f).

[0064] Capacitor C1 allows generator 214 to be powered by a positive voltage Vdd, while the voltage V at node 212 oscillates around the reference potential GND. In other words, capacitor C1 is a DC blocking capacitor.

[0065] As an example, when the voltage V oscillates between +0.5V and -0.5V and the voltage at node 210 relative to the potential GND reference oscillates between 2.2V and 0.8V, a voltage Vdd of 3V is sufficient to power generator 214.

[0066] Generator 214 is controlled by the control circuit of device 1' such that the frequency of voltage V is equal to the resonant frequency f0 of the LC filter formed by elements L and C. Therefore, at frequency f0, the impedance module of the impedance observed by node 212 is given by the following relationship:

[0067] [Mathematical Expression 1]

[0068]

[0069] Z fo R is the complex impedance of node 212 at the resonant frequency f0, and R is the equivalent series resistor of the LC filter, with the inherent resistance RL of element L included in the equivalent resistor R.

[0070] Furthermore, the quality factor QfL(f) of component L at a given frequency f can be expressed by the following relationship: [Mathematical Equation 2]

[0071]

[0072] Where w is the pulse corresponding to the given frequency f, and the pulse w is equal to 2*π*f.

[0073] Therefore, based on mathematical expressions 1 and 2, the quality factor QfL(f0) at the resonant frequency f0 can be expressed by the following relationship:

[0074] [Mathematical Expression 3]

[0075]

[0076] Where i is the amplitude of current I, v is the amplitude of voltage V, and w0 is the pulse at the resonant frequency f0.

[0077] Since the pulse w0 at the resonant frequency f0 of the LC filter can be expressed by the following relationship:

[0078] [Mathematical Expression 4]

[0079]

[0080] Therefore, the quality factor QfL(f0) at the resonant frequency f0 can be expressed by the following relationship:

[0081] [Mathematical Expression 5]

[0082]

[0083] Device 1' includes circuitry configured to measure voltage V, and more specifically, to measure the amplitude v of voltage V. Figure 2 (Not shown in the image).

[0084] Device 1' also includes a circuit configured to measure the pulse w of voltage V on node 212. Figure 2 (Not shown in the image), this circuit allows device 1' to know the value of pulse w0.

[0085] Therefore, device 1' can determine the values ​​of w0 and v at the resonant frequency f0. Furthermore, the values ​​of element C and i are constants and are known to device 1'. Therefore, device 1' can determine the value of the quality factor QfL(f0) of the inductor element L at the resonant frequency using the above mathematical formula 5.

[0086] According to an embodiment, device 1' is also configured to determine the quality factor QfL(f) for a given frequency f using the following relationship:

[0087] [Mathematical Expression 6]

[0088]

[0089] In other words, device 1' is configured to determine the value of the quality factor QfL(f) of inductor element L at any frequency f based on the measured voltage V at the resonant frequency f0 of the LC filter, the measured frequency f0, the known value of current I, and the known value of element C.

[0090] As an example, device 1' includes a processing unit ( Figure 2 (not shown in the figure), such as a microcontroller, which is configured to determine the value of the quality factor QfL(f) based on the measured voltage V at the resonant frequency f0 of the LC filter, the measured frequency f0, the known value of the current I, and the known value of the component C using the above mathematical formulas 5 and 6.

[0091] The operation of device 1' during the evaluation phase of the quality factor QfL(f) of the inductor element L has been described. Now, the normal operation of device 1', i.e., when the evaluation phase of the quality factor QfL(f) is not being implemented, such as when device 1' is providing wireless power, will be described.

[0092] During normal operation, device 1' is configured to close switch IT and maintain switch IT in a closed state. Therefore, since node 210 is at the reference potential GND, even if the magnitude of voltage V is high relative to the maximum voltage that generator 214 can support, this will not affect generator 214. In other words, when device 1' wirelessly powers another device, the closed switch IT protects generator 214 from the high voltage V.

[0093] It can be noted that when switch IT is closed, capacitor elements C and C1 are connected in parallel between nodes 212 and 204.

[0094] According to one embodiment, the value of capacitor element C1 is at least 100 times lower than the value of capacitor element C, such that during normal operation, the contribution of element C1 to the equivalent capacitor is negligible, which is formed by connecting elements C1 and C in parallel between nodes 212 and 204.

[0095] According to an alternative embodiment, the value of element C1 is selected such that the equivalent capacitor formed by connecting elements C1 and C in parallel between nodes 212 and 204 has a target value, for example, a target value determined by the frequency of the AC voltage applied to node 200 during normal operation.

[0096] In device 1', generator 214 preferably provides a current I with a sinusoidal waveform shape. However, the generator can also provide a current I with a square waveform. In the latter case, the harmonics of the current I are filtered by an LC filter formed by elements L and C.

[0097] In device 1', according to one embodiment, in order to ensure that the current I is at the resonant frequency f0 of the LC filter when evaluating the quality factor QfL(f0) of the inductor element L, device 1' is configured to switch the frequency of generator 214 until the amplitude of voltage V at node 212 is at its maximum value, which indicates that voltage V (and therefore current I) has a frequency equal to the resonant frequency f0 of the LC filter.

[0098] According to one embodiment, the maximum value Qfmax that the quality factor QfLC of the LC filter can take at its resonant frequency is known, and this value Qfmax is determined, for example, by means of simulation or calculation tools. Therefore, during the estimation phase of the quality factor QfL(f), the maximum amplitude vmax that can be taken by the voltage V at the resonant frequency f0 can be expressed by the following relationship:

[0099] [Mathematical Expression 7]

[0100] vmax=i*L*w0(1+Qfmax)

[0101] Therefore, to ensure that the value vmax does not exceed the target value vtarget (e.g., equal to 1V peak-to-peak in the Qi specification), the peak-to-peak amplitude i of the current I should be lower than the value imax, which can be expressed by the following relationship:

[0102] [Mathematical Expression 8]

[0103] imax <vtarget / (L*w0*(1+Qfmax)

[0104] For example, when component L has an inductance of 10 μH, a frequency f0 of approximately 100 kHz, a peak-to-peak target value vtarget of 1 V, and a maximum quality factor Qfmax of 100, the value imax is approximately 1.6 mA.

[0105] Therefore, the magnitude of the current I of device 1' is preferably selected such that the magnitude of the voltage V does not exceed the target value vtarget, which is low enough to not wake up the wirelessly powered device, which is placed in the magnetic field emitted by device 1'.

[0106] In the above description, the estimation of the quality factor QfL(f) implemented by device 1' is completed with regard to the equivalent series resistance R, which is actually equal to the on-state resistance RT2 of transistor T2 plus the inherent resistance RL of element L.

[0107] According to one embodiment, device 1' (e.g., a processing unit of device 1' configured to determine the quality factor QfL(f) at a given frequency f) is further configured to provide a correction value QfLc(f) for the quality factor QfL(f), which takes into account the on-state resistance RT2. The correction value QfLc(f) can be determined by the following relationship:

[0108] [Mathematical Expression 9]

[0109]

[0110] According to another embodiment, since the resistance RT2 is actually at least 5 times or even at least 10 times lower than the resistance RL, the effect of the on-state resistance RT2 on the determination of the quality factor QfL(f) is considered negligible.

[0111] Figure 3 The diagram shows Figure 2 Alternative embodiments of device 1'.

[0112] Figure 3 Device 1' and Figure 2 The only difference between device 1' and device 2' is that node 202 is not directly coupled to node 204, but is coupled to node 204 via MOS transistor T3. In other words, transistor T3 is connected between nodes 202 and 204.

[0113] Preferably, transistor T3 is part of half-bridge 300. Half-bridge 300, together with half-bridge 206, is configured to provide an AC signal to antenna 103 when device 1' provides wireless power to another device. Half-bridge 300 is connected between nodes 204 and 208. Figure 3 In the example, half-bridge 300 includes transistor T3 and MOS transistor T4 connected in series between nodes 204 and 208, with transistor T4 connected between nodes 202 and 208.

[0114] Apart from Figure 3 Device 1' is also configured to switch transistor T3 to the on state at the start of the estimation phase of the quality factor QfL(f) and to keep transistor T3 in the on state for the entire duration of that phase. Figure 3 The operation of device 1' during the estimation phase of quality factor QfL(f) is similar to Figure 2 The operation of device 1' is the same. Therefore, during the estimation phase of the quality factor QfL(f), the reference potential GND is applied to both nodes 200 and 202.

[0115] Those skilled in the art should be able to [describe / describe] the relevant information. Figure 2 Other aspects of the description of device 1' apply to Figure 3Device 1'. For example, those skilled in the art should be able to adjust relational formula 9 to take into account the on-state resistance RT3 of transistor T3 when calculating the correction value QfLc(f).

[0116] Figure 4 A more detailed illustration is provided. Figure 2 Example embodiment of device 1'.

[0117] In this embodiment, device 1' includes a circuit or detector 400 (block ZCD) connected to node 212. Circuit 400 is configured to provide a binary signal cmd (i.e., a signal cmd that switches between two values), or levels, referred to as high and low levels. Circuit 400 is also configured to switch the signal cmd whenever the voltage V crosses the potential GND. In other words, circuit 400 is configured to switch the binary signal cmd between its low and high levels whenever the voltage V crosses zero. In other words, circuit 400 is a zero-crossing detector. As an example, circuit 400 is implemented by a comparator having an input that receives the voltage V, another input that receives the potential GND (i.e., the zero-point voltage), and an output that provides the signal cmd.

[0118] The signal cmd is used as a control signal for generator 214, and more specifically, as a control signal for the frequency of generator 214. In other words, in this embodiment, circuit 400 is a control circuit for generator 214, and more precisely, a control circuit for the frequency of generator 214.

[0119] In this embodiment, generator 214 is configured to provide a square current I. In other words, current I can take both a high level and a low level, switching between its low and high levels. For example, the high and low values ​​of current I are equal in absolute value but have opposite polarities.

[0120] In this embodiment, generator 214 is also configured to switch current I between its low and high values ​​each time signal cmd is switched.

[0121] Therefore, during the estimation of the quality factor QfL(f), in steady state, the frequency of the current I is equal to the resonant frequency f0 of the LC filter.

[0122] Preferably, after each start of the estimation phase of the quality factor QfL(f), the circuit 400 is configured to implement a startup function to ensure that the voltage V begins to oscillate.

[0123] As an example, in order to implement this startup function, even if the voltage V does not cross the reference potential GND, the circuit 400 is also configured to switch the state of the signal cmd at the end of the delay duration, which begins at the start of each estimation phase of the quality factor QfL(f).

[0124] As another example, in order to implement this startup function, circuit 400 is also configured to inject current noise into node 212 at the end of the delay duration, which begins each time the estimation phase of the quality factor QfL(f) is started, even though the voltage V has not crossed the reference potential GND.

[0125] In this embodiment, to ensure that the frequency of the current I is equal to the resonant frequency f0 of the LC filter, rather than the frequency of the alternating generator 214, the generator 214 is controlled based on the detection that the voltage V is zero until the measured voltage V reaches its maximum value. Therefore, in steady state, the frequency of the voltage V is equal to the resonant frequency f0, which allows for better control compared to device 1' where the frequency of the generator 214 is constantly alternating until the measured voltage V reaches its maximum value. Figure 4 The duration of the estimation phase of the quality factor QfL(f) in device 1' is shorter.

[0126] Figure 4 The advantage of device 1' is that, at the steady state during the estimation phase of the quality factor QfL(f), the frequency of the signal cmd is equal to the resonant frequency f0 of the LC filter.

[0127] According to an embodiment, device 1' includes circuitry 402 configured to measure the frequency of a signal cmd. Since the signal cmd is a binary signal, circuitry 402 is, for example, a counter or timer configured to measure the duration of each low level of the signal cmd, the duration of each high level of the signal cmd, the duration between rising edges of the signal cmd, and the duration between two falling edges of the signal, and then determine the frequency f0 based on the measured durations.

[0128] Various embodiments and variations have been described. Those skilled in the art will understand that certain features of these embodiments can be combined, and other variations will be readily apparent to them. Specifically, those skilled in the art should be able to... Figure 4 Example embodiments applicable Figure 3 Device 1'. Furthermore, although the power supply voltage Vdd_bridge of node 209 is described as different from that of node 208, these two voltages may be equal.

[0129] Finally, based on the functional descriptions provided above, the actual implementation of the embodiments and variations described herein is within the capabilities of those skilled in the art.

Claims

1. An electronic device, comprising: The inductor and the first capacitor are connected in series between the first node and the second node; A first metal-oxide-semiconductor transistor is connected between the first node and a third node configured to receive a reference potential, and the second node is coupled to the third node directly or via a second metal-oxide-semiconductor transistor. A second capacitor element is connected between the fourth node and the interconnection node, wherein the interconnection node is located between the first capacitor element and the inductor element; A current generator is configured to provide AC current to the fourth node; as well as A switch is connected between the fourth node and the third node.

2. The electronic device according to claim 1, wherein the first capacitance of the first capacitor element is at least 100 times higher than the second capacitance of the second capacitor element.

3. The electronic device of claim 1, wherein the current generator is connected between the fourth node and the fifth node configured to receive a power supply voltage.

4. The electronic device of claim 3, wherein the first metal-oxide-semiconductor transistor is part of a half-bridge connected between the third node and a sixth node configured to receive a second power supply voltage.

5. The electronic device of claim 4, wherein the second metal-oxide-semiconductor transistor is part of another half-bridge, the other half-bridge connecting the third node and the sixth node.

6. The electronic device of claim 1, wherein the frequency of the current generator is controllable.

7. The electronic device of claim 6, further comprising circuitry configured to control the frequency of the current generator such that the frequency of the current generator is equal to the frequency of the voltage of the interconnect node.

8. The electronic device of claim 7, further comprising a second circuit configured to measure the frequency of the voltage of the interconnect node.

9. The electronic device of claim 7, wherein the circuitry includes a detector configured to provide a binary signal and to switch the binary signal whenever the voltage of the interconnect node crosses the reference potential, and wherein the current generator is configured to switch the AC current between a high level and a low level at each switching of the binary signal.

10. The electronic device of claim 9, further comprising a second circuit configured to measure the frequency of the voltage of the interconnect node, wherein the second circuit includes a counter configured to measure the frequency of the binary signal.

11. The electronic device of claim 1, further comprising circuitry configured to measure the voltage of the interconnect node.

12. The electronic device of claim 1, further comprising a control circuit configured to couple the first node and the second node to the third node, and the control circuit configured to disconnect the switch during the estimation phase of the quality factor of the inductor element, and to close the switch in other circumstances.

13. A wireless charger, comprising: The antenna includes an inductor and a capacitor connected in series between the first node and the second node. as well as Electronic devices, including: A first metal-oxide-semiconductor transistor is connected between the first node and a third node configured to receive a reference potential, and the second node is coupled to the third node directly or via the second metal-oxide-semiconductor transistor. A second capacitor element is connected between the fourth node and the interconnection node, wherein the interconnection node is located between the first capacitor element and the inductor element; A current generator is configured to provide AC current to the fourth node; and A switch is connected between the fourth node and the third node.

14. A method of operating an electronic device, the electronic device comprising: The inductor and the first capacitor are connected in series between the first node and the second node; A first metal-oxide-semiconductor transistor is connected between the first node and a third node coupled to a reference potential, and the second node is coupled to the third node directly or via a second metal-oxide-semiconductor transistor; A second capacitor element is connected between the fourth node and the interconnection node, wherein the interconnection node is located between the first capacitor element and the inductor element; And a switch, connected between the fourth node and the third node, the method includes: The current generator provides AC current to the fourth node; The first node and the second node are coupled to the third node, and the switch is turned off at the beginning of the estimation phase of the quality factor of the inductor element; During the estimation phase, the voltage of the interconnect node is measured in response to the AC current having a frequency equal to the resonant frequency of the series-connected inductor and the first capacitor. Measure the resonant frequency; and The switch is closed at the end of the estimation phase.

15. The method of claim 14, further comprising estimating the quality factor of the inductor based on the measured voltage, the capacitance of the first capacitor element, the value of the AC current, and the measured resonant frequency.

16. The method of claim 14, wherein the first capacitance of the first capacitor element is at least 100 times higher than the second capacitance of the second capacitor element.

17. The method of claim 14, further comprising circuitically controlling the frequency of the current generator such that the frequency of the current generator is equal to the frequency of the voltage of the interconnect node.

18. The method of claim 14, further comprising: The frequency of the current generator is controlled by the first circuit; as well as The frequency of the voltage at the interconnect node is measured by a second circuit.

19. The method of claim 14, further comprising: The frequency of the current generator is controlled by the first circuit; The detector of the first circuit provides the binary signal; Whenever the voltage of the interconnect node crosses the reference potential, the detector switches the binary signal; as well as The current generator switches the AC current between high and low levels each time the binary signal is switched.

20. The method of claim 19, further comprising: The frequency of the voltage at the interconnect node is measured by a second circuit; as well as The frequency of the binary signal is measured by a counter in the second circuit.

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