Single FET Multiplexer Switch for Coil Selection

Abstract

An integrated circuit is described. Such an integrated circuit may include a wireless charger transmitter including a driver circuit electrically coupled to multiple branches associated with multiple transmission coils. A given branch may include or may be electrically coupled to: a capacitor, a multiplexer (MUX) switch including a single field effect transistor (FET) or a single integrated gate bipolar transistor (IGBT), and a given transmission coil. Moreover, the wireless charger transmitter may include a control circuit that provides a control signal to the gate of the FET or IGBT in the branch, the control signal selectively activating at least the MUX switch in the given branch and selectively deactivating the remaining MUX switches in the remaining branches. In addition, the driver circuit may perform wireless charging by driving a given transmission coil in an activated given branch using an electrical signal having a fundamental frequency component.

Description

Technical Field

[0001] The present disclosure relates to techniques for wireless charging using a wireless charger transmitter. Background Art

[0002] To cover a large area, a wireless charger transmitter may include multiple transmission coils. In some wireless charger transmitters, each transmission coil is used as half of a transformer, sometimes referred to as a "half-bridge driver". However, when an electronic device (such as a cellular phone) is placed on the wireless charger transmitter, only a subset of the transmission coils may be used. Typically, a wireless charger transmitter uses a multiplexer (MUX) switch (sometimes referred to as a "coil selection MUX switch") to select one or more transmission coils to be driven by a power driver in a given switching cycle. It is worth noting that a subset of active transmission coils may be connected or electrically coupled to a surrounding network through printed circuit board traces and / or MUX switches (and more generally, through a low impedance path), which may include (one or more) capacitors and (one or more) half-bridge or full-bridge power drivers. (Note that each active coil may have an associated capacitor and an associated half-bridge or full-bridge driver. In Figures 1 and 2, which present circuit diagrams and circuit models of existing wireless charger transmitters, there is only a single capacitor because only one coil is active at a given time.) Moreover, the remaining transmission coils may be disabled. For example, disabled transmit coils may be open circuited so that little or no current flows through them.

[0003] Furthermore, a single field effect transistor (FET) is often insufficient to implement a MUX switch, since a FET may only block current in one direction due to the parasitic body diode. It is worth noting that for an NFET, there is effectively a body diode in parallel with the FET, with the forward direction being from its source to its drain. Therefore, even if the gate is shorted to the source, current can still flow from the source to the drain via the body diode.

[0004] Therefore, many existing wireless charger transmitters use back-to-back FETs to implement MUX switches. This is shown in Figure 1. It is worth noting that in Figure 1, each NMOS MUX switch can include two back-to-back FETs. When the gate is shorted to the source, each of the two back-to-back FETs can be disconnected. Moreover, the two body diodes associated with the two back-to-back FETs can block current in both directions.

[0005] However, the architecture shown in Figure 1 often has several disadvantages. Notably, the cost of the wireless charger transmitter is increased because two FETs are used. Also, the two FETs in series can double the drain-source on-resistance of the MUX switch, which can reduce system power efficiency.

[0006] Furthermore, to keep both FETs off, the gate voltage may need to follow the source voltage. However, even if a pair of back-to-back FETs are off, a small current may still flow through them. For example, a disabled coil may have a voltage across it due to mutual coupling with the active coil, which may cause a small current. Therefore, because the source voltage is typically different from ground, the level shifter network in many existing wireless charger transmitters may include a floating drive circuit to level shift the ground-referenced control signal to the gate-source reference domain in order to control each pair of back-to-back FETs.

[0007] These limitations of existing wireless charger transmitters are illustrated in FIG2 . In FIG2 , an existing wireless charger transmitter includes two transmit coils. V1 models a half-bridge driver that outputs a voltage at 128kHz, 50% duty cycle, and a 25V peak-to-peak square waveform. Moreover, Lp1 models an inactive transmit coil, and Lp2 models an active / connected transmit coil. Note that each pair of back-to-back NFETs (such as M1 and M2 or M3 and M4) represents a MUX switch. In addition, V_ctrl_1 and V_ctrl_2 model control voltages in the 5V domain (e.g., generated by a 5V general purpose input / output (I / O)), and E1 and E2 are voltage-controlled voltage sources with a gain of 2. These voltage-controlled voltage sources model the level shifters and drive networks that turn the MUX switches on and off.

[0008] Figure 3 presents the simulated steady-state electrical waveform in the prior art wireless charger transmitter of Figure 1. In Figure 3, note that the current through Lp1 is much smaller than the current through Lp2. Also, the gate and source voltages of the MUX switches in the disconnected branch vary by tens of volts between cycles at a frequency of 128kHz. Summary of the invention

[0009] An embodiment of an integrated circuit is described. This integrated circuit includes a wireless charger transmitter, which includes a driver circuit electrically coupled to multiple branches associated with multiple transmission coils. A given branch includes or is electrically coupled to: a capacitor, a MUX switch including a single FET or a single integrated gate bipolar transistor (IGBT), and a given transmission coil. Moreover, the wireless charger transmitter includes a control circuit that provides a control signal to the gate of the FET or IGBT in the branch, and the control signal selectively activates at least the MUX switch in the given branch and selectively deactivates the remaining MUX switches in the remaining branches. In addition, the driver circuit performs wireless charging by driving a given transmission coil in the activated given branch using an electrical signal having a fundamental frequency component.

[0010] Note that one or more of the capacitor, FET or IGBT and / or a given transmission coil may be external components to the integrated circuit.

[0011] Furthermore, the FET or IGBT may be included on a second integrated circuit separate from the integrated circuit.

[0012] In addition, the control circuit can dynamically adjust the wireless charging by changing the amplitude and / or base frequency of the electrical signal. In addition, the wireless charger transmitter can receive feedback about the wireless charging from the electronic device, and the dynamic adjustment can be based at least in part on the feedback. In some embodiments, the feedback can be received via a communication channel using the physical component in the given branch that is activated and / or via an out-of-band communication channel.

[0013] Note that the FET may block current flow in a given branch for a capacitor voltage having a first polarity in a non-conducting state, and the capacitor may charge and bias the body diode of the FET to block current flow in a given branch for a capacitor voltage having a second polarity after a predefined number of fundamental frequency cycles.

[0014] Furthermore, the control signal may selectively activate the MUX switches in more than one branch.

[0015] Furthermore, the MUX switch may include only FETs or IGBTs.

[0016] Furthermore, for a given control signal and a given FET state, the gate-source voltage of the FET can be approximately constant as a function of time.

[0017] In some embodiments, the fundamental frequency may be approximated as a resonant frequency corresponding to the capacitance of the capacitor and the inductance of a given transmission coil.

[0018] Another embodiment provides an electronic device including the integrated circuit.

[0019] Another embodiment provides a system including the integrated circuit.

[0020] Another embodiment provides a method for performing wireless charging. The method includes at least some of the operations performed by a wireless charger transmitter.

[0021] The purpose of providing this disclosure is to illustrate some exemplary embodiments in order to provide a basic understanding of some aspects of the subject matter described herein. Thus, it will be appreciated that the above features are examples and should not be interpreted as narrowing the scope or spirit of the subject matter described herein in any way. Other features, aspects and advantages of the subject matter described herein will become clear from the following detailed description, accompanying drawings and claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] FIG. 1 is a block diagram illustrating a circuit diagram of a conventional wireless charger transmitter.

[0023] FIG. 2 is a block diagram illustrating a circuit model of a conventional wireless charger transmitter.

[0024] FIG. 3 is a diagram illustrating a simulated steady-state electrical waveform in the conventional wireless charger transmitter of FIG. 1 .

[0025] Figure 4 is a block diagram illustrating an example of a wireless charger transmitter according to some embodiments of the present disclosure.

[0026] Figure 5 is a diagram illustrating some embodiments of the present disclosure Figure 4 A block diagram of an example of a circuit model of a wireless charger transmitter.

[0027] Figure 6 is a diagram illustrating some embodiments of the present disclosure Figure 4 Figure 2 is a graph of the simulated steady-state electrical waveform in the wireless charger transmitter.

[0028] Figure 7 is a diagram illustrating some embodiments of the present disclosure Figure 4 Figure 2. A graph of the simulated electrical waveform of a capacitor in a wireless charger transmitter.

[0029] Figure 8 is a flow chart illustrating an example of a method for performing wireless charging according to some embodiments of the present disclosure.

[0030] Note that like reference numerals refer to corresponding parts throughout the drawings. Also, multiple instances of the same part are designated by a common prefix separated by a dash and the instance number. DETAILED DESCRIPTION

[0031] An integrated circuit is described. Such an integrated circuit may include a wireless charger transmitter including a driver circuit electrically coupled to multiple branches associated with multiple transmission coils. A given branch may include or may be electrically coupled to: a capacitor, a multiplexer (MUX) switch including a single field effect transistor (FET) or a single integrated gate bipolar transistor (IGBT), and a given transmission coil. In some embodiments, the MUX switch may include only a FET or an IGBT. Moreover, the wireless charger transmitter may include a control circuit that provides a control signal to the gate of the FET or IGBT in the branch, the control signal selectively activating at least the MUX switch in the given branch and selectively deactivating the remaining MUX switches in the remaining branches. In addition, the driver circuit may perform wireless charging by driving a given transmission coil in an activated given branch using an electrical signal having a fundamental frequency component.

[0032] By using a single FET or a single IGBT in a given MUX switch, the disclosed circuit technology can eliminate one of the FETs in existing wireless charger transmitters. This can reduce the complexity, die area, and cost of the wireless charger transmitter, and can improve system power efficiency. In addition, the disclosed circuit technology can also eliminate the need for a level shifter network in the wireless charger transmitter, which is used in existing wireless charger transmitters to shift control signals. Therefore, the circuit technology can facilitate the use of USB 2.0 when using wireless charger transmitters in various systems, electronic devices, and applications.

[0033] We now describe embodiments of circuit techniques. These circuit techniques may be performed using one or more integrated circuits described. The one or more integrated circuits may include some or all of the components of a wireless charger transmitter having multiple transmit coils and associated functionality. Moreover, during operation, the one or more integrated circuits may use a MUX switch to select at least a subset of the transmit coils. A given MUX switch may include one FET, rather than two back-to-back FETs used in many existing wireless charger transmitters.

[0034] In addition, the circuit technology can provide a solution for a wireless charger transmitter that can be implemented on-chip or off-chip. Such a wireless charger transmitter can include fewer active components and therefore can be less complex, can have reduced cost, can use less die area (if integrated on-chip), and can have improved system power efficiency. It is worth noting that the wireless charger transmitter can use one FET (or integrated gate bipolar transistor) to implement the MUX switch. This is Figure 4 It is shown in Figure 4A block diagram of an example of a wireless charger transmitter 400 is presented. Note that the wireless charger transmitter 400 includes a driver circuit 410 having a capacitor (such as capacitor 414-1) (rather than a second FET) in each branch 412 that drives a different transmit coil 416. In addition, each branch 412 can include a FET (such as FET 418-1) that can be a MUX switch (as indicated by M1, M2, or M3) that turns off current flow in one direction (such as for a positive voltage) based at least in part on a control signal provided by a control circuit 420. (It is worth noting that a control signal from control circuit 420 can be applied to the gate of FET 418 in branch 412, which selectively activates at least the MUX switch in a given branch and selectively deactivates the remaining MUX switches in at least some or the remaining branches in branch 412.) Although the parasitic body diode cannot prevent current flow in the other direction (such as for negative voltages), when capacitor 414-1 is charged (e.g., after several switching cycles), it will keep the parasitic body diode reverse biased (so it will not turn on) and current will stop flowing. Moreover, as further described below, wireless charger transmitter 400 can simplify or eliminate the level shifter network (e.g., in control circuit 420, as previously discussed, which can be used to shift the control signal in the wireless charger transmitter) because the source of FET 418-1 is grounded.

[0035] In some embodiments, a given inductance (such as Lp1, Lp2, or Lp3) of a given transmission coil (such as transmission coil 416-1) may be 12 μH, and a given capacitance (such as Cp1, Cp2, or Cp3) ​​of a given capacitor (such as capacitor 414-1) may be 200 nF. Note that a given transmission coil may be made using magnet wire or a litz coil (such as braided magnet wire). Furthermore, wireless charger transmitter 400 may have a power consumption of 15 W.

[0036] Figure 5 A wireless charger transmitter 400 ( Figure 4 ) is an example of a circuit model 500. Figure 5 In Figure 1, M1 is off and M2 is on. Note that Lp2, Cp2, and M2 can form a connected branch. Also, while the body diode of M1 will initially conduct current, the voltage across Cp1 will increase until the body diode of M1 is no longer on, effectively blocking current in both directions in the steady state. Figure 6 A wireless charger transmitter 400 ( Figure 4 ) in the simulated steady-state electrical waveform.

[0037] like Figure 6 As shown in , the current through Lp1 can be much smaller than the current through Lp2. Moreover, the voltage of the control signal of the MUX switch can usually be ground referenced or referenced, which can simplify the wireless charger transmitter 400 ( Figure 4 ) in the drive network. In other words, the drive network can have a well-controlled source voltage (such as a gate-source voltage of 5-10V), which can simplify or eliminate the level shifter network. Figure 6 In the example, V(LX, v_coil1) is the voltage across the Cp1 capacitor. It maintains a DC voltage. This voltage can be high enough that the body diode of M1 is always reverse biased. Figure 7 The wireless charger transmitter 400 ( Figure 4 ) is a simulated waveform of the charging of Cp1 in FIG. 1 . Note that for a given control signal and a given FET state, the gate-source voltage of the FET can be approximately constant as a function of time.

[0038] The disclosed circuit technology can provide benefits, including the use of only one FET in each transmit coil branch and fewer (overall) components for the driver circuit, at the expense of using an additional capacitor in each transmit coil branch. All considered, this architecture can reduce the cost of the wireless charger transmitter. Moreover, for the same type of FET used in existing wireless charger transmitters, the drain-source resistance can be halved. Therefore, the system power efficiency can be increased.

[0039] In some embodiments, a unit receiving power (such as an electronic device being wirelessly charged) can request more or less power from a wireless charger transmitter via in-band and / or out-of-band communication. Note that wireless charging can use resonant charging or non-resonant charging. Therefore, the fundamental frequency of the electrical signal driving a given branch being activated in the driver circuit can be approximated to the resonant frequency corresponding to the capacitance of the capacitor and the inductance of a given transmission coil. In response to a request for more or less power, the wireless charger transmitter can have a fixed operating frequency and the drive voltage can be changed dynamically (this can be used, for example, in automotive wireless charging). Alternatively or additionally, the wireless charger transmitter can have a variable operating frequency. For example, the driver circuit in the wireless charger transmitter can perform wireless charging by changing the fundamental frequency component in the electrical signal driving a given transmission coil in a given branch being activated in the driver circuit. Note that the wireless coupling coefficient between the wireless charger transmitter and the unit receiving power can be changed.

[0040] We now describe an embodiment of a method. Figure 8 Presented are diagrams illustrating the use of a wireless charger transmitter (such as wireless charger transmitter 400 ( Figure 4))A flow chart of an example of a method 800 for performing wireless charging. During operation, a wireless charger transmitter may electrically couple a driver circuit to multiple branches associated with multiple transmission coils (operation 810), wherein a given branch may include or may be electrically coupled to: a capacitor, a MUX switch including a single FET or a single IGBT, and a given transmission coil. The wireless charger transmitter may then provide a control signal from a control circuit to the gate of the FET or IGBT in the branch (operation 812), the control signal selectively activating at least the MUX switch in the given branch and selectively deactivating the remaining MUX switches in the remaining branches. Next, the wireless charger transmitter may use the driver circuit to drive a given transmission coil in the activated given branch using an electrical signal having a fundamental frequency component to perform wireless charging (operation 814).

[0041] In some embodiments of method 800, there may be additional or fewer operations. Furthermore, the order of the operations may be changed, and / or two or more operations may be combined into a single operation.

[0042] For example, the control circuit can dynamically adjust the wireless charging by changing the amplitude and / or base frequency of the electrical signal. In addition, the wireless charger transmitter can receive feedback about the wireless charging from the electronic device, and the dynamic adjustment can be based at least in part on the feedback. In some embodiments, the feedback can be received via a communication channel using a physical component in a given branch that is activated and / or via an out-of-band communication channel. In addition, the control signal can selectively activate the MUX switch in more than one branch.

[0043] The disclosed wireless charger transmitter and circuit technology may be any electronic device or system (or may be included therein). For example, the electronic device may include: a cellular phone or smart phone, a tablet computer, a laptop computer, a notebook computer, a personal or desktop computer, a netbook computer, a media player device, an e-book device, A device, a wireless charger device, a wireless charging system, a smart watch, a wearable computing device, a portable computing device, a consumer electronic device, an access point, a router, a switch, communication equipment, test equipment, a vehicle, a ship, an aircraft, an automobile, a truck, a bus, a motorcycle, manufacturing equipment, agricultural equipment, construction equipment, or another type of electronic device.

[0044] Although specific components are used to describe embodiments of a wireless charger transmitter and / or an integrated circuit including a wireless charger transmitter, in alternative embodiments, different components and / or subsystems may be present in the wireless charger transmitter and / or the integrated circuit including the wireless charger transmitter. Therefore, embodiments of the wireless charger transmitter and / or the integrated circuit including the wireless charger transmitter may include fewer components, additional components, different components, two or more components may be combined into a single component, a single component may be divided into two or more components, one or more positions of one or more components may be changed, and / or different types of components may exist. For example, a given branch in a wireless charger transmitter may include a single IGBT instead of a single FET. Note that one or more of the capacitor, FET or IGBT, and / or a given transmission coil may be an external component of the wireless charger transmitter. In some embodiments, the FET or IGBT may be included on a second integrated circuit separate from the integrated circuit including the wireless charger transmitter. In addition, in some embodiments, the MUX switch may include only a FET or an IGBT. In some embodiments, the wireless charger power stage may be an external component of the wireless charger transmitter.

[0045] Moreover, the circuits and components in the embodiments of the wireless charger transmitter and / or integrated circuit including the wireless charger transmitter can be implemented using any combination of analog and / or digital circuit systems, including: bipolar, PMOS and / or NMOS gates or transistors. In addition, the signals in these embodiments may include digital signals with approximately discrete values ​​and / or analog signals with continuous values. In addition, the components and circuits can be single-ended or differential, and the power supply can be unipolar or bipolar. It is noted that the electrical coupling or connection in the foregoing embodiments can be direct or indirect. In the foregoing embodiments, a single line corresponding to a path can indicate one or more single lines or paths.

[0046] As previously indicated, an integrated circuit may implement some or all of the functionality of a circuit technology. Such an integrated circuit may include hardware and / or software mechanisms used to implement the functionality associated with the circuit technology.

[0047] In some embodiments, the output of the process for designing an integrated circuit or a part of an integrated circuit including one or more of the circuits described herein can be a computer-readable medium, such as, for example, a tape or an optical disk or a disk. The computer-readable medium can be encoded with a data structure or other information describing a circuit system that can be physically instantiated as an integrated circuit or a part of an integrated circuit. Although various formats can be used for such encoding, these data structures are generally written in the following formats: Caltech Intermediate Format (CIF), Calma GDS II Stream Format (GDSII), Electronic Design Interchange Format (EDIF), OpenAccess (OA) or Open Artwork System Interchange Standard (OASIS). Technicians in the field of integrated circuit design can develop such data structures based on the schematic diagrams and corresponding descriptions of the types described in detail above, and encode the data structures on a computer-readable medium. Technicians in the field of integrated circuit manufacturing can use such encoded data to manufacture integrated circuits including one or more of the circuits described herein.

[0048] Although some operations in the foregoing embodiments are implemented in hardware or software, generally the operations in the foregoing embodiments can be implemented in a variety of configurations and architectures. Therefore, some or all of the operations in the foregoing embodiments can be performed in hardware, software, or both. For example, at least some of the operations in the circuit technology can be implemented using program instructions executed by firmware in a processor or integrated circuit.

[0049] Furthermore, although examples of numerical values ​​are provided in the foregoing discussion, different numerical values ​​are used in other embodiments. Therefore, the numerical values ​​provided are not intended to be limiting.

[0050] In the foregoing description, we referred to “some embodiments.” Note that “some embodiments” describes a subset of all possible embodiments, but does not always specify the same subset of implementation examples.

[0051] The foregoing description is intended to enable any person skilled in the art to make and use the present disclosure, and is provided in the context of a specific application and its requirements. Moreover, the foregoing description of the embodiments of the present disclosure is presented only for the purpose of illustration and description. They are not intended to be exhaustive or to limit the present disclosure to the disclosed form. Thus, many modifications and variations will be clear to those skilled in the art, and the general principles defined herein can be applied to other embodiments and applications without departing from the spirit and scope of the present disclosure. In addition, the discussion of the foregoing embodiments is not intended to limit the present disclosure. Therefore, the present disclosure is not intended to be limited to the embodiments shown, but should be given the widest scope consistent with the principles and features disclosed herein.

Claims

1. An integrated circuit comprising a wireless charger transmitter, wherein: Wireless charger transmitter includes: a driver circuit electrically coupled to a plurality of branches associated with a plurality of transmission coils, wherein a given branch includes or is configured to be electrically coupled to: a capacitor, a multiplexer MUX switch including a single field effect transistor FET or a single integrated gate bipolar transistor IGBT, and a given transmission coil; and A control circuit is configured to provide a control signal to the gate of the FET or IGBT in the branch, the control signal selectively activating at least the MUX switch in the given branch and selectively deactivating the remaining MUX switches in the remaining branches, wherein the driver circuit is configured to perform wireless charging by driving a given transmission coil in the activated given branch using an electrical signal having a fundamental frequency component.

2. The integrated circuit of claim 1, wherein: One or more of the capacitor, FET or IGBT or a given transmission coil are external components to the integrated circuit.

3. The integrated circuit of claim 1, wherein: The FET or IGBT is included on a second integrated circuit separate from the integrated circuit.

4. The integrated circuit of claim 1, wherein: The control circuit is configured to dynamically adjust the wireless charging by changing the amplitude, fundamental frequency, or both of the electrical signal.

5. The integrated circuit of claim 4, wherein: The wireless charger transmitter is configured to receive feedback from the electronic device regarding wireless charging, and the dynamic adjustment is based at least in part on the feedback.

6. The integrated circuit of claim 5, wherein: The feedback is received via a communication channel using the physical component in the given branch being activated or via an out-of-band communication channel.

7. The integrated circuit of claim 1, wherein: The FET is configured to, in a non-conducting state, block current flow in a given branch for a capacitor voltage having a first polarity, and the capacitor is configured to charge and bias a body diode of the FET to block current flow in the given branch for a capacitor voltage having a second polarity after a predefined number of fundamental frequency cycles.

8. The integrated circuit of claim 1, wherein: The control signal selectively activates the MUX switches in more than one branch.

9. The integrated circuit of claim 1, wherein: The MUX switch is composed of FET or IGBT.

10. The integrated circuit of claim 1, wherein: For a given control signal and a given FET state, the gate-source voltage of the FET is approximately constant as a function of time.

11. The integrated circuit of claim 1, wherein: The fundamental frequency is approximately the resonant frequency corresponding to the capacitance of the capacitor and the inductance of a given transmission coil.

12. An electronic device comprising: An integrated circuit, comprising a wireless charger transmitter, wherein the wireless charger transmitter comprises: a driver circuit electrically coupled to a plurality of branches associated with a plurality of transmission coils, wherein a given branch includes or is configured to be electrically coupled to: a capacitor, a multiplexer MUX switch including a single field effect transistor FET or a single integrated gate bipolar transistor IGBT, and a given transmission coil; and A control circuit is configured to provide a control signal to the gate of the FET or IGBT in the branch, the control signal selectively activating at least the MUX switch in the given branch and selectively deactivating the remaining MUX switches in the remaining branches, wherein the driver circuit is configured to perform wireless charging by driving a given transmission coil in the activated given branch using an electrical signal having a fundamental frequency component.

13. The electronic device of claim 12, wherein one or more of the capacitor, the FET or the IGBT or the given transmission coil is an external component of the integrated circuit.

14. The electronic device according to claim 12, wherein: The control circuit is configured to dynamically adjust the wireless charging by changing the amplitude, fundamental frequency, or both of the electrical signal.

15. The electronic device according to claim 14, wherein: The wireless charger transmitter is configured to receive feedback from the second electronic device regarding the wireless charging, and the dynamic adjustment is based at least in part on the feedback.

16. The electronic device according to claim 15, wherein: The feedback is received via a communication channel using the physical component in the given branch being activated or via an out-of-band communication channel.

17. An electronic device as described in claim 12, wherein the FET is configured to block current flow in a given branch for a capacitor voltage having a first polarity in a non-conducting state, and the capacitor is configured to charge and bias the body diode of the FET to block current flow in the given branch for a capacitor voltage having a second polarity after a predefined number of fundamental frequency cycles.

18. The electronic device according to claim 12, wherein: The MUX switch is composed of FET or IGBT.

19. A method for performing wireless charging, comprising: The wireless charger transmitter implements the following functions: electrically coupling the driver circuit to a plurality of branches associated with the plurality of transmission coils, wherein a given branch comprises or is electrically coupled to: a capacitor, a multiplexer MUX switch comprising a single field effect transistor FET or a single integrated gate bipolar transistor IGBT, and a given transmission coil; providing a control signal from a control circuit to the gates of the FETs or IGBTs in the branches, the control signal selectively activating at least the MUX switch in a given branch and selectively deactivating the remaining MUX switches in the remaining branches; as well as Wireless charging is performed by driving a given transmission coil in a given branch that is activated using an electrical signal having a fundamental frequency component using the driver circuit.

20. The method of claim 19, wherein: The method includes receiving feedback from the electronic device regarding wireless charging, and dynamically adjusting based at least in part on the feedback.

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