Electronic devices with a triangular frequency dithering profile

Abstract

To provide an electronic device having an inverter. [Solution] The electronic device may include an inverter. The inverter can receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil. The dithered clock signal may have multiple frequency steps during the iterative cycle of the dithered clock signal. The iterative cycle of the dithered clock signal may include a step function that approximates a triangular waveform having steps with a specific frequency magnitude during the iterative cycle.

Description

[Technical Field]

[0001] This application claims priority to U.S. Patent Application No. 19 / 359,295, filed on 15 October 2025, and U.S. Provisional Patent Application No. 63 / 723,413, filed on 21 November 2024, both of which are incorporated herein by reference in their entirety. Technical field This application relates in general to electronic devices, and more specifically to electronic devices having an inverter. [Background technology]

[0002] Electronic devices may include inverters that convert direct current (DC) power to alternating current (AC) power. An inverter can use a clock signal of a given frequency to output a corresponding AC signal. Care should be taken to improve the electromagnetic compatibility of the inverter. [Overview of the Initiative]

[0003] The electronic device may include an inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, and a control circuit configured to generate the dithered clock signal.

[0004] A dithered clock signal may have multiple frequency steps during its iterative cycle, the iterative cycle of the dithered clock signal may include a step function that approximates a triangular waveform, and the dithered clock signal may have a unique frequency magnitude for each of the multiple frequency steps during its iterative cycle.

[0005] A dithered clock signal may have multiple frequency steps during its iterative cycle, the iterative cycle of the dithered clock signal may include a step function that approximates a triangular waveform, the magnitude of the frequency may decrease over time during a first subset of the multiple frequency steps, the magnitude of the frequency may increase over time during a second subset of the multiple frequency steps, and each one in the second subset of the multiple frequency steps may have a magnitude of frequency that lies between the magnitudes of each of the two respective frequencies in the first subset of the multiple frequency steps.

[0006] A dithered clock signal may have multiple frequency steps during its iterative cycle, the iterative cycle of the dithered clock signal may include a step function approximating a triangular waveform, the triangular waveform may be centered on a frequency designated as the radio power transmission frequency of an electronic device, the undithered version of the clock signal at the radio power transmission frequency may have a first maximum radiation magnitude at the radio power transmission frequency, the dithered clock signal may have a second maximum radiation magnitude at the radio power transmission frequency and an additional radiation magnitude at the sideband frequency, the second maximum radiation magnitude may be less than the first maximum radiation magnitude by a first difference, the additional radiation magnitude may be less than the first maximum radiation magnitude by a second difference, the second difference may be greater than the first difference, and the second difference may be within 1.2 dB of the first difference. [Brief explanation of the drawing]

[0007] [Figure 1] This is a schematic diagram of an exemplary wireless power system according to several embodiments.

[0008] [Figure 2] These are circuit diagrams of exemplary wireless power transmission and wireless power reception circuits in a wireless power system according to several embodiments.

[0009] [Figure 3] This is an illustrative circuit diagram of an inverter according to several embodiments.

[0010] [Figure 4] This is a schematic diagram of an exemplary electronic device including a dithering circuit, according to several embodiments.

[0011] [Figure 5] This is a graph of an exemplary dithered clock signal in several embodiments.

[0012] [Figure 6] This is a graph of an exemplary modulated signal according to several embodiments.

[0013] [Figure 7] Figure 5 shows a graph of radiation as a function of frequency of an exemplary dithered clock signal, according to several embodiments.

[0014] [Figure 8] This is a flowchart illustrating an exemplary method for selecting a dithered clock signal according to several embodiments. [Modes for carrying out the invention]

[0015] An exemplary wireless power system (also referred to as a wireless charging system) is shown in FIG. 1. As shown in FIG. 1, the wireless power system 8 may include one or more wireless power transmitting devices such as the wireless power transmitting device 12, and one or more wireless power receiving devices such as the wireless power receiving device 24. The wireless power system 8 may also be referred to herein as a wireless power transmission (WPT) system 8 or a wireless power system 8. The wireless power transmitting device 12 may also be referred to herein as a power transmitter (PTX) device 12 or simply PTX 12. The wireless power receiving device 24 may also be referred to herein as a power receiver (PRX) device 24 or simply PRX 24.

[0016] The PTX device 12 includes a control circuit 16. The control circuit 16 is mounted within a housing 30. The PRX device 24 includes a control circuit 38 mounted within a corresponding housing 52 for the PRX device 24. The exemplary control circuit 16 and control circuit 38 are used when controlling the operation of the WPT system 8. This control circuit may include a processing circuit including one or more processors such as a microprocessor, a power management unit, a baseband processor, a digital signal processor, a microcontroller, a graphics processing unit (GPU), a central processing unit (CPU), an application processor (AP), an application-specific integrated circuit having a processing circuit, and / or other processing circuits. The processing circuit performs desired control and communication functions within the PTX device 12 and the PRX device 24. For example, the processing circuit may control power to one or more coils, determine and / or set the transmission level, generate and / or process sensor data (e.g., to detect foreign objects and / or external electromagnetic signals or electromagnetic fields), process user input, process negotiation between the PTX device 12 and the PRX device 24, transmit and receive in-band and out-of-band data, make measurements, and / or be used when controlling the operation of the WPT system 8.

[0017] The control circuit (e.g., control circuits 16 and / or 38) within the WPT system 8 may be configured to perform operations within the WPT system 8 using hardware (e.g., dedicated hardware or circuitry), firmware, and / or software. Software code for performing operations within the WPT system 8 is stored on a non-transitory computer-readable storage medium (e.g., a tangible computer-readable storage medium) within the control circuit of the WPT system 8. The software code may be referred to as software, data, program instructions, instructions, or code. The non-transitory computer-readable storage medium can include non-volatile memory such as non-volatile random-access memory (NVRAM), one or more hard drives (e.g., magnetic drives or solid-state drives), one or more removable flash drives, or other removable media. The software stored on the non-transitory computer-readable storage medium can be executed on the processing circuits of control circuit 16 and / or control circuit 38.

[0018] The PTX device 12 may be a standalone power adapter (e.g., a wireless charging mat or charging pack including a power adapter circuit), a wireless charging mat or pack connected by cable to a power adapter or other device, an electronic device (e.g., a laptop computer, a desktop computer, a computer monitor with a built-in embedded computer, a tablet computer, a mobile phone, a media player, or other handheld or portable electronic device, a small device such as a wristwatch device, a pendant device, headphones or earphone devices, glasses, goggles, or a device incorporated into other equipment worn on the user's head, or other wearable or miniature devices, a television, a computer display without a built-in embedded computer, a gaming device, a navigation device, a wireless internet-connected voice-controlled speaker, a home entertainment device, a remote control device, a gaming controller, a peripheral user input device, a wireless base station or access point, equipment implementing two or more functions of these devices, or other electronic equipment), equipment incorporated into furniture, a vehicle, or other system, a removable battery case, or other wireless power transmission equipment.

[0019] The PRX device 24 may be an electronic device such as a laptop computer, desktop computer, computer monitor including an embedded computer, tablet computer, cellular phone, media player, or other handheld or portable electronic device; a wristwatch device, pendant device, headphone device or earphone device, a device embedded in eyeglasses or goggles or other device worn on the user's head, or a small device such as other wearable devices or miniature devices; a wireless tracking tag, television, computer display not including an embedded computer, gaming device, navigation device, internet-connected voice-controlled wireless speaker, home entertainment device, remote control device, gaming controller, peripheral user input device, wireless base station or access point, a device that implements two or more functions of these devices, or other electronic equipment.

[0020] The PTX device 12 may be connected to a wall outlet (e.g., an AC power source), coupled to a wall outlet via an external power adapter, have a battery for power supply, and / or have another power source. In an implementation where the PTX device 12 is coupled to a wall outlet via an external power adapter, the adapter may have an AC-DC power converter that converts alternating current (AC) power from the wall outlet or other power source to direct current (DC) power. If necessary, the PTX device 12 may include a DC-DC power converter for converting DC power between different DC voltages. Additionally or alternatively, the PTX device 12 may include an AC-DC power converter that generates DC power from AC power provided by a wall outlet (e.g., in an implementation where the PTX device 12 is connected to a wall outlet without an external power adapter). DC power can be used to power the control circuit 16. During operation, the controller in the control circuit 16 transmits wireless power to the power receiving circuit 46 of the PRX device 24 using the power transmission circuit 22.

[0021] The power transmission circuit 22 may have a switching circuit (e.g., an inverter circuit 26 formed from transistors) that is turned on and off based on a control signal supplied by the control circuit 16 to generate an AC current signal via one or more wireless power transmission coils, such as the wireless power transmission coil 32. These coil drive signals cause the coil(s) 32 to transmit wireless power. In implementations where the coil(s) 32 includes multiple coils, the coils may be arranged on a ferromagnetic structure, arranged in a planar coil array, or arranged to form a cluster of coils (e.g., two or more coils, 5 to 10 coils, at least 10 coils, 10 to 30 coils, fewer than 35 coils, fewer than 25 coils, or any other appropriate number of coils). In some implementations, the PTX device 12 includes only a single coil 32.

[0022] When an AC current flows through one or more coils 32, an AC electromagnetic field (e.g., a magnetic field) (a radio power signal 44) is generated, which is received by one or more corresponding receiving coils, such as one or more coils 48 in the PRX device 24. In other words, one or more of the coils 32 are inductively coupled to one or more of the coils 48. The PRX device 24 may have a single coil 48, at least two coils 48, at least three coils 48, at least four coils 48, or any other preferred number of coils 48. When an AC electromagnetic field is received by one or more coils 48, a corresponding AC current is induced in one or more coils 48. The AC signal used when transmitting radio power can have any desired frequency (e.g., 100-400 kHz, 1-100 MHz, 1.7 MHz-1.8 MHz, less than 2 MHz, 100 kHz-2 MHz, 6.78 MHz, 13.56 MHz, etc.). A rectifier circuit, such as a rectifier circuit 50, which includes rectifier components such as synchronous rectifier transistors located within the bridge network, converts the received AC signal (the received AC signal associated with the radio power signal 44) into a DC voltage signal for supplying power to the PRX device 24 from one or more coils 48. The radio power signal 44 may be referred to herein as radio power 44 or radio charging signal 44. Coil 32 may be referred herein as radio power transmission coil 32, radio charging coil 32, or radio power transmission coil 32. Coil 48 may be referred herein as radio power transmission coil 48, radio charging coil 48, or radio power receiving coil 48.

[0023] The DC voltage generated by the rectifier circuit 50 (sometimes called the rectifier output voltage Vrect) may be used to charge a battery such as the battery 34, or to supply power to other components in the PRX device 24, such as the control circuit 38 and the input / output (I / O) device 54. The PTX device 12 may also include input / output devices such as the input / output device 28. The input / output device 54 and / or the input / output device 28 may include input devices for collecting user inputs and / or performing environmental measurements, and may include output devices for providing outputs to the user.

[0024] For example, input / output devices 28 and / or 54 may include a display (screen) for generating a visual output, a speaker for presenting the output as an audio signal, a light-emitting diode status indicator light and other light-emitting components for emitting light to provide status information and / or other information to the user, a tactile device for generating vibration and other tactile outputs, and / or other output devices. Input / output devices 28 and / or 54 may also include sensors for collecting user input and / or making measurements of the surroundings of the WPT system 8.

[0025] The example of a PRX device 24 including a battery 34 in Figure 1 is illustrative. More generally, the electronic device may include an energy storage device 34. The energy storage device 34 may be a battery or, for example, a supercapacitor that stores electric charge.

[0026] The PTX device 12 and the PRX device 24 can communicate wirelessly using in-band or out-of-band communication. Implementations using in-band communication, for example, can utilize frequency-shift keying (FSK) and / or amplitude-shift keying (ASK) techniques to communicate in-band data between the PTX device 12 and the PRX device 24. Wireless power and in-band data transmission can be carried using coils 32 and 48 simultaneously. When the PTX 12 transmits in-band data to the PRX 24, the wireless transceiver (TX / RX) circuit 20 can modulate the wireless charging signal 44 to provide FSK or ASK communication, and the wireless transceiver circuit 40 can demodulate the wireless charging signal 44 to obtain the transmitted data. When PRX 24 transmits in-band data to PTX 12, the wireless transceiver (TX / RX) circuit 40 can modulate the wireless charging signal 44 to provide FSK or ASK communication, and the wireless transceiver circuit 20 can demodulate the wireless charging signal 44 to obtain the transmitted data.

[0027] Implementations using out-of-band communication can utilize, for example, a hardware antenna structure and a communication protocol such as Bluetooth or NFC to communicate out-of-band data between the PTX device 12 and the PRX device 24. Power can be wirelessly carried between coils 32 and 48 simultaneously with the transmission of out-of-band data. The wireless transceiver circuit 20 can wirelessly transmit and / or receive out-of-band signals to and / or from the PRX device 24 using an antenna such as antenna 56. The wireless transceiver circuit 40 can wirelessly transmit and / or receive out-of-band signals to and / or from the PTX device 12 using an antenna such as antenna 58.

[0028] Antennas 56 and 58 are connected to wireless local area network (WLAN) communication bands such as the 2.4GHz and 5GHz Wi-Fi® (IEEE802.11) bands, wireless personal area network (WPAN) communication bands such as the 2.4GHz Bluetooth® band, cellular low band (LB) (e.g., 600~960MHz), cellular low-midband (LMB) (e.g., 1400~1550MHz), cellular midband (MB) (e.g., 1700~2200MHz), cellular high band (HB) (e.g., 2300~2700MHz), cellular ultra-high band (UHB) (e.g., 3300~5000MHz), or other cellular communication bands of approximately 600MHz to approximately 5000MHz (e.g., 3G band, 4G band). It can handle cellular telephone communication bands such as LTE bands and 5G Frequency Range 1 (FR1) bands below 10GHz, near-field communications (NFC) bands (e.g., at 13.56MHz), satellite navigation bands (e.g., L1 global positioning system (GPS) band at 1575MHz, L5 GPS band at 1176MHz, Global Navigation Satellite System (GLONASS) band, BeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband (UWB) communication bands (one or more) supported by the IEEE 802.15.4 protocol, and / or other UWB communication protocols (e.g., a first UWB communication band at 6.5GHz and / or a second UWB communication band at 8.0GHz), and / or any other desired communication band.

[0029] Antennas 56 and 58 can support communication in the extremely high frequency (EHF) or millimeter-wave communication band of approximately 30 GHz to 300 GHz, and / or in the centimeter-wave communication band of approximately 10 GHz to 30 GHz (sometimes called the super high frequency (SHF) band). For example, antennas 56 and 58 can support communication in the IEEE K communication band of approximately 18 GHz to 27 GHz, and the K band of approximately 26.5 GHz to 40 GHz. a Communication bandwidth, approximately 12GHz~18GHz K u The communication band can support communication in the V communication band of approximately 40GHz to 75GHz, the W communication band of approximately 75GHz to 110GHz, or any other desired frequency band of approximately 10GHz to 300GHz. If desired, the millimeter-wave / centimeter-wave transceiver circuit can support IEEE 802.11ad communication at 60GHz (e.g., the WiGig or 60GHz Wi-Fi band around 57-61GHz) and / or the 5th generation mobile network or 5th generation wireless system (5G) new radio (NR) frequency range 2 (FR2) communication band of approximately 24GHz to 90GHz.

[0030] Antennas 56 and 58 may include antennas having resonant elements formed from loop antenna structures, patch antenna structures, inverted F antenna structures, slot antenna structures, planar inverted F antenna structures, helical antenna structures, dipole antenna structures, monopole antenna structures, or hybrids of these designs. Different types of antennas may be used for different bandwidths and combinations of bandwidths. For example, one type of antenna may be used to form a local radio link, and another type of antenna may be used to form a remote radio link antenna.

[0031] Each of the housings 30 and 52 can be formed from plastic, metal, fiber composite materials such as carbon fiber materials, wood and other natural materials, glass, other materials, and / or combinations of two or more of these materials.

[0032] The example in Figure 1, where PTX 12 transmits wireless power and PRX 24 receives wireless power, is merely illustrative. PTX 12 can optionally receive wireless power signals using one or more coils 32, and PRX 24 can optionally transmit wireless power signals using one or more coils 48. When a device is capable of both transmitting and receiving wireless power signals, the device may include both an inverter and a rectifier.

[0033] Figure 2 is a schematic diagram of an exemplary wireless charging circuit for system 8. As shown in Figure 2, the circuit 22 may include an inverter circuit, such as one or more inverters 26, or other drive circuits that generate a wireless power signal transmitted via an output circuit, such as one or more coils 32 and a capacitor, such as a capacitor 70. In some embodiments, the device 12 may include a plurality of individually controlled inverters 26, each supplying a drive signal to an individual coil 32. In other embodiments, the inverters 26 are shared among the plurality of coils 32 using a switching circuit.

[0034] During operation, control signals for one or more inverters 26 are provided by the control circuit 16 at control inputs 74. While a single inverter 26 and a single coil 32 are shown in the embodiment of Figure 2, multiple inverters 26 and multiple coils 32 may be used as needed. In a multiple-coil configuration, a switching circuit (e.g., a multiplexer circuit) can be used to couple a single inverter 26 to multiple coils 32, and / or each coil 32 to an individual inverter 26. During wireless power transmission operation, transistors in one or more selected inverters 26 are driven by AC control signals from the control circuit 16. The relative phase between inverters can be dynamically adjusted (e.g., a pair of inverters 26 may produce in-phase or out-of-phase output signals).

[0035] By applying a drive signal using an inverter (one or more) 26 (for example, a transistor or other switch in circuit 22), the output circuit formed from the selected coil 32 and capacitor 70 generates an AC electromagnetic field (signal 44) which is received by the wireless power receiving circuit 46 using a wireless power receiving circuit formed from one or more coils 48 and one or more capacitors 72 in device 24.

[0036] The rectifier circuit 50 is coupled to one or more coils 48 and converts the received power from AC to DC, supplying a corresponding DC output voltage Vrect between the rectifier output terminals 76 to power load circuits within the device 24 (for example, to charge the battery 34, to power the display and / or other input / output devices 54, and / or other components).

[0037] Figure 3 shows an exemplary inverter 26 within the PTX 12. As shown in Figure 3, the inverter 26 can receive a DC voltage Vdc (e.g., from an AC-DC converter, battery, etc.). The inverter 26 includes transistors T1 and T2. Each transistor (T1 and T2) has a separate gate 74. Transistors T1 and T2 are coupled in series between a positive voltage terminal (positive power supply voltage Vdc) and a ground voltage terminal (ground power supply voltage Vss, sometimes simply called ground voltage Vss).

[0038] The control circuit 16 can generate control signals that are applied to the gate terminals 74 of inverter transistors T1 and T2. The gates 74 of transistors T1 and T2 can receive complementary signals such that when the gate of transistor T2 is low, the gate of transistor T1 is high, and vice versa. In other words, transistors T1 and T2 are asserted in a mutually exclusive manner, so that while T1 is asserted, T2 is deasserted, and vice versa.

[0039] In one exemplary configuration, transistors T1 and T2 may be supplied with an AC signal (e.g., a clock signal) at an appropriate operating frequency with a desired pulse width (or duty cycle) to control the amount of power transmitted. Generally, the control signal may be applied to T1 and T2 at any desired frequency. The embodiment in Figure 3 is merely illustrative, and the inverter 26 may include additional transistors if desired.

[0040] Component 80 can be coupled between node 82 and the ground power terminal Vss. Node 82 is inserted between T1 and T2 and may also be called the output node or output of the inverter 26. When control signals are applied to the gates 74 of transistors T1 and T2, the DC voltage Vdc is converted into an AC signal that passes through component 80. Component 80 may be a wireless charging coil (as shown in Figure 2), a transformer coil, an antenna, or any other desired component.

[0041] Several electronic devices having inverters, such as the PTX 12 shown in Figures 1 and 2, can employ signal dithering to improve the electromagnetic radiation characteristics of the system (e.g., to reduce conducted radiation and / or radioactive emissions). For example, the PTX 12 can dither the clock signal used to control the inverter 26. This effectively dithers the frequency of the AC signal output by the inverter 26.

[0042] In this specification, various signals (e.g., clock signals) may be referred to as having a corresponding waveform (e.g., the shape of the signal voltage over time). A given waveform may have a repeating shape that repeats at a given frequency (i.e., a given waveform may be periodic). The repeating shape does not necessarily have to be a regular shape (e.g., a sinusoidal curve). In fact, the repeating shape may deviate from a sinusoidal shape. However, this type of waveform may still have frequencies associated with periodic repetitions of a non-sinusoidal waveform.

[0043] Figure 4 shows an exemplary PTX 12 with a dithering circuit. In one possible configuration, a dithering circuit 84 and a clock modulation circuit 86 can be used to implement spread spectrum clocking technique (sometimes called clock dithering). The dithering circuit 84 and the clock modulation circuit 86 can be considered as part of the control circuit 16. In spread spectrum clocking, the clock waveform is intentionally modified so that the spectrum of the signal spreads around a target frequency of the clock signal. This target frequency is sometimes called the fundamental frequency of the clock signal. This improves the electromagnetic compatibility (EMC) associated with the target frequency of the clock signal. The dithering circuit 84 can determine a modulation waveform 88 used to modulate the clock waveform 92 (sometimes called the native clock waveform 92, initial clock waveform 92, undithered clock waveform 92, system clock 92, etc.). To improve EMC, the modulation waveform 88 is applied to the clock waveform 92 by the clock modulation circuit 86. The clock modulation circuit 86 can frequency modulate the clock waveform 92 using the modulation waveform 88. The resulting switching signal 90 (sometimes called a modified clock signal 90, a dithered clock signal 90, or a dithered switching signal 90) is then supplied to the inverter 26 to generate a frequency-dithered AC signal.

[0044] The modulated waveform 88 output by the dithering circuit 84 may be fixed or adjusted based on the real-time operating conditions of the wireless power system 8. For example, the dithering circuit 84 can generate the modulated waveform 88 based on the charge state of the battery 34 in the PRX 24, the output voltage and / or current of the rectifier 50, the output voltage and / or current of the coil 48, the voltage and / or current of the coil 32, and so on.

[0045] Figure 5 is a graph of a dithered clock signal that can be supplied to the inverter 26 of the PTX 12. The dithered clock signal in Figure 5 can be used with a PTX having a specified radio power transmission frequency (sometimes called the nominal radio power transmission frequency or simply radio power transmission frequency) of 360 kHz. As shown in Figure 5, the dithered clock signal may also be a step function approximating a triangular waveform. Thus, the dithered clock signal can be referred to as having a triangular shape. The dithered clock signal in Figure 5 may be repeated in multiple iteration cycles, each iteration cycle containing one period of the waveform shown in Figure 5. It is desirable that the triangular waveform has a smooth transition between each iteration cycle of the dither pattern.

[0046] One iterative cycle of the dithered clock signal has a total of 32 frequency steps. Figure 5 shows the instantaneous frequency of the clock signal over time. The period of each frequency step is 1 / f. s Equal to (in the formula, f s (where is the instantaneous frequency of the clock signal). In other words, the dithered clock signal remains at the instantaneous frequency associated with each frequency step for exactly one cycle.

[0047] Each of the 32 frequency steps can have a unique frequency magnitude. The 32 unique frequency steps have a first subset of descending steps (sometimes called decreasing steps) where the frequency magnitude decreases with each subsequent step of the waveform. The 32 unique frequency steps have a second subset of ascending steps (sometimes called increasing steps) where the frequency magnitude increases with each subsequent step of the waveform. In the embodiment of Figure 5, steps 1-17 are descending steps of the waveform, and steps 18-32 are ascending steps of the waveform. The intermediate step of the ascending steps (i.e., step 24) is equal to the radio power transmission frequency of 360 kHz. The intermediate step of the descending steps (i.e., step 9) is close to the radio power transmission frequency of 360 kHz (but not exactly equal to 360 kHz, since step 24 is already equal to 360 kHz and each frequency step has a unique frequency magnitude).

[0048] Each of the ascending frequency steps can be shifted relative to the corresponding frequency step of the descending frequency step. For example, the magnitude of the frequency in step 18 is slightly greater than the magnitude of the frequency in step 16, the magnitude of the frequency in step 19 is slightly greater than the magnitude of the frequency in step 15, the magnitude of the frequency in step 20 is slightly greater than the magnitude of the frequency in step 14, and so on.

[0049] The magnitude of the frequency in each ascending frequency step may be between two of the magnitudes of the frequencies in each descending frequency step. For example, the magnitude of the frequency in step 18 may be between the magnitudes of the frequencies in steps 15 and 16, the magnitude of the frequency in step 19 may be between the magnitudes of the frequencies in steps 14 and 15, the magnitude of the frequency in step 20 may be between the magnitudes of the frequencies in steps 13 and 14, and so on.

[0050] Modulation frequency (f) of the dithered clock signal m) may be equal to the reciprocal of the period of the waveform in Figure 5. Each frequency step has a duration of one period at the instantaneous frequency in that frequency step, and since the dithered clock signal is centered on a specified radio power transmission frequency, the modulation frequency of the dithered clock signal may also be equal to the radio power transmission frequency divided by the number of steps in the frequency profile. Thus, the modulation frequency of the dithered clock signal in Figure 5 is 11.25 kHz (e.g., 360 kHz / 32 = 11.25 kHz).

[0051] The dithered clock signal in Figure 5 may also have a characteristic frequency deviation Δf. The magnitude of Δf may be equal to the maximum difference between the frequency of the dithered clock signal and the radio power transmission frequency. In the waveform of Figure 5, frequency step 1 has the maximum frequency, and frequency step 17 has the minimum frequency. Frequency step 17 may have the largest deviation from the radio power transmission frequency, and therefore the magnitude of Δf is equal to 360 kHz minus the frequency at step 17. Here, the frequency at step 17 may be equal to 341.23 kHz, and therefore Δf is equal to 18.77 kHz.

[0052] The dithered clock signal in Figure 5 is Δf / f m It can have a characteristic modulation index (h) defined as follows. In the case of the waveform in Figure 5, the modulation index is equal to 1.67 (for example, 18.77kHz / 11.25kHz=1.67).

[0053] Figure 6 shows a modulated waveform that can be used to generate the dithered clock signal of Figure 5. In one embodiment, the clock modulation circuit 86 can modulate the clock waveform 92 by dividing the clock frequency by the denominator provided by the modulated waveform 88. In one embodiment, the system clock frequency may be 288 MHz. The denominator used to divide the system clock frequency is shown in Figure 6. The waveform in Figure 6 has 32 steps, each step corresponding to an individual step of the dithered clock signal of Figure 5.

[0054] In a specific embodiment, the modulated waveform in Figure 6 may have denominators of 764, 768, 772, 776, 780, 784, 788, 792, 796, 802, 810, 816, 822, 828, 836, 842, 844, 840, 834, 824, 820, 814, 808, 800, 794, 790, 786, 782, 778, 774, 770, and 766 (in this order). The resulting frequency ranges are 376.96kHz (e.g., 288MHz / 764=376.96kHz), 375.00kHz (e.g., 288MHz / 768=375.00kHz), 373.06kHz, 371.13kHz, 369.23kHz, 367.35kHz, 365.48kHz, 363.64kHz, 361.81kHz, 359.10kHz, 355.56kHz, 352.94kHz, 350.36kHz, These are equal to 347.83kHz, 344.50kHz, 342.04kHz, 341.23kHz, 342.86kHz, 345.32kHz, 349.51kHz, 351.22kHz, 353.81kHz, 356.44kHz, 360kHz, 362.72kHz, 364.56kHz, 366.41kHz, 368.29kHz, 370.18kHz, 372.09kHz, 374.03kHz, and 375.98kHz (in this order). For each pair of adjacent frequency steps, the difference in magnitude between the frequencies may be between 0.5kHz and 4.5kHz. The minimum difference in magnitude between adjacent frequency steps may be 0.81kHz. The maximum difference in magnitude between adjacent frequency steps may be 4.19kHz.

[0055] Each of the 32 unique denominator steps in Figure 6 can have a unique magnitude. The 32 unique denominator steps have a first subset of ascending steps (sometimes called increasing steps) in which the magnitude of the denominator increases with each subsequent step of the waveform. The 32 unique denominator steps have a second subset of descending steps (sometimes called decreasing steps) in which the magnitude of the denominator decreases with each subsequent step of the waveform. In the embodiment of Figure 6, steps 1 to 17 are ascending steps of the waveform, and steps 18 to 32 are descending steps of the waveform.

[0056] One or more of the descending denominator steps can be shifted by a certain amount relative to the corresponding denominator step of the ascending frequency step. In Figure 6, the magnitude of the shift is equal to 2. The size of the denominator in step 18 is 2 less than the size of the denominator in step 16, the size of the denominator in step 19 is 2 less than the size of the denominator in step 15, the size of the denominator in step 21 is 2 less than the size of the denominator in step 13, and so on.

[0057] The specific embodiments shown in Figures 5 and 6 are merely illustrative examples. Modulation frequency f m The modulation frequency f may be greater than 9kHz, greater than 10kHz, greater than 11kHz, greater than 15kHz, less than 30kHz, less than 20kHz, etc. Lower modulation frequencies may be desirable to reduce the magnitude of Δf, as this places less stress on the radio power system. Since 9kHz is the resolution bandwidth (RBW) used in some electromagnetic interference (EMI) test protocols, the modulation frequency f m It can also be desirable for the frequency to be greater than 9kHz.

[0058] The magnitude of the modulation index (h) of the dithered clock signal may be less than 2.0, less than 1.9, less than 1.8, less than 1.7, less than 1.6, greater than 1.4, greater than 1.5, greater than 1.6, 1.4 to 1.8, 1.5 to 1.7, 1.6 to 1.7, etc. The magnitude of the frequency deviation (Δf) of the dithered clock signal may be greater than 5kHz, greater than 10kHz, greater than 15kHz, greater than 20kHz, greater than 30kHz, less than 20kHz, less than 15kHz, 10kHz to 30kHz, 10kHz to 20kHz, etc. The magnitude of the frequency deviation (Δf) of the dithered clock signal may be less than 20% of the wireless power transmission frequency, less than 10%, less than 5%, less than 3%, greater than 1%, greater than 2%, greater than 5%, greater than 10%, or between 1% and 10% of the wireless power transmission frequency.

[0059] The dithered clock signal in Figure 5 can have a time-weighted average frequency within 1 kHz of the wireless power transmission frequency (e.g., 359 kHz to 361 kHz, 127 kHz to 129 kHz, etc.).

[0060] One objective of the frequency dithering schemes described herein is to improve EMC at a given radio power transmission frequency. Generally, a greater reduction in EMI at a given radio power transmission frequency is desirable. However, the maximum radiated peak associated with the dithered clock signal must remain at the radio power transmission frequency and not at the sideband frequencies. In other words, it is desirable that the radiated peak at the sideband frequencies associated with the radio power transmission frequency is smaller than the radiated peak at the radio power transmission frequency. By reducing the radiated peak at the radio power transmission frequency, it is possible to increase the radiated peak at the sideband frequencies. Therefore, the dithering patterns described herein can be selected to reduce the radiated peak at the radio power transmission frequency as much as possible while also ensuring that the radiated peak at the sideband frequencies is smaller than the radiated peak at the radio power transmission frequency.

[0061] Figure 7 is a graph of the radiation spectrum associated with the dithered clock signal in Figure 5. The graph shows the radiation as a function of frequency (in units of dBμA / m). The difference in radiation may have units of dB. The dashed profile 102 shows the radiation of the undithered version of the clock signal at the radio power transmission frequency. In the embodiments of Figures 5-7, profile 102 shows the radiation of the undithered clock signal at a constant frequency of 360 kHz. The magnitude of profile 102 at 360 kHz can be defined as 0 with respect to the Y-axis scale in Figure 7.

[0062] The solid line profile 104 represents the radiation of the dithered clock signal in Figure 5. As shown in Figure 7, the maximum radiation peak of profile 104 has a magnitude E1 and is located at the radio power transmission frequency (e.g., 360 kHz). The radiation peak of profile 104 at 360 kHz (e.g., E1) is 106 smaller than the radiation peak of profile 102 at 360 kHz. Thus, the difference 106 characterizes the EMC improvement at the radio power transmission frequency. In the case of the dithered clock signal in Figure 5, the magnitude of the difference 106 is -4.8 dB.

[0063] Profile 104 has peaks at the sideband frequencies in addition to the radio power transmission frequency. The sideband frequencies can be separated from each other by the modulation frequency of the dithered clock signal. In the embodiment of Figure 5, the modulation frequency is equal to 11.25 kHz. Therefore, in Figure 7, each radiated peak is separated from adjacent radiated peaks by a frequency of 11.25 kHz.

[0064] The radiated peak can decrease as the deviation from the radio power transmission frequency increases. The dithering pattern in Figure 5 is chosen to ensure that the magnitude of radiation at the sideband frequency closest to the radio power transmission frequency is smaller than the magnitude of radiation at the radio power transmission frequency. Figure 7 shows how the magnitude of radiation E2 at the first sideband frequency of 348.75 kHz and the magnitude of radiation E3 at the second sideband frequency of 371.25 kHz exist. The magnitude of radiation E2 is 108 less than the radiated peak of profile 102. The magnitude of radiation E3 is 110 less than the radiated peak of profile 102. For the dithered clock signal in Figure 5, the magnitude of the difference 108 is -5.9 dB, and the magnitude of the difference 110 is -5.3 dB.

[0065] To ensure that the peak at the specified radio power transmission frequency is the maximum radiation magnitude of the dithered clock signal, the differences 108 and 110 may be greater than the difference 106. However, the differences 108 and 110 may be close to the difference 106 in order to improve the sum of the differences 106. The difference 108 may be within 2 dB of the difference 106, within 1.5 dB of the difference 106, within 1 dB of the difference 106, etc. The difference 110 may be within 2 dB of the difference 106, within 1.5 dB of the difference 106, within 1 dB of the difference 106, etc.

[0066] The dithering patterns described herein are used for a radio power transmission frequency of 360 kHz. However, it should be understood that the same concepts can be applied to dithering patterns regardless of the magnitude of the radio power transmission frequency. For example, dithering patterns at any desired radio power transmission frequency (e.g., 100-400 kHz, 128 kHz, 1-100 MHz, 1.7 MHz-1.8 MHz, less than 2 MHz, 100 kHz-2 MHz, 6.78 MHz, 13.56 MHz, etc.) may have the number of frequency steps, modulation frequency, waveform shape, frequency deviation, modulation index, and / or radiation profile characteristics described herein.

[0067] FIG. 8 is a flowchart of an exemplary method for selecting a dithering pattern for a given wireless power transfer frequency. During operation of block 202, the number of frequency steps can be selected. The modulation frequency f m is a function of the number of selected steps. For a given wireless power transfer frequency f c , the modulation frequency f m is equal to the wireless power transfer frequency divided by the number of selected steps (N) (e.g., f m = f c / N). To generate a smaller modulation frequency that is advantageous for reducing the magnitude of Δf, the number of steps may desirably be large. However, the number of steps may be low enough to ensure that f m is greater than a threshold such as 9 kHz.

[0068] During operation of block 204, the waveform shape can be selected. A step function that approximates a triangular shape can be selected to ensure a smooth transition between each repetition cycle of the dithered clock signal.

[0069] During operation of block 206, a preliminary modulation index (h) can be selected. There may be a known relationship between the modulation index and the sideband amplitude. A modulation index of about 1.5 can have a known sideband amplitude close to the carrier amplitude, and thus 1.5 can be used as the preliminary modulation index. If desired, other preliminary modulation index values (e.g., 1.55, 1.6, 1.65, 1.7, 1.75, 1.8, etc.) can be used.

[0070] During operation of block 208, the frequency deviation (Δf) can be selected. The magnitude of Δf may be equal to the maximum difference between the magnitude of the waveform frequency and the wireless power transfer frequency. The preliminary modulation index selected in block 206 and the modulation frequency selected in block 202 can be used to determine the frequency deviation (Δf) using the equation Δf = f m × h.

[0071] During the operation of block 210, a backup dithering pattern can be selected. The backup dithering pattern is centered on the radio power transmission frequency, f c It has a maximum frequency that is approximately equal to +Δf, and f c The number of frequency steps (determined in block 202) arranged in a roughly triangular step function has a minimum frequency approximately equal to -Δf. In the preliminary dithering pattern, the magnitude of the frequency change between adjacent frequency steps may be approximately constant (for example, the change in the denominator used to define the modulated waveform may be constant). In one embodiment, the preliminary dithering pattern may include N / 2+1 descending steps and N / 2-1 ascending steps (as in the embodiment in Figure 5). The ascending steps may be shifted relative to the descending steps (as described in relation to Figures 5 and 6).

[0072] During the operation of block 212, the radiation spectrum associated with the preliminary dithering pattern can be evaluated. In particular, it can be determined whether the difference between the radiation reduction at the radio power transmission frequency and the radiation reduction at the nearest sideband frequency is 0 to 1 dB. Consider the radiation spectrum in Figure 7. During the operation of block 212, it can be determined whether the difference 108 is 0 to 1 dB greater than the difference 106, and / or whether the difference 110 is 0 to 1 dB greater than the difference 106. If this criterion is met, the method can proceed to the operation of block 216. If this criterion is met, the method can proceed to the operation of block 214.

[0073] During the operation of block 214, the modulation index (h) may be adjusted. After adjusting the modulation index, the method can return to the operation of block 208, and the operations of blocks 208, 210, and 212 can be repeated. The modulation index may be adjusted until the criteria in block 212 are met.

[0074] When the criteria in block 212 are met, the method proceeds to the operation of block 216. During the operation of block 216, the dithering pattern can be fine-tuned. Fine-tuning the dithering pattern may include adjusting one or more of the highest and lowest frequencies from the preliminary dithering pattern.

[0075] During the operation of block 218, the finely tuned dithering pattern can be evaluated to determine whether 1) the difference between radiation reduction at the radio power transmission frequency and radiation reduction at the nearest sideband frequency is approximately equal to 1 dB, and 2) whether the time-weighted frequency average is within 1 kHz of the specified radio power transmission frequency.

[0076] Regarding criterion #1, consider the radiation spectrum in Figure 7. During the operation of block 218, it is possible to determine whether difference 108 is approximately 1 dB larger than difference 106 (e.g., 0.9-1.1 dB, 0.8-1.2 dB, 0.9-1.2 dB, 1-1.2 dB, etc.) and / or whether difference 110 is approximately 1 dB larger than difference 106 (e.g., 0.9-1.1 dB, 0.8-1.2 dB, 0.9-1.2 dB, 1-1.2 dB, etc.).

[0077] Regarding criterion #2, it is possible to calculate the time-weighted frequency average of the finely tuned dithering pattern. It is possible to determine whether the time-weighted frequency average is within 1 kHz (or some other threshold) of a specified radio power transmission frequency (e.g., 360 kHz, 128 kHz, etc.).

[0078] If both criteria in block 218 are met, the method may proceed to block 220 and terminate. The dithering pattern most recently output during the operation of block 216 can be used as the dithering pattern during the wireless power transmission operation in PTX 12.

[0079] If one or both of the criteria in block 218 are not met, the method can return to block 216 for further fine-tuning. The operation of blocks 216 and 218 can be repeated until the dithering pattern meets the criteria in block 218.

[0080] According to the embodiment, the electronic device includes an inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, and a control circuit configured to generate a dithered clock signal, wherein the dithered clock signal has a plurality of frequency steps during an iterative cycle of the dithered clock signal, the iterative cycle of the dithered clock signal includes a step function that approximates a triangular waveform, and the dithered clock signal has a unique frequency magnitude for each of the plurality of frequency steps during the iterative cycle.

[0081] According to another embodiment, the multiple frequency steps in the iterative cycle optionally include 32 frequency steps in the iterative cycle.

[0082] According to another embodiment, the dithered clock signal is optionally present in each frequency step for a distinct duration before proceeding to the subsequent frequency step, and the duration of each of the multiple frequency steps is optionally unique.

[0083] According to another embodiment, during each iteration cycle, the dithered clock signal is optionally present in each frequency step for only one period before proceeding to the subsequent frequency step.

[0084] According to another embodiment, the triangular waveform is optionally centered on a frequency designated as the wireless power transmission frequency of the electronic device.

[0085] According to another embodiment, the time-weighted average of the frequency magnitude of the dithered clock signal is within 1 kHz of the frequency designated as the radio power transmission frequency of the electronic device during the iterative cycle.

[0086] According to another embodiment, the wireless power transmission frequency is optionally 127-129 kHz or 359-361 kHz.

[0087] According to another embodiment, the repetitive cycle is optionally repeated at a modulation frequency greater than 9 kHz.

[0088] According to another embodiment, the modulation frequency is optionally less than 20 kHz.

[0089] According to another embodiment, the dithered clock signal optionally has a maximum frequency magnitude, optionally has a difference between the maximum frequency magnitude and the radio power transmission frequency, and the difference divided by the modulation frequency is optionally 1.6 to 1.7.

[0090] According to another embodiment, during a first subset of multiple frequency steps, the magnitude of the frequency optionally decreases over time, and during a second subset of multiple frequency steps, the magnitude of the frequency optionally increases over time, with each of the second subsets of multiple frequency steps optionally having a magnitude of frequency that lies between the respective two magnitudes of frequencies in each of the first subsets of multiple frequency steps.

[0091] According to another embodiment, the triangular waveform is optionally centered at a frequency designated as the wireless power transmission frequency of the electronic device, and the dithered clock signal optionally has the greatest radiation magnitude at the wireless power transmission frequency.

[0092] According to another embodiment, the triangular waveform is optionally centered on a frequency designated as the wireless power transmission frequency of an electronic device, the undithered version of the clock signal at the wireless power transmission frequency optionally has a first maximum radiation magnitude at the wireless power transmission frequency, and the dithered clock signal optionally has a second maximum radiation magnitude at the wireless power transmission frequency and an additional radiation magnitude at the sideband frequency, the second maximum radiation magnitude optionally being less than the first maximum radiation magnitude by a first difference, the additional radiation magnitude optionally being less than the first maximum radiation magnitude by a second difference, the second difference optionally being greater than the first difference, and the second difference optionally being within 1.2 dB of the first difference.

[0093] According to one embodiment, the electronic device includes an inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, and a control circuit configured to generate a dithered clock signal, the dithered clock signal having a plurality of frequency steps during an iterative cycle of the dithered clock signal, the iterative cycle of the dithered clock signal including a step function that approximates a triangular waveform, the magnitude of the frequency decreases over time during a first subset of the plurality of frequency steps, the magnitude of the frequency increases over time during a second subset of the plurality of frequency steps, and each one in the second subset of the plurality of frequency steps has a magnitude of frequency that is between the magnitudes of each of the two respective frequencies in the first subset of the plurality of frequency steps.

[0094] According to another embodiment, the control circuit optionally generates a dithered clock signal by dividing the system clock signal by its denominator, where each of the multiple frequency steps optionally has a separate denominator, and each of the second subset of the multiple frequency steps optionally has a denominator shifted by the same amount to one of the separate denominators of the first subset of the multiple frequency steps.

[0095] According to another embodiment, the time-weighted average of the magnitude of the frequency of the dithered clock signal is optionally within 1 kHz of the frequency designated as the radio power transmission frequency of the electronic device during the iterative cycle, and the radio power transmission frequency is optionally 127-129 kHz or 359-361 kHz.

[0096] According to another embodiment, the repetitive cycle is optionally repeated at modulation frequencies of 9 kHz to 20 kHz.

[0097] According to one embodiment, the electronic device includes an inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, and a control circuit configured to generate a dithered clock signal, the dithered clock signal having a plurality of frequency steps during the iterative cycle of the dithered clock signal, the iterative cycle of the dithered clock signal including a step function that approximates a triangular waveform, the triangular waveform centered on a frequency designated as the wireless power transmission frequency of the electronic device, the undithered version of the clock signal at the wireless power transmission frequency having a first maximum radiation magnitude at the wireless power transmission frequency, the dithered clock signal having a second maximum radiation magnitude at the wireless power transmission frequency and an additional radiation magnitude at the sideband frequency, the second maximum radiation magnitude being smaller than the first maximum radiation magnitude by a first difference, the additional radiation magnitude being smaller than the first maximum radiation magnitude by a second difference, the second difference being larger than the first difference, and the second difference being within 1.2 dB of the first difference.

[0098] According to another embodiment, the sideband frequency is optionally a first sideband frequency, the magnitude of the additional radiation is the magnitude of the first radiation, the dithered clock signal optionally has a second magnitude of radiation at a second sideband frequency, the first sideband frequency is optionally less than the radio power transmission frequency, the second sideband frequency is optionally greater than the radio power transmission frequency, the magnitude of the second radiation is optionally less than the first maximum radiation magnitude by a third difference, the third difference is optionally greater than the first difference, and the third difference is optionally within 1.2 dB of the first difference.

[0099] According to another embodiment, the dithered clock signal optionally has a magnitude of a unique frequency for each of a plurality of frequency steps during the iterative cycle.

[0100] The above is merely illustrative, and various modifications may be made to the described embodiments. The aforementioned embodiments may be implemented individually or in any combination.

Claims

1. It is an electronic device, An inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, A control circuit configured to generate the dithered clock signal, Equipped with, The dithered clock signal has multiple frequency steps during the iterative cycle of the dithered clock signal. The repetition cycle of the dithered clock signal includes a step function that approximates a triangular waveform. The dithered clock signal has a unique frequency magnitude for each of the plurality of frequency steps during the iterative cycle. Electronic devices.

2. The electronic device according to claim 1, wherein the plurality of frequency steps in the iterative cycle include 32 frequency steps in the iterative cycle.

3. The electronic device according to claim 1, wherein the dithered clock signal is present in each frequency step for an individual duration before proceeding to the subsequent frequency step, and the duration of each of the plurality of frequency steps is unique.

4. The electronic device according to claim 1, wherein during each iteration cycle, the dithered clock signal is present in each frequency step for only one period before advancing to the subsequent frequency step.

5. The electronic device according to claim 1, wherein the triangular waveform is centered on a frequency designated as the wireless power transmission frequency of the electronic device.

6. The electronic device according to claim 1, wherein the time-weighted average of the magnitude of the frequency of the dithered clock signal is within 1 kHz of the frequency designated as the wireless power transmission frequency of the electronic device during the iterative cycle.

7. The electronic device according to claim 6, wherein the wireless power transmission frequency is 127 to 129 kHz or 359 to 361 kHz.

8. The electronic device according to claim 7, wherein the repeating cycle is repeated at a modulation frequency greater than 9 kHz.

9. The electronic device according to claim 8, wherein the modulation frequency is less than 20 kHz.

10. The electronic device according to claim 8, wherein the dithered clock signal has a maximum frequency magnitude, there is a difference between the maximum frequency magnitude and the wireless power transmission frequency, and the difference, when divided by the modulation frequency, is 1.6 to 1.

7.

11. During the first subset of the plurality of frequency steps, the magnitude of the frequency decreases over time. During the second subset of the plurality of frequency steps, the magnitude of the frequency increases over time. Each of the second subsets of the plurality of frequency steps has a frequency magnitude that lies between the magnitudes of each of the two frequencies in the first subset of the plurality of frequency steps. The electronic device according to claim 1.

12. The triangular waveform is centered on the frequency designated as the wireless power transmission frequency of the electronic device. The dithered clock signal has the greatest radiation magnitude at the wireless power transmission frequency. The electronic device according to claim 1.

13. The triangular waveform is centered on the frequency designated as the wireless power transmission frequency of the electronic device. The undithered version of the clock signal at the aforementioned wireless power transmission frequency has a first maximum radiation magnitude at the aforementioned wireless power transmission frequency. The dithered clock signal has a second maximum radiation magnitude at the wireless power transmission frequency and an additional radiation magnitude at the sideband frequency. The magnitude of the second maximum radiation is smaller than the magnitude of the first maximum radiation by a first difference, The magnitude of the additional radiation is smaller than the magnitude of the first maximum radiation by a second difference. The second difference is greater than the first difference. The second difference is within 1.2 dB of the first difference. The electronic device according to claim 1.

14. It is an electronic device, An inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, A control circuit configured to generate the dithered clock signal, Equipped with, The dithered clock signal has multiple frequency steps during the iterative cycle of the dithered clock signal. The repetition cycle of the dithered clock signal includes a step function that approximates a triangular waveform. During the first subset of the plurality of frequency steps, the magnitude of the frequency decreases over time. During the second subset of the plurality of frequency steps, the magnitude of the frequency increases over time. Each of the second subsets of the plurality of frequency steps has a frequency magnitude that lies between the magnitudes of each of the two frequencies in the first subset of the plurality of frequency steps. Electronic devices.

15. The electronic device according to claim 14, wherein the control circuit generates the dithered clock signal by dividing the system clock signal by the denominator, and each of the plurality of frequency steps has a separate denominator, and each of the second subset of the plurality of frequency steps has a denominator that is shifted by the same amount with respect to one of the separate denominators of the first subset of the plurality of frequency steps.

16. The electronic device according to claim 14, wherein the time-weighted average of the magnitude of the frequency of the dithered clock signal is within 1 kHz of the frequency designated as the wireless power transmission frequency of the electronic device during the iterative cycle, and the wireless power transmission frequency is 127 to 129 kHz or 359 to 361 kHz.

17. The electronic device according to claim 16, wherein the repeating cycle is repeated at a modulation frequency of 9 kHz to 20 kHz.

18. It is an electronic device, An inverter configured to receive a switching signal based on a dithered clock signal and output a corresponding AC signal to a wireless power transmission coil, A control circuit configured to generate the dithered clock signal, Equipped with, The dithered clock signal has multiple frequency steps during the iterative cycle of the dithered clock signal. The repetition cycle of the dithered clock signal includes a step function that approximates a triangular waveform. The triangular waveform is centered on the frequency designated as the wireless power transmission frequency of the electronic device. The undithered version of the clock signal at the aforementioned wireless power transmission frequency has a first maximum radiation magnitude at the aforementioned wireless power transmission frequency. The dithered clock signal has a second maximum radiation magnitude at the wireless power transmission frequency and an additional radiation magnitude at the sideband frequency. The magnitude of the second maximum radiation is smaller than the magnitude of the first maximum radiation by a first difference, The magnitude of the additional radiation is smaller than the magnitude of the first maximum radiation by a second difference. The second difference is greater than the first difference. The second difference is within 1.2 dB of the first difference. Electronic devices.

19. The aforementioned sideband frequency is the first sideband frequency, and the magnitude of the additional radiation is the magnitude of the first radiation. The dithered clock signal has a second radiation magnitude at a second sideband frequency. The first sideband frequency is smaller than the wireless power transmission frequency, The second sideband frequency is greater than the wireless power transmission frequency. The magnitude of the second emission is smaller than the magnitude of the first maximum emission by a third difference. The third difference is greater than the first difference. The third difference is within 1.2 dB of the first difference. The electronic device according to claim 18.

20. The electronic device according to claim 19, wherein the dithered clock signal has a magnitude of a unique frequency for each of the plurality of frequency steps during the iterative cycle.

Images