Abstract: Some embodiments relate to a multi-mode wireless power transmitter. The transmitter includes an inverter configured to produce at its output a first signal having a first frequency or a second signal having a second frequency. The transmitter also includes a first transmit coil coupled to the output of the inverter and configured to wirelessly transmit power at the first frequency. The transmitter also includes a second transmit coil coupled to the output of the inverter and configured to wirelessly transmit power at the second frequency. The transmitter further includes at least one matching network coupled to the first transmit coil, the second transmit coil, and the output of the inverter. The at least one matching network is configured to provide power to the first transmit coil in response to the first signal and inhibit providing power to the second transmit coil in response to the first signal.

Abstract: A resonant wireless power (RWP) system is provided that includes a signal generator that provides an input signal waveform. An amplifier structure amplifies signals for transmissions to a receiver that is powered from a fixed DC voltage supply. The amplifier structure is operated either using differential or single-ended amplifiers to provide two different output power levels, in burst mode to provide a range of output power levels, or using a capacitor in a matching network that is adjusted to provide a range of output power levels.

Abstract: A resonant wireless power (RWP) receiver is provided that includes an inductor element that couples with a resonant wireless power source. A capacitor arrangement is coupled to the inductor element altering the open-circuit impedance of the RWP receiver to reduce the ac voltage under certain defined situations. The capacitor arrangement includes a plurality capacitors tuned to a control ac voltage in the RWP receiver.

Abstract: A synchronous rectifier using only n-channel devices in which the low-side switches are effectively cross-coupled using low-side comparators and the high-side switches perform an accurate zero-voltage-switching (ZVS) comparison. The charging path of each bootstrap domain is completed through the low-side switches, which are each always on for every half-cycle independent of loading. This scheme gives rectifier efficiency gain because a) each bootstrap domain receives maximum charging time, and b) the charging occurs through a switch rather than a diode. Both these factors ensure the bootstrap domain is fully charged, thereby reducing conduction losses through the rectifier switches. Furthermore, settings may be adjusted by software to optimize the resistive and capacitive losses of the rectifier. Using data for die temperature and operating frequency, software can create a feedback loop, dynamically adjusting rectifier settings in order to achieve the best possible efficiency.

Abstract: A dual-mode receiver is provided that includes an electromagnetic resonator having one or more inductive elements that are arranged to form a receiver coil and a network of passive components arranged to form a matching network. The electromagnetic resonator includes a first selective frequency defined in a low frequency range and a second selective frequency defined in a high frequency range allowing for a rectification circuit to operate in both the high frequency range and low frequency range making maximum use of active circuits.

Abstract: A dual-mode receiver is provided that includes an electromagnetic resonator having one or more inductive elements that are arranged to form a receiver coil and a network of passive components arranged to form a matching network. The electromagnetic resonator includes a first selective frequency defined in a low frequency range and a second selective frequency defined in a high frequency range allowing for a rectification circuit to operate in both the high frequency range and low frequency range making maximum use of active circuits.

Abstract: A dual-mode receiver is provided that includes an electromagnetic resonator having one or more inductive elements that are arranged to form a receiver coil and a network of passive components arranged to form a matching network.

Abstract: A wireless charging system is provided that includes a charger portion that receives one or more portable elements for charging wirelessly. The charger portion controls the amount of power needed to charge the one or more portable elements. An inband communication module receives inband communications with the one or more portable elements using a random access mode. The charger portion utilizes the inband communications to determine how much power is needed, via energy based reporting, to charge the one or more portable elements that avoids conveying identification information.

Abstract: A wireless power transmitter includes an inverter in which a voltage varies in response to a resonant network and circuitry configured to (A) measure a characteristic indicative of a load seen by the wireless power transmitter, (B) determine a duty cycle of the inverter based upon the characteristic, and (C) switch the inverter with the determined duty cycle.

Abstract: A resonant wireless power receiver that includes an electromagnetic resonator having one or more inductive elements that are arranged to form a receiver coil and a network of passive components arranged to form a matching network. A rectifier circuit converts ac power from the electromagnetic resonator to dc power. An available-power indicator measures the rectified power to assess the instantaneous power available to the receiver.

Abstract: Methods and apparatus for providing closed loop current control in a wireless power transmitter. The method comprises adjusting a transmitter coil current generated by the wireless power transmitter based, at least in part, on first feedback reported by at least one wireless power receiver and second feedback based on a measurement of the transmitter coil current.

Abstract: A resonant wireless power system includes a source circuit having a source coil, an ac driver with a first resistance, representing the equivalent output impedance of the ac driver, and a matching network. A current probe measures the magnitude signal of the instantaneous source coil current. A voltage probe measures the instantaneous ac driver voltage. A phase detector compares the phase of the instantaneous source coil current and the instantaneous ac driver voltage, and produces a first output signal proportional to the phase difference. A first amplifier compares the magnitude signal and a target signal, and produces an error signal proportional to the difference. A first compensation filter produces the control voltage that determines the ac driver supply voltage. A second amplifier amplifies the first output signal. A second compensation filter produces the control voltage that determines the impedance of a variable element in the source circuit.

Abstract: A mobile device includes a housing having a conductive region and a wireless power receiver having a receive coil configured to receive wireless power through the conductive region. The thickness of the conductive region is less than ?/10, wherein ? is a skin depth of the conductive region at a primary frequency of an electromagnetic signal that provides the wireless power.

Abstract: A variable gain circuit used in an in-band communication system is provided that includes a current sense pickup that is coupled to the output of a DC power source that senses current from the DC power source and provides a first output signal. A variable controlled amplifier structure, that is coupled to the DC power source, receives the first output signal and provides a specified amount of gain to the first output signal so as to produce a second output signal. A digital signal is produced using the second output having a selected frequency bandwidth.

Abstract: An apparatus and method for performing foreign object detection for a wireless power transmitter. A matching network and transmit coil are energized, and a resonance is excited. The resonance is allowed to decay. A temporal characteristic of the decay is measured. The temporal characteristic is analyzed to determine whether a foreign object is coupled to an electromagnetic field generated by the transmit coil.

Abstract: Apparatus and methods for sensing current carried by one or more planar conductors is described. A plurality of sensing coils may be fabricated adjacent to one or more planar, current-carrying conductors. The sensing coils may detect a magnetic field generated by time-varying current flowing through the one or more planar conductors. The sensing coils may be arranged to cancel uniform and linear-gradient magnetic fields.

Abstract: A synchronous rectifier using only n-channel devices in which the low-side switches are effectively cross-coupled using low-side comparators and the high-side switches perform an accurate zero-voltage-switching (ZVS) comparison. The charging path of each bootstrap domain is completed through the low-side switches, which are each always on for every half-cycle independent of loading. This scheme gives rectifier efficiency gain because a) each bootstrap domain receives maximum charging time, and b) the charging occurs through a switch rather than a diode. Both these factors ensure the bootstrap domain is fully charged, thereby reducing conduction losses through the rectifier switches. Furthermore, settings may be adjusted by software to optimize the resistive and capacitive losses of the rectifier. Using data for die temperature and operating frequency, software can create a feedback loop, dynamically adjusting rectifier settings in order to achieve the best possible efficiency.

Abstract: Methods and apparatus for dynamically selecting one of two power paths in a wireless power receiver. A first power path of the two power paths provides a regulated voltage to output circuitry electrically connected to the wireless power receiver. A second power path of the two power paths provides an unregulated voltage to the output circuitry.

Abstract: Apparatus and methods for detecting the presence of a wireless power receiving device to be charged by a wireless power transmitter are described. A first low-power sensing apparatus and method may be used to detect the presence of a device placed in a charging area of the wireless power transmitter. A second sensing apparatus and method may be used to confirm the presence of a device placed in a charging area, and initiate charging of the device.

Abstract: Apparatus and methods for configuring power settings of a wireless power transmitter installed adjacent to a partition are described. A wireless power receiver may detect an amount of power transmitted through the partition from the power transmitter, and identify at least one power setting to the power transmitter that produces an acceptable level of wirelessly transferred power at the wireless power receiver. The power transmitter may store an identified power setting and subsequently operate at the setting identified by the wireless power receiver to provide wireless power through the partition for powering or charging a wirelessly powered device. By configuring a wireless power transmitter at an installation site, various partition thicknesses may be accommodated for through-table, wireless power transfer, for example.