A wireless electric field power transmission system comprises: a transmitter comprising a transmitter antenna, the transmitter antenna comprising at least two conductors defining a volume therebetween; and at least one receiver, wherein the transmitter antenna transfers power wirelessly via electric field coupling when the at least one receiver is within the volume.

The present invention provides an amplifier circuit, wherein the amplifier circuit includes a DAC, an output stage and a detector. In the operations of the amplifier circuit, the DAC is arranged for performing a digital-to-analog converting operation upon a digital input signal to generate an analog signal, the output stage is arranged for receiving the analog signal to generate an output signal, and the detector is arranged for detecting a characteristic of the input signal, and referring to the characteristic of the input signal to generate at least one control signal to adjust the output stage at a zero-crossing point of the output signal.

Envelope trackers providing compensation for power amplifier output load variation are provided herein. In certain configurations, a radio frequency (RF) system includes an antenna, a power amplifier that receives a radio frequency signal and outputs an amplified radio frequency signal to the antenna, a plurality of detectors coupled to the power amplifier and operable to generate a plurality of detection signals, and an envelope tracker that controls a supply voltage of the power amplifier based on an envelope of the radio frequency signal. The envelope tracker processes the plurality of detection signals to generate a load variation detection signal indicating a change in an output load of the power amplifier arising from a change in a voltage standing wave ratio (VSWR) of the antenna. Additionally, the envelope tracker adjusts a gain of the power amplifier based on the load variation detection signal.

A wireless receiving device includes a wake-up receiver, a main receiver and a calibration circuit. The wake-up receiver operates in a monitoring mode or a sleep mode. When operating in the monitoring mode, the wake-up receiver monitors whether a request signal is transmitted by a communication device and issues a wake-up signal after receiving the request signal. The main receiver operates in a sleep mode or a transmission mode. When operating in the sleep mode, the main receiver is woken up and enters the transmission mode to transmit and receive data to and from the communication device when receiving the wake-up signal. The calibration circuit is coupled to the wake-up receiver and the main receiver and configured to receive a calibration signal from the main receiver and calibrate a reception frequency of the wake-up receiver in the background in response to the calibration signal.

An apparatus and method for improving the efficiency of a D class amplifier, particularly at lower output levels. A class D amplifier having a load with inductance, such as a transducer, is configured to concurrently act as its own buck regulator. A capacitor connected to ground and to both ends of the transducer through switches functions as the buck regulator in connection with the inductance of the transducer, providing the class D amplifier with additional voltage levels such as might be provided by a G/H class amplifier but without the added complexity or expense of the G/H configurations. Better efficiency is possible than that provided by a 100% efficient conventional buck regulator. No envelope detector is required, nor any change to the gain of the digital signal to the class D amplifier. Feedback may be used if desired, but is not required to obtain a high quality output signal.

Envelope tracking power supply circuitry includes a look up table (LUT) configured to provide a target supply voltage based on a power envelope measurement. The target supply voltage is dynamically adjusted based on a delay between the power envelope of an RF signal and a provided envelope tracking supply voltage. The envelope tracking supply voltage is generated from the adjusted target supply voltage in order to synchronize the envelope tracking supply voltage with the power envelope of the RF signal.

Various embodiments disclose a method and a device including: an antenna, a switching regulator, communication chip including an amplifier and a linear regulator operably connected to the amplifier and the switching regulator, the communication chip configured to transmit a radio-frequency signal from the electronic device through the antenna, and control circuitry configured to control the communication chip such that the linear regulator provides the amplifier with a voltage corresponding to an envelope of an input signal input to the amplifier, the input signal corresponding to the radio-frequency signal.

An envelope stacking power amplifier system reduces current for a given output power level without sacrificing the ability to support large voltage swings at saturation and therefore increases efficiency at the maximum linear operating power and all power levels below that. The system includes a stack/unstack controller including circuitry configured to switch the RF power amplifier system between a stacked mode in which first and second RF amplifiers are coupled in a stacked configuration and an unstacked mode in which the first and second RF amplifiers are coupled in an unstacked configuration in response to one or more mode-control signals, the stacked configuration providing reduced current compared to the unstacked configuration.

A power supply apparatus for a power amplifier includes a converter configured to convert input power into driving power for the power amplifier, a detector configured to transfer the driving power from the converter to the power amplifier, including an inductor formed on a detection path of the driving power, and configured to detect power information regarding the driving power to generate a detected signal, and a controller configured to control power conversion of the converter based on an envelope signal of a signal input to the power amplifier and the detected signal.

A supply modulator for providing a first power supply voltage and a second power supply voltage to a first power amplifier and a second power amplifier, respectively, includes a first modulation circuit including a linear regulator and a switching regulator, the first modulation circuit being configured to generate a first modulation voltage in accordance with envelope tracking, and provide the first modulation voltage to the first power amplifier as the first power supply voltage; and a single inductor multiple output converter configured to generate a first output voltage and a second output voltage based on an input voltage having a fixed level, provide the first output voltage to the linear regulator of the first modulation circuit as a power supply voltage, and provide the second output voltage to the second power amplifier as the second power supply voltage.