A power supply for a radio frequency (RF) power amplifier that amplifies an RF input signal into an RF output signal and a method of operation in the power supply. The power supply comprises a first power converter to convert an input voltage to the power supply into a first supply voltage of the RF power amplifier. The power supply comprises a second power converter to receive the input voltage and the first supply voltage and to selectively convert either the input voltage or the first supply voltage into at least a portion of a second supply voltage of the RF power amplifier.

Technologies for RFID positioning and tracking apparatus and methods are disclosed herein. The apparatus and methods disclose a radio-frequency identification positioning system that includes a radio-frequency identification reader and a phased-array antenna coupled to the radio-frequency identification reader. Techniques are applied to reduce in-reader and in-antenna signal leakages. Techniques are applied to position and track RFID tags. Circuits with leakage cancellation abilities are also disclosed. Reflective vector attenuators with tunable impedance load are also disclosed. Polarization adjustable antennas with matching circuits used in the RFID positioning system are also disclosed. Circuits to re-transmit a received signal at a higher amplitude to enhance radio link range are also disclosed. Techniques are applied to increase the level of scattered radio signals from RFID tags.

Wireless communications circuitry in an electronic device may include power amplifier circuitry that is powered using a bias voltage supplied by adjustable power supply circuitry. The power supply circuitry may include envelope tracking circuitry that continuously adjusts the bias voltage. The wireless communications circuitry may generate test signals and may generate performance metric data from the test signals. Processing circuitry may generate bias voltage calibration data based on the performance metric data and may provide the calibration data to the envelope tracking circuitry. After the calibration data has been generated, the envelope tracking circuitry may continuously select bias voltages to provide to the amplifier based on the magnitude of signals that are transmitted and the calibration data. By actively adjusting the bias voltage in this way, power consumption may be minimized without generating undesirable harmonics or other radio-frequency performance requirement violations.

An RF amplifier with enhance power efficiency is disclosed. The RF amplifier traces the envelope of the input RF signal and varies the supply voltage to the final FET depending on the detected envelope through a linear power supply and a switching power supply superposed on the linear power supply. The linear power supply promptly responds the change of the envelope and gradually decreases the supply current as maintaining the supply voltage. The switching power supply takes over the supplement of the supply current to the final FET.

A device to receive a first signal from a driver. The device comprising a first circuit, a second circuit, a third circuit, and a fourth circuit. The first circuit to provide a second signal having a first level. The second circuit to detect the first level of the first signal and to provide a third signal to control a third circuit of the device. The third circuit to provide a fourth signal, the fourth signal having a first level in response to a difference being smaller than a predetermined value, and the fourth signal having a second level in response to the difference being larger than the predetermined value. The fourth circuit to provide a fifth signal, the fifth signal having a first level based at least on the second signal, and the fifth signal having a second level based at least on the second signal and the fourth signal.

The present power amplifier linearizing module linearizes operation of a power amplifier and operates in parametrizing mode and operation mode. A processing module executes a feed-forward transfer functions set, which includes at least: a transfer function P and a summing function. The transfer function P derives a change signal V.sub.a relative to the control signal component received and the summing function summing the incremental change signal V.sub.a to an input signal to generate an adjusted input signal. A transfer function G uses the adjusted input signal to generate an RF signal representative of the amplifying of the adjusted input signal based on the control signal component. The processing module determines a linearizing control signal component based on the generated RF signal representative.

Amplifier circuits, radio communication circuits, radio communication devices, and methods provided in this disclosure provide an amplifier circuit. The amplifier circuit may include an amplifier configured to amplify an input signal to provide an output signal. The amplifier circuit may further include an amplifier stack including a first transistor coupled to the amplifier. The amplifier stack may be configured to receive the output signal to amplify the output signal. The amplifier stack may be configured to receive an input control signal to control the first transistor based on an envelope of the input signal.

The disclosure provides a voltage control device for controlling supply voltages of a power amplifier (PA). The voltage control device includes a first processing circuit to provide a first supply voltage to at least one driving stage amplifier of the PA, and a second processing circuit to provide a second supply voltage to an output stage amplifier of the PA. The first supply voltage is generated according to an average-power-tracking (APT) mechanism related to an average power level of a radio frequency (RF) signal transmitted by the PA.

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.

Apparatus and methods for load modulated power amplifiers are provided. In certain embodiments, a load modulated power amplifier system includes a power amplifier that receives a radio frequency signal at an input and provides an amplified radio frequency signal at an output, and a controllable load impedance coupled to the output of the power amplifier. The controllable load impedance receives an envelope signal that changes in relation to an envelope of the radio frequency signal, and the envelope signal is operable to control an impedance of the controllable load impedance to modulate a load at the output of the power amplifier.