A Cartesian loop circuit includes a reference signal amplifier, a forward path coupled to the reference signal amplifier, a feedback path coupled to the forward path, and a controller. The forward path includes an up-mixer to up mix a forward path signal to a radio frequency signal. The feedback path includes a down-mixer to down mix a feedback signal to a frequency of a baseband reference signal inputted to the forward path. The feedback path provides the down-mixed feedback signal to the forward path. The controller is to perform power control at a low power by controlling a gain of the reference signal amplifier and is to perform power control at a high power by controlling a gain of the down-mixer. At the high power, the controller may perform power control by further controlling the gain of the up-mixer.

A power amplifier includes an output signal generator constructed to generate, on the basis of an input AC signal, an output signal including, in cycles, a first pulse being width higher in voltage than a first reference voltage and a second pulse being width lower in voltage than the first reference voltage and a feedback circuit constructed to generate a first bias signal corresponding to the output signal and feed back the first bias signal to an input side of the output signal generator to equalize a width of the first pulse and a width of the second pulse in the cycles of the output signal.

A transceiver circuit and related radio frequency (RF) circuit are provided. An RF circuit is coupled to a transceiver circuit configured to generate an envelope tracking (ET) target voltage. The RF circuit includes a tracker circuit and a power amplifier circuit(s). The tracker circuit may have inherent frequency-dependent impedance that can interact with a load current of the amplifier circuit(s) to cause degradation in an ET modulated voltage, which can lead to spectral distortions in an RF offset spectrum. As such, a voltage compensation circuit is provided in the transceiver circuit and configured to add a voltage compensation term in the ET target voltage. By adding the voltage compensation term into the ET target voltage, it is possible to compensate for the degradation in the ET modulated voltage, thus helping to reduce the spectral distortions in the RF offset spectrum and improve linearity and efficiency of the amplifier circuit(s).

A multicarrier-radio transmitter has a digital signal processor to produce a multicarrier signal at IF, and a transmit amplifier circuit to amplify and transmit the multicarrier signal at RF. A feedback loop of the transmit amplifier circuit has a subtractor, an I/Q demodulator in the forward path, a loop-filter system in the forward path at baseband, an I/Q modulator in the forward path, a power amplifier in the forward path, a pick-off node to pick off the multicarrier RF signal, and a down converter in the reverse path to down-convert the picked-off multicarrier RF signal to IF.

A Cartesian loop circuit includes a reference signal amplifier, a forward path coupled to the reference signal amplifier, a feedback path coupled to the forward path, and a controller. The forward path includes an up-mixer to up mix a forward path signal to a radio frequency signal. The feedback path includes a down-mixer to down mix a feedback signal to a frequency of a baseband reference signal inputted to the forward path. The feedback path provides the down-mixed feedback signal to the forward path. The controller is to perform power control at a low power by controlling a gain of the reference signal amplifier and is to perform power control at a high power by controlling a gain of the down-mixer. At the high power, the controller may perform power control by further controlling the gain of the up-mixer.

An apparatus and a method include receiving, by a transmitter integrated circuit (IC) having a serial data communications interface, a digital transmit signal, and generating a first signal that is an analog radio frequency (RF) modulated signal based on the digital transmit signal and a second signal that is a phase-offset version of the first signal. An amplified signal is generated by amplifying the first signal and includes an amplified version of the first signal and an out-of-band distortion signal. A reduced-power signal is generated from the amplified signal. The reduced-power signal is subtracted from the second signal to output a distortion cancellation signal. An amplified distortion cancellation signal is generated by amplifying the distortion cancellation signal using an error amplifier. The amplified distortion cancellation signal and a delayed version of the amplified signal are combined to output an amplified version of the first signal with reduced distortion.

Power amplifier circuits can behave in a non-linear manner particularly when operated to produce output signal swings approaching an amplifier saturation region. A pre-distortion signal can be applied to a signal to be transmitted to compensate for such power amplifier non-linearity. In applications where two or more transmitter power amplifiers are used, a beam-former can be configured to modify a digitally pre-distorted transmission signal by applying respective beam-forming weighting factors to the digitally pre-distorted transmission signal to provide input transmission signals for respective ones of the power amplifier circuits. The pre-distortion signal can be established at least in part using one or more of a sensed or estimated representation of a transmitted beam formed by spatially aggregating transmitted outputs from the two or more power amplifier circuits. In this manner, power amplifier efficiency can be enhanced without entirely separate pre-distortion compensation for each of the power amplifier circuits.

The present disclosure relates to an apparatus and a method for transmitting a signal using a power amplifier in a wireless communication system in which a transceiver comprises a digital pre-distorter configured to distort an input signal based on a distortion control value, a power amplifier configured to amplify an output signal from the digital pre-distorter, an antenna configured to transmit an output signal from the power amplifier, an echo signal canceller configured to remove an echo signal which returns to the power amplifier due to a return loss of a path between the power amplifier and the antenna, from a feedback signal obtained at an output stage of the power amplifier, and a digital pre-distortion adaptation unit configured to determine the distortion control value based on an output signal from the echo signal canceller.

Ultra-Wideband (UWB) technology is a wireless technology for the transmission of large amounts of digital data as modulated coded impulses over a very wide frequency spectrum with very low power over a short distance. However, to support their deployment in a wide range of applications it would be beneficial to provide solutions which: exploit multiple directive antennas oriented in different directions to ensure spatial filtering of undesired signals and increase signal strength; exploit dynamic configuration of the multi-pulse bundles employed to transmit the bits/symbols within the packets to enhance link quality of service; exploit dynamic configuration of the band or bands which the transmitter operates upon; and exploit antenna sub-systems providing omnidirectional radiation patterns with implementations offering filtering and balun functions with small footprint and low cost.

A transmitter includes a shift register, a lookup table, and a digital to analog converter. The shift register is configured to receive an input signal and to output delayed copies of the input signal. The lookup table is configured to store compensation values estimated based on the input signal and the delayed copies of the input signal. The digital to analog converter is configured to output a transmit signal based on the input signal and the compensation values. The compensation values are designed to mitigate distortion of the transmit signal from conversion of the input signal to a digital signal.