A method of pre-compensating for transmitter in-phase (I) and quadrature (Q) mismatch (IQMM) may include sending a signal through an up-converter of a transmit path to provide an up-converted signal, determining the up-converted signal, determining one or more IQMM parameters for the transmit path based on the determined up-converted signal, and determining one or more pre-compensation parameters for the transmit path based on the one or more IQMM parameters for the transmit path. In some embodiments, the up-converted signal may be determined through a receive feedback path. In some embodiments, the up-converted signal may be determined through an envelope detector.

Systems and methods for linearizing a radio system are disclosed. In some embodiments, a radio system comprises an antenna array, transmit branches comprising respective power amplifiers, a predistortion subsystem comprising predistorters for the transmit branches respectively, a receive antenna element, a transmit observation receiver having an input coupled to the receive antenna element, and an adaptor. The predistorters predistort respective transmit signals to provide predistorted transmit signals to the respective transmit branches for transmission via respective active antenna elements in the antenna array. The transmit observation receiver is operable to receive, via the receive antenna element, a combined receive signal due to coupling between the receive antenna element and the active antenna elements. The adaptor is operable to generate a combined reference signal based on the transmit signals and configure predistortion parameters input to the predistorters based on the combined reference signal and the combined receive signal.

Provided is a distortion compensation device performing distortion compensation on a signal to be amplified by an amplifier, of which an internal state affecting a distortion characteristic varies, using a distortion compensation model, wherein the distortion compensation model includes a plurality of calculation models having respective distortion compensation characteristic for the amplifier in different internal states, and a combiner combining the plurality of calculation models at a combination ratio corresponding to the internal state that varies.

According to one mode of the inventive concept, an amplification device includes a first amplifier configured to amplify an input multi-band signal to a first level, a separating unit configured to separate the multi-band signal having the first level into a first band signal and a second band signal, and a second amplifier configured to amplify the second band signal to a second level.

Methods, apparatuses, and computer-readable medium for DPD are provided. An example method may include receiving, from a base station, an uplink grant associated with one or more resources. The example method may further include transmitting, to the UE via the one or more resources, a DPD training signal at a first port of a plurality of ports. The example method may further include receiving, at a second port of the plurality of ports, the DPD training signal.

A wireless communication system including a phased array comprising a plurality of antennas configured to emit a respective radio wave based on a respective antenna signal. Further, the system includes a plurality of power amplifiers each coupled to one of the plurality of antennas via a feed line and configured to output the antenna signal to the feed line. Also, the system includes a plurality of directional couplers each coupled into one of the feed lines and comprising a third port configured to output a fraction of a power received at a first port coupled to the power amplifier via the feed line, likewise a fourth port configured to output a fraction of a power received at a second port. Additionally, the system includes switching circuitry configured to alternately couple the third port to a first feedback receiver, and to alternately couple the fourth port to a second feedback receiver.

The invention discloses a transmitter comprising a pulse encoder for creating pulses from the amplitude of an input signal to the transmitter, a compensation signal generator for cancelling quantization noise caused by the pulse encoder, a mixer or I/Q modulator for mixing an output of the pulse encoder with the phase of an input signal to the transmitter, said output of the pulse encoder comprising the amplitude of the complex input signal plus the quantization noise caused by the pulse encoder, and an amplifier for creating an output signal from the transmitter. In the transmitter, a control signal (C.sub.A) for controlling a function of the amplifier comprises an output signal from the compensation signal generator, and an input signal to the amplifier comprises an output from the mixer having been modulated to a desired frequency.

A digital frontend circuit for a radio frequency (RF) comprises a digital predistortion (DPD) block, a plurality of sub-sample delay elements, and a selection circuit. The DPD block for computing predistorted transmit signals according to a Volterra series approximation model. The DPD block has an input for receiving input samples at a first sample rate and an output for providing the predistorted transmit signals at the first sample rate. Each of the sub-sample delay elements provides a delay to an input sample as specified by the Volterra series approximation model, where each of the delays is based on a fraction of the first sample rate. The selection circuit selects one of the plurality of sub-sample delay elements in response to a selection signal from the digital predistortion block. The selection signal for selecting a delay as specified by the Volterra series approximation model.

A method for predistorting an input signal of an amplifier device comprises evaluating a selection criterion for a computational model of the amplifier device. The computational model provides an output signal of the amplifier device for the input signal of the amplifier device. Further, the method comprises selecting between a first computational model of the amplifier device and a second computational model of the amplifier device based on the evaluated selection criterion. Additionally, the method comprises predistorting the input signal of the amplifier device using the selected computational model.

A digital microwave radio system includes a splitter that splits a common baseband input into two baseband outputs, first and second transmitters, each transmitter electrically connected to a baseband output of the splitter via a mixer, a common local oscillator electrically connected to the mixer of the first transmitter and the mixer of the second transmitter via an adjustable phase shifter, respectively, and a combiner. The common local oscillator is configured to up-convert each baseband output into a radio-frequency signal using a corresponding mixer. The combiner combines the two radio-frequency signals into a 0-degree phase-shift output and a 180-degree phase-shift output, respectively. A phase error control loop adjusts the phase shifter to minimize the 180-degree phase-shift radio-frequency output. A combiner gain control loop adjusts the output power level of the two transmitters in accordance with an actual power detector reading at the 0-degree phase-shift radio-frequency output.