A digital predistortion (DPD) system includes an input configured to receive an input signal. In some examples, a first signal path configured to generate a first signal based on the input signal. In some examples, an error model provider configured to generate an error model signal modeled after a gate bias error voltage associated with the DPD system. In some examples, a first combiner configured to combine the first signal and the error model signal to generate a first intermediate signal, and the DPD system generates an output signal based at least on the first intermediate signal.

Circuits and operating methods thereof for correcting phase errors introduced by amplifiers employing gallium nitride (GaN) transistors are described. The phase errors are caused by trapping effects exhibited by the GaN transistors. The circuits described herein pre-distort the phase of the input signal to compensate for the phase error introduced by the amplifier. Thereby, the phase of the output signal of the amplifier has a reduced phase error. For example, the output signal may have a near zero (or zero) phase error.

A distortion compensation device includes a first table, a second table, a calculating unit, a first updating unit, and a second updating unit. The first table holds a coefficient of a nonlinear term included in a filtering coefficient associated with an address other than a prescribed address obtained from the input signal x(n). The second table holds a coefficient of a linear term related to the prescribed address. The calculating unit calculates, based on the output signal, each of the update amounts of the coefficient of the nonlinear term and the coefficient of the linear term. The first updating unit updates each of the coefficients in the first table based on the update amount of the coefficient of the nonlinear term. The second updating unit updates each of the coefficients of the second table based on the update amount of the coefficient of the linear term.

There is provided mechanisms for enabling linearization of a non-linear electronic device. A method is performed by a linearizer device. The method comprises receiving an input signal destined to be input to the non-linear electronic device. Input-output characteristics of the non-linear electronic device is represented by a model. The model is defined by a mathematical expression, and wherein input-output characteristics of the linearizer device is given by the linearization function. The linearization function is determined by applying a function recursion to the mathematical expression of the model. The method comprises obtaining an output signal by subjecting the input signal to the linearization function. The method comprises providing the output signal, instead of the input signal, as input to the non-linear electronic device, thereby enabling linearization of the non-linear electronic device.

The present disclosure relates to a transmitter system that includes a radio frequency (RF) power amplifier (PA) and a baseband processor. The RF PA is configured to amplify an RF input signal to an RF output signal and configured to receive an analog bias adjustment signal, which is applied to correct dynamic bias errors in the RF PA caused by amplification variations that have time constants. The baseband processor, in response to an input envelope and a feedback output envelope, is configured to generate a feedback envelope error signal. Herein, the input envelope is estimated based on a baseband input signal received by the baseband processor, and the feedback output envelope is estimated based on the RF output signal. The RF input signal and the analog bias adjustment signal fed to the RF PA are generated from the baseband input signal and the feedback envelope error signal, respectively.

A transmitter for a communication system comprises a digital pre-distortion (DPD) circuit and adaptation circuitry. The DPD circuit is configured to generate a digital intermediate signal by compensating an input signal for distortions resulting from an amplifier. The amplifier is configured to output an output signal based on the digital intermediate signal. The DPD circuit includes one or more an infinite impulse response (IIR) filters configured to implement a first transfer function based on a first parameter, and a second transfer function based on the first parameter and a time constant. The DPD circuit is configured to generate an adjustment signal based on the first transfer function and the second transfer function. The adaptation circuitry is configured to update the first parameter based on the adjustment signal, the input signal, and the output signal.

Envelope tracking systems for power amplifiers are provided herein. In certain embodiments, an envelope tracker is provided for a power amplifier that amplifies an RF signal. The envelope tracker includes an error amplifier that controls a voltage level of a power amplifier supply voltage of the power amplifier based on amplifying a difference between a reference signal and an envelope signal indicating an envelope of the RF signal. The envelope tracker further includes a multi-level switching circuit that generates an error amplifier supply voltage based on sensing a current of the error amplifier, and uses the error amplifier supply voltage to power the error amplifier.

The present disclosure provides a method of linearization for a non-linear system, comprising: a group of steps comprising: inputting an input signal to the non-linear system; obtaining an output signal from the non-linear system in response to the input signal being input to the non-linear system; obtaining a desired signal for the non-linear system; comparing the output signal with the desired signal, to determine whether the input signal is a target signal for the non-linear system to achieve a desired performance; and in response to determining that the input signal is not the target signal for the non-linear system to achieve the desired performance, generating an updated signal in frequency domain by applying a coefficient to eliminate a difference between the output signal and the desired signal, for updating the input signal to the non-linear system. The present disclosure also provides a corresponding device, computer programs, and computer-readable storage.

Systems and methods for improving output stability of an RFPA. The systems may obtain an initial radio frequency signal to be amplified by the RFPA. The systems may also generate a compensated radio frequency signal by performing, based on a preset compensation rule and a set of compensation parameters, a gain compensation operation for the initial radio frequency signal. The set of compensation parameters may include a supply voltage of the RFPA and a transistor junction temperature of the RFPA. The systems may further generate, by performing a non-linear correction operation on the compensated radio frequency signal, a corrected radio frequency signal, which is transmitted to the RFPA.

The invention relates to a device for linearising a power amplifier by employing digital predistortion, comprising: a digital predistortion module, configured to infer a polar domain predistortion to be applied to a signal, and comprising a first neural network and a second neural network respectively configured to correct amplitude and phase distortion produced by the amplifier; an optimisation module of each of said neural networks configured to implement meta-learning, using: a meta-initialisation providing a prior initialisation of the initial weights of each of said neural networks; a meta-matching of the initial weights into optimal weights of each of said neural networks.