Phase and amplitude error correction in a transmission circuit is provided. The transmission circuit includes a transceiver circuit, a power management integrated circuit (PMIC), and a power amplifier circuit(s). The transceiver circuit generates a radio frequency (RF) signal(s) from an input vector, the PMIC generates a modulated voltage, and the power amplifier circuit(s) amplifies the RF signal(s) based on the modulated voltage. When the power amplifier circuit(s) is coupled to an RF front-end circuit, unwanted amplitude-amplitude (AM-AM) and amplitude-phase (AM-PM) errors may be created across a modulation bandwidth of the transmission circuit. In this regard, in embodiments disclosed herein, the input vector is equalized based on multiple complex filters to thereby cause the AM-AM and AM-PM errors to be corrected in the transmission circuit. As a result, it is possible to reduce undesired instantaneous excessive compression and/or spectrum regrowth across the modulation bandwidth of the transmission circuit.

A method comprises obtaining a transmission signal to be power-amplified in a power amplifier (361) prior to transmission; separating the transmission signal into two or more polyphase components of the transmission signal; feeding one or more polyphase components of the transmission signal comprised in the two or more polyphase components to each of two or more parallel predistortion circuits (320,321,322); selecting a dedicated predistortion model and dedicated predistortion coefficients for each of the two or more parallel predistortion circuits (320,321,322); performing non-linear memory-based modeling on the transmission signal according to the selected dedicated predistortion models and coefficients using the one or more polyphase components; and combining output signals of the two or more parallel predistortion circuits (320,321,322) to form a predistorted transmission signal (y[n]) to be applied to the power amplifier (361).

An embodiment of the present disclosure relates to a method of controlling a power amplifier (PA). The PA can comprise a main PA path and an auxiliary PA path. The auxiliary PA path can have a plurality of turn-on settings. The method can comprise: determining a power back off gain and a lower bound gain for the PA; and performing an iterative auxiliary PA turn-on setting selection process. The selection process can comprise: determining an instantaneous power input to the PA; based on the instantaneous power input, choosing a turn-on setting in the plurality of turn-on settings of the auxiliary PA path that causes an instantaneous gain of the PA to be between the power back off gain and the lower bound gain; and applying the chosen turn-on setting to the auxiliary PA path.

A wireless communications system includes a pre-distortion actuator configured to receive a carrier-modulated signal and convert the carrier-modulated signal into an output signal. The system includes one or more antennas configured to receive the output signal and transmit the output signal, one or more power amplifiers electrically coupled between the pre-distortion actuator and the one or more antennas and a receiver configured to receive the output signal over-the-air and generate feedback based on the output signal. The pre-distortion actuator is configured to generate the output signal by applying a correction to the carrier-modulated signal that cancels out nonlinearities associated with the one or more antennas and/or the one or more power amplifiers. The pre-distortion actuator is configured based on the feedback.

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.

The behavioral model and predistorter for modeling and reducing nonlinear effects in power amplifiers addresses the model size estimation problem. The GMP model is replaced by the hybrid memory polynomial/envelope memory polynomial (HMEM) model within a twin nonlinear two-box structure to reduce the number of variables involved in the model size estimation problem, without compromising model accuracy and digital predistorter performance. A sequential approach is presented to efficiently estimate the model size. Experimental validation is carried out to evaluate the performance of the size estimation and the accuracy of the HMEM-based twin-nonlinear two-box model with respect to that of the GMP-based twin-nonlinear two-box model.

A predistortion circuit for a wireless transmitter includes a signal input configured to receive a baseband signal. Further, the predistortion circuit includes a predistorter configured to generate a predistorted baseband signal using the baseband signal and a select of one of a first predistorter configuration and a second predistorter configuration.

An envelope tracking system includes an envelope tracking digital baseband (ETDBB) circuit, a digital-to-analog converter circuit, and an envelope tracking supply modulator (ETSM) circuit. The ETDBB circuit performs envelope detection upon a transmit (TX) baseband signal to generate an envelope detection result, and generates a digital envelope input according to the envelope detection result. The digital-to-analog converter circuit converts the digital envelope input into a supply envelope signal. The ETSM circuit generates a modulated supply voltage according to the supply envelope signal, and outputs the modulated supply voltage to a power amplifier. At least one of the ETDBB circuit and the ETSM circuit dynamically adjusts gain compression (GC) of the PA in response to a number of active resource blocks (RBs) in a channel bandwidth.

Various examples are directed to systems and methods for digital predistortion (DPD). A linear digital predistortion (DPD) circuit may be programmed to generate a pre-distorted signal linear component based at least in part on a complex baseband signal. A nonlinear DPD circuit may be programmed to generate a pre-distorted signal nonlinear component based at least in part on the complex baseband signal. A mixer circuit programmed to generate a pre-distorted signal based at least in part on the pre-distorted signal linear component and the pre-distorted signal nonlinear component.