Various digital pre-distortion systems for use in transmitters are disclosed. The digital pre-distortion system comprises an observing path, which performs either undersampling or radio frequency sampling of the output of a power amplifier. Undersampling may be performed at a rate, which causes aliasing to occur in the undersampled frequency domain. Both undersampling and radio frequency sampling reduces the complexity of the digital pre-distortion system by removing any down mixing modules or anti-aliasing modules, while maintaining reasonable performance of the digital pre-distortion systems.

A multi-stage Radio Frequency (RF) power amplifier is presented herein. According to one embodiment, the amplifier comprises: a first amplification stage configured to amplify an input signal to provide a first output signal having a phase distortion; a second amplification stage having an input and configured to amplify the first output signal that is received at the input to provide a second output signal, wherein the second output signal has a carrier frequency (F.sub.C) modulated by a signal content (S) having a signal content bandwidth (F.sub.S); and a resonant circuit comprising an inductor and a capacitor and having a resonant frequency (F.sub.R), the resonant circuit coupled to the input of the second amplification stage and compensating for the phase distortion caused by the first amplification stage at frequencies within the signal content bandwidth F.sub.S, wherein the resonant frequency F.sub.R is less than the signal content bandwidth F.sub.S.

An apparatus relates generally to preconditioning an input signal. In this apparatus, a first digital predistortion module and a second digital predistortion module are for receiving the input signal for respectively providing a first predistorted signal and a second predistorted signal. A combiner is for combining the first predistorted signal and the second predistorted signal for providing an output signal. The first digital predistortion module includes a moving mean block for receiving the input signal for providing a moving mean signal. The first digital predistortion module further includes a digital predistorter for receiving the input signal and the moving mean signal for providing the first predistorted signal.

An apparatus relates generally to preconditioning an input signal. In this apparatus, a first digital predistortion module and a second digital predistortion module are for receiving the input signal for respectively providing a first predistorted signal and a second predistorted signal. A combiner is for combining the first predistorted signal and the second predistorted signal for providing an output signal. The first digital predistortion module includes a moving mean block for receiving the input signal for providing a moving mean signal. The first digital predistortion module further includes a digital predistorter for receiving the input signal and the moving mean signal for providing the first predistorted signal.

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.

Embodiments of the present disclosure provide digital predistortion method and digital predistortion apparatus. The digital predistortion method for power amplifier, PA, comprises: in accordance with a predicted traffic condition associated with a future time, determining PA related parameters for the future time; and applying the determined PA related parameters when the future time comes.

Provided is a method for implementing a digital predistortion scheme. The method includes obtaining (S210) artificial-intelligence-digital-predistortion (AI-DPD) schemes of eight neural-networks by using a unified digital predistortion (DPD) hardware structure and using software configuration.

In one example, an apparatus includes: an operational amplifier (opamp) to amplify a difference between a reference voltage and a feedback voltage and output a bias signal based on the difference; a replica device coupled to the opamp, the replica device having a gate terminal to receive the bias signal; and an output stage coupled to the replica device and to output a regulated voltage, the output stage having a pass device and a plurality of feedback devices coupled to the pass device. A selected number of the plurality of feedback devices can be enabled based at least in part on an output power level of a power amplifier that is to receive the regulated voltage.

An apparatus may be configured to receive a signal to be transmitted via an array of antennas by a zero-forcing precoder, wherein the signal is processed by the linear precoder based on one or more input power criteria for power amplifiers of the array of antennas; apply a distortion reducing matrix to the processed signal, wherein the distortion reducing matrix is trained to reduce the distortion at each output of the power amplifiers based on minimizing an error signal corresponding to a difference between measured and calculated outputs of the power amplifiers after a coupling effect between the power amplifiers based on the applied matrices; and provide an output of the distortion reducing matrix to be used in digital pre-distortion processing of an input signal for the power amplifiers.

A power amplification system includes: a first power amplifier configured to amplify a first radio-frequency signal; a second power amplifier configured to amplify a second radio-frequency signal; a switched-capacitor circuit configured to generate multiple discrete voltages based on a regulated voltage supplied from a pre-regulator; an output switch circuit configured to selectively output at least one of the multiple discrete voltages as a first power supply of the first power amplifier; and a digital predistortion circuit configured to predistort the first and second radio-frequency signals. The pre-regulator circuit is configured to convert an input voltage to the regulated voltage. The regulated voltage is provided as a second power supply of the second power amplifier without using the switched-capacitor circuit. The digital predistortion circuit predistorts the first radio-frequency signal by using a first mathematical-expression model for digital predistortion. The first mathematical-expression model is not applied on the second radio-frequency signal.