INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS

Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57.

BACKGROUND

Field

Embodiments of the described technology relate to electronic systems, and in particular, to systems including power amplifiers for radio frequency (RF) electronics.

Description of the Related Technology

Power amplifiers can be included in mobile devices to amplify an RF signal for transmission via an antenna. For example, in mobile devices having a time division multiple access (TDMA) architecture, such as those found in Global System for Mobile Communications (GSM), code division multiple access (CDMA), wideband code division multiple access (W-CDMA) systems, long term evolution (LTE) systems, and new radio (NR) 5G systems, a power amplifier can be used to amplify an RF signal having a relatively low power. Power amplifiers can be included in mobile device front end modules that also include duplexers, antenna switch modules, and couplers. Modern front end modules can experience significant performance impairment under certain circumstances, including degraded linearity and memory effects.

SUMMARY

To address the degradation in linearity and the memory effects of a power amplifier, certain techniques can be used to extract a model of the linearity and memory effects of the power amplifier. The model can then be used to pre-distort input signals prior to be provided to the power amplifier to compensate for the non-linearity and memory effects of the power amplifier. Certain techniques used to extract the power amplifier model may be limited to the waveform and power level of the input signal used in extracting the model. Thus, the model may not adequately compensate for input signals having a substantially different waveform and/or power level. It may be desirable to produce a model that can be more generally used for different input waveforms and at different power levels without requiring additional extraction using an updated input signal.

Aspects of this disclosure relate to techniques and input waveforms which can be used to extract a power amplifier model which addresses the above limitations. For example, in one aspect, a universal memory-based model can be extracted for a power amplifier which can be used for a variety of waveforms and power levels. In particular, a method for modelling a power amplifier is provided according to at least one aspect of the disclosure. The method includes generating an extraction waveform having a plurality of tones each having a different frequency, a difference between the frequencies of two adjacent tones of the plurality of tones not being an integer multiple of a difference in frequency between any two other adjacent tones of the plurality of tones. The method further includes providing the extraction waveform to the power amplifier; receiving output from the power amplifier generated in response to the extraction waveform; and generating a model of the power amplifier based on the output.

A power amplifier modelling system is provided according to another aspect of the disclosure. The system includes a signal generator configured to generate an extraction waveform having a plurality of tones each having a different frequency, a difference between the frequencies of two adjacent tones of the plurality of tones not being an integer multiple of a difference in frequency between any two other adjacent tones of the plurality of tones. The system further includes a power amplifier configured to receive the extraction waveform; and model extraction hardware configured to receive output from the power amplifier generated in response to the extraction waveform, and generate a model of the power amplifier based on the output.

A mobile device is provided according to yet another aspect of the disclosure. The mobile device includes a modulator configured to generate a radio frequency transmit signal; and a power amplifier configured to amplify a digitally pre-distorted radio frequency transmit signal to generate an amplified radio frequency signal. The mobile device also includes digital pre-distortion hardware configured to receive the radio frequency transmit signal, apply digital pre-distortion to the radio frequency transmit signal based on the inverse of a model of the power amplifier, and generate the digitally pre-distorted radio frequency transmit signal, the model of the power amplifier generated using an extraction waveform comprising a plurality of tones each having a different frequency, a difference between the frequencies of two adjacent tones of the plurality of tones not being an integer multiple of a difference in frequency between any two other adjacent tones of the plurality of tones. The mobile device further includes an antenna configured to receive the amplified radio frequency signal from the front end module; and a non-volatile memory storing the inverse of the model of the power amplifier

