Linearisation of RF PA by even-order nonlinear baseband signal processed in digital domain

Linearization of the Fifth Generation Power Amplifiers by Injection of the Second Order Digitally Processed Signals

“…A variety of techniques for amplifier linearization such as feedforward, feedback, predistortion [3] and different approaches of digital predistortion [3], [4] can be found in the literature. The authors of this paper anteriorly developed the digital linearization approach (DEB_LIN) [5][6][7][8] that uses the 2nd order digital signals adequately processed in magnitude and phase angles in the baseband, which then modulate the 2nd harmonic of the fundamental carrier. The generated linearization signals are injected at the gate and drain (input and output) of the PA transistor.…”

“…The generated linearization signals are injected at the gate and drain (input and output) of the PA transistor. The results of the linearization obtained by this linearization approach in the simulation were already published for the single stage PA [5], [6] and the two-way DA [8], and tested for QAM, WCDMA, OFDM and LTE modulation schemes. Also, the linearization results were published for the single stage PA that operates in frequency around 3.5 GHz for UFMC, FBMC, and FOFDM modulation schemes with 50 MHz useful signal bandwidth [7].…”

“…Also, the linearization results were published for the single stage PA that operates in frequency around 3.5 GHz for UFMC, FBMC, and FOFDM modulation schemes with 50 MHz useful signal bandwidth [7]. The DEB_LIN approach was validated in experiments using the asymmetrical two-way microstrip Doherty amplifier for both the 16QAM signal with a 1 MHz frequency bandwidth and the 64QAM signal with a 2 MHz frequency bandwidth [6], [8]. The linearization of the DA in simulation and the ADA in experiments was performed in [8] by injecting the formed signals for the linearization at the input and output of the carrier amplifier stage (approach-1), or at the outputs of both carrier and peaking amplifiers (approach-2) at the Doherty amplifier configuration.…”

Experimental Verification of the Impact of the 2nd Order Injected Signals on Doherty Amplifiers Nonlinear Distortion

“…The linearization signals formed in this manner are led at the gate and drain (input and output) of the amplifier transistor to decrease the nonlinearity of the power amplifier. The results of the linearization were predominantly analyzed in simulation software for the single stage PA [3], and the two-way DA [4] in terms of the input signal power and also in experiments. Measurements included in [4], which carried out on a DA, compare three cases -when the signals for linearization are inserted only at the input of the main DA amplifier transistor, only at its output and simultaneously at its input and output, but for the certain power levels.…”

Doherty Amplifier Linearization in Experiments by Digital Injection Methods

“…We deployed in earlier work the digital linearization technique [2]- [6] which processes the I and Q signals to generate the adequate 2 nd order baseband linearization signals adjusted in the magnitudes and phase angles. These signals are then driven at the gate and drain of the amplifier transistor, after modulate the 2 nd harmonic of the fundamental carrier, in order to lower the nonlinearity of the single stage PA [2], [5], and the two-way DA [3]- [5]. In [6], DA was linearized by inserting the modulated signals for linearization at the outputs of the main and auxiliary amplifier transistors.…”