Robust digital predistorter for RF power amplifier linearisation

Manai, M.; Chenini, Hanen; Harguem, A.; Boulejfen, Noureddine; Ghannouchi, Fadhel M.

doi:10.1049/iet-map.2018.5680

Cited by 4 publications

(4 citation statements)

References 15 publications

(22 reference statements)

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“…Digital pre-distortion based on memory polynomial model is one of the popular and efficient models that is used to compensate the PA nonlinearity but can experience the numerical instability problem that reduces the performance of the DPD. To overcome this problem, various methods have been proposed to convert the conventional polynomials to a set of orthogonal basis functions [14], [16]- [19] and thus improve the condition number of the observation matrix. But these orthogonal polynomials have some limitations in signal statistics or some of them are complicated in the calculation [14].…”

Section: Chebyshev Polynomials As the Pre-distorter Modelmentioning

confidence: 99%

“…Although this method improved the DPD performance, it was limited to the input signal values distributed in [0, 1], and the combined LMS and RLS algorithm increased the computational complexity. Manai et al [19] proposed a numerically stable digital pre-distorter based on the Gegenbauer polynomials to linearize the radio frequency (RF) power amplifiers without the IQ impairments compensation. Although the Gegenbauer polynomials were orthogonal and the pre-distorter based on the Gegenbauer basis functions was numerically stable, it worked only on the real-valued variable on the input values of the interval [−1, 1] and only considered the PA nonlinearity while all the other impairments of the transmitter affected on the DPD performance.…”

Section: Introductionmentioning

confidence: 99%

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Joint digital pre-distortion model based on Chebyshev expansion

Majdinasab

Jannesari

2022

IJECE

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<span>In this paper, a new low complexity model is proposed for the joint digital pre-distortion of in-phase/quadrature-phase (I/Q) imbalance, local oscillator (LO) leakage, and power amplifier nonlinearity in direct-conversion transmitters (DCTs). In this structure, we proposed a set of orthogonal basis functions based on Chebyshev expansion to attenuate the problem of numerical instability created during the conventional model identification method. This robust joint digital pre-distortion (DPD) utilized the indirect learning architecture and updated the coefficients vector based on the recursive least square (RLS) algorithm. To verify the operation and efficiency of the proposed model, an extensive simulation in MATLAB was carried out. The results showed a significant reduction in the conditional number and the coefficient dispersion of the observation matrix. Furthermore, the power of the signal in the adjacent channel decreased by more than 16 dB for the orthogonal frequency division multiplexing (OFDM), 16 QAM input signal. In comparison to the previous digital pre-distorter models, the proposed DPD builds strong numerical stability with the least coefficients.</span>

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Section: Chebyshev Polynomials As the Pre-distorter Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Joint digital pre-distortion model based on Chebyshev expansion

Majdinasab

Jannesari

2022

IJECE

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“…Additional efforts related to linearization and spectral regulation have been made for LTE and W-CDMA, a cubic spline (CS) has been developed for a DPD system for the outphasing angles and power level correction applied to Class-F PA for a W-CDMA 5-MHz and an LTE 10-MHz [ 11 ]. Additionally, a numerically stable digital predistorter for RF PA linearization based on Gegenbauer polynomials has been implemented for PA output under 4-channel W-CDMA and LTE drive signals [ 12 ]. An interesting feature to provide real-time prototyping systems for developing new DPD approaches is offered with software-defined radio (SDR), which is a favorable solution to address such problems.…”

Section: Introductionmentioning

confidence: 99%

A Crest Factor Reduction Technique for LTE Signals with Target Relaxation in Power Amplifier Linearization

Cárdenas-Valdez

Galaviz-Aguilar

Vargas-Rosales

et al. 2022

Sensors

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The signal conditioning treatment to achieve good relation of power with radio-frequency (RF) conversion in conventional transceiver systems require precise baseband models. A developed framework is built to provide a demonstration of the modeling figures of merit with orthogonal frequency division multiplexing (OFDM) support under signal conditioning and transmission restrictions to waveforms with high peak to average power ratio (PAPR) in practical applications. Therefore, peak and average power levels have to be limited to correct high PAPR for a better suited correction power from the amplifier that can lead to compression or clipping in the signal of interest. This work presents an alternative joint crest factor reduction (CFR) algorithm to correct the performance of PAPR. A real-time field-programmable gate array (FPGA) testbed is developed to characterize and measure the behavior of an amplifier using a single-carrier 64–QAM OFDM based on long-term evolution (LTE) downlink at 2.40 GHz as stimulus, across wide modulation bandwidths. The results demonstrate that the CFR accuracy capabilities for the signal conditioning show a reliable clipping reduction to give a smooth version of the clipping signal and provide a factor of correction for the unwanted out-of-band emission validated according to the adjacent channel power ratio (ACPR), PAPR, peak power, complementary cumulative distribution function (CCDF), and error vector magnitude (EVM) figures of merit.

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“…The RLS estimator was dis-cussed in perspective of a transmitter with adaptive digital predistortion for compensating non-linearities in the RF power amplifier. The proposed DPD algorithm in [28] was elaborated on the basis of Gegenbauer polynomials adapted for maximum predistorter effectiveness and steadiness under various input signal conditions. In this research, four popularly accepted algorithms named as Memory Polynomial, Cross-term Memory Polynomial, Generalized Hammerstein and Cross-term Hammerstein are individually analyzed for characterizing RF power amplifier with and without implementation of suitable DPD algorithm under two tone and 16 QAM signals.…”

Section: Introductionmentioning

confidence: 99%

Characterization of RF Power Amplifier for Narrow and Wide Band Memory Polynomial Implementations

Mohiuddin

Shaikh

Dahri

et al. 2021

QUEST Research Journal

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Linearly efficient RF power amplifiers have a tremendous role in wireless communication and radar systems as they lie at the front end of most RF systems. In today’s world of wireless communication, it is not an easy task to design a RF power amplifier that is linearly efficient. There are two main key challenges that one face for making RF power amplifier’s behavior linearly efficient. First is to characterize RF power amplifier’s coefficients smartly. Second is to propose an approach that works on input signal and make its behavior inverse to that of the designed amplifier behavior so that overall response of the system becomes linear. For countering first challenge, most advanced universally accepted algorithms like Memory Polynomial, Generalized Hammerstein, Cross-term Memory Polynomial and Cross-term Hammerstein are implemented to design RF power amplifier models. For countering second challenge, latest DPD algorithms are implemented which make net response of a system linear. The memory models for modelling RF power amplifier are categorized for narrowband and wideband applications. The narrowband power amplifier models include Memory Polynomial and Cross-term Memory Polynomial models whereas wideband power amplifier models include Generalized Hammerstein and Cross-term Hammerstein models. In this paper, various performance indicators like Standard Deviation (SD), Third Order Intercept (TOI), Intermodulation Distortion Products (IMD3), Modulation Error Ratio (MER), Spurious Free Dynamic Range (SFDR) and Error Vector Magnitude (EVM) are used to characterize RF power amplifier for both narrow and wide band applications. The simulation results show that under narrowband applications, Cross-term Memory Polynomial model works best as it has least standard deviation and is also satisfying other performance parameters up to appreciable level with and without DPD algorithm implementation. While for wideband applications, Cross-term Hammerstein model satisfies the performance measuring parameters excellently.

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Robust digital predistorter for RF power amplifier linearisation

Cited by 4 publications

References 15 publications

Joint digital pre-distortion model based on Chebyshev expansion

Joint digital pre-distortion model based on Chebyshev expansion

A Crest Factor Reduction Technique for LTE Signals with Target Relaxation in Power Amplifier Linearization

Characterization of RF Power Amplifier for Narrow and Wide Band Memory Polynomial Implementations

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