Academic literature on the topic 'Digital pre-distortion, DPD'
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Journal articles on the topic "Digital pre-distortion, DPD"
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Lee, Kwang-Pyo, Soon-Il Hong, and Eui-Rim Jeong. "A Polynomial Digital Pre-Distortion Technique Based on Iterative Architecture." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 1 (February 1, 2016): 106. http://dx.doi.org/10.11591/ijece.v6i1.9338.
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A digital predistortion (DPD) technique based on an iterative adaptation structure is proposed for linearizing power amplifiers (PAs). To obtain proper DPD parameters, a feedback path that converts the PA’s output to a baseband signal is required, and memory is also needed to store the baseband feedback signals. DPD parameters are usually found by an adaptive algorithm by using the transmitted signals and the corresponding feedback signals. However, for the adaptive algorithm to converge to a reliable solution, long feedback samples are required, which increases hardware complexity and cost. Considering that the convergence time of the adaptive algorithm highly depends on the initial condition, we propose a DPD technique that requires relatively shorter feedback samples. Specifically, the proposed DPD iteratively utilizes the short feedback samples in memory while keeping and using the DPD parameters found at the former iteration as the initial condition at the next iteration. Computer simulation shows that the proposed technique performs better than the conventional technique, as the former requires much shorter feedback memory than the latter.
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Lee, Kwang-Pyo, Soon-Il Hong, and Eui-Rim Jeong. "A Polynomial Digital Pre-Distortion Technique Based on Iterative Architecture." International Journal of Electrical and Computer Engineering (IJECE) 6, no. 1 (February 1, 2016): 106. http://dx.doi.org/10.11591/ijece.v6i1.pp106-112.
Full textAbstract:
A digital predistortion (DPD) technique based on an iterative adaptation structure is proposed for linearizing power amplifiers (PAs). To obtain proper DPD parameters, a feedback path that converts the PA’s output to a baseband signal is required, and memory is also needed to store the baseband feedback signals. DPD parameters are usually found by an adaptive algorithm by using the transmitted signals and the corresponding feedback signals. However, for the adaptive algorithm to converge to a reliable solution, long feedback samples are required, which increases hardware complexity and cost. Considering that the convergence time of the adaptive algorithm highly depends on the initial condition, we propose a DPD technique that requires relatively shorter feedback samples. Specifically, the proposed DPD iteratively utilizes the short feedback samples in memory while keeping and using the DPD parameters found at the former iteration as the initial condition at the next iteration. Computer simulation shows that the proposed technique performs better than the conventional technique, as the former requires much shorter feedback memory than the latter.
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Majdinasab, Elham, and Abumoslem Jannesari. "Joint digital pre-distortion model based on Chebyshev expansion." International Journal of Electrical and Computer Engineering (IJECE) 12, no. 4 (August 1, 2022): 3781. http://dx.doi.org/10.11591/ijece.v12i4.pp3781-3791.
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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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Chen, Boyuan, and Wei Wu. "Principles, applications, and challenges of digital predistortion technology." Applied and Computational Engineering 54, no. 1 (March 29, 2024): 64–75. http://dx.doi.org/10.54254/2755-2721/54/20241262.
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A power amplifier plays a crucial role in the transmitter end of wireless communication systems. Despite enhancing operational efficiency, it inadvertently introduces nonlinear distortion, leading to signal degradation and spectral regrowth. This occurrence necessitates the incorporation of additional linearization techniques in transmitter terminals to optimize both efficiency and linearity concurrently. Among these, Digital Pre-Distortion (DPD) technology stands out as a well-researched and extensively employed strategy for alleviating the nonlinear distortion induced by power amplifiers. This paper embarks on a comprehensive exploration of DPD technology, offering insight into its evolutionary path and elaborating on its foundational principles and essential techniques. The discussion extends to elucidate the significant technical challenges and the burgeoning trends within the DPD technology landscape. The narrative underscores the significance of DPD in enhancing the performance and efficiency of wireless communication systems, particularly in the context of burgeoning technological advancements and escalating demands for superior communication quality and broader bandwidth. Through a meticulous examination of the DPD technology paradigm, this paper contributes to the ongoing discourse and research, shedding light on prospective developmental avenues and potential enhancements that could further augment the efficacy and reliability of DPD technology in contemporary communication systems.
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Chen, Qingyue, Zhugang Wang, Gert Frølund Pedersen, and Ming Shen. "Joint Satellite-Transmitter and Ground-Receiver Digital Pre-Distortion for Active Phased Arrays in LEO Satellite Communications." Remote Sensing 14, no. 17 (September 1, 2022): 4319. http://dx.doi.org/10.3390/rs14174319.
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A novel joint satellite-transmitter and ground-receiver (JSG) digital pre-distortion (DPD) (JSG-DPD) technique is proposed to improve the linearity and power efficiency of the space-borne active phased arrays (APAs) in low Earth orbit (LEO) satellite communications. Different from the conventional DPD technique that requires a complex RF feedback loop, the DPD coefficients based on a generalized memory polynomial (GMP) model are extracted at the ground-receiver and then transmitted to the digital baseband front-end of the LEO satellite-transmitter via a satellite–ground bi-directional transmission link. The issue of the additive white Gaussian noise (AWGN) of the satellite–ground channel affecting the extraction of DPD coefficients is tackled using a superimposing training sequences (STS) method. The proposed technique has been experimentally verified using a 28 GHz phased array. The performance improvements in terms of error vector amplitude (EVM) and adjacent channel power ratio (ACPR) are 7.5% and 3.6 dB, respectively. Requiring limited space-borne resources, this technique offers a promising solution to achieve APA DPD for LEO satellite communications.
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Sharma, Vipin, Rajeev Kumar Arya, and Sandeep Kumar. "Power Amplifier Optimization for M2M Node using DPD and Hybrid DFT-s-OFDM with CFR." Engineering, Technology & Applied Science Research 13, no. 6 (December 5, 2023): 12080–85. http://dx.doi.org/10.48084/etasr.6220.
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Power Amplifiers (PAs) play a vital role in mobile communication. However, their inherent nonlinearity can lead to issues such as unwanted radiation, interference with neighboring channels, and distortion within the desired frequency range. To address these problems, PAs are typically operated at a lower power level than their saturation point, sacrificing power efficiency to improve Error Vector Magnitude (EVM) performance. Consequently, more than 70-80% of the DC power is wasted as heat. This inefficiency necessitates the exploration of techniques to enhance PA efficiency while maintaining acceptable linearity and performance. Digital Pre-Distortion (DPD) is a useful technique to linearize PAs. DPD allows affordable nonlinear PAs to function with minimal distortion in their nonlinear operating regions. This results in amplified signals with increased power output and improved power efficiency. Using nonlinear functions, the output signal of the PA can be linearized, mitigate distortions, and be effectively optimized. When using various operating channels and varying time, temperature, and PA nonlinearity, the DPD must adjust. In order to increase the power efficiency of 5G systems, DPD-enabled systems are inculcating with adaptive DFT-s-OFDM employed 5G physical layer along with the Crest Factor Reduction (CFR) algorithm.
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Alizadeh, Mahmoud, Peter Händel, and Daniel Rönnow. "Behavioral modeling and digital pre-distortion techniques for RF PAs in a 3 × 3 MIMO system." International Journal of Microwave and Wireless Technologies 11, no. 10 (June 20, 2019): 989–99. http://dx.doi.org/10.1017/s1759078719000862.
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AbstractModern telecommunications are moving towards (massive) multi-input multi-output (MIMO) systems in 5th generation (5G) technology, increasing the dimensionality of the systems dramatically. In this paper, the impairments of radio frequency (RF) power amplifiers (PAs) in a 3 × 3 MIMO system are compensated in both the time and the frequency domains. A three-dimensional (3D) time-domain memory polynomial-type model is proposed as an extension of conventional 2D models. Furthermore, a 3D frequency-domain technique is formulated based on the proposed time-domain model to reduce the dimensionality of the model, while preserving the performance in terms of model errors. In the 3D frequency-domain technique, the bandwidth of the system is split into several narrow sub-bands, and the parameters of the model are estimated for each sub-band. This approach requires less computational complexity, and also the procedure of the parameters estimation for each sub-band can be implemented independently. The device-under-test consists of three RF PAs including input and output cross-talk channels. The proposed techniques are evaluated in both behavioral modeling and digital pre-distortion (DPD) perspectives. The experimental results show that the proposed DPD technique can compensate the errors of non-linearity and memory effects in the both time and frequency domains.
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Li, Yunfeng, Yonghui Huang, Martin Hedegaard Nielsen, Feridoon Jalili, Wei Wei, Jian Ren, Yingzeng Yin, Ming Shen, and Gert Frølund Pedersen. "A Cross-Mode Universal Digital Pre-Distortion Technology for Low-Sidelobe Active Antenna Arrays in 5G and Satellite Communications." Electronics 10, no. 16 (August 22, 2021): 2031. http://dx.doi.org/10.3390/electronics10162031.
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A cross-mode universal digital pre-distortion (CMUDPD) technology is proposed here to linearize low-sidelobe active antenna arrays with non-uniform fixed power levels for each branch, which are desired in satellite communications with stringent requirements to minimize interference. In low-sidelobe arrays formed by nonuniform amplitude excitation, conventional digital pre-distortion (DPD) techniques require multiple feedback paths for either one-to-one or average linearization of the PAs, which increases system complexity and is infeasible for large-scale arrays. This is because the power amplifiers (PAs) usually operate in different modes where the supply voltages, bias voltages, and input power levels are different. The proposed CMUDPD method aims at solving this issue by intentionally arranging the PAs to work in different modes but with shared nonlinear characteristics. Based on the nonlinear correlation established among the PAs’ different operating modes, a single feedback path is sufficient to capture the common nonlinearity of all the PAs and determine the parameters of the CMUDPD module. The concept is explained in theory and validated by simulations and experiments using GaN PAs operating with three significantly different output power levels and two orthogonal frequency division multiplexing (OFDM) signal bandwidths.
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Ma, Chuan Hui, Wen Sheng Pan, You Xi Tang, and Chao Jin Qing. "Design of Unsymmetrical Doherty Power Amplifier for 460MHz LTE-Advanced Applications." Applied Mechanics and Materials 347-350 (August 2013): 1768–72. http://dx.doi.org/10.4028/www.scientific.net/amm.347-350.1768.
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An unsymmetrical Doherty power amplifier (DPA) at 460MHz is presented in this paper. The carrier and peaking amplifier of the DPA, which base on two equal-sized devices, are matched with different networks to mitigate the performance degradation caused by the limited load modulation. Measured with continuous wave (CW), the unsymmetrical DPA saturates at an output power of 49.2dBm and achieves a drain efficiency of 51% at 6dB back-off. Using a one-carrier long term evolution advanced (LTE-Advanced) signal with 20MHz bandwidth, the unsymmetrical DPA exhibits a drain efficiency of 48.7% at an average output power of 42.1dBm, along with adjacent channel leakage ratio (ACLR) of-34.1dBc and-53.3dBc before and after digital pre-distortion (DPD), respectively.
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Hadi, Muhammad Usman, Jian Song, Sunish Kumar Orappanpara Soman, Ardavan Rahimian, and Adnan Ahmad Cheema. "Experimental Evaluation of Hybrid Fibre–Wireless System for 5G Networks." Telecom 3, no. 2 (April 2, 2022): 218–33. http://dx.doi.org/10.3390/telecom3020014.
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This article describes a novel experimental study considering a multiband fibre–wireless system for constructing the transport network for fifth-generation (5G) networks. This study describes the development and testing of a 5G new radio (NR) multi-input multi-output (MIMO) hybrid fibre–wireless (FiWi) system for enhanced mobile broadband (eMBB) using digital pre-distortion (DPD). Analog radio over fibre (A-RoF) technology was used to create the optical fronthaul (OFH) that includes a 3 GHz supercell in a long-range scenario as well as a femtocell scenario using the 20 GHz band. As a proof of concept, a Mach Zehnder modulator with two independent radio frequency waveforms modifies a 1310 nm optical carrier using a distributed feedback laser across 10 km of conventional standard single-mode fibre. It may be inferred that a hybrid FiWi-based MIMO-enabled 5G NR system based on OFH could be a strong competitor for future mobile haul applications. Moreover, a convolutional neural network (CNN)-based DPD is used to improve the performance of the link. The error vector magnitude (EVM) performance for 5G NR bands is predicted to fulfil the Third Generation Partnership Project’s (3GPP) Release 17 standards.
Dissertations / Theses on the topic "Digital pre-distortion, DPD"
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Nandi, Om Prakash. "Behavioral Modeling of Power Amplifier with Memory Effect and Linearization Using Digital Pre Distortion." Thesis, Högskolan i Gävle, Elektronik, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:hig:diva-22830.
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This thesis work studied the behavioral modeling, estimation of parameters, model performance and linearization of power amplifier (PA) using Digital Pre Distortion (DPD) technique. PAs are one of the fundamental block in communication systems and also one of the main sources of nonlinearities in the system, as these devices are frequently subjected to signals characterized by considerable bandwidths and non-constant envelopes due to use of modern modulation technique. Moreover, PAs have high efficiency level at its nonlinear region. So, to operate the PA at its high efficiency region, linearization operation needs to be done. This has been investigated in this thesis work with the help of behavioral modeling and DPD. An essential initial step in designing a linearizer for a PA is to model the PA nonlinearity accurately. Behavioral modeling has been used for PA model for its computational efficiency, which means by relating input and output signals without addressing to the physical analysis of the device. DPD technique has been chosen for linearizing the performance of PA based on their low requirement of resources for implementation. In this thesis, five different PA models with memory effect, based on Volterra series, are studied and compared for three different PAs selected by Ericsson. These PAs are designed for third and fourth generation telecommunication system. Two different signals with different peak to average ratios and different bandwidths have been used as input signals of PA for this study. The main result in this thesis work includes the comparison of all five forward behavioral modeling results for all three PA’s. The results also describe that; two of the given PA’s can be linearized by using the DPD technique within the 3GPP standard regulations for ACPR.
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Trinh, Jessica. "ADS och Matlab för optimering av pre-distortion av effektförstärkare." Thesis, Linköpings universitet, Institutionen för systemteknik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-119222.
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This master’s thesis deals with integrating simulations using Agilents Electronic Design Automation tool ADS with customized Matlab scripts, for solving complex analog and digital radio architectures. In particular, it addresses predistortion, realized in the digital domain, of power amplifiers, modeled in the analog domain. The former is implemented in Matlab while the latter is implemented in ADS. Two versions of integrating the two systems have been tested: 1) Iterative approach on sample basis and 2) Scheduled batch solution by matrix inversion. The concept has been tested on two different PA configurations: 1) a standard class-AB PA and 2) a Doherty PA architecture. Evaluation has also been done on ADS ability to correctly simulate memory effects in PAs and on the actual DPD-algorithms ability to compensate for these memory effects. An integrated simulation environment for ADS and Matlab was successfully established within the work of this thesis. Matlab scripts, used in predistortion algorithms in the digital domain, could interact directly with component-based PA models, in an enclosed simulation system. The simulation results show that sample basis method is the most accurate, fast and reliable method to linearize a PA. The PA1 proved to be easier than the DPA to linearize, except for when being close to saturation where better IMD-suppression was achieved with the DPA. ADS is clearly able to simulate memory effects in the analog domain. At low gain-levels the applied compensating memory-algorithms showed a great improvement to the linearization of the output signal of the PA. At higher gain-levels though, the compensation for memory effects lost their efficiency because the non-linearity of the PA became too significant.
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Fu, Zhu. "Digital Pre-distortion for Interference Reduction in Dynamic Spectrum Access Networks." Digital WPI, 2014. https://digitalcommons.wpi.edu/etd-dissertations/152.
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Given the ever increasing reliance of today’s society on ubiquitous wireless access, the paradigm of dynamic spectrum access (DSA) as been proposed and implemented for utilizing the limited wireless spectrum more efficiently. Orthogonal frequency division multiplexing (OFDM) is growing in popularity for adoption into wireless services employing DSA frame- work, due to its high bandwidth efficiency and resiliency to multipath fading. While these advantages have been proven for many wireless applications, including LTE-Advanced and numerous IEEE wireless standards, one potential drawback of OFDM or its non-contiguous variant, NC-OFDM, is that it exhibits high peak-to-average power ratios (PAPR), which can induce in-band and out-of-band (OOB) distortions when the peaks of the waveform enter the compression region of the transmitter power amplifier (PA). Such OOB emissions can interfere with existing neighboring transmissions, and thereby severely deteriorate the reliability of the DSA network. A performance-enhancing digital pre-distortion (DPD) technique compensating for PA and in-phase/quadrature (I/Q) modulator distortions is proposed in this dissertation. Al- though substantial research efforts into designing DPD schemes have already been presented in the open literature, there still exists numerous opportunities to further improve upon the performance of OOB suppression for NC-OFDM transmission in the presence of RF front-end impairments. A set of orthogonal polynomial basis functions is proposed in this dissertation together with a simplified joint DPD structure. A performance analysis is presented to show that the OOB emissions is reduced to approximately 50 dBc with proposed algorithms employed during NC-OFDM transmission. Furthermore, a novel and intuitive DPD solution that can minimize the power regrowth at any pre-specified frequency in the spurious domain is proposed in this dissertation. Conventional DPD methods have been proven to be able to effectively reduce the OOB emissions that fall on top of adjacent channels. However more spectral emissions in more distant frequency ranges are generated by employing such DPD solutions, which are potentially in violation of the spurious emission limit. At the same time, the emissions in adjacent channel must be kept under the OOB limit. To the best of the author’s knowledge, there has not been extensive research conducted on this topic. Mathematical derivation procedures of the proposed algorithm are provided for both memoryless nonlinear model and memory-based nonlinear model. Simulation results show that the proposed method is able to provide a good balance of OOB emissions and emissions in the far out spurious domain, by reducing the spurious emissions by 4-5 dB while maintaining the adjacent channel leakage ratio (ACLR) improvement by at least 10 dB, comparing to the PA output spectrum without any DPD.
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Tchambake, Yapti Kelly. "Wideband Analog-to-Digital Converter (ADC) design for power amplifiers linearization." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLT047.
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De nos jours, la consommation d’énergie devient un des principaux défis à surmonter dans le développement des réseaux de communications mobiles. L’amplificateur de puissance est le composant le plus gourmand en énergie dans les stations de base. La cinquième génération de téléphonie mobile de part ses larges bandes de communication et ses modulations complexes augmente encore plus les contraintes sur l’amplificateur de puissance. Pour palier ce problème, il est courant de faire appel à des techniques de pré-distorsion. Une contrainte importante dans la mise en oeuvre de cette technique est la numérisation de la sortie de l’amplificateur qui, dû aux non-linéarités, s’étale sur un spectre significativement plus large que le signal utile, environ 5 fois en pratique voire plus. Habituellement, pour cette opération de numérisation, un Convertisseur Analogique Numérique (CAN) du type pipeline est utilisé car il permet d’obtenir des résolutions supérieures à 10 bits sur une bande de plusieurs dizaines voire centaines de MHz. Cependant, sa consommation d’énergie élevée pousse à explorer d’autres pistes. L’architecture "Multi Stage Noise Band Cancellation" (MSNBC) à base de modulateurs Delta Sigma a l’avantage de réaliser des dynamiques différentes par sous bande et est ainsi un candidat de choix pour le CAN de la boucle de retour des techniques de pré-distortion. L’objectif de ce travail est de démontrer la faisabilité de l’architecture MSNBC qui jusqu’à présent a été uniquement étudiée au niveau système. Ces études nous ont permis de proposer une architecture adaptée pour la numérisation d’un signal de bande RF 20 MHz avec des résolutions différentes par sous bande. Une architecture Zéro-IF tempscontinu avec un modulateur primaire du second ordre et un modulateur secondaire du quatrième ordre avec des quantificateurs 4 bits a été adoptée. Cette architecture a été implémentée en une technologie CMOS 65 nm. Les simulations électriques du MSNBC 2-4 avec un signal LTE ont permis d’obtenir 84.5 dB de SNDR dans la bande principale et 29.2 dB dans la bande adjacente contenant les produits d’intermodulationPower consumption is nowadays one of the main challenges to overcome in the development of mobile communications networks. The power amplifier (PA) is the most power hungry component in base transceiver stations. The upcoming fifth generation of mobile telephony with wider communication bands and complex modulations further increases the constraints on the PA. To overcome this problem, it is common to use predistortion techniques that enable the power amplifier to operate with greater linearity and efficiency. An important constraint in the implementation of this technique is the digitization of the output of the amplifier which, due to non-linearities, spreads over a significantly wider spectrum than the initial signal, about 5 times in practice or even more. Pipeline Analog-to-Digital Converters (ADCs) are commonly used for this operation because it allows resolutions of greater than 10 bits to be obtained over a band of several tens or even hundreds of MHz. However, its high energy consumption pushes to find a better solution. The "Multi Stage Noise Band Cancellation" (MSNBC) architecture based on Delta Sigma modulators has the advantage of realizing different dynamics per subband and is thus a prime candidate for the feedback loop ADC of predistortion techniques. The purpose of this work is to demonstrate the feasibility of the MSNBC architecture that has so far only been studied at the system level. Our investigations allowed us to propose a suitable architecture to digitize a 20 MHz RF band signal with different resolutions per subband. A continuous time Zero-IF architecture with a second-order primary modulator and a fourth-order secondary modulator with 4-bit quantizers was adopted. This architecture has been implemented in a 65 nm CMOS technology. Transistor level simulations of the 2-4 MSNBC architecture simulations with an LTE test signal resulted in 84.5 dB SNDR in the main band and 29.2 dB in the adjacent band which contains the intermodulation products
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Abdi, Abyaneh Mohammad. "Génération des signaux agrégés en fréquences dans le contexte de LTE-A." Electronic Thesis or Diss., Paris, ENST, 2016. https://pastel.hal.science/tel-03689710.
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Dans ce travail de thèse, on a proposé une structure de génération des signaux multi-porteuse afin de créer plusieurs oscillateurs locaux (OL ) tout en utilisant qu’un modulateur I/Q. Ces signaux peuvent être utilisés dans les récepteurs de LTE-A pour la transposition des signaux agrégé en fréquence vers la bande de base. On développe la structure afin de l’utiliser en émetteur répondant aux normes du standard LTE-A. La nouvelle structure nous permet de générer n signaux agrégés en fréquences, de manière simultanée, par une seule chaîne de transmission (c.a.d un modulateur I/Q, un OL). En utilisant cette structure on réduit le nombre de circuits utilisés, en comparaison du cas où n signaux agrégés en fréquences sont générés par n émetteurs. La fréquence d’échantillonnage est réduite dans notre cas par rapport au cas où les signaux sont générés directement de la bande de base à la bande RF avec des convertisseurs analogiques numériques adéquats. Dans la troisième partie, on se concentre sur les imperfections et les non linéarités du modulateur I/Q dans le cadre de notre structure multibande. On modélise le fonctionnement du modulateur multi-bande en utilisant les échantillons en entrée et en sortie. Notre modèle est dérivé de la série de Volterra qui prends en compte les effets non linéaires et les effets mémoires ainsi que les imperfections du modulateur I/Q. Puis, on obtient la fonction "inverse" du modèle et on l’applique à l’entrée du modulateur afin de corriger et linéariser la sortie du modulateur I/Q. La fonction "inverse" est appelée DPD (en anglais : Digital Pre-Distortion). Enfin, on a évalué le modèle et la DPD en simulations et en mesuresIn this dissertation, a signal generation structure is proposed using which a multitone Local Oscillator (LO) signal is created by a single I/Q modulator. These LOs can be used in the CA receivers to down-convert the transmitted component carriers simultaneously. The multi-tone LO signal structure is further developed to be used at the transmitter as a CA generation solution. Using the proposed structure n-component carriers can be generated in parallel. This structures requires lower sampling rates with respect to the case where RF signals are synthesized directly by digital-to- analog converters. Moreover, less circuitry is required, because one single I/Q modulator is used to generate n component carriers, instead of n I/Q modulators. This work follows on investigating the origin of impairments and mild nonlinearities in our I/Q modulator. To overcome these problems, we focus on the functionality of the overall system rather than each component of the I/Q modulator. This method is called behavioral modeling. Once the nonlinear model is obtained, if its inverse function is applied to the input, a linearized output is expected. The generation of the inverse function is called Digital Pre-Distortion (DPD). We propose a tri-band behavioral model for nonlinearities and impairments in tri-band CA using our I/Q modulator. Furthermore, the DPD of the model is evaluated in simulations and experiments
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(5931197), Tunir Dey. "Linearizing E- Class Power Amplifier by Using Memoryless Pre-Distortion." Thesis, 2020.
Find full textAbstract:
Radio Frequency Power Amplifiers (PA) are essential components of wireless systems and nonlinear in a permanent way. So, high efficiency and linearity at a time are imperative for power amplifiers. However, it is hard to obtain because high efficiency Power Amplifiers are nonlinear and linear Power Amplifiers have poor efficiency. To meet both linearity and efficiency, the linearization techniques such as Digital Predistortion (DPD) has arrested the most attention in industrial and academic sectors due to provide a compromising data between efficiency and linearity. This thesis proposed on digital predistortion techniques to control nonlinear distortion in radio frequency transmitters.
By using predistortion technique, both linearity and efficiency can obtain. In this thesis a new generic Saleh model for use in memoryless nonlinear power amplifier (PA) behavioral modelling is used. The results are obtained by simulations through MATLAB and experiments. We explore the baseband 13.56 MHz Power Amplifier input and output relationships and reveal that they apparent differently when the Power Amplifier shows long-term, short-term or memory less effects. We derive a SIMULINK based static DPD design depend on a memory polynomial. A polynomial improves both the non-linearity and memory effects in the Power Amplifier. As PA characteristics differs from time to time and operating conditions, we developed a model to calculate the effectiveness of DPD. We extended our static DPD design model into an adaptive DPD test bench using Indirect Learning Architecture (ILA) to implement adaptive DPD which composed of DPD subsystem and DPD coefficient calculation. By this technique, the output of PA achieves linear, amplitude and phase distortions are eliminated, and spectral regrowth is prevented.
The advanced linearity performance executed through the strategies and methods evolved on this thesis can allow a higher usage of the capability overall performance of existing and emerging exceptionally performance PAs, and therefore an anticipated to have an effect in future wireless communication systems.
Conference papers on the topic "Digital pre-distortion, DPD"
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Chang, Kai-Wen, Yu-Cheng Yu, Chia-Chien Wei, Chin Shih Huang, Hao Chun Hsieh, Hung Chun Pan, Wei-Jo Ting, and Heng Li. "Simplified Pre-Distortion Technique for PAM4 Modulation based on a Micro-Ring Modulator." In Conference on Lasers and Electro-Optics/Pacific Rim. Washington, D.C.: Optica Publishing Group, 2022. http://dx.doi.org/10.1364/cleopr.2022.ctua9c_03.
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This study analyzes the performance of digital pre-distortion (DPD) for micro-ring-modulator-based PAM4 modulation. With limited taps for practicality, the optimal de-sign of the DPD was shown to depend on the operating conditions of the modulator.