Дисертації з теми "Techniques de linéarisation"
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Cesari, Albert. "Implémentation de techniques de linéarisation et d'amélioration du rendement pour les amplificateurs de puissance RF." Phd thesis, Université Paul Sabatier - Toulouse III, 2008. http://tel.archives-ouvertes.fr/tel-00538808.
Cesari, Bohigas Albert. "Implémentation de techniques de linéarisation et d'amélioration du rendement pour les amplificateurs de puissance RF." Toulouse, INSA, 2008. http://eprint.insa-toulouse.fr/archive/00000239/.
The antagonism between information capacity and energetic efficiency in the context of wireless communications, more precisely : the trade-off between transmitter linearity and its efficiency ; is the main driver of this thesis. A FPGA5-based architecture for digital predistortion (DPD) linearizers for RF power amplifiers is proposed in this thesis. By means of separating the adaptation process from the predistortion itself, a convenient, simple hardware building block for the DPD architecture inside the FPGA {the Basic Predistortion Cell (BPC){ has been identified. A BPC-based architecture provides independency from the particular DPD function derivation method, and it is easily scalable and reconfigurable, depending on the operation mode and degree of impairments introduced by the transmitter chain in each particular case. In order to support those claims and provide experimental evidence, two main different prototyping scenarios have been developed. In the first one, a DPD adaptive linearizer based on the passivity theory (hyperstable systems) has been designed and implemented on a low-cost mixed FPGA/DSP platform. Besides experimental results, complementary signal proces sing techniques to DPD are also addressed, thus giving a wide insight on realistic scenarios of DPD systems. In the second scenario, an advanced, adaptive DPD system aimed at compensating not only PA's nonlinear behavior, but also its memory effects, is presented. It is based on a Nonlinear Auto-Regressive Moving Average7 structure which is mapped into hardware using a BPC grid-structure. Besides the experimental results on PA efficiency and linearity, FPGA implementation issues {such as adaptation and power consumption{ are also studied. The manipulation of the PA class of operation to improve its efficiency, provided that DPD may be unavoidable due to the impact of memory effects, is discussed as well. Finally, to further improve efficiency, a DPD linearizer with dynamic supply built-in capabilities has been proposed and implemented as discussed in the last part of this thesis. There, an efficient, bandwidth limited, switched DC-DC converter is in charge of the PA supply modulation. The thorough design procedure targeting a FPGA implementation shows how the necessary functions for commanding the supply modulator can be seamlessly integrated within the DPD processor. The experimental results highlight how the proposed solution maintains linearity and enhances the PA efficiency when compared to a DPD-only method
Raynal, Carole. "Etude des techniques de linéarisation des amplificateurs de puissance dans le cadre de la télévision numérique terrestre." Limoges, 2007. http://www.theses.fr/2007LIMO4004.
Among others, the spurious levels must be lower than the threshold imposed by regulation authorities to avoid disturbing the other channels. Taking in account the non linearity nature of power amplifiers, increase the emitted power leads to increase the efficiency but also the spurious level. Consequently, broadcasters should reach a compromise between spurious level and transmitters cost. DVB-T programs are currently amplified in mono-channel, i. E. Each multiplex is amplified by its own amplifier. The efficiency is improved using a digital predistorter and a band-pass filter. The digital predistorter minimizes in band and out of band intermodulations, and the filter cleans the spectrum. The digital predistortion method, simulated in this memory, allows a great improvement of the shoulders and the BER. Multi-channel amplification would conduce to a high profit because only one amplifier is necessary to treat several channels. However without linearization, the amplifier must be used with a very high output back-o? in order to keep the spurious level below the fixed threshold. In this thesis we present a multi-channel predistorter that highly improves the shoulders and the spurious level
Saad, El Dine Mohamad. "Linéarisation des amplificateurs de puissance à haut rendement en combinant les techniques de pré distorsion numérique et le contrôle de polarisation." Limoges, 2011. http://aurore.unilim.fr/theses/nxfile/default/159b8ebd-0d26-4b99-9c48-fc7f17ff3bf4/blobholder:0/2011LIMO4021.pdf.
Modern communication systems require the use of modulation schemes that lead to non envelope constant microwave signals. The peak to average power ratio (PAPR) of these signals is large. In such conditions, power amplifiers used in transmitters are critical devices because they need to be optimized in terms of both electrical efficiency and linearity which are antagonist parameters if conventional power amplifier architectures are considered. Consequently there is a major interest in research activities dealing with new power amplifier architectures that enable to obtain either high efficiency or good linearity performances. This can be reached if linearization techniques are applied to high efficiency power amplifiers designs. In such a context it is of prime interest to develop a laboratory set up that includes dynamic biasing of power amplifiers and digital predistortion capabilities to investigate novel high efficiency and linear amplification solutions. This has been accomplished in this work and applied to the optimisation of both efficiency and linearity of a 10 Watt GaN amplifier at S Band. Finally an experimental study that consists in low pass filtering the dynamic drain bias voltage is reported. The goal is to find a possible solution to enhance the efficiency of the bias modulator circuit without impacting to much linearity performances
Feng, Xiaowen. "Efficient baseband digital predistortion techniques for linearizing power amplifier by taking into account nonlinear memory effect." Nantes, 2015. https://archive.bu.univ-nantes.fr/pollux/show/show?id=3619006c-f9da-4c0b-8b67-4445eda2c7b1.
Baseband digital predistortion (DPD) techniques for linearizing power amplifiers (PA) with memory effects are investigated in this thesis. Firstly, the relevant elements concerning PA linearization are introduced, such as PA nonlinearity behavior, its influence on the communication systems, its modeling and characterization. . . Then some existing linearization techniques are presented, such as power backoff, feedforward, feedback, linear amplification with nonlinear components and DPD. DPD is the most promising linearization technique. After that, the implementation architecture and identification algorithms of DPD are described. In this thesis, four DPD methods are proposed. The first method (MP/LUT DPD) is to combine a memory polynomial (MP) model and a simple non-interpolated LUT. Both the amplitude and phase of the predistorted signal are calculated by LUT. The second method is to add linear interpolation technique to MP/LUT DPD. The third method improves the second one by using a quadratic interpolation technique to MP/LUT DPD. The fourth method is to combine MP DPD and feed forward neural network. The principal innovation is that the training samples of the neural networks are the predistorded signal obtained by MP DPD. Finally, simulation results and experimental results are given and analyzed. The proposed methods provide different trade-off between the linearization performance, time efficiency and complexity
Testylier, Romain. "Techniques pour l'analyse formelle de systèmes dynamiques non-linéaires." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00910330.
Letailleur, Lucas. "Éléments d'architecture d'émetteur linéarisé en technologie GaN pour des applications 5G millimétrique." Electronic Thesis or Diss., Université Gustave Eiffel, 2023. http://www.theses.fr/2023UEFL2073.
This thesis focuses on architectures and circuits for 5G FR2-1 communication systems. These systems operate in millimeter waves and use massive Multiple Input Multiple Output (MIMO) techniques. A gallium nitride (GaN) power amplifier (PA) from Macom is characterized and modelled. The results show that the PA do not meet the requierements of the 5G FR2-1 standard. A digital predistorsion (DPD) and an analog predistortion (APD) are therefore investigated and compared. DPD offers better linearization performance than the APD, but cannot linearize bandwiths grater than 100 MHz. The APD, on the other hand, allows to linearized a signal with a bandwidth up to 400 MHz on the n258 frequency band, and can be co-integrated with the PA. Both linearization techniques enable the amplifier to meet the requirements of 5G FR2-1 standard. The use of massive MIMO suggests that conventional architectures need to be reviewed. Consequently, a new approach for sizing the critical elements of the emission architectures is proposed. The main objective is to find the most suitable trade-off between the emitted power, linearity and the consumption of the overall architecture. For beamforming, a Butler matrix, using the same substrate as the power amplifier, is designed, and a new architecture is investigate. The architecture uses a co-design of a single power amplifier, a switch and a Butler matrix network, and enables 32 radiating elements to be fed. Finally, a comparative analysis of low-noise amplifiers based on GaN and gallium arsenide (GaAs) is carried out and a figure of merit is proposed. This study shows that it is possible to use the same technology for all front-end elements
Hamoud, Houssam Eddine. "Linéarisation par pré-distorsion numérique d'amplificateurs de puissance pour les nouvelles générations des systèmes de télécommunications." Thesis, Limoges, 2019. http://www.theses.fr/2019LIMO0110.
Modern communications systems converge towards multi-standard operation combined with high PAPR modulation formats where the power amplifier must first be optimized in efficiency and where linearity will then be corrected by adding a predistorter. If this solution seems functional, it seems inadequate and ineffective on 5G systems where the targeted bandwidths pose both architectural problems (complexity of the observation path) and problems of accuracy of the usual behavioural models based on a simplification of the Volterra series in its discrete form (GMP, DDR) in the face of exacerbated memory effects but also of energy efficiency of the linearized system (DPD+PA). In this context, it becomes necessary to move towards a predistorter model less dependent on the characteristics of the signal to be linearized, in particular by the TPM (Two path Memory) model developed at XLIM, based on a simplification of the Volterra series in its continuous form, is independent of the characteristics of the signal to be linearized.Our work focused on evaluating the linearity performance of the classical models (GMP, DDR) and the TPM model on different power amplifiers either from simulations or from physical measurements of the PA. To do this, we have set up a simulation environmentand an evaluation bench for predistortion models with physical PA in order to quantify ACPR performance according to the variation in signal characteristics (power, frequency, statistics). All these experiments made it possible to verify, on the one hand,the poor robustness of traditional approaches (GMP/DDR) and, on the other hand, the stability of the performance of the TPM approach, whatever the scenario envisaged. This study therefore paves the way for a new generation of pre-distributor which, if extracted once and for all, would only require an update on slow dynamic phenomena (ageing) and would make it possible to consider a simplified architecture of the DPD observation path; thus improving the overall energy efficiency of the linearizedsystem
Larie, Aurélien. "Conception d'amplificateurs de puissance hautement linéaires à 60 GHz en technologies CMOS nanométriques." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0210/document.
The CMOS 60GHz power amplifier (PA) remains one of the most design-challenging components. Indeed, a high linearity associated with a large back-off range are required due to complex modulated signals.In this context, this work focuses on the design of architectures and linearization techniques which are usable at millimeter-wave frequencies. First, a CMOS PA state of the art is presented to define all bottlenecks. Then, the physical phenomena impacting on passive device performances are described. Elementary PAs are implemented in CMOS 65nm and 28nm Bulk and the most suitable topologies are selected. Finally, two highly linear circuits are designed in 65nm Bulk and 28nm FD-SOI. They achieve the highest ITRS figures of merit reported to this day. In addition, the 28nm FD-SOI PA exhibits the best linearity/consumption tradeoff
Cheng, Xinying. "Study and mitigation techniques of RF impairments for beyond 5G multi-carrier waveforms." Electronic Thesis or Diss., Sorbonne université, 2021. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2021SORUS181.pdf.
Fundamental research towards beyond 5G cellular networks is ongoing and the vision of 2020 and beyond includes a significant amount use cases considering a massive number of devices with a wide range of characteristics and demands. On the one hand, the good spectral efficiency gives more capacity for the transmission while on the other hand, building compact and low-cost flexible and high-quality radio equipment is a very challenging task. The context of this thesis is the study of massive MIMO techniques with the presence of radio frequency (RF) imperfections, in particular, the non-linear (NL) power amplifiers (PA). The large number of PAs equipped in the base station (BS) creates various constraints which lead to strong degradation of the transmission quality both in the band and out of band. On the other hand, 5G standardization introduced the concept of different numerologies together with the massive MIMO technique. The influence of the different numerologies used by the different users will also be studied in this thesis
Gowda, Veerapa. "Eléments finis discontinus pour les lois de conservation scalaires non linéaires." Paris 9, 1988. https://portail.bu.dauphine.fr/fileviewer/index.php?doc=1988PA090038.
Daucher, Dimitri. "Modélisation de comportements dynamiques aléatoires complexes par une technique de linéarisation spectrale vectorielle." Clermont-Ferrand 2, 2005. http://195.221.120.247/simclient/consultation/binaries/stream.asp?INSTANCE=UCFRSIM&eidmpa=DOCUMENTS_THESES_91.
Lemrabott, Mohamed. "Méthode d'optimisation pour la gestion de portefeuille sous des coûts de transaction discontinues et affines par morceaux." Le Havre, 2009. http://www.theses.fr/2009LEHA0015.
The choice of optimal portfolio is a broad topic that has been treated in the presence of transaction costs (proportional, continuous, convex,…) so that we can make use of classical optimization techniques (linear programming). In this work we consider the problem of portfolio selection in presence of transaction costs as in real market (discontinuous and piecewise affine). This leads us to an Integers Nonlinear Optimization Problem (INOP). For this purpose, we first adapt the enumerative method in order to obtain optimal explicit solutions. This approach is more suitable in the case of a small portfolio and can be implemented in standard programming language (VBA, MatLab, C++) On the one hand, we also solve the original problem by reducing problem to a quadratic problem which can be handelled by a linearization technique. This latter approach is well suited in the case of large portfolio, but its implementation requires the use of commercial software such as Cplex
Yahiaoui, Meriem. "Modèles statistiques avancés pour la segmentation non supervisée des images dégradées de l'iris." Electronic Thesis or Diss., Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLL006.
Iris is considered as one of the most robust and efficient modalities in biometrics because of its low error rates. These performances were observed in controlled situations, which impose constraints during the acquisition in order to have good quality images. The renouncement of these constraints, at least partially, implies degradations in the quality of the acquired images and it is therefore a degradation of these systems’ performances. One of the main proposed solutions in the literature to take into account these limits is to propose a robust approach for iris segmentation. The main objective of this thesis is to propose original methods for the segmentation of degraded images of the iris. Markov chains have been well solicited to solve image segmentation problems. In this context, a feasibility study of unsupervised segmentation into regions of degraded iris images by Markov chains was performed. Different image transformations and different segmentation methods for parameters initialization have been studied and compared. Optimal modeling has been inserted in iris recognition system (with grayscale images) to produce a comparison with the existing methods. Finally, an extension of the modeling based on the hidden Markov chains has been developed in order to realize an unsupervised segmentation of the iris images acquired in visible light
Luong, Giap. "Conception d’un amplificateur de puissance reconfigurable en CMOS nanométrique pour les applications LTE dans les drones." Thesis, Bordeaux, 2018. http://www.theses.fr/2018BORD0122/document.
Unmanned aerial vehicles (UAVs), often known as drones, have been finding numerous applications in life. Drones applications need several essential performance indicators such as coverage, signal strength, latency, and mobility under scenarios. Therefore, the use of wireless communications in drones is critical to address all requirements. Because of high-speed connections between drones and users to transfer high-resolution high-volume data, latest wireless generations, namely the LTE standard, are privileged. It is straightforward that the integration of RF blocks is essential to build a system-on-chip and shrink the size of drones. To answer the above question, this thesis aims to develop a fully integrated reconfigurable high-performance innovated PA that supports 4G LTE standard to be used in UAVs’ applications. The fully integrated 65-nm CMOS power amplifier (PA) provides a watt-level output power, addresses the linearity/efficiency trade-off. A four-winding transformer is implemented to configure the multi-mode operation of the PA. The “segmented bias” technique allows the PA to increase the linearity. The PA not only obtains high radiofrequency performances but also demonstrates a potential to adopt it design in the lower 5G band
Yahiaoui, Meriem. "Modèles statistiques avancés pour la segmentation non supervisée des images dégradées de l'iris." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLL006/document.
Iris is considered as one of the most robust and efficient modalities in biometrics because of its low error rates. These performances were observed in controlled situations, which impose constraints during the acquisition in order to have good quality images. The renouncement of these constraints, at least partially, implies degradations in the quality of the acquired images and it is therefore a degradation of these systems’ performances. One of the main proposed solutions in the literature to take into account these limits is to propose a robust approach for iris segmentation. The main objective of this thesis is to propose original methods for the segmentation of degraded images of the iris. Markov chains have been well solicited to solve image segmentation problems. In this context, a feasibility study of unsupervised segmentation into regions of degraded iris images by Markov chains was performed. Different image transformations and different segmentation methods for parameters initialization have been studied and compared. Optimal modeling has been inserted in iris recognition system (with grayscale images) to produce a comparison with the existing methods. Finally, an extension of the modeling based on the hidden Markov chains has been developed in order to realize an unsupervised segmentation of the iris images acquired in visible light