Abstract This thesis studies the design methods and properties of supply-modulated switch-mode radio frequency power amplifiers. Besides simulation based studies and theory review, two amplifiers were designed: a discrete MESFET class E amplifier (0.5 W at 1 GHz), and an integrated pHEMT class E-1 amplifier (2.0 W at 1.6 GHz) with an on-chip resonator. The existing design methods of the resonant output network of switching amplifiers were reviewed and some extensions on the handling of nonlinear capacitances were proposed. The effects of varying supply voltage were studied and suggestions were given to minimize Vdd / AM and Vdd / PM distortion in supply modulated amplifiers. The implementation of the bias feed was also discussed resulting in proposing a combination of a short transmission line and a small inductor, which provides both fast supply modulation and little effect on harmonic impedances. The main contributions are related to the study of the input impedance of a class E power amplifier, where the effects of supply dependent input impedance and timing skew generated by injected harmonic distortion were analyzed. The stabilization of the amplifier was also discussed. Based on the findings, a push-pull class E amplifier with extra cross-coupled feedback capacitors and second harmonic traps at the gates appears to be a very good starting point for a further study. / Tiivistelmä Tämä väitöstyö käsittelee radiotaajuuksilla toimivien käyttöjännitemoduloitujen kytkintehovahvistimien ominaisuuksia ja suunnittelumenetelmiä. Suunnittelumenetelmiin liittyvän katsauksen ja simulaatioihin perustuvan tutkimusten lisäksi kaksi vahvistinta toteutettiin väitöstutkimuksen aikana: diskreettikomponentein toteutettu E-luokan vahvistin (MESFET, 0.5 W ja 1 GHz) ja integroituna piirinä toteutettu käänteinen E-luokan vahvistin (pHEMT, 2.0 W ja 1.6 GHz), jonka lähdön resonaattoripiiri sisällytettiin integroituun piiriin. Kytkinvahvistimien suunnittelumenetelmiä verrattiin ja kehitettiin edelleen siten, että suunnitteluvaiheessa voidaan ottaa huomioon esim. transistoripiirin takaisinkytkennässä olevan kapasitanssin epälineaarisuus. Työssä tutkittiin myös käyttöjännitemodulaation vaikutusta kytkinvahvistimien toimintaan, ja tutkimuksen tuloksena annettiin muutamia ehdotuksia käyttöjänniteriippuvan amplitudi- (Vdd / AM) ja vaihemodulaation (Vdd / PM) vähentämiseksi. Lähdön biasointipiirin toteutukseen suositeltiin pienen kelan ja siirtolinjan yhdistelmää. Yhdistelmän avulla pyritään maksimoimaan modulaationopeus ja minimoimaan vaikutukset harmonisiin impedansseihin. Pääkohtina väitöksessä ovat E-luokan kytkinvahvistimesta saadut tutkimus- ja mittaushavainnot käyttöjännitteen funktiona muuttuvasta transistorin tuloimpedanssista sekä suurikokoisen transistorin tuloissa tapahtuvan, säröytymisen aiheuttaman tulosignaalien ajoitusvirheen analyysi. Näiden lisäksi vahvistimen stabiilisuuteen kiinnitettiin huomiota. Saatujen havaintojen perusteella voimme todeta, että push-pull -tyyppinen E-luokan vahvistin olisi mielenkiintoinen valinta jatkotutkimuksille.

L'amplificateur de puissance est le module le plus critique dans les équipements de communication radio. Il détermine la qualité de la liaison par sa linéarité et a une contribution conséquente dans la consommation de l'émetteur ; environ 60% de l'énergie consommée est consacré à l'amplification. Il est donc crucial de le faire fonctionner avec un rendement énergétique élevé. Cependant, ces deux spécifications principales de l'amplificateur que sont la linéarité et le rendement énergétique sont antagoniques. Par conséquent, la conception d'un module d'amplification de puissance suppose de trouver un compromis entre la linéarité et le rendement. L'optimisation de ce compromis est la raison d'être des techniques de linéarisation d'amplificateurs et d'amélioration du rendement, parmi lesquelles la prédistorsion numérique (DPD) et les techniques de réduction du PAPR du signal (CFR).Le cœur de cette thèse est la linéarisation d'amplificateurs RF haute-puissance et large-bande par prédistorsion numérique (DPD). Dans ces travaux, nous abordons trois problématiques liées à la prédistorsion et qui constituent des verrous technologiques importants. Le premier aspect concerne l'implémentation de la prédistorsion numérique dans un contexte multi-bande où le signal à linéariser comporte plusieurs formes d'ondes, situées à des fréquences différentes. La seconde problématique est l'utilisation conjointe de la prédistorsion avec une technique de CFR. Dans la majorité des applications haute-puissance, les techniques de DPD et de CFR sont présentes de manière complémentaire, cependant elles sont utilisées de façon autonome et disjointe. Celles-ci gagneraient en performances de linéarisation en étant implémentées de manière plus concertée. . Le dernier thème abordé par cette thèse est l'effet des désadaptations d'impédance de l'antenne sur le mode de fonctionnement de l'amplificateur. La variation de l'impédance d'antenne entraine des réflexions de signal vers l'amplificateur qui modifient ses spécifications de linéarité et de rendement. Nous améliorons la linéarité du système DPD + AP, lorsque l'amplificateur est soumis à des variations de l'impédance à sa charge, grâce à une correction adaptative de gain / Power amplifier is one of the most critical element within radiocommunications systems. The PA is their main source of nonlinearities and it has a great contribution on the emitter's power consumption. Running the PA with highest power efficiency is thus as crucial as having it linear for a good communication quality. However these two specifications of the PA are antagonistic and PA manifacturers need to find a compromise between linearity and power efficiency. Digital Predistortion (DPD) and Crest factor Reduction techniques are intended to improve power efficiency while preserving linearity or inversely. Linearization of wideband RF power amplifiers using Digital Predistortion is the focus of this thesis. Three DPD issues are investigated in these works. The first issue deals with multiband linearization where signals with various waveforms located at different frequency bands are amplified. The second objective of this thesis is to study a concurrent DPD/CFR systems based on an automatic estimation of the necessary CFR gain. The last part of this dissertation deals with PA linearization under antenna load variations. Indeed, the impedance of antenna may vary because of electromagnetic objects that are present in its vicinity. Those impedance variations may instigate signal reflections toward the PA, that modify some of its main specifications (linearity, delivered power and efficiency). Our goal in this field is to preserve DPD linearization performances under antenna load mismatch

This paper shows that the two most common impedance transformation networks for power amplifiers (PAs) can be designed to achieve optimum transformation at two frequencies. Hence, a larger bandwidth for the required impedance transformation ratio is achieved. A design procedure is proposed, which takes imperfections like losses into account. Furthermore, an analysis method is presented to estimate the maximum uncompressed output power of a PA with respect to frequency. Based on these results, a fully integrated PA with a dual-band impedance transformation network is designed and its functionality is proven by large signal measurement results. The amplifier covers the frequency band from 450 MHz to 1.2 GHz (3 dB bandwidth of the output power and efficiency), corresponding to a relative bandwidth of more than 100%. It delivers 23.7 dBm output power in the 1 dB compression point, having a power-added efficiency of 33%.

Dans cette thèse une étude des performances des systèmes OFDM et FBMC/OQAM en présence d'amplificateur de puissance sans mémoire en terme de TEB est présentée. Ensuite, nous avons proposé une technique de linéarisation d'AP par pré-distorsion adaptative neuronale. Aussi, nous avons proposé deux techniques de correction des non-linéarités au niveau du récepteur. / In our work, we have studied the impact of in-band non linear distortions caused by PA on both OFDM and FBMC/OQAM systems. A theoretical approach was proposed to evaluate the BER performance for the two systems. This approach is based on modeling the in-band non-linear distortion with a complex gain and an uncorrelated additive white Gaussian noise, given by the Bussgang theorem. Then, we have proposed different techniques to compensate this NLD either on the transmitter or the receiver sides.

No description available.

The work presents a novel voltage biasing design that helps the CMOS RF circuits resilient to variability and reliability. The biasing scheme provides resilience through the threshold voltage (VT) adjustment, and at the mean time it does not degrade the PA performance. Analytical equations are established for sensitivity of the resilient biasing under various scenarios. Power Amplifier (PA) and Low Noise Amplifier (LNA) are investigated case by case through modeling and experiment. PTM 65nm technology is adopted in modeling the transistors within these RF blocks. A traditional class-AB PA with resilient design is compared the same PA without such design in PTM 65nm technology. Analytical equations are established for sensitivity of the resilient biasing under various scenarios. A traditional class-AB PA with resilient design is compared the same PA without such design in PTM 65nm technology. The results show that the biasing design helps improve the robustness of the PA in terms of linear gain, P1dB, Psat, and power added efficiency (PAE). Except for post-fabrication calibration capability, the design reduces the majority performance sensitivity of PA by 50% when subjected to threshold voltage (VT) shift and 25% to electron mobility (μn) degradation. The impact of degradation mismatches is also investigated. It is observed that the accelerated aging of MOS transistor in the biasing circuit will further reduce the sensitivity of PA. In the study of LNA, a 24 GHz narrow band cascade LNA with adaptive biasing scheme under various aging rate is compared to LNA without such biasing scheme. The modeling and simulation results show that the adaptive substrate biasing reduces the sensitivity of noise figure and minimum noise figure subject to process variation and iii device aging such as threshold voltage shift and electron mobility degradation. Simulation of different aging rate also shows that the sensitivity of LNA is further reduced with the accelerated aging of the biasing circuit. Thus, for majority RF transceiver circuits, the adaptive body biasing scheme provides overall performance resilience to the device reliability induced degradation. Also the tuning ability designed in RF PA and LNA provides the circuit post-process calibration capability.

The rapidly expanding wireless market requires low cost, high integration and high performance of wireless communication systems. CMOS technology provides benefits of cost effectiveness and higher levels of integration. However, the design of highly efficient linear CMOS power amplifier that meets the requirement of advanced communication standards is a challenging task because of the inherent difficulties in CMOS technology. The objective of this research is to realize PAs for wireless communication systems that overcoming the drawbacks of CMOS process, and to develop design approaches that satisfying the demands of the industry. In this dissertation, a cascode bias technique is proposed for improving linearity and reliability of the multi-stage cascode CMOS PA. In addition, to achieve load variation immunity characteristic and to enhance matching and stability, a fully-integrated balanced PA is implemented in a 0.18-m CMOS process. A triple-mode balanced PA using switched quadrature coupler is also proposed, and this work saved a large amount of quiescent current and further improved the efficiency in the back-off power. For the low losses and a high quality factor of passive output combining, a transformer-based quadrature coupler was implemented using integrated passive device (IPD) process. Various practical approaches for linear CMOS PA are suggested with the verified results, and they demonstrate the potential PA design approach for WCDMA applications using a standard CMOS technology.

Next generation mobile communication systems require the use of linear RF power amplifier for higher data transmission rates. However, linear RF power amplifiers are inherently inefficient and usually require additional circuits or further system adjustments for better efficiency. This dissertation focuses on the development of new efficiency enhancement schemes for linear RF power amplifiers. The multistage Doherty amplifier technique is proposed to improve the performance of linear RF power amplifiers operated in a low power level. This technique advances the original Doherty amplifier scheme by improving the efficiency at much lower power level. The proposed technique is supported by a new approach in device periphery calculation to reduce AM/AM distortion and a further improvement of linearity by the bias adaptation concept. The device periphery adjustment technique for efficiency enhancement of power amplifier integrated circuits is also proposed in this work. The concept is clearly explained together with its implementation on CMOS and SiGe RF power amplifier designs. Furthermore, linearity improvement technique using the cancellation of nonlinear terms is proposed for the CMOS power amplifier in combination with the efficiency enhancement technique. In addition to the efficiency enhancement of power amplifiers, a scalable large-signal MOSFET model using the modified BSIM3v3 approach is proposed. A new scalable substrate network model is developed to enhance the accuracy of the BSIM3v3 model in RF and microwave applications. The proposed model simplifies the modeling of substrate coupling effects in MOS transistor and provides great accuracy in both small-signal and large-signal performances.

Ce travail de thèse s'intéresse à l'optimisation des performances de transmissions multimédias par une approche originale combinant des circuits radiofréquences, tel que l'am-plificateur de puissance et les distorsions du canal de transmission. Les signaux OFDM sont très sensibles aux non-linéarités de l'amplificateur à cause des fortes fluctuations du niveau du signal, caractérisées par le PAPR. Afin de réduire le PAPR, on propose tout d'abord d'améliorer la méthode TR en termes de rapidité de convergence et de réduction du PAPR, en comparant plusieurs algorithmes d'optimisation. On montre que l'algorithme du gradient con-jugué offre les meilleures performances tout en respectant les spécifications fréquentielles du standard IEEE 802.11a. Par la suite, la méthode TR est évaluée expérimentalement en pré-sence d'un amplificateur de puissance (SZP-2026Z) en utilisant un banc de mesures. On montre ainsi que la méthode TR permet une amélioration de la qualité de transmission. Cette amélioration peut être utilisée pour modifier le point de fonctionnement de l'amplificateur et per-mettre ainsi une réduction de 18 % de la puissance consommée. Les résultats expérimentaux ont conduit au choix d'un modèle réaliste d'amplificateur en considérant les effets mémoires. Ce dernier a été intégré dans une chaîne de simulation SISO comprenant également un modèle réaliste de canal de transmission. La chaîne décrite a permis d'évaluer les performances de la méthode TR dans des conditions de transmission réalistes. Enfin, on propose d'appliquer la méthode TR dans une chaîne MIMO-OFDM en boucle fermée dédiée à la transmission de contenus multimédias scalables dans un environnement réaliste, en utilisant le standard IEEE 802.11n. Cette étude présente une évaluation originale de l'impact de la méthode TR sur la qualité visuelle des images transmises, en prenant en compte le contenu multimédia, la non-linéarité de l'amplificateur et les distorsions apportées par le canal. / In this thesis, we are interested on the performances optimization of multimedia transmissions systems with an original contribution combining RF circuits' imperfections presented by the power amplifier (PA) nonlinearities and the transmission channel distortions. The studied system uses the OFDM technique which is the most widespread multicarrier modulation in recent radio communications systems. However, its major drawback is the high PAPR value, which degrades the transmission quality due to the PA nonlinearities. To reduce the PAPR, we first propose to improve the TR method in terms of convergence speed and PAPR reduction, by studying several optimization algorithms. We show that the conjugate gradient algorithm provides the best performance while respecting the frequency specifica-tions of the IEEE 802.11a standard. Thereafter, TR method has been evaluated experimentally in the presence of a commercial PA (SZP-2026Z) and using a measurement bench. It is shown that the TR method improves the quality of service (QoS), with 18% reduction in PA power consumption. The experimental study has resulted to choosing a realistic PA model consider-ing memory effects. This PA model has been integrated into a SISO simulation chain includ-ing also a realistic channel model. This chain is used to evaluate the TR method performances under realistic transmission conditions. Finally, we propose to apply the TR method in a closed-loop MIMO-OFDM chain dedicated to the transmission of scalable multimedia con-tent in a realistic context with the IEEE 802.1n standard. This study presents a new contribu-tion of the TR method evaluation to improve the visual quality of the JPWL transmitted imag-es, considering in the same time the multimedia content, the PA nonlinearity and the channel transmission distortions.

Les systèmes radar nécessitent d’être de plus en plus performants et doivent émettre des impulsions les plus identiques possibles. Un critère permet de quantifier la bonne régularité des impulsions radar au cours du temps : la stabilité pulse à pulse. L’amplificateur de puissance est un élément essentiel du système radar. Dans ce sens, ce travail présente une analyse du critère de stabilité pulse à pulse dans le cas d’un amplificateur HEMT GaN. Les formules mathématiques permettant d’extraire la valeur de la stabilité pulse à pulse des mesures temporelles d’enveloppe sont présentées. La conception et la réalisation d’un amplificateur de puissance RF connectorisé 50 Ω sont décrites. Divers cas de rafales radar ont été étudiés au travers des mesures temporelles d’enveloppe pour en quantifier l’impact sur les valeurs de stabilité pulse à pulse. Un banc de mesure hétérodyne de la stabilité pulse à pulse a été spécialement développé pendant ces travaux de thèse. Finalement, ces résultats de stabilité pulse à pulse ont été utilisés pour optimiser le modèle électrique non linéaire du transistor HEMT GaN afin de prendre en compte lors des simulations temporelles d’enveloppe les effets de la thermique et des pièges. / Radar-oriented applications require stringent performances. Among them, emitting pulse train with uniform envelope characteristics in term of amplitude and phase. The criterion to quantify the self-consistency of radar signals over the pulse train is the pulse to pulse stability. The power amplifier is the most critical element in the RF radar chain because it has a strong impact on the overall pulse to pulse stability performances. In this context, this work is focused on the study of the impact of a HEMT GaN power amplifier on the pulse to pulse stability. Mathematical approach is presented to derive the pulse to pulse stability from time domain envelope measurements. Design and implementation of a 50Ω matched RF power amplifier are presented. Different radar bursts scenario are investigated and their impact on the pulse to pulse stability are quantified through extensive time domain envelope measurements. For that purpose, a dedicated experimental heterodyne time domain envelope test bench has been developed. These pulse to pulse stability measurements are finally used to optimize and fully validate a nonlinear electrical model of a HEMT GaN, allowing to quantify the relative impact of thermal and trapping effects during circuit envelope simulation in radar-oriented applications.