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No description available.

In 1997 the Federal Communications Commission (FCC) released 300 MHz of spectrum between 5-6 GHz designated the unlicensed national information infrastructure (U-NII) band. The intention of the FCC was to provide an unlicensed band of frequencies that would enable high-speed wireless local area networks (WLANs) and facilitate wireless access to the national information infrastructure with a minimum interference to other devices. Currently, there is a lack of cost-effective technologies for developing U-NII band components. With the commercial market placing emphasis on low cost, low power, and highly integrated implementations of RF circuitry, alternatives to the large and expensive distributed element components historically used at these frequencies are needed. Silicon Germanium (SiGe) BiCMOS technology represents one possible solution to this problem. The SiGe BiCMOS process has the potential for low cost since it leverages mature Si process technologies and can use existing Si fabrication infrastructure. In addition, SiGe BiCMOS processes offer excellent high frequency performance through the use of SiGe heterojunction bipolar transistors (HBTs), while coexisting Si CMOS offers compatibility with digital circuitry for high level 'system-on-a-chip' integration. The work presented in this thesis focuses on the development of a SiGe RFIC front-end for operation in the U-NII bands. Specifically, three variants of a packaged low noise amplifier (LNA) and a packaged active x2 sub-harmonic mixer (SHM) have been designed, simulated and measured. The fabrication of the Rifts was through the IBM SiGe foundry; the packaging was performed by RF Micro devices. The mixer and LNA designs were fabricated on separate die, packaged individually, and on-chip matched to a 50 ohm system so they could be fully characterized. Measurements were facilitated in a coaxial system using standard FR4 printed circuit boards. The LNA designs use a single stage, cascoded topology. The input ports are impedance matched using inductive emitter degeneration through bondwires to ground. One version of the LNA uses an shunt inductor/series capacitor output match while the other two variation use a series inductor output match. Gain, isolation, match, linearity and noise figure (NF) were used to characterize the performance of the LNAs in the 5 - 6 GHz frequency band. The best LNA design has a maximum gain of 9 dB, an input VSWR between 1.6:1 and 2:1, an output match between 1.7:1 and 3.6:1, a NF better than 3.9 dB and an input intercept point (IIP3) greater than 5.4 dBm. The LNA operates from a 3.3 V supply voltage and consumes 4 mA of current. The SHM is an active, double-balance mixer that achieves x2 sub-harmonic mixing through two quadrature (I/Q) driven, stacked Gilbert-cell switching stages. Single-ended-to-differential conversion, buffering and I/Q phase separation of the LO signal are integrated on-chip. Measurements were performed to find the optimal operating range for the mixer, and the mixer was characterized under these sets of conditions. It was found that the optimal performance of the mixer occurs at an IF of 250-450 MHz and an LO power of -5 dBm. Under these conditions, the mixer has a measured conversion gain of 9.3 dB, a P_1-dB of -15.7 dBm and an 2LO/RF isolation greater than 35 dB at 5.25 GHz. At 5.775 GHz, the conversion gain is 7.7 dB, the P_1-dB is -15.0 dBm, and the isolation is greater than 35 dB. The mixer core consumes 9.5 mA from a 5.0 V supply voltage. This work is sponsored by RF Microdevices (RFMD)through the CWT affiliate program.The author was supported under a Bradley Foundation fellowship. / Master of Science

Analysis and design of millimeter-wave integrated circuits for emerging communication/sensing and cryogenic applications with an emphasis on transistor model verification.

Les progrès de la technologie silicium germanium (SiGe) suscitent sa possible utilisation dans les applications à haute fréquence. Les travaux décrit dans ce mémoire visent à étudier les potentialités de cette technologie pour la réalisation de circuits intégrés monolithiques (MMIC) faibles bruit dans la bande de 10 GHz. Ce mémoire est articulé autour de trois chapitres. Le premier rappelle les contraintes auxquelles doit répondre un transistor bipolaire afin d'être utilisable dans les circuits RF millimétriques. La technologie qu'à développé STMicroelectronics pour ce domaine d'application est ensuite présentée. Enfin, le travail de caractérisation qui a été réalisé afin de valider le comportement des modèles que nous allons utiliser pour concevoir des circuits RF est présenté. Le second chapitre est consacré à la conception de circuits amplificateurs à faible bruit. La méthode de travail ainsi que les topologies de circuits sont présentées. Le résultat des caractérisations effectuées est ensuite présenté. Nous terminons en concluant au sujet des performances en terme de consommation, linéarité, gain et facteur de bruit des différents circuits. Le troisième chapitre aborde la conception de sources radiofréquence à faible bruit de phase. Les différentes topologies de circuits que nous avons étudiés sont présentées, ce qui nous a permis de mettre en évidence les topologies offrant les meilleures performances. Enfin, une technique basée sur le principe de dégénérescence de bruit, est également présentée. Ce travail nous a permis d'intégrer sur un circuit MMIC, autour d'un circuit oscillateur de type Colpitts, un dispositif réducteur de bruit. Les résultats théoriques de cette étude ont montré l'efficacité de cette méthode.

Spatial confinement of electrons and their interactions as well as confinement of the spin dimensionality often yield drastic changes of the electronic and magnetic properties of solids. Novel quantum transport and optical phenomena, involving electronic spin degrees of freedom in semiconductor heterostructures, as well as a rich variety of exotic quantum ground states and magnetic excitations in complex transition metal oxides that arise upon such confinements, belong therefore to topical problems of contemporary condensed matter physics. In this work electron spin systems in reduced dimensions are studied with Electron Spin Resonance (ESR) spectroscopy, a method which can provide important information on the energy spectrum of the spin states, spin dynamics, and magnetic correlations. The studied systems include quasi onedimensional spin chain materials based on transition metals Cu and Ni. Another class of materials are semiconductor heterostructures made of Si and Ge. Part I deals with the theoretical background of ESR and the description of the experimental ESR setups used which have been optimized for the purposes of the present work. In particular, the development and implementation of axial and transverse cylindrical resonant cavities for high-field highfrequency ESR experiments is discussed. The high quality factors of these cavities allow for sensitive measurements on μm-sized samples. They are used for the investigations on the spin-chain materials. The implementation and characterization of a setup for electrical detected magnetic resonance is presented. In Part II ESR studies and complementary results of other experimental techniques on two spin chain materials are presented. The Cu-based material Linarite is investigated in the paramagnetic regime above T > 2.8 K. This natural crystal constitutes a highly frustrated spin 1/2 Heisenberg chain with ferromagnetic nearest-neighbor and antiferromagnetic next-nearestneighbor interactions. The ESR data reveals that the significant magnetic anisotropy is due to anisotropy of the g-factor. Quantitative analysis of the critical broadening of the linewidth suggest appreciable interchain and interlayer spin correlations well above the ordering temperature. The Ni-based system is an organic-anorganic hybrid material where the Ni2+ ions possessing the integer spin S = 1 are magnetically coupled along one spatial direction. Indeed, the ESR study reveals an isotropic spin-1 Heisenberg chain in this system which unlike the Cu half integer spin-1/2 chain is expected to possess a qualitatively different non-magnetic singlet ground state separated from an excited magnetic state by a so-called Haldane gap. Surprisingly, in contrast to the expected Haldane behavior a competition between a magnetically ordered ground state and a potentially gapped state is revealed. In Part III investigations on SiGe/Si quantum dot structures are presented. The ESR investigations reveal narrowlines close to the free electron g-factor associated with electrons on the quantum dots. Their dephasing and relaxation times are determined. Manipulations with sub-bandgap light allow to change the relative population between the observed states. On the basis of extensive characterizations, strain, electronic structure and confined states on the Si-based structures are modeled with the program nextnano3. A qualitative model, explaining the energy spectrum of the spin states is proposed.

Les transistors rapides actuels présentent un retard lorsqu’ils fonctionnent à très hautes fréquences ou en régime transitoire rapide. Cet effet est appelé effet non quasi-statique (NQS). Dans cette thèse, l’effet NQS est analysé de manière concise de façon à être directement implanté dans les modèles de composant pour les bibliothèques de circuit en utilisant le langage standard VerilogA. Les mécanismes physiques à la base de l’effet NQS sont évalués dans le domaine de fonctionnement petit signal et les résultats sont comparés aux travaux déjà publiés. S’agissant du modèle standard bipolaire HICUM, les effets NQS latéraux et verticaux sont examinés séparément à partir du même modèle, en régime de fonctionnement transitoire et fréquentiel grâce à un sous-circuit dédié au calcul de la phase du signal. A partir de ce sous-circuit, la modélisation compacte avec HICUM est comparée aux données issues de mesures et issues de simulation amont. Enfin, un nouveau sous-circuit calculant l’excès de phase est proposé pour prendre mieux en compte les effets non quasi-statiques dans les transistors bipolaires. / Modern high speed (RF) transistors encounter certain delay while operated at high frequency or under fast transient condition. This effect is named as Non Quasi Static (NQS) effect. In the current work, NQS effect is analyzed in a concise manner so that it can be readily implemented in a compact model using the VerilogA description language. The basic physics behind this effect is investigated in small signal domain and the results are compared with the published work. In popular bipolar model HICUM lateral and vertical NQS are examined separately and uses the same model for both transient and AC operation which requires an additional minimum phase type sub circuit. Compact modeling with HICUM model is performed in both measurement and device simulated data. At last, an improved excess phase circuit is proposed to model the NQS effect.

This paper presents an overview of the research work currently being performed within the frame of project DAAB and its successor DAAB-TX towards the integration of ultra-wideband transceivers operating at mm-wave frequencies and capable of data rates up to 100 Gbits–¹. Two basic systemarchitectures are being considered: integrating a broadband antenna with a distributed amplifier and integrate antennas centered at adjacent frequencies with broadband active combiners or dividers. The paper discusses in detail the design of such systems and their components, fromthe distributed amplifiers and combiners, to the broadband silicon antennas and their single-chip integration. All components are designed for fabrication in a commercially available SiGe:C BiCMOS technology. The presented results represent the state of the art in their respective areas: 170 GHz is the highest reported bandwidth for distributed amplifiers integrated in Silicon; 89 GHz is the widest reported bandwidth for integrated-system antennas; the simulated performance of the two antenna integrated receiver spans 105 GHz centered at 148GHz, which would improve the state of the art by a factor in excess of 4 even against III-V implementations, if confirmed by measurements.

Spatial confinement of electrons and their interactions as well as confinement of the spin dimensionality often yield drastic changes of the electronic and magnetic properties of solids. Novel quantum transport and optical phenomena, involving electronic spin degrees of freedom in semiconductor heterostructures, as well as a rich variety of exotic quantum ground states and magnetic excitations in complex transition metal oxides that arise upon such confinements, belong therefore to topical problems of contemporary condensed matter physics. In this work electron spin systems in reduced dimensions are studied with Electron Spin Resonance (ESR) spectroscopy, a method which can provide important information on the energy spectrum of the spin states, spin dynamics, and magnetic correlations. The studied systems include quasi onedimensional spin chain materials based on transition metals Cu and Ni. Another class of materials are semiconductor heterostructures made of Si and Ge. Part I deals with the theoretical background of ESR and the description of the experimental ESR setups used which have been optimized for the purposes of the present work. In particular, the development and implementation of axial and transverse cylindrical resonant cavities for high-field highfrequency ESR experiments is discussed. The high quality factors of these cavities allow for sensitive measurements on μm-sized samples. They are used for the investigations on the spin-chain materials. The implementation and characterization of a setup for electrical detected magnetic resonance is presented. In Part II ESR studies and complementary results of other experimental techniques on two spin chain materials are presented. The Cu-based material Linarite is investigated in the paramagnetic regime above T > 2.8 K. This natural crystal constitutes a highly frustrated spin 1/2 Heisenberg chain with ferromagnetic nearest-neighbor and antiferromagnetic next-nearestneighbor interactions. The ESR data reveals that the significant magnetic anisotropy is due to anisotropy of the g-factor. Quantitative analysis of the critical broadening of the linewidth suggest appreciable interchain and interlayer spin correlations well above the ordering temperature. The Ni-based system is an organic-anorganic hybrid material where the Ni2+ ions possessing the integer spin S = 1 are magnetically coupled along one spatial direction. Indeed, the ESR study reveals an isotropic spin-1 Heisenberg chain in this system which unlike the Cu half integer spin-1/2 chain is expected to possess a qualitatively different non-magnetic singlet ground state separated from an excited magnetic state by a so-called Haldane gap. Surprisingly, in contrast to the expected Haldane behavior a competition between a magnetically ordered ground state and a potentially gapped state is revealed. In Part III investigations on SiGe/Si quantum dot structures are presented. The ESR investigations reveal narrowlines close to the free electron g-factor associated with electrons on the quantum dots. Their dephasing and relaxation times are determined. Manipulations with sub-bandgap light allow to change the relative population between the observed states. On the basis of extensive characterizations, strain, electronic structure and confined states on the Si-based structures are modeled with the program nextnano3. A qualitative model, explaining the energy spectrum of the spin states is proposed.:Abstract i Contents iii List of Figures vi List of Tables viii 1 Preface 1 I Background and Experimental 5 2 Principles of ESR 7 2.1 The Resonance Phenomenon . . . . . . . . . . . . . . . . . . . 7 2.2 ESR Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10 2.2.1 The g -factor . . . . . . . . . . . . . . . . . . . . . . . . . 11 2.2.2 Relaxation Times . . . . . . . . . . . . . . . . . . . . . . 12 2.2.3 Lineshape Properties . . . . . . . . . . . . . . . . . . . . 13 2.3 Effective Spin Hamiltonian . . . . . . . . . . . . . . . . . . . . . 15 2.4 Spin-Orbit Coupling . . . . . . . . . . . . . . . . . . . . . . . . . 16 2.5 d-electrons in a Crystal Field . . . . . . . . . . . . . . . . . . . . 17 2.6 Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 2.6.1 Dipolar Coupling . . . . . . . . . . . . . . . . . . . . . . 23 2.6.2 Exchange Interaction . . . . . . . . . . . . . . . . . . . . 23 2.6.3 Superexchange . . . . . . . . . . . . . . . . . . . . . . . 24 2.6.4 Symmetric Anisotropic Exchange . . . . . . . . . . . . 25 2.6.5 Antisymmetric Anisotropic Exchange . . . . . . . . . . 25 2.6.6 Hyperfine Interaction . . . . . . . . . . . . . . . . . . . 26 3 Experimental 27 3.1 Setup for Experiments at 10GHz . . . . . . . . . . . . . . . . . 27 3.2 Implementation of an EDMR Setup . . . . . . . . . . . . . . . . 29 3.2.1 Basic Characterization . . . . . . . . . . . . . . . . . . . 31 3.3 High Frequency Setup . . . . . . . . . . . . . . . . . . . . . . . . 31 3.3.1 MillimeterWave Vector Network Analyzer . . . . . . . 33 3.3.2 Waveguides and Cryostats . . . . . . . . . . . . . . . . . 34 3.4 Development of the Resonant Cavity Setup . . . . . . . . . . . 35 3.4.1 Mode Propagation . . . . . . . . . . . . . . . . . . . . . 38 3.4.2 Resonant CavityModes . . . . . . . . . . . . . . . . . . 40 3.4.3 Resonant Cavity Design . . . . . . . . . . . . . . . . . . 41 3.4.4 Resonant Cavity Sample Stick . . . . . . . . . . . . . . . 45 3.4.5 Experimental Characterization . . . . . . . . . . . . . . 47 3.4.6 Performing an ESR Experiment . . . . . . . . . . . . . . 53 II Quasi One-Dimensional Spin-Chains 57 4 Motivation 59 5 Quasi One-Dimensional Systems 61 5.1 Magnetic Order and Excitations . . . . . . . . . . . . . . . . . . 63 5.2 Competing Interactions . . . . . . . . . . . . . . . . . . . . . . . 64 5.3 Haldane Spin Chain . . . . . . . . . . . . . . . . . . . . . . . . . 66 6 Linarite 69 6.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 6.2 Magnetization and ESR . . . . . . . . . . . . . . . . . . . . . . . 71 6.3 NMR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 6.4 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . 81 6.5 Outlook . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 82 7 The Ni-hybrid NiCl3C6H5CH2CH2NH3 83 7.1 Structure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 83 7.2 Susceptibility andMagnetization . . . . . . . . . . . . . . . . . 85 7.3 ESR . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 88 7.4 Further Investigations . . . . . . . . . . . . . . . . . . . . . . . . 95 7.5 Summary and Conclusion . . . . . . . . . . . . . . . . . . . . . 96 8 Summary 99 III SiGe Nanostructures 101 9 Motivation 103 10 SiGe Semiconductor Nanostructures 107 10.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 10.1.1 Silicon and Germanium . . . . . . . . . . . . . . . . . . 107 10.1.2 Epitaxial Growth of SiGe Heterostructures . . . . . . . 109 10.1.3 Strain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 10.1.4 Band Deformation . . . . . . . . . . . . . . . . . . . . . 112 10.2 Sample Structure and Characterization . . . . . . . . . . . . . 114 11 Modelling of SiGe/Si Heterostructures 119 11.1 Program Structure . . . . . . . . . . . . . . . . . . . . . . . . . . 120 11.2 Implementation of Si/Ge System . . . . . . . . . . . . . . . . . 121 11.3 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 123 11.3.1 Single Quantum Dot . . . . . . . . . . . . . . . . . . . . 123 11.3.2 Multiple Quantum Dots . . . . . . . . . . . . . . . . . . 127 11.4 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 130 11.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 132 12 ESR Experiments on Si/SiGe Quantum Dots 135 12.1 ESR on Si Structures . . . . . . . . . . . . . . . . . . . . . . . . . 135 12.2 Experimental Results . . . . . . . . . . . . . . . . . . . . . . . . 137 12.2.1 Samples grown at 600◦C . . . . . . . . . . . . . . . . . . 138 12.2.2 Samples grown at 700◦C . . . . . . . . . . . . . . . . . . 139 12.2.3 T1-Relaxation Time . . . . . . . . . . . . . . . . . . . . . 143 12.2.4 Effect of Illumination . . . . . . . . . . . . . . . . . . . . 145 12.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 148 12.3.1 Quantum Dots . . . . . . . . . . . . . . . . . . . . . . . 149 12.3.2 Assignment of ESR Lines . . . . . . . . . . . . . . . . . . 150 12.3.3 Relaxation Times . . . . . . . . . . . . . . . . . . . . . . 153 12.3.4 Donors in Heterostructures . . . . . . . . . . . . . . . . 153 12.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 156 13 Summary and Outlook 157 Bibliography 163 Acknowledgements 176

A K-band integrated super-regenerative amplifier (SRA) in a 130nm SiGe BiCMOS technology is designed and characterized. The circuit is based on a novel stacked transistor differential cross-coupled oscillator topology, with a controllable tail current for quenching the oscillations. The fabricated integrated circuit (IC) occupies an area of 0.63mm2, and operates at the free-running center frequency of 25.3 GHz. Characterization results show circuit operation from a minimum input power level required for a phase coherent output as −110 dBm, and the input power level corresponding to the linear to logarithmic mode transition of −85 dBm, the lowest reported for K-band integrated logarithmic mode SRAs to date to the knowledge of the authors. The measured output power is 7.8dBm into a 100 differential load. The power consumption of the circuit is 110mW with no quench signal applied, and 38mW with 30 % duty cycle quenching. The quench waveform designed for the reported measurement result is also discussed.