High efficiency power amplifiers for modern mobile communications: The load-modulation approach

Modern mobile communication signals require power amplifiers able to maintain very high efficiency in a wide range of output power levels, which is a major issue for classical power amplifier architectures. Following the load-modulation approach, efficiency enhancement is achieved by dynamically changing the amplifier load impedance as a function of the input power. In this paper, a review of the widely-adopted Doherty power amplifier and of the other load-modulation efficiency enhancement techniques is presented. The main theoretical aspects behind each method are introduced, and the most relevant practical implementations available in recent literature are reported and discussed

Performance improvement and cost reduction techniques for radio over fiber communications

Advanced cost reduction and performance improvement techniques conceived for Radio Over Fiber (ROF) communications are considered. ROF techniques are expected to form the backbone of the future 5G generation of wireless networks. The achievable link performance and the associated deployement cost constitute the most salient metrics of a ROF architecture. In this paper, we commence by providing a rudimentary overview of the ROF architecture and then elaborate on ROF techniques designed for improving the attainable system performance. We conclude by describing the ROF techniques conceived for reducing the ROF system installation costs

CMOS power amplifier and transmitter front-end design in wireless communication.

Ng, Yuen Sum.Thesis (M.Phil.)--Chinese University of Hong Kong, 2009.Includes bibliographical references.Abstract also in Chinese.Chapter 1. --- INTRODUCTION --- p.11Chapter 1.1 --- Motivation --- p.11Chapter 1.2 --- Specifications --- p.12Chapter 1.3 --- Organization of the Thesis --- p.16Chapter 1.4 --- References --- p.16Chapter 2. --- BASIC THEORY OF POWER AMPLIFIER AND TRANSMITTER FRONT-END --- p.18Chapter 2.1 --- Classification of Power Amplifier --- p.18Chapter 2.1.1 --- Class A --- p.20Chapter 2.1.2 --- Class B --- p.21Chapter 2.1.3 --- Class AB --- p.22Chapter 2.1.4 --- Class C --- p.23Chapter 2.1.5 --- Class D --- p.24Chapter 2.1.6 --- Class E --- p.25Chapter 2.1.7 --- Class F --- p.28Chapter 2.2 --- Figure-of-Mhrit of Power Amplifier --- p.28Chapter 2.2.1 --- Small Signal Analysis --- p.29Chapter 2.2.1.1 --- S-parameter --- p.29Chapter 2.2.1.2 --- Gain and Stability --- p.29Chapter 2.2.2 --- Large Signal Analysis --- p.32Chapter 2.2.2.1 --- 1-dB compression point --- p.33Chapter 2.2.2.2 --- Third-order intermodulation point --- p.33Chapter 2.2.2.3 --- Power Gain --- p.35Chapter 2.2.2.4 --- Drain Efficiency and Power Added Efficiency --- p.35Chapter 2.2.2.5 --- AM-AM and AM-PM conversion --- p.36Chapter 2.2.3 --- Modulation Analysis --- p.36Chapter 2.2.3.1 --- Constellation Diagram and Error Vector Magnitude --- p.36Chapter 2.3 --- Reference --- p.37Chapter 3. --- CIRCUIT DESIGN OF POWER AMPLIFIER --- p.39Chapter 3.1 --- Introduction --- p.39Chapter 3.2 --- Topology of the Power Amplifier Design --- p.39Chapter 3.3 --- Design in Power Amplifier --- p.40Chapter 3.2.1 --- Power Stage --- p.40Chapter 3.2.2 --- Driver Stage and Input matching --- p.46Chapter 3.4 --- Simulation Result on Power Amplifier --- p.49Chapter 3.5 --- Layout consideration --- p.50Chapter 3.6 --- Measurement Result on Power Amplifier --- p.51Chapter 3.4.1 --- Small signal measurement --- p.52Chapter 3.4.2 --- Large signal measurement --- p.55Chapter 3.4.3 --- Modulation measurement --- p.56Chapter 3.7 --- Performance Summary --- p.58Chapter 3.8 --- Reference --- p.59Chapter 4. --- CIRCUIT DESIGN OF TRANSMITTER FRONT-END --- p.60Chapter 4.1 --- Introduction --- p.60Chapter 4.2 --- Topology of the Transmitter Front-End Design --- p.61Chapter 4.3 --- Design in transmitter front-end circuit --- p.64Chapter 4.2.1 --- I/Q Modulator --- p.64Chapter 4.2.2 --- Power Amplifier --- p.66Chapter 4.2.3 --- On-chip LC Balun --- p.72Chapter 4.4 --- Simulation Result of the Transmitter Front-End Design --- p.74Chapter 4.5 --- Layout consideration --- p.75Chapter 4.6 --- Measurement Result of the Transmitter Front-End Design --- p.76Chapter 4.4.1. --- Transmitter Front-End Measurement --- p.77Chapter 4.4.1.1 --- Output Reflection coefficient --- p.77Chapter 4.4.1.2 --- Large Signal Measurement --- p.78Chapter 4.4.1.3 --- Modulation Measurement --- p.81Chapter 4.4.2. --- LC Balun Measurement --- p.84Chapter 4.7 --- Performance Summary of the transmitter front-end circuit --- p.86Chapter 4.8 --- Reference --- p.89Chapter 5. --- CONCLUSION --- p.90Chapter 6. --- FUTURE WORK --- p.9

Antennas and Propagation Aspects for Emerging Wireless Communication Technologies

The increasing demand for high data rate applications and the delivery of zero-latency multimedia content drives technological evolutions towards the design and implementation of next-generation broadband wireless networks. In this context, various novel technologies have been introduced, such as millimeter wave (mmWave) transmission, massive multiple input multiple output (MIMO) systems, and non-orthogonal multiple access (NOMA) schemes in order to support the vision of fifth generation (5G) wireless cellular networks. The introduction of these technologies, however, is inextricably connected with a holistic redesign of the current transceiver structures, as well as the network architecture reconfiguration. To this end, ultra-dense network deployment along with distributed massive MIMO technologies and intermediate relay nodes have been proposed, among others, in order to ensure an improved quality of services to all mobile users. In the same framework, the design and evaluation of novel antenna configurations able to support wideband applications is of utmost importance for 5G context support. Furthermore, in order to design reliable 5G systems, the channel characterization in these frequencies and in the complex propagation environments cannot be ignored because it plays a significant role. In this Special Issue, fourteen papers are published, covering various aspects of novel antenna designs for broadband applications, propagation models at mmWave bands, the deployment of NOMA techniques, radio network planning for 5G networks, and multi-beam antenna technologies for 5G wireless communications

Design and analysis of wideband passive microwave devices using planar structures

A selected volume of work consisting of 84 published journal papers is presented to demonstrate the contributions made by the author in the last seven years of his work at the University of Queensland in the area of Microwave Engineering. The over-arching theme in the author’s works included in this volume is the engineering of novel passive microwave devices that are key components in the building of any microwave system. The author’s contribution covers innovative designs, design methods and analyses for the following key devices and associated systems: Wideband antennas and associated systems Band-notched and multiband antennas Directional couplers and associated systems Power dividers and associated systems Microwave filters Phase shifters Much of the motivation for the work arose from the desire to contribute to the engineering o

Conception de circuits micro-ondes multi-bandes et à fréquences agiles pour la réalisation de systèmes sans fil reconfigurables

RÉSUMÉ Les travaux effectués dans cette thèse sont centrés sur la conception et la réalisation de composantes et d’un système récepteur complet Radio Fréquence (RF) et Micro-onde qui possèdent des caractéristiques multifonctionnelles telles que des bandes de fréquences d’opération multiples et reconfigurables par l’utilisation des diodes varactors semi-conducteurs ou des matériaux ferroélectrique (BST) contrôlés par des tensions électriques. Dans la première partie de cette thèse, une méthode de mesure simple et rapide est développée et utilisée pour extraire la perte tangentielle et la constante diélectrique du matériel ferroélectrique (BST) à partir de mesures de capacités interdigitales BST. Un modèle électrique de la capacité BST est aussi obtenu à différentes tensions de polarisation du BST, afin de représenter ainsi la variation des pertes résistives et le pourcentage d’accordabilité de la capacitance par rapport à la tension de polarisation. De façon globale, les capacités interdigitales BST caractérisées présentent une accordabilité capacitive de 52% pour une tension appliquée variant de 0 à 25 volts. Dans le but de concevoir un démodulateur frontal six-port reconfigurable, deux coupleurs hybrides quadrature multi bande accordables contrôlés par une tenson à l’aide de diode varactor et par des capacités ferroélectriques (BST) sont caractérisés et comparés dans la seconde partie de cette thèse. Les deux structures sont composées de quatre sections de ligne de transmission microruban d’un quart de longueur d’onde à une fréquence centrale entre les deux fréquences d’opérations, et de deux paires de lignes de transmission ouvertes connectées en parallèle.---------- ABSTRACT The research work in this thesis concerned with the design and realization of radio frequency (RF) and microwave components, and a complete receiver system, with multiple functionality such as multi-bands and reconfigurable operation frequencies bands based on standard silicon or ferroelectric (BST – barium strontium-titanate) varactors. In the first part of this thesis, a simple and fast measurement technique is developed to extract BST loss tangent and dielectric constant through an interdigital BST capacitor. Also, the electrical model obtained for the BST capacitor presents features of resistive loss variation and capacitance tunability. Thin-film BST-based and conventional silicon varactor-based tunable dual-band quadrature hybrid couplers are characterized and compared in this thesis. Both structures are composed of four quarter-wavelength sections at a frequency located between the two operating frequencies and with two pairs of open-ended stubs. Frequency tuning makes use of both BST interdigital and silicon varactor diode capacitors connected at the open-ended stubs. The characterized BST interdigital capacitor (IDC) presents a capacitive-tunability of 52% through an applied voltage of 0 to 25 volt, while 82.5% is achieved for the selected commercial silicon varactor diode. The silicon varactor-tuned dual-band coupler exhibits 45.9 % and 5.2 % tuning range of center frequency for the first and the second band, respectively, while 29.2 % and 4.3 % are achieved for the BST tunable coupler. With two-tone non-linear characterization test, the BST tunable coupler biased at 0 and 25 volt presents an IIP3 of +25.45 and +35 dBm, respectively, while +11.5 and +34 dBm are obtained for the silicon varactor tunable coupler

Investigations into Optically Controlled Phase Contrast, Polarisation Switchable Narrow Band RF Detection Techniques.

This thesis describes an investigation into S-band microwave frequency phase-contrast imaging. Resolution is a critical issue so system enhancements such as optical remote connection and polarisation-dependant sensing have been implemented within an end-to-end sensing system. Initially, the feasibility of phase-contrast measurements was considered and the limits of phase and amplitude measurements established. A switching matrix was then designed and incorporated into a tri-antenna array to demonstrate triangulation-based location. Commercial, linearly-polarised antennas were then used to demonstrate basic object location. A comprehensive experimental investigation into optical transmission of phase sensitive data using Radio over Fibre (RoF) techniques is then described. Reflective technology and directly modulated Vertical Cavity Surface Emitting Lasers (VCSELs) are assessed for suitability as are Coarse Wavelength Division Multiplexed (CWDM) architectures. These are believed to be a novel contribution in the imaging context as are the techniques employed to enhance and extend the matching and performance of the optical devices. A directly modulated VCSEL based CWDM method was then used over the extended range of 1 km of standard single mode optical fibre. Subsequently, dual polarisation plane techniques were used to generate sequential, orthogonally-separated measurements, which required the development of a suitable antenna. The design, modelling, construction and deployment of a high cross-polar isolation, patch antenna is then described. An antenna with single symmetrical forward lobes (on both polarisation planes) and low back radiation pattern was devised so enabling sensing from a single coincident point. With the device integrated into the final measurement system the resulting “Polarisation Switched, Narrowband, RF Probe System Using a VCSEL Optical Feed” was used to demonstrate improved resolution of a phase contrast RF measurement system at an optically-remoted distance of 1km