Parametric analog signal amplification applied to nanoscale cmos wireless digital transceivers

Thesis presented in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Electrical and Computer Engineering by the Universidade Nova de Lisboa,Faculdade de Ciências e TecnologiaSignal amplification is required in almost every analog electronic system. However noise is also present, thus imposing limits to the overall circuit performance, e.g., on the sensitivity of the radio transceiver. This drawback has triggered a major research on the field, which has been producing several solutions to achieve amplification with minimum added noise. During the Fifties, an interesting out of mainstream path was followed which was based on variable reactance instead of resistance based amplifiers. The principle of these parametric circuits permits to achieve low noise amplifiers since the controlled variations of pure reactance elements is intrinsically noiseless. The amplification is based on a mixing effect which enables energy transfer from an AC pump source to other related signal frequencies. While the first implementations of these type of amplifiers were already available at that time, the discrete-time version only became visible more recently. This discrete-time version is a promising technique since it is well adapted to the mainstream nanoscale CMOS technology. The technique itself is based on the principle of changing the surface potential of the MOS device while maintaining the transistor gate in a floating state. In order words, the voltage amplification is achieved by changing the capacitance value while maintaining the total charge unchanged during an amplification phase. Since a parametric amplifier is not intrinsically dependent on the transconductance of the MOS transistor, it does not directly suffer from the intrinsic transconductance MOS gain issues verified in nanoscale MOS technologies. As a consequence, open-loop and opamp free structures can further emerge with this additional contribution. This thesis is dedicated to the analysis of parametric amplification with special emphasis on the MOS discrete-time implementation. The use of the latter is supported on the presentation of several circuits where the MOS Parametric Amplifier cell is well suited: small gain amplifier, comparator, discrete-time mixer and filter, and ADC. Relatively to the latter, a high speed time-interleaved pipeline ADC prototype is implemented in a,standard 130 nm CMOS digital technology from United Microelectronics Corporation (UMC). The ADC is fully based on parametric MOS amplification which means that one could achieve a compact and MOS-only implementation. Furthermore, any high speed opamp has not been used in the signal path, being all the amplification steps implemented with open-loop parametric MOS amplifiers. To the author’s knowledge, this is first reported pipeline ADC that extensively used the parametric amplification concept.Fundação para a Ciência e Tecnologia through the projects SPEED, LEADER and IMPAC

Novel Current-Mode Sensor Interfacing and Radio Blocks for Cell Culture Monitoring

Since 2004 Imperial College has been developing the world’s first application-specific instrumentation aiming at the on-line, in-situ, physiochemical monitoring of adult stem cell cultures. That effort is internationally known as the ‘Intelligent Stem Cell Culture Systems’ (ISCCS) project. The ISCCS platform is formed by the functional integration of biosensors, interfacing electronics and bioreactors. Contrary to the PCB-level ISCCS platform the work presented in this thesis relates to the realization of a miniaturized cell culture monitoring platform. Specifically, this thesis details the synthesis and fabrication of pivotal VLSI circuit blocks suitable for the construction of a miniaturized microelectronic cell monitoring platform. The thesis is composed of two main parts. The first part details the design and operation of a two-stage current-input currentoutput topology suitable for three-electrode amperometric sensor measurements. The first stage is a CMOS-dual rail-class AB-current conveyor providing a low impedancevirtual ground node for a current input. The second stage is a novel hyperbolic-sinebased externally-linear internally-non-linear current amplification stage. This stage bases its operation upon the compressive sinh−1 conversion of the interfaced current to an intermediate auxiliary voltage and the subsequent sinh expansion of the same voltage. The proposed novel topology has been simulated for current-gain values ranging from 10 to 1000 using the parameters of the commercially available 0.8μm AMS CMOS process. Measured results from a chip fabricated in the same technology are also reported. The proposed interfacing/amplification architecture consumes 0.88-95μW. The second part describes the design and practical evaluation of a 13.56MHz frequency shift keying (FSK) short-range (5cm) telemetry link suitable for the monitoring of incubated cultures. Prior to the design of the full FSK radio system, a pair of 13.56MHz antennae are characterized experimentally. The experimental S-parameter-value determination of the 13.56MHz wireless link is incorporated into the Cadence Design Framework allowing a high fidelity simulation of the reported FSK radio. The transmitter of the proposed system is a novel multi-tapped seven-stage ring-oscillator-based VCO whereas the core of the receiver is an appropriately modified phase locked loop (PLL). Simulated and measured results from a 0.8μm CMOS technology chip are reported

System-on-Package Low-Power Telemetry and Signal Conditioning unit for Biomedical Applications

Recent advancements in healthcare monitoring equipments and wireless communication technologies have led to the integration of specialized medical technology with the pervasive wireless networks. Intensive research has been focused on the development of medical wireless networks (MWN) for telemedicine and smart home care services. Wireless technology also shows potential promises in surgical applications. Unlike conventional surgery, an expert surgeon can perform the surgery from a remote location using robot manipulators and monitor the status of the real surgery through wireless communication link. To provide this service each surgical tool must be facilitated with smart electronics to accrue data and transmit the data successfully to the monitoring unit through wireless network. To avoid unwieldy wires between the smart surgical tool and monitoring units and to reap the benefit of excellent features of wireless technology, each smart surgical tool must incorporate a low-power wireless transmitter. Low-power transmitter with high efficiency is essential for short range wireless communication. Unlike conventional transmitters used for cellular communication, injection-locked transmitter shows greater promises in short range wireless communication. The core block of an injection-locked transmitter is an injection-locked oscillator. Therefore, this research work is directed towards the development of a low-voltage low-power injection-locked oscillator which will facilitate the development of a low-power injection-locked transmitter for MWN applications. Structure of oscillator and types of injection are two crucial design criteria for low-power injection-locked oscillator design. Compared to other injection structures, body-level injection offers low-voltage and low-power operation. Again, conventional NMOS/PMOS-only cross-coupled LC oscillator can work with low supply voltage but the power consumption is relatively high. To overcome this problem, a self-cascode LC oscillator structure has been used which provides both low-voltage and low-power operation. Body terminal coupling is used with this structure to achieve injection-locking. Simulation results show that the self-cascode structure consumes much less power compared to that of the conventional structure for the same output swing while exhibiting better phase noise performance. Usage of PMOS devices and body bias control not only reduces the flicker noise and power consumption but also eliminates the requirements of expensive fabrication process for body terminal access

NASA Tech Briefs Index, 1977, volume 2, numbers 1-4

Announcements of new technology derived from the research and development activities of NASA are presented. Abstracts, and indexes for subject, personal author, originating center, and Tech Brief number are presented for 1977

Exploration of Nonlinear Devices and Nonlinear Transmission Line Techniques for Microwaves Applications

RÉSUMÉ Les systèmes de communication modernes dépendent fortement des circuits non linéaires, tels que les amplificateurs de puissance (PA), les mélangeurs, les multiplicateurs, les oscillateurs, les commutateurs, etc., qui sont construits à partir de composants non linéaires passifs (comme des diodes) ou actifs (par exemple des transistors). Cette thèse étudie les dispositifs non linéaires passifs traditionnels et émergents, ainsi que les techniques de lignes de transmission non linéaires (NLTL). Plusieurs de leurs applications micro-ondes ont également été étudiées, y compris la récupération d'énergie sans fil, la synthèse d’impédance électronique et l’adaptation d’impédance bidimensionnelle (inductive et capacitive). Dans le chapitre 1, sont d'abord étudiés les dispositifs non linéaires traditionnels résistifs, capacitifs et inductifs. Les dispositifs non linéaires émergents, y compris les dispositifs MEMS et la spindiode, sont ensuite explorés. La construction physique de base, les principes de fonctionnement, ainsi que les caractéristiques et applications pour divers types de dispositifs non linéaires sont expliqués et comparés. Les lignes de transmission non-linéaires (NLTL) traditionnelles utilisant des dispositifs non linéaires capacitifs (varactor, BST etc.) ou inductifs (ferrite saturée), et la technique hybride NLTL émergente utilisant à la fois des dispositifs non linéaires capacitifs et inductifs sont également étudiées. Le chapitre 2 examine les techniques de conversion d'énergie micro-ondes à courant-continu de faible puissance à la fine pointe de la technologie. Une image complète de l'état de l'art sur cet aspect est donnée graphiquement. Elle compare différentes technologies telles que le transistor, la diode et les technologies CMOS. Depuis le tout début des techniques intégrées RF et micro-ondes et de la récupération d'énergie, les diodes Schottky ont été le plus souvent utilisées dans les circuits de mélange et de redressement. Cependant, dans des applications spécifiques de récupération d'énergie, la technique des diodes Schottky ne parvient pas à fournir une efficacité satisfaisante de conversion RF-dc. Suite aux limitations mises en évidence des dispositifs actuels, ce travail introduit, pour la première fois, un composant non linéaire pour une redressement de faible puissance, basé sur une découverte récente en spintronique, à savoir, la jonction tunnel magnétique, parfois appelée spindiode. Un modèle équivalent de spindiode est développé pour décrire le comportement en fréquence.----------ABSTRACT Modern communication systems are heavily dependent on nonlinear circuits, such as PA, mixer, multiplier, oscillator, switch, etc., the core of which are either passive nonlinear elements and devices (e.g. diodes) or active nonlinear components and devices (e.g. transistors). This thesis aims at investigating a number of traditional and emerging passive nonlinear devices and nonlinear transmission line (NLTL) techniques, and developing four of their microwave applications such as wireless power harvesting, electronic impedance synthesizer, and two-dimensional tuning circuit. In Chapter 1, traditional nonlinear devices in terms of the categories of resistive, capacitive and inductive are firstly investigated. Emerging nonlinear devices including microelectromechanical system (MEMS) devices and spindiodes are then explored. The basic physical constructions, operation principles, and characteristics as well as applications of various types of nonlinear devices are explained and compared. Traditional NLTL techniques make use of either capacitive nonlinear devices (varactor, BST etc.) or inductive nonlinear devices (saturated ferrite), and emerging hybrid NLTL techniques are also studied through the deployment of both nonlinear capacitive and inductive devices. Chapter 2 examines the state-of-the-art low-power microwave-to-dc energy conversion techniques. A comprehensive picture of the state-of-the-art on this aspect is given graphically, which compares different technologies such as transistor, diode, and CMOS schemes. Since the very beginning of RF and microwave integrated techniques and energy harvesting, Schottky diodes as the undisputable dominant choice, have been widely used in mixing and rectifying circuits. However, in specific μW power-harvesting applications, the Schottky diode technique seemingly fails to provide a satisfactory RF–dc conversion. Subsequent to the highlighted limitations of current devices, this work introduces, for the first time, a nonlinear component for low-power rectification based on a recent discovery in spintronics, namely, the Magnetic Tunnel Junction, also called spindiode. An equivalent model of spindiode is developed to describe the frequency behavior. Full parametric studies show that the interfacial capacitance, rather than the geometric capacitance, as it is usually the case for diode, plays a crucial role in the drop of efficiency in microwave frequency applications

Analysis and design of wideband voltage controlled oscillators using self-oscillating active inductors.

Voltage controlled oscillators (VCOs) are essential components of RF circuits used in transmitters and receivers as sources of carrier waves with variable frequencies. This, together with a rapid development of microelectronic circuits, led to an extensive research on integrated implementations of the oscillator circuits. One of the known approaches to oscillator design employs resonators with active inductors electronic circuits simulating the behavior of passive inductors using only transistors and capacitors. Such resonators occupy only a fraction of the silicon area necessary for a passive inductor, and thus allow to use chip area more eectively. The downsides of the active inductor approach include: power consumption and noise introduced by transistors. This thesis presents a new approach to active inductor oscillator design using selfoscillating active inductor circuits. The instability necessary to start oscillations is provided by the use of a passive RC network rather than a power consuming external circuit employed in the standard oscillator approach. As a result, total power consumption of the oscillator is improved. Although, some of the active inductors with RC circuits has been reported in the literature, there has been no attempt to utilise this technique in wideband voltage controlled oscillator design. For this reason, the dissertation presents a thorough investigation of self-oscillating active inductor circuits, providing a new set of design rules and related trade-os. This includes: a complete small signal model of the oscillator, sensitivity analysis, large signal behavior of the circuit and phase noise model. The presented theory is conrmed by extensive simulations of wideband CMOS VCO circuit for various temperatures and process variations. The obtained results prove that active inductor oscillator performance is obtained without the use of standard active compensation circuits. Finally, the concept of self-oscillating active inductor has been employed to simple and fast OOK (On-Off Keying) transmitter showing energy eciency comparable to the state of the art implementations reported in the literature

Micropower Impulse Radio For Remote Controlled Insect Flight

Insects have remarkable strength and stamina compared to their body mass and fly and manuver effortlessly in ways that are impossible for present day robotic flyers. Therefore, efforts to control and direct flying insects for our own purposes have a huge potential payoff. One such effort, discussed in this dissertation, concerns the control of a Manduca Sexta moth by sending commands by radio to neural probes implanted in the thorax. The electronics hardware represents a major challenge in itself because the moth can carry only 700 milligrams, most of which is occupied by a small watch-battery. Ultimately, the moth must carry not only a radio receiver to pick up commands sent by the controller, but also a transmitter to return gathered information and fulfill its mission. Commercial "low-power", burst-mode radios have proven inadeqate because the battery cannot satisfy their peak power consumption. Instead, this dissertation focuses on the development of an alternative "impulse radio", which consumes power only during the ~100 picosecond interval required to generate a microwave pulse. The specific transmitter architecture presented here uses a nonlinear transmission line to directly convert digital signals provided by a microcontroller into microwave pulses broadcast by an antenna. This dissertation discusses (1) the background and theory of impulse-radios and (2) nonlinear transmission lines, (3) circuit board prototypes and (4) a CMOS implementation of the trans- mitter, (5) a study of the wireless link between the moth and its controller, as well as (6) efforts to implement the radio using light-weight, inexpensive plastic and polymer materials, before (7) reflecting on the potential of the new transmitter and possible directions for future work

Above-IC RF MEMS devices for communication applications

Wireless communications are showing an explosive growth in emerging consumer and military applications of radiofrequency (RF), microwave, and millimeter-wave circuits and systems. Applications include wireless personal connectivity (Bluetooth), wireless local area networks (WLAN), mobile communication systems (GSM, GPRS, UMTS, CDMA), satellite communications and automotive electronics. Future cell phones and ground communication systems as well as communication satellites will require more and more sophisticated technologies. The increasing demand for size and weight reduction, cost savings, low power consumption, increased frequency and higher functionality and reconfigurability as part of multiband and multistandard operation is necessitating the use of highly integrated RF front-end circuits. Chip scaling has made a major contribution to this goal, but today a situation has been reached where the presence of numerous off-chip passive RF components imposes a critical bottleneck to further integration and miniaturization of wireless transceivers. Microelectromechanical systems (MEMS) technology is a rapidly emerging enabling technology that is intended to replace the discrete passives by their integrated counterparts. In this thesis, an original metal surface micromachining process, which is compatible with CMOS post-processing, for above-IC integration of RF MEMS tunable capacitors and suspended inductors is presented. A detailed study on SF6 inductively coupled plasma (ICP) releasing has been performed in order to ascertain the optimal process parameters. This study has emphasized the fact that temperature plays an important role in this process by limiting silicon dioxide etching. Moreover, the optimized recipe has been found to be independent of the sacrificial layer used (amorphous or polycrystalline silicon) and its thickness. Using this recipe, 15.6 µm/min Si underetch rate with high Si: SiO2 selectivity (> 20000: 1) has been obtained. Single-air-gap and double-air-gap parallel-plate MEMS tunable capacitors have been designed, fabricated and characterized in the pF range, from 1 MHz to 13.5 GHz. It has been shown that an optimized design of the suspended membrane and direct symmetrical current feed at both ports can significantly improve the quality factor and increase the self-resonant frequency, pushing it to 12 GHz and beyond. The maximum capacitance tuning range obtained for a single-air-gap capacitor is 29% for a bias voltage of 20 V. The maximum capacitance tuning range obtained for a double-air-gap capacitor is 207% for a bias voltage of 70 V. The post-processing of X-FAB BiCMOS wafers has been successfully demonstrated to fabricate monolithically integrated VCOs with above-IC MEMS LC tank. Comparing a suspended inductor and the X-FAB inductor with the same design, it has been shown that increasing the thickness of the spiral from 2.3 to 4 µm and having the spiral suspended 3 µm above the passivation layers lead to an improvement factor of 2 for the peak quality factor and a shift of the self-resonant frequency beyond 15 GHz. No significant variation on bipolar and MOS transistors characteristics due to the post-processing has been observed and we conclude that the variation due to post-processing is in the same range as the wafer-to-wafer variation. Based on our metal surface micromachining process, coplanar waveguide (CPW) MEMS shunt capacitive switches and variable true-time delay lines (V-TTDLs) have been designed, fabricated and characterized in the 1 - 20 GHz range. A novel MEMS device architecture: the SG-MOSFET, which combines a solid-state MOS transistor and a metal suspended gate has been proposed as DC current switch. The corresponding fabrication process using polysilicon as a sacrificial layer has been developed to release metal gate suspended over gate oxide by SF6 plasma. Very abrupt current switches have been demonstrated with subthreshold slope better than 10 mV/decade (better than the theoretical solid-state bulk or SOI MOSFET limit of 60 mV/decade) and ultra-low gate leakage (less than 0.001 pA/µm2) due to the air-gap