[신간안내] Computational Electrodynamics (the finite difference time - domain method)

This expanded and thoroughly revised edition of Thomas H. Lee's acclaimed guide to the design of gigahertz RF integrated circuits features a completely new chapter on the principles of wireless systems. The chapters on low-noise amplifiers, oscillators and phase noise have been significantly expanded as well. The chapter on architectures now contains several examples of complete chip designs that bring together all the various theoretical and practical elements involved in producing a prototype chip. First Edition Hb (1998): 0-521-63061-4 First Edition Pb (1998); 0-521-63922-0

The Design of CMOS Radio-Frequency Integrated Circuits: RF CIRCUITS THROUGH THE AGES

Wireless medical telemetry permits the measurement of physiological signals at a distance through wireless technologies. One of the latest applications is in the field of implantable and ingestible medical devices (IIMDs) with integrated antennas for wireless radiofrequency (RF) communication (telemetry) with exterior monitoring/control equipment. Implantable medical devices (MDs) perform an expanding variety of diagnostic and therapeutic functions, while ingestible MDs receive significant attention in gastrointestinal endoscopy. Design of such wireless IIMD telemetry systems is highly intriguing and deals with issues related to: operation frequency selection, electronics and powering, antenna design and performance, and modeling of the wireless channel. In this paper, we attempt to comparatively review the current status and challenges of IIMDs with wireless telemetry functionalities. Full solutions of commercial IIMDs are also recorded. The objective is to provide a comprehensive reference for scientists and developers in the field, while indicating directions for future research.

Implantable and ingestible medical devices with wireless telemetry functionalities: a review of current status and challenges.

The application of microfabrication to the development of biomedical implants has produced a new generation of miniaturized technology for assisting treatment and research. Microfabricated implantable devices (μID) are an increasingly important tool, and the development of new μIDs is a rapidly growing field that requires new microtechnologies able to safely and accurately function in vivo. Here, we present a review of μID research that examines the critical role of material choice in design and fabrication. Materials commonly used for μID production are identified and presented along with their relevant physical properties and a survey of the state-of-the-art in μID development. The consequence of material choice as it pertains to microfabrication and biocompatibility is discussed in detail with a particular focus on the divide between hard, rigid materials and soft, pliable polymers.

Materials for microfabricated implantable devices: a review

The results of a comprehensive investigation into the characteristics and optimization of Inductors fabricated with the top-level metal of a submicron silicon VLSI process are presented. A computer program which extncts a physics-based model of microstrip components that is suitable for circuit (SPICE) simulation has been used to evaluate the effect of variations in melallization, layout geometry, and substrate parameters upon monolithic inductor performance. Three-dimensional (3-D) numerical simulations and experimental measurements of inductors were also used to benchmark the model aecuncy. It is shown in this work that low inductor Q is primarily due to the restrictions imposed by the thin interconnect metallization available in most very large scale integration (VLSI) technolocies, and that computer optimization of the inductor layout can be used to achieve a 50% improvement in component Q-factor over unoptimized designs.

The Modeling, Characterization, and Design of Monolithic Inductors for Silicon RF IC's

This study quantifles the detuning and impedance mismatch of antennas implanted inside the human body. Maximum frequency shifts caused by variations in the electrical properties of body tissues and difierent anatomical distributions were derived. The results are relevant to the design of implantable antennas. They indicate the bandwidth enhancement and initial tuning necessary for correct functioning. The study was carried out using electromagnetic modeling based on the flnite-difierence time-domain method and high- resolution anatomical models. Four anatomical computer models of two adults and two children were used. The implanted antennas operated in the Medical Implant Communication Service band. The most important detuning and impedance mismatch was found for subcutaneous locations and in areas where a layer of fat tissue was present. The maximum frequency shift towards higher frequencies was 70MHz. The frequency shift did not occur symmetrically around 403MHz, but was shifted towards higher frequencies.

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Detuning study of implantable antennas inside the human body

A new design methodology for radiofrequency circuits is presented that includes electromagnetic (EM) simulation of the inductors into the optimization flow. This is achieved by previously generating the Pareto-optimal front (POF) of the inductors using EM simulation. Inductors are selected from the Pareto front and their ${S}$ -parameter matrix is included in the circuit netlist that is simulated using an RF simulator. Generating the EM-simulated POF of inductors is computationally expensive, but once generated, it can be used for any circuit design. The methodology is illustrated both for a single-objective and a multiobjective optimization of a low noise amplifier.

/pdf/an-automated-design-methodology-of-rf-circuits-by-using-49rwvior32.pdf

An Automated Design Methodology of RF Circuits by Using Pareto-Optimal Fronts of EM-Simulated Inductors

In this paper, a new methodology for the automated generation of the optimal performance trade-offs of integrated inductors is presented. The methodology combines a multiobjective optimization algorithm with electromagnetic simulation to get highly accurate results. A set of sized inductors is obtained showing the best performance trade-offs for a given technology. Unlike reported approaches for inductor synthesis, performance trade-offs are generated offline, i.e., before any specific inductance or quality factor are required. The tight efficiency versus accuracy trade-off of existing approaches is, in this way, avoided and performance evaluation via electromagnetic simulation becomes affordable.

/pdf/automated-generation-of-the-optimal-performance-trade-offs-37ddmaq88k.pdf

Automated Generation of the Optimal Performance Trade-Offs of Integrated Inductors

This paper presents a study of the design, fabrication, and electromagnetic (EM) characterization of 3-D printed conical inductors for broadband radio frequency applications. A process flow for the design and fabrication of these components using stereolithographic 3-D printing in combination with electroless copper plating is proposed. A whole set of the samples corresponding to different geometrical parameters has been designed and fabricated using the proposed process flow. These parameters include the cone angle, the number of turns of the spiral, the metal width, and metal pitch. Experimental measurements and EM simulations have been carried out to determine the performance of conical inductors in terms of the equivalent inductance, the quality factor, and the frequency of the first resonance. The obtained results are discussed and correlated with the geometrical parameters of the samples and technological parameters of the fabrication process.

Study of 3-D Printed Conical Inductors for Broadband RF Applications

Changes in electromagnetic energy absorption were studied in the presence of subcutaneous antenna devices implanted for biotelemetry applications. We examined the influence on energy absorption of these devices as passive metallic implants when incoming RF energy is present. We aim to contribute to the optimization of the implant location in order to reduce a possible energy increase on tissues. The research was carried out using electromagnetic modeling based on the finite-difference time-domain method. The calculations were performed in terms of electric field and SAR distributions calculated for five different frequency bands (from 0.9 to 17 GHz) covering most current telecommunications standards. The focus was on both far-field and near-field exposure. The results lead us to propose the subcutaneous zone nearest to the surface of the skin as the most appropriate place to locate these devices.

N. Vidal

Papers

Detuning study of implantable antennas inside the human body

An Automated Design Methodology of RF Circuits by Using Pareto-Optimal Fronts of EM-Simulated Inductors

Automated Generation of the Optimal Performance Trade-Offs of Integrated Inductors

Study of 3-D Printed Conical Inductors for Broadband RF Applications

Changes in Electromagnetic Field Absorption in the Presence of Subcutaneous Implanted Devices: Minimizing Increases in Absorption