Areas Of Circuits Research Articles

Special issue on IEEE LASCAS2010

This special issue of the Springer Analog Integrated Circuits and Signal Processing (ALOG) is devoted to selected topics from the First IEEE Latin American Symposium on Circuits and Systems (LASCAS2010) that was held in Iguacu Falls, Brazil, 24th–26th February 2010. LASCAS is intended to be the IEEE Circuits and Systems Society flagship and international conference in Latin America. The selected papers reflect continuing trends toward higher levels of analog and digital circuit techniques covering a wide variety of subjects within the Analog and RF Integrated Circuits, Signal Processing, Digital Integrated Circuits and EDA fields, ranging from basic analog building blocks to system applications on several related domains. The major areas of Electronics, Circuits and Systems covered by LASCAS2010, drew 125 submissions from 30 countries spanning the globe (52% of submitted papers were from out of Latin America) and 53 contributions were selected by more than 75 reviewers for oral presentations and 21 for poster presentation. Among the published contributions in the LASCAS2010 proceedings, a pre-selection of 11 papers has been completed and corresponding Authors were invited for contributions to this Special issue. After receiving the full manuscripts and the assessment of reviewers, eight of them have been accepted for publication in this Special issue. The presented contributions in this Special issue deal with arithmetic circuits, IC architectures, power amplifiers, switching, FFT and variability and defects monitoring circuits dedicated for numerous building blocks of several applications. These contributions includes: (1) FPGA realization of high performance large size computational functions: multipliers and applications; (2) Design challenges of a fully integrated 65 nm CMOS half cascode SFDS PA; (3) An efficient parallel architecture for raytracing; (4) A linear 60 GHz 65 nm-CMOS power amplifier realization and characterization for OFDM signal; (5) Automatic adjustment of a medical imaging data acquisition system to unknown delays in the input communication channels; (6) Analysis of the conditions for the worst case switching activity in integrated circuits; (7) FPGA implementation and testing of a 128 FFT for a MB-OFDM receiver; (8) Delay sensing for long-term variations and defects monitoring in safety–critical applications. Selecting only 8 papers out of 125 contributions of the conference presentations is a difficult and critical task. We are aware that we probably missed many excellent contributions, but we do know that we did our best to put together a special issue as complete as possible. The Technical Program of LASCAS2010 is the result of a truly international cooperation of experts. We feel very much indebted to Technical Program Committee for their invaluable help to start LASCAS at the high standard that our scientific community has grown accustomed to expect from an CASS symposium. We wish to thank our coresearchers from all around the world, for choosing to submit their contributions to LASCAS for review. Due to their many and important contributions, we managed to create a Technical Program of high scientific quality. E. Kerherve IMS Laboratory, Universite Bordeaux 1, Bordeaux, France e-mail: eric.kerherve@ims-bordeaux.fr

Special issue on: advances in multidimensional systems and signal processing

The past five decades, in particular, have seen a continually growing interest in so-called two-dimensional (2D) or, more generally, multidimensional (nD) systems. This is clearly related to the wide variety of applications of both practical and/or theoretical interest. The key unique feature of an nD system is that the plant or process dynamics (input, output and state variables) depend on more than one indeterminate and hence information is propagated in several independent directions. Many physical processes have a clear nD structure. Also, the nD approach is frequently used as an analysis tool to assist, or in some cases enable, the solution of a wide variety of problems. A key point is that the applications areas for nD systems theory/engineering can be found within the general areas of Circuits, Control (with particular emphasis for Repetitive Processes and Iterative Learning Control) and Signal Processing (and many others). There are also still many unsolved problems in this area, solving of which requires new sophisticated mathematical methods and hence mathematical nD systems theory is still hot and developing extensively. The objective of this special issue is to report some recent advances in multidimensional systems and signal processing, in both theoretical development and practical applications. The contributions in this special issue can be grouped into three thematic areas:

Methylphenidate administration determines enduring changes in neuroglial network in rats

Repeated exposure to psychostimulant drugs induces complex molecular and structural modifications in discrete brain regions of the meso-cortico-limbic system. This structural remodeling is thought to underlie neurobehavioral adaptive responses. Administration to adolescent rats of methylphenidate (MPH), commonly used in attention deficit and hyperactivity disorder (ADHD), triggers alterations of reward-based behavior paralleled by persistent and plastic synaptic changes of neuronal and glial markers within key areas of the reward circuits. By immunohistochemistry, we observe a marked increase of glial fibrillary acidic protein (GFAP) and neuronal nitric oxide synthase (nNOS) expression and a down-regulation of glial glutamate transporter GLAST in dorso-lateral and ventro-medial striatum. Using electron microscopy, we find in the prefrontal cortex a significant reduction of the synaptic active zone length, paralleled by an increase of dendritic spines. We demonstrate that in limbic areas the MPH-induced reactive astrocytosis affects the glial glutamatergic uptake system that in turn could determine glutamate receptor sensitization. These processes could be sustained by NO production and synaptic rearrangement and contribute to MPH neuroglial induced rewiring.

Guest Editorial—ISCAS 2010 Special Issue

This special issue of the IEEE Transactions on Biomedical Circuits and Systems comprises expanded versions of selected papers presented at the 2010 IEEE International Symposium of Circuits and Systems (ISCAS 2010) held in Paris, France, from May 30 to June 2, 2010. The main theme of ISCAS 2010, Nano-bio circuit fabrics and systems, was highly synergistic with the focus of the Transac tions on emerging advances at the interface between circuits, systems, and biomedicine. Starting from a comprehensive list of 120 papers that were presented at the Biomedical Circuits and Systems, Sensors, Neural Systems, and Live demonstration sessions at the symposium, we selected eight papers which were highly rated by the ISCAS 2010 reviewers and which represented different areas of biomedical circuits and systems. After a thorough peer-review process, we selected a final set of papers for this Special Issue, covering circuits and sys tems-related topics in neural prosthesis, bio-telemetry, power management, and stimulators. While there were undoubtedly many other excellent papers that were presented at the ISCAS 2010, in this compilation, we strived to include high-quality papers that cover diverse areas of interest for the readers of this journal.

Guest Editorial Special Issue on ISCAS 2009

The 13 papers in this special issue present the latest advancements in the areas of analog and mixed-mode circuits and systems, digital circuits and systems and VLSI, and circuits and systems for communications.

Altered small-world brain functional networks and duration of heroin use in male abstinent heroin-dependent individuals

Although previous studies reported addiction-related alteration in resting-state brain connectivity, it is unclear whether these resting-state connectivity alterations were associated with chronic heroin use. In the current study, graph theory analysis (GTA) was applied to detect abnormal topological properties in heroin-dependent individuals. Several statistical parameters, such as degree ( D), clustering coefficient ( C) and shortest absolute path length ( L), were included to test whether or not there was significant correlation between these parameters and the duration of heroin use. Our results demonstrated abnormal topological properties in several brain regions among our heroin-dependent subjects. Some of these regions are key areas of drug addiction-related circuits (control, reward, motivation/drive and memory), while others are involved in stress regulation. In addition, the duration of heroin use was positively correlated with the parameter D in the right parahippocampal gyrus, left putamen and bilateral cerebellum, but negatively correlated with the parameter L in the same regions. Our findings suggested that there is abnormal functional organization in heroin-dependent individuals and that the duration of heroin use is a critical factor leading to the altered brain connectivity.

Recently published papers: Changing bandwagons, innovations and questioning dogma

This issue's Recently published papers commentary considers the popular and muddy waters of glycaemic control, stops briefly to ponder the incidence of pulmonary embolus in acute exacerbations of chronic obstructive pulmonary disease, promotes novel studies in the areas of traumatic brain injury and extracorporeal circuits, and rounds off with a potentially dogma-challenging study in cardiac arrest.

Ethanol-induced Changes in Proenkephalin mRNA Expression in the Rat Nigrostriatal Pathway

Endogenous opioid systems have been suggested to play a key role in ethanol reinforcement mechanisms and alcohol-drinking behavior. Ethanol induces differential alterations in opioid peptide expression in brain areas of the reward circuits, which may be linked to the reinforcing effects of ethanol. In addition, ethanol-induced alterations in opioidergic nigrostriatal transmission could be involved in brain sensitivity to ethanol and play a role in addictive processes. The aim of this work was to study the effects of acute ethanol administration on proenkephalin (proenk) mRNA expression in the rat substantia nigra and caudate-putamen (CP) for up to 24 h post treatment. Male Wistar rats received ethanol (2.5 g/kg) or distilled water by intragastric administration, and proenk mRNA expression was studied by in situ hybridization and densitometry. Ethanol transiently increased proenk mRNA expression in the CP 1 h after drug administration. Proenk mRNA levels remained elevated 2 h post treatment in the anterior-medial and medial-posterior regions of the CP. In contrast, ethanol decreased proenk mRNA expression in the substantia nigra pars compacta and pars reticulata 2 h after drug exposure. Alterations in enkephalin expression in the substantia nigra and CP in response to ethanol exposure could be involved in the mechanisms underlying brain sensitivity to the drug.

2 Gbit/s 05 μm complementary metal-oxide semiconductor optical transceiver with event-driven dynamic power-on capability

A 2 Gb/s0.5 microm complementary metal-oxide semiconductor optical transceiver designed for board- or backplane level power-efficient interconnections is presented. The transceiver supports optical wake-on-link (OWL), an event-driven dynamic power-on technique. Depending on external events, the transceiver resides in either the active mode or the sleep mode and switches accordingly. The active-to-sleep transition shuts off the normal, gigabit link and turns on dedicated circuits to establish a low-power (approximately 1.8 mW), low data rate (less than 100 Mbits/s) link. In contrast the normal, gigabit link consumes over 100 mW. Similarly the sleep-to-active transition shuts off the low-power link and turns on the normal, gigabit link. The low-power link, sharing the same optical channel with the normal, gigabit link, is used to achieve transmitter/receiver pair power-on synchronization and greatly reduces the power consumption of the transceiver. A free-space optical platform was built to evaluate the transceiver performance. The experiment successfully demonstrated the event-driven dynamic power-on operation. To our knowledge, this is the first time a dynamic power-on scheme has been implemented for optical interconnects. The areas of the circuits that implement the low-power link are approximately one-tenth of the areas of the gigabit link circuits.

Repetitive Peripheral Magnetic Stimulation (RPMS) for Rehabilitation of Central Paresis – Clinical Experimental Investigations and Technical Approach

Concept of Repetitive Peripheral Magnetic Stimulation (RPMS) is based on the activation of a reorganization process in the CNS (neuromodulation) by induction of a proprioceptive inflow to the CNS, which corresponds physiologically to the lost inflow during active movements. For the induction of this inflow, we use RPMS which depolarizes thick myelinated nerve fibers of the terminal sensorimotor branches. In contrast to fES, the magnetic field penetrates to deeper regions of the muscle, whereas the current caused by the electrical field will take the way of lowest resistance, thus being fairly limited spatially on the surface. Various components of an improvement due to RPMS are clinically and experimentally investigated: 1) Spasticity independent of the level of origin can always be suppressed by RPMS. In a clinical experimental investigation with spastic paresis of finger and hand extensors a dramatic decrease of spasticity together with an increase of voluntary movement could be demonstrated. 2) In a PET study of eight patients it was shown that, due to RPMS, areas of the fronto-parietal circuits which are involved in goal-directed controlled movements, are activated. 3) In disturbed goal-directed motor performances such as reaching and grasping, the regularity of the performed trajectory could be improved. 4) In patients with local tactile extinction (neglect), RPMS reduces the recognition error of different local tactile stimuli. Also the spatial cognition (position sense) can be improved by means of RPMS. We may assume that these various and long-lasting effects on the spinal and cortical levels are based on neuromodulation which is caused by muscle mechanoreceptor afferents. The development of a non-linear adaptive closed-loop control to induce coordinated finger movements by RPMS is the overall target in order to increase the therapeutic outcome. For this purpose our physiological findings from RPMS form the basis to realize the dominant and time-variant components (i.e., recruitment, spasticity, muscle fatigue and rehabilitation progress). These components have to be identified and compensated for by closed-loop control.

Physics and applications of the Schottky junction transistor

This paper presents the results from numerical simulations of a novel subthreshold transistor configuration. The device uses the input current from a forward-biased Schottky gate to control the larger current flowing in a depleted channel. Analytical approximations are used to derive the current gain of the transistor. The numerical simulations confirm the analytical derivation and show that a 0.5 /spl mu/m gate length device would have a cutoff frequency approaching 10 GHz for supply voltages less than 0.5 V. Possible applications of the device in the areas of micropower analog circuits and ULSI logic are discussed.

An undergraduate computer engineering rapid systems prototyping design laboratory

This paper describes a new two-quarter undergraduate capstone design class in our computer engineering curriculum. Design groups comprised of students from several different areas of specialization (e.g., software systems, very large scale integration (VLSI) devices and circuits, and computer architecture) design, simulate, implement, and evaluate a complete computing system. Typical examples of projects in the current sequence include a pipelined 32-bit RISC processor, a four-cell systolic array processor, and a video game. The goal is to produce simulation and hardware/software codesign as early as possible in the design process. Students execute software on simulation models prior to any hardware implementation. An assembler and a compiler are developed for the new design. Throughout the sequence, students participate in design reviews and must provide documentation of their designs. The final designs are implemented using an array of field programmable gate arrays (FPGAs) contained in a device called a hardware emulator. This allows for ease of design modifications while still having actual hardware for experimentation.

Characterization of Tungsten Deposited by GeH4 Reduction of WF 6, and Its Application as Contact Material to Si

W deposition by reduction of is a promising alternative for W deposition from and . The structure and composition of W layers deposited from and , are determined mainly by the deposition temperature. At temperatures between 300 and 400°C, W layers with the A15 bcc β‐W crystal structure are formed. These β‐W layers contain a substantial amount of homogeneously distributed Ge, roughly between 10 and 15 atomic percent (a/o). At higher temperatures, films are formed which consist of a mixture of β‐W and α‐W. At temperatures greater than 500°C, the layers consist exclusively of α‐W, and the Ge concentration is less than 1 a/o. The amount of β‐W in the film correlates with the resistivity and the amount of incorporated Ge. The incorporated Ge may promote the formation of the β‐W phase. Other process parameters, such as the total pressure and the ratio, have a minor effect on the structure and composition of the films. The β‐W deposited at ≈375°C is well suited for use as contact material to active Si areas of ULSI circuits. The contact resistivity of the β‐W layers to contacts is as low as the contact resistivity of annealed Al(Si 1%)/Si reference samples. The contact resistivity to the p+ diffusions was slightly higher than to the n+ diffusions. No leakage current was observed, indicating that no harmful attack of the active Si areas occurred during the deposition of β‐W. High resolution SEM pictures confirmed the absence of any significant Si consumption, encroachment, or tunnels at the Si interface. The β‐W layers are stable and transform to α‐W only at temperatures greater than 600°C during 30‐min anneals. After transformation to α‐W, silicidation to occurs. The β‐W is an effective diffusion barrier between Al and Si. During 30‐min anneals at 500°C, a β‐W film as thin as 60 nm prevented all Al/Si interdiffusion. A 120 nm thick β‐W film prevented Al/Si interdiffusion to at least 540°C. Finally, a deposition sequence consisting of the reduction of followed by or reduction of , combines the excellent interface properties of the process with the higher growth rate and better selectivity of the or process.

SiGe resonant tunneling hot-carrier transistor

A SiGe three-terminal hot-hole transistor using a double-barrier resonant tunneling structure as an emitter is fabricated. Injected carriers from the emitter are transferred near-ballistically into the collector through a thin base. The demonstrated main feature of the device is a controllable negative differential resistance in the collector current. Utilizing the high-speed characteristics of the tunneling process and negative differential resistance, integration of the device into Si technology could find applications in the areas of high-speed digital circuits, frequency multipliers, and tunable oscillators/amplifiers.

Trends in Motion Control Technology

Motion control systems constitute the workhorses in today's automated industrial environment. The vital role of motion control systems is being felt increasingly due to the recent trends of computer automation of factories, homes and offices which is ushering a new era of industrial revolution.Electronic motion control technology has moved a long way since the introduction of power semiconductor devices in the middle of the nineteen fifties. In the course of its dynamic evolution during the last three decades, motion control has grown as a diverse interdisciplinary technology and embraces the areas of power semiconductor devices, converter circuits, electrical machines, control theory, and signal electronics. The frontier of this technology has been considerably expanded recently with the advent of today's powerful microcomputers, VLSI circuits, power integrated circuits, and advanced computer-aided design techniques.This paper gives a comprehensive review of state-of-the-art motion control technology. It reviews the salient technical features of electrical machines, power electronic circuits, microcomputer control, VLSI circuits, machine controls, and computer-aided design techniques, and wherever possible, the salient trends of the technology have been indicated.

Conflict within dyadic interactions as a stimulant for conceptual change in physics

Research suggests that conventional teaching techniques have proved largely ineffective for dealing with the problem of science students’ misconceptions or alternative frameworks. This paper reports an investigation whereby inter‐personal conflict within dyadic interactions is used as a strategy for promoting development towards correct scientific conceptions in specific areas of electrical circuits and mechanics amongst first‐year tertiary physics students. The data indicate that a large number of physics students at the tertiary level hold non‐scientific conceptions of these physical phenomena. The dyadic interaction strategy proved effective as a means of encouraging students to actively and closely consider their own thinking about basic physical concepts. Further, results highlight the importance of inter‐personal conflict in the process of conceptual change.

Laser-enhanced patterning using photothermal effects: maskless plating and etching

We review our work on laser-enhanced plating and etching with emphasis on the chemical, electrochemical, and thermal mechanisms giving rise to the experimental observations. The metallurgical properties of the deposits and their applications, particularly in the field of microelectronics, are also discussed. The work on laser-enhanced electroplating and electrodeless plating includes high-speed deposition of copper, gold, and nickel by using the argon-ion laser as the source of localized energy. Deposition rates up to 3 orders of magnitude higher have been observed for laser-irradiated regions compared with nonirradiated ones. Mechanisms responsible for the plating enhancement are (1) enhanced chemical and electrochemical kinetics with increased temperature, (2) shifts in the local rest potential with temperature, and (3) local agitation of the solution as a result of large temperature gradients. Applications of these techniques to circuit design and repair as well as to high-speed plating of precious metals onto electrical contact areas of microelectronic circuits are considered. Experiments on high-speed laser-enhanced etching of several dielectrics are also reviewed. Volume removal rates as high as 106μm3/sec for an alumina/TiC ceramic and 105μm3/sec for 〈111〉 silicon using KOH as the etchant have been obtained.

Application of multioutput threshold-logic gates to digital-network design

Recent work in the areas of combinatorial logic-design theory and logic-gate circuits is leading to new concepts of logic-network realisation. In the paper, the multioutput threshold-logic gate is considered as a powerful configuration for future use both in s.s.i. package form and also for internal m.s.i./l.s.i. subsystem use. Design techniques to always fully utilise its logic power, particularly for multifunction applications, are, however, still awaited, although techniques which may be applied for simple networks are discussed, together with the possible line of further research in this area of increasing significance.

Mechanical Design Consideration in the ERMA System

This paper examines some of the early 1954 design concepts of ERMA (Electronic Recording Machine, Accounting), developed for the Bank of America to record commercial checking-account activity. Standardized plug-in circuit and relay modules are described which include printed wiring, an adapter for in-rack testing, and controlled air flown Emphasis is placed on reliability and easy access for maintenance and repair, by the use of integrated inter-rack raceway wiring, internal rack printed-wiring busses, and rear-access inter-connector wiring . The exclusive adoption of solderless connections for inter-package wiring, and the use of stock parts in preference to specials is stressed. It is discussed how standardization was accomplished in 22 different forms of 1500 electronic circuit packages, in the areas of connector pins, supply voltages, and distribution circuits. An integrated method of cooling is outlined, beginning with module-guiding metal rails fastened to a hollow shelf assembly; embracing shelf, rack, and cabinet ducts; and completed with underfloor plenums. The associated closed-loop cooling and filtering system is shown, which used a bypassed chilled-water arrangement and an electrostatic air filter. Special equipment, such as magnetic drums, cross-bar switch assemblies, and tape-transport mechanisms are treated. It is pointed out, when any complex device such as ERMA is being pioneered, that the design of the individual components must often be based on incomplete information -- leading to a change in specifications as functional relationships become more apparent. A specific warning is sounded that the number of inter-rack leads are usually underestimated, with an attendant poor access to terminals. Sixteen photographs contribute to a detailed presentation of the completed design.