Use Of Circuits Research Articles

Optical Cache Memory Peripheral Circuitry: Row and Column Address Selectors for Optical Static RAM Banks

We demonstrate WDM-enabled all-passive optical row and column address selector (RAS/CAS) circuits for use as optical static RAM (SRAM) bank peripherals in future optical cache memory implementations. We show that the introduction of the wavelength dimension in both the memory address and data word fields can lead to RAS and CAS architectures that rely exclusively on all-passive wavelength-selective configurations. An all-optical 2 × 4 RAS comprising a wavelength-selective filtering matrix (λ-matrix) and a wavelength-based CAS unit formed by a simple AWG element are demonstrated in proof-of-principle experiments at 10 Gb/s with error-free operation at 10 -9 BER value using two different types of WDM SRAM row Access Gate (AG): a cross-phase modulation SOA-MZI gate and a single SOA cross-gain modulation gate, with the first providing the higher performance compared to SOA module and the second offering lower power requirements between the two WDM AG. A chip-scale optical cache peripheral circuitry development path using Silicon-on-Insulator (SOI) ring resonators for the λ-matrix implementation is also presented and the proposed architecture is evaluated via physical layer simulations using SOAs as SRAM row AGs at 10 Gb/s for a 16×4 optical SRAM bank. Moreover, we discuss on possible improvements towards reducing insertion losses of the RAS/CAS modules in order to allow for increased block sizes. Finally, we provide a detailed analysis on the design and parameter specifications required for RAS and CAS block size scaling towards supporting higher-capacity optical SRAM banks.

Blaming the balloon: the risk of post-intubation tracheobronchial rupture

The pre-hospital retrieval service attended the home of an 82-year-old, 68 kg woman found unconscious with no evidence of trauma. Her airway was obstructed by vomit, oxygen saturation was 48 % and Glasgow Coma Score was six. The pupils were small and reactive. A cerebrovascular accident was presumed. The airway was suctioned, followed by rapid sequence induction with etomidate and succinylcholine. Intubation was performed with a size 7 Mallinckrodt endotracheal tube (ETT) (Mallinckrodt HiContour Oral Tracheal Tube Cuffed, Covidien llc, 15 Hampshire Street, Mansfield, MA 02048) containing a preformed stylet, which was removed once the ETT passed through the vocal cords. Post-intubation auscultation was symmetric, oxygen saturation rose to 95 %, and the ETT position was confirmed by capnography. No further drugs were administered for transfer while the hemodynamic profile was uneventful. A CT brain scan was normal, while a cervico-thoracic CT scan revealed mediastinal emphysema predominant in the left para-tracheal region, subcutaneous emphysema of the neck and a sub-glottic ETT cuff measuring 3 cm in diameter. No pneumothorax was present. Lesions of the trachea or oesophagus were not demonstrated. Changes in the lung fields were suggestive of bronchoaspiration, and the patient subsequently developed acute respiratory distress syndrome. The initial chest radiograph is shown in Fig. 1. While intubation had been uneventful, the patient was observed to cough vigorously on the ETT in the emergency department (ED), but administration of further sedation or neuromuscular blocking agent was withheld to allow subsequent neurological assessment. At this time, the Ambu bag circuit in use had no expiratory valve. Bronchoscopy showed an ETT tip 4 cm above the carina, food debris and purulent secretions at the carina and throughout the tracheobronchial tree. There was a 4 cm vertical tear of the posterior wall of the membranous trachea between the first and fifth tracheal rings. The ETT cuff was repositioned distal to the lesion. Surgical repair was not performed. Spontaneous tracheal healing on day 23 was confirmed by bronchoscopy, but the patient redeveloped pneumonia with no neurological improvement. An MRI imaging of the brain showed diffuse leucoencephalopathy, thought to be from hypoxia secondary to bronchoaspiration, on a background of dysphagia. After discussion with the family, treatment limits were agreed, and the patient subsequently died on day 40. J. R. Reilly Emergency Department and Anaesthesia Department, Lausanne University Hospital, Lausanne, Switzerland

A detailed look at electrical equivalents of uniform electrochemical diffusion using nonuniform resistance–capacitance ladders

This paper discusses equivalent-circuit modeling of the electrochemical impedance corresponding to one-dimensional diffusion in a uniform medium. It argues that, of the several equivalent circuits in use for such modeling, one – namely the nonuniform resistance–capacitance ladder – has attractive properties that are not shared by any other equivalent circuit. Explicit, analytical expressions are derived for the efficient development of this ladder equivalent, which provide advantages compared to computer optimization. Although the context of this work is battery modeling, the results presented can be of value in other fields where diffusion is studied and modeled.

Design of low‐noise CMOS transimpedance amplifier

PurposeThe purpose of this paper is to design a very low‐noise transimpedance amplifier (TIA) for a novel multi‐pixel CMOS photon detector which performs secondary electron (SE) detection in the scanning electron microscope (SEM).Design/methodology/approachThe TIA, which is implemented with three‐stage push‐pull inverters, is optimised using a nomograph technique developed in MATLAB. SPICE simulations are conducted to verify the results generated from MATLAB. Important performance figures are obtained experimentally and these measurements are compared with simulation results.FindingsA low‐noise TIA fabricated in a standard 0.35 μm CMOS technology was tested. Experimental results obtained show that the TIA connected to a photodiode with a junction capacitance of 0.8 pF can carry out its task effectively with a transimpedance gain of 126.9 dBΩ, a bandwidth of 9.8 MHz, an input‐referred noise of 2.50×10−13 A/√Hz and an SNR of 12.8. The power consumption of the TIA was 49.3 mW. These encouraging results have exhibited the potential of the circuit for use in the CMOS photon detector.Originality/valueThis paper presents a low‐noise transimpedance amplifier that is highly suitable to be used as a critical constituent block for the CMOS photon detector which aims to take over the role of photomultiplier tube in SE detection in the SEM. Solid‐state approaches have recently been reinvigorated for improving certain aspects of SE detection in scanning electron microscopy and this work has supported and contributed to the trend.

Reconfigurable gate array architecture for logic functions in tunneling transistor technology

This work describes the design of a reconfigurable logic gate array composed of single-electron tunneling (SET) transistors currently under investigation as potential post-CMOS candidates for future nano-scale integrated circuits for use in low-power embedded systems. A layer in the proposed array consists of a SET summing-inverter block replicated in subsequent blocks and extended to implement flexible logic functions in terms of the sum-of-products (SoP) and products-of-sum (PoS) forms. The reconfiguring of the array can be accomplished through the alteration of a block's logic function by way of a control voltage. The reconfigurable array can work normally at room temperature and can flexibly realize functions with better performance at lower power compared with pure MOSFET circuits.

Strain Gauge Amplifier Circuits

This paper presents several amplifier circuits for use with strain gauges. The circuits are inherently linear, produce four times the output of the standard Wheatstone bridge, and can easily be extended to accommodate multiple strain gauges. The implementation platform is the low-cost operational amplifier instead of the more expensive instrumentation amplifier, and circuit functionality has been verified using PSPICE simulations, and laboratory tests.

Organic half-wave rectifier fabricated by stencil lithography on flexible substrate

► A half-wave organic rectifier circuit is presented. ► The rectifier generates the DC supply voltage needed for organic RFID tags. ► Fabrication process is ambitious combination of stencil and classic lithography. We demonstrate the feasibility of fabrication method combining classic and stencil lithography for producing simple organic rectifying circuits for use in radio frequency range. Two stencil lithography steps are crucial because pentacene, once deposited on the wafer, cannot survive classic lithography resist removal. The presented rectifier is made of one organic Schottky diode followed by a MIM (Metal–Insulator–Metal) capacitor, integrated on the same flexible substrate. The devices are fabricated on a flexible polyimide foil by two aligned levels of stencil lithography using ALD deposited high-k hafnium-oxide, (HfO 2 – experimental κ ∼ 19).

Hierarchical Benchmark Circuit Generation for FPGA Architecture Evaluation

We describe a stochastic circuit generator that can be used to automatically create benchmark circuits for use in FPGA architecture studies. The circuits consist of a hierarchy of interconnected modules, reflecting the structure of circuits designed using a system-on-chip design flow. Within each level of hierarchy, modules can be connected in a bus, star, or dataflow configuration. Our circuit generator is calibrated based on a careful study of existing system-on-chip circuits. We show that our benchmark circuits lead to more realistic architectural conclusions than circuits generated using previous generators.

Design and Simulation of a MGy Radiation Tolerant Signal Conditioning Circuit for Resistive Sensors in 0.7 $\mu$m CMOS

This paper presents the design and simulation results of a radiation tolerant configurable discrete time CMOS signal conditioning circuit for use with resistive sensors like strain gauge pressure sensors. The circuit is intended to be used for remote handling in harsh environments in the International Thermonuclear Experimental fusion Reactor (ITER) (experimental validation still needs to be performed). The design features a 5 V differential preamplifier using a Correlated Double Sampling (CDS) architecture at a sample rate of 20 kHz and a 24 V discrete time post amplifier. The gain is digitally controllable between 27 and 400 in the preamplifier and between 1 and 8 in the post amplifier. The nominal input referred noise voltage is only 8.5 $\mu {\rm V}_{\rm rms}$ while consuming only 1 mW. The circuit has a simulated radiation tolerance of more than 1 MGy.

A Low Noise 2.7 THz Waveguide-Based Superconducting Mixer

We report on a low noise waveguide-based heterodyne mixer utilizing a superconductiang NbN hot electron bolometer (HEB) operating near 2.7 THz. The mixer is an NbN nano-bridge integrated with a gold bowtie planar antenna on an ultra-thin silicon substrate of ~ 2-3 μm thickness. To produce the waveguide embedding circuit for use at such a high frequency, we adopted a novel approach combining UV-lithography and micro-plating techniques. The mixer response agreed precisely with model predictions, and we measured a minimum uncorrected DSB receiver noise temperature of 965 K at an LO frequency of 2.74 THz.

An alternative improved method for the homogeneous dispersion of CNTs in Cu matrix for the fabrication of Cu/CNTs composites

Copper has a wide range of applications due to its excellent properties (high thermal and electrical conductivity). Carbon nanotubes (CNTs) are widely used as a reinforcing material due to their superior properties. Copper/Carbon nanotube (Cu/CNTs) composites show enhanced mechanical, electrical and thermal properties as compared to pure Cu and Cu composites. Hence, Cu/CNTs composites have tremendous applications. Cu/CNTs are being developed for use as antifungal and antimicrobial agents, which can lead to their further use in biomedical devices and implant materials. The versatility of this material is such that Cu/CNTs are being developed for use in ultra-large scale integrated circuits for use in the latest integrated circuits and semiconductor chips. The composite material is being used as heat sinks for various industries. Cu/CNTs are now also being employed as catalysts for various industrial reactions. Fuel cell electrodes based on Cu/CNTs are being developed to replace expensive Pt/Pd-based electrodes, currently being used. Another application in the energy sector is the use of Cu/CNTs in direct methanol fuel cells and in methanol gas reforming for H2 production. These extensive applications provided motivation for the current work. However, these applications can only be realized if a stable and uniform Cu/CNTs composite powder can be made. The challenges in fabricating Cu/CNTs composites are: (1) homogeneous dispersion of CNTs in Cu matrix, (2) interfacial bonding between CNTs and Cu matrix and (3) retention of structural integrity of CNTs. Powder metallurgy (PM) has been widely used, but dispersion of Cu/CNTs remains an issue. We employed the molecular level mixing method (MLM), coupled with high energy ball milling (BM) to overcome above mentioned issues. To the best of our knowledge, this is a new process for the homogeneous dispersion of CNTs in copper and has been reported for the first time. To produce a homogenous mixture of Cu and CNTs, a combination of MLM and BM was used in the present work. This method involves using a Cu salt/CNTs mixture in desirable weight ratio (CNTs being were taken in a high concentration), followed by chemical reduction in aqueous medium using NABH4 as reducing agent and EDTA as the oxidation control agent. The resultant mixture (Copper/Carbon nanotube) was mixed with pure Cu using BM. The composites were fabricated using PM, in which the composite powders were first cold pressed at 500–550 MPa followed by sintering at 550–900 °C in a vacuum of 10−2 Torr. Characterization was carried out using SEM, XRD and HRTEM, and various mechanical properties were measured using a Universal testing Instron machine.

1 GHz and counting

A 1 gigacount/second single photon detector has been built by UK-based researchers at Toshiba in collaboration with the Cambridge University Engineering Department. By developing a ‘self-differencing’ circuit for use with a thermoelectrically cooled semiconductor avalanche photodiode (APD) they have achieved the highest count rate among any single photon detectors.“We are developing quantum key distribution (QKD) to protect future communication networks,” said Dr Zhiliang Yuan from the Quantum Information Group at Toshiba Research Europe Ltd. “This technology is advantageous because its security is guaranteed by quantum mechanics. However, it also poses technical challenges, one of which is high-performance single photon detectors.“So far, our self-differencing APDs have allowed the QKD secure key rate to break the 1 Mbit/s barrier for the first time. As a practical device they have withstood rigorous tests in the field environment in the 2010 Tokyo QKD network.”

A general approach to low noise readout of terahertz imaging arrays

This article describes the theory and design of an ultra-low noise electronic readout circuit for use with room temperature video-rate terahertz imaging arrays. First, the noise characteristics of various imaging detectors, including low resistance bolometers and high resistance diodes are discussed. Theoretical approaches to white and 1/f noise mitigation are examined, and a corresponding low-noise readout circuit is designed, built, and tested. It is shown that the circuit is capable of achieving detector limited noise performance for use in room temperature terahertz imaging systems. A thorough noise analysis of the circuit provides the necessary information for applying the readout circuit to any type of imaging detector, and more generally, any measurement of small signals from various source impedances in the presence of white and 1/f noise. W-band measurements of an 8-element, high-resistance detector array, and a 32-element, low-resistance detector array demonstrate the usefulness of the readout circuit. Finally, recommended circuit configurations for various detectors in the literature are provided, with theoretical performance metrics summarized.

An Autocalibrated All-Digital Temperature Sensor for On-Chip Thermal Monitoring

This brief presents an autocalibrated all-digital temperature sensor circuit for use with on-chip thermal sensing applications. The proposed temperature sensor eliminates the need for two-temperature-point calibration in prior temperature sensors. Therefore, temperature sensor calibration efforts in high-volume production can be significantly reduced. The proposed design uses reference clock period information to perform self-calibration, and thus, effects of process variation can be removed. Subsequently, the accuracy of the proposed temperature sensor can be improved with very small area cost and low power consumption. The temperature sensor is implemented with a standard performance 65-nm complementary metal-oxide-semiconductor technology. The core area is 0.01 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , and the power consumption of the proposed circuit is 150 μW with a 1-V supply. Since the proposed temperature sensor can be easily calibrated with a reference clock, the proposed design is very suitable for dynamic thermal management applications in a system-on-a-chip era.

The Influence of the Cathode Heating System of the Inverter Ballast on the Position of the Cathode Spot

Recently, fluorescent lamps having a higher output and longer life have been developed in the field of residential lighting. If lamp life can be estimated by measuring electronic signals such as lamp current and cathode heating current, the estimation would be very useful for designing lamp operating systems. To estimate lamp life, it is very important to know where the light-spot position, which is the spot that emits electrons, exists on the cathode. It was reported that the light-spot position for one operating system could be located by measuring the electronic signals. However, there are many kinds of electronic circuits for use in fluorescent lamp operating systems. It has not been confirmed whether this method for locating the light-spot position is useful for other kinds of electronic circuits. In this paper, the authors reveal that the method mentioned above is useful and that the way of heating the cathode in the electronic circuit influences how the spot moves as burning time passes.

A Ka-band tunable direct-conversion correlation reflectometer for NSTX

The recent availability of broadband microwave quadrature mixers in the Ka-band (28-40 GHz) of frequencies has allowed the fabrication of low-cost direct-conversion detection circuits for use in the variable-frequency correlation reflectometer on the National Spherical Torus eXperiment (NSTX). The quadrature receiver in this case can be implemented as a simple homodyne circuit, without the complication of a single-sideband modulator or a feedforward tracking circuit present in more typical designs. A pair of direct-conversion receivers is coupled with broadband microwave voltage-controlled oscillators to construct a flexible dual-channel radar system with a fast frequency settling time of ∼160 μs. A detailed description of the design and a full characterization of the hardware are provided. Examples of turbulence measurements from radial and poloidal correlation reflectometry on NSTX using a poloidal array of antennas (oriented normal to the magnetic flux surfaces for conventional reflectometry) are presented.

Compact feed circuit with quarter‐wavelength transmission line matrix controlling beams in three directions including boresight

AbstractA compact feed circuit with a λ/4 transmission line matrix circuit for use in array antennas to control beams in three directions, including boresight, is presented. The feed circuit antenna is composed of five switches and λ/4 transmission lines, and the feeding matrix circuit yields phase differences of ±90° and 0°. The feed circuit can obtain a reliable output signal, as there is only a small degree of deviation of output signal with variations in the line width. The feed circuit is simulated, fabricated, and evaluated for the ISM band, and the measured characteristics agree well with the results of the simulation. The size of the feed circuit is 45 (H) ×48 (W) ×3 (T) mm. © 2010 Wiley Periodicals, Inc. Electron Comm Jpn, 93(4): 10–17, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10218

Application of Response Surface Methodology (RSM) in Microspeaker Design Used in Mobile Phones

This paper proposes a technique for designing magnetic circuits for use in microspeakers, using the finite element method (FEM) and response surface methodology (RSM). RSM is a collection of statistical and mathematical techniques, used to find the best-fit representation of the response of the physical system under investigation. RSM was used to optimize the dimensions of the magnetic circuit. The optimization resulted in the following dimensions: an inner magnet radius (variable A) of 3.595 mm, a yoke thickness (variable B) of 0.4 mm, and a top plate thickness (variable C) of 0.25 mm.

Battery powered neuromuscular stimulator circuit for use during simultaneous recording of myoelectric signals

Surface Functional Electrical Stimulation (FES) requires high stimulation voltages. A step-up transformer in the output stage of the stimulation circuit is often used. In the present technical paper a voltage controlled current source (VCCS) is presented as an alternative to the transformer coupling. Two (master–slave) coupled transconductance amplifiers (TAs)—in series with pre-charged capacitors—are used to drive the output current. After each stimulation pulse the capacitors are recharged to a high voltage by a switch mode power supply (SMPS). A multiplexer in the output stage is used to provide biphasic output. Output rise-time (10–90%) was less than 2 μs at 100 mA output. Biphasic charge balanced stimulation current can be produced with a net current to ground of less than 20 nA, thus virtually separated from ground. The circuit permits recording of the volitional myoelectric signal from the stimulated muscle. It is part of a portable myoelectrically controlled FES system powered by 2 AA batteries and currently used in clinical trials.

An optimized 2.4GHz VCO circuit design and simulation with high-Q MEMS LC-tank

This paper focuses on design of high-performance MEMS LC-tank circuit for use in CMOS voltage controlled oscillators (VCO) operating at 2.4 GHz. The high-Q air suspended inductor has been designed by inductance of 2.87 nH using MEMS technology to reduce the resistive loss and the substrate loss. A MEMS two-gap tunable capacitor has been designed. The DC voltage is 2.5 V which is applied to the plates and the results of 2.04 pF could be achieved. The pull-in voltage has been optimized to achieve low phase noise, low power consumption VCO. Through this optimization, less phase noise (−117.7 dBc/Hz at 100 KHz) and lower power consumption (11 mW) have been obtained.