Power Supply Conditions Research Articles

1-V 100-MHz embedded SRAM techniques for battery-operated MTCMOS/SIMOX ASICs

Multithreshold-voltage CMOS (MTCMOS) has a great advantage of lowering physical threshold voltages without increasing the power dissipation due to large subthreshold leakage currents. This paper presents the embedded SRAM techniques for high-speed low-power MTCMOS/SIMOX application-specified integrated circuits (ASICs) that are operated with a single battery cell of around 1 V. In order to increase SRAM operating frequency, a pseudo-two stage pipeline architecture is proposed. The address decoder using a pass-transistor-type NAND gate and a segmented power switch presents a short clocked wordline selection time. The large bitline delay in read operations is greatly shortened with a new memory cell using extra low-V/sub th/ nMOSs. The small readout signal from memory cells is detected with a high-speed MTCMOS sense amplifier, in which a pMOS bitline selector is merged. The wasted power dissipation in writing data is reduced to zero with a self-timed writing action. A 8 K-words/spl times/16-bits SRAM test chip, fabricated with a 0.35-/spl mu/m MTCMOS/SIMOX process (shortened effective channel length of 0.17 /spl mu/m is available), has demonstrated a 100-MHz operation under the worst power-supply condition of 1 V. At a typical 1.2 V, the power dissipation during the standby time is 0.2-/spl mu/W and that of a 100-MHz operation with a checkerboard test pattern is 14 mW for single fan-in loads.

Structure of Polycrystalline Silicon Films by Glow-Discharge Decomposition using SiH4/H2/SiF4 at Low Temperature

ABSTRACTFor poly-Si films prepared by a plasma-enhanced chemical vapor deposition, we examined the changes in the local structure caused by adding H2 and/or SiF4 in the SiH4 feed gases and by changing supplied rf power values. The conditions of low rf power supply, low H2 addition, and SiF4 addition allow formation of films with microcrystalline or nanocrystalline structures. In addition, the H2 or SiF4 addition was found to be effective in promotive growth of <111> or <110> grains, respectively. In such low crystallized films, it was suggested that high-angle boundary would be formed, leading to a decrease in the density of SiH2 and Si dangling bonds, and to an increase in g values.

DC harmonic distortion minimization of thyristor converters under unbalanced voltage supply using asymmetrical firing angle

Noncharacteristic harmonics of significant magnitude are produced at the output and input terminals of phase-controlled power converters under unbalanced voltage supply conditions. The concept of switching functions has been proposed before to evaluate the harmonics produced by a phase-controlled six-pulse power converter under both balanced and unbalanced power supply conditions. This paper extends the switching-functions approach to establish analytical equations for the DC output voltage harmonics produced by 12-, 18-, and 24-pulse power converters. The problem is approached from the standpoint of symmetrical voltage components. The increase in distortion under unbalance is caused by the appearance of a second harmonic component. A method, based on an asymmetrical firing angle, to cancel the second harmonic at the power converter output under unbalanced voltage supply is also presented. Cancellation of the second harmonic improves power converter DC output voltage quality.

Berlin bounds from insular to integrated operations [electricity supply

After 40 years of insular operation, the Bewag electric utility is now part of the Western European power supply grid. This article looks back at the power supply situation that developed in the West and East during the post-war period and describes the measures required to establish comparable power supply conditions after unification, the integration into the western European grid system and the control system put in place to optimize operations.

The pulse shape requirements of an ETC gun

An assessment of the trade-offs between total electrical energy, the pulse shape which is delivered to the gun and the chemical energy is presented for a future medium/large calibre (circa 130 mm) electrothermal-chemical (ETC) indirect fire gun system. In particular, this paper discusses the implications on total gun system volume i.e. including the electrical power supply and pulse conditioning system. The study considered electrical requirements of up to 25 MJ per shot. The potential performance improvements, compared with a similar sized chemical gun system, are also presented. The FNGUN finite difference based internal ballistics code has been used to simulate the likely trade-offs between electrical input energy, chemical energy and gun performance. This has shown that there is a dependence of the overall system performance on such parameters as: the anticipated electrical behaviour of the plasma; the shape of the electrical pulse supplied to the gun; and the internal ballistics of the gun. In particular it has been found that there is potentially a practical limit to the extent of pulse forming which is worth carrying out before parasitic losses in the pulse conditioning system become too great. Consequently, it is concluded that while some pulse shaping is necessary to meet the requirements of the internal ballistics, i,e, power increasing with time, there is little benefit from further optimisation of the pulse shape.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A single-bit-line cross-point cell activation (SCPA) architecture for ultra-low-power SRAM's

This paper describes a single-bit-line cross-point cell activation (SCPA) architecture, which has been developed to reduce active power consumption and to avoid increase in the size of high-density SRAM chips, such as 16-Mb SRAM's and beyond. A new PMOS precharging boost circuit, introduced to realize the single-bit-line structure, is also discussed. This circuit is suitable for operation under low-voltage power supply conditions. The SCPA architecture with the new word-line boost circuit is demonstrated with the experimental device, which is fabricated by a 0.4- mu m CMOS wafer process technology.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Calculation of harmonic currents in a three-phase convertor with unbalanced power supply conditions

The paper proposes a practical new method for calculating the harmonic currents of a three-phase bridge controlled rectifier under unbalanced supply conditions. Analytical equations for the harmonic currents are derived, taking into account the effects of DC current ripple and overlap angle. The proposed method is based on the frequency domain method and the rectifier switching functions. All the calculations are conducted only by algebraic calculations, and the accuracy is within 1.1% and 2.6% for the DC and AC side harmonics, respectively. The validity of the proposed method is demonstrated by comparison with the results of digital simulation.

The Bangladesh Meghna–Dhonagoda irrigation project

AbstractThe Meghna‐‐Dhonagoda Irrigation Project (MDIP) began in 1977 as an effort to reduce the constant threat of floods in the Chandpur district of Bangladesh, to expand agricultural production and employment opportunities, and to improve power supply, communication, social services, and health conditions. With a US $24 million loan from the Asian Development Bank (ADB), the project was to have been completed in 1983. Unfortunately, it remains incomplete and defective, despite long delays and an expenditure many times more than originally estimated. The project's failures primarily stem from inability or unwillingness of the Bangladesh Water Development Board (BWDB) to supervise the consultants and contractors and then to correct their mistakes. However, the ADB could also have played a more useful role in facilitating technical and managerial improvements.

Changing trends in the design of uninterruptible power supplies

In recent years the design of uninterruptible power supplies has undergone several major changes, mainly to benefit from developments in power semiconductor devices. This article describes the more important of these changes, and their influence on the application of power-supply protection and conditioning products

ワイヤカット放電加工における最適制御について（第２報）

This paper deals with the fundamental problems and their solutions in the machining with variable thickness in wire cutting EDM.So far, in this kind of machining, there have been such problems that the machining feed rate is not only slower, but also the machining accuracy is worse because of the constant electrical conditions of power supply. Then, the optimum control method has been developed to solve the above problems and was introduced by the first report.In this paper, the fundamental experiments were done to investigate the influences to the machining characteristics in the case of machining workpiece with variable thickness, and consequently the new optimum control method was developed on the basis of the above investigations, which appeared to be very effective to the improvement of the machining characteristics such as machining feed rate, machining accuracy.

Discussion on “Simulation studies of energy saving with chopper control on the Jubilee Line” and “Simulator for studying operational and power-supply conditions in rapid-transit railways”

Discussion on “Simulation studies of energy saving with chopper control on the Jubilee Line” and “Simulator for studying operational and power-supply conditions in rapid-transit railways”

Characterization of an MOS sense amplifier

A novel technique to characterize MOS sense amplifiers is described. The technique does not perturb the operation of the sense amplifier during characterization. An MOS sense amplifier has been characterized using this technique for various power supply and clock conditions. The characterization results are given to demonstrate the sensitivity of the technique.

Simulator for studying operational and power-supply conditions in rapid-transit railways

The paper describes the development of a computer-based simulator which may be used to study the relationships between train movements and power-supply conditions in a 2-road rapid-transit railway. The work was specifically undertaken to enumerate the energy saving consequent on the introduction of chopper-controlled traction-control equipment with regenerative-braking capability. In the simulator, track topology and signalling constraints are represented by a sequential block structure which is analogous to the fixed-block signalling arrangements. Tractive characteristics of the traction equipment are represented by models which are train speed and line voltage dependent. Powering and braking trains are represented by piecewise linearised models and a complete power-network solution is obtained at each update period. The simulator is written in extended Fortran IV and is reasonably efficient in computer processing time; e.g. running a 1 h service at 90 s headway on a 5 km section of track typically requires 4 min of central processor time on an ICL 1906A. Simulating 20 km of double track, with up to 100 trains per track, typically requires 36 Kwds of core. Although the simulator was developed specifically for energy-consumption calculations, the methods of representation are quite general. The simulator may thus be used to study other problems of interest in train performance and signalling studies.

Regional electric power system planning using mixed integer linear programming

The problem discussed in this paper is the “horizon year” planning of the electrical power supply system of a region. The technique discussed is based on handling information concerning the land use of the planning area. The results of the investigation will lead to a location of electrical power supply stations, valuation of their supply capacities and service boundaries, and an approximate measure of the system investment cost. The approach will be useful when analysing different trends in land use development with respect to the need for electric supply facilities.

Rate of Heat Release in Diesel Engines and Its Correlation with Fuel Injection Data

Basic heat release data have been obtained by analysis of cylinder pressure diagrams from a variety of engines, two-stroke and four-stroke, small (3·4-in bore) to medium size (12-in bore) over ranges of power, speed, and air supply conditions. The paper gives an account of early attempts to obtain a simple formula for heat release suitable for performance calculations by computer, using the simple and widely used single-zone model for conditions in the cylinder. The conclusion is reached that although it is possible to obtain useful calculations in this way, more sophisticated models are necessary for better understanding of conditions in the engine.

Television Broadcasting Facilities for Developing Areas

In planning construction of TV broadcasting facilities in developing areas, various restrictions such as shortage of skilled engineers and technicians, climate, quality of power supply and other environmental conditions must be considered. Precautions taken in the installation of facilities and the designing of equipment under such restrictions have been studied. The latest studio system in which an automatic operation selecting system aiming mainly at mechanization and rationalization of program operation has been introduced in an attempt to eliminate mistakes in operation.

Conversion of a railway system from d.c. to a.c. high-voltage operation

The paper describes the conversion from the 1500 V d.c. to the 25 kV and 6-25kV a.c. 50c/s system of electrification of the British Railways Eastern Region lines between Liverpool Street, Shenfield, Chelmsford and Southend (Victoria). The history of the projects and reasons for change are set out, together with the effect of electrification of other lines in the area. An endeavour has been made to cover in a balanced manner all principal aspects of the conversion operation from planning to conclusion, power supply, substations and switching stations, supervisory control, overhead-line equipment, rolling stock, signalling and telecommunications, civil engineering and the actual change-over sequence.It was a combined operation requiring most meticulous planning if the very heavy electric services operating over the lines concerned were not to be disrupted, with great inconvenience to hundreds of thousands of regular, daily passengers. The operation was successfully completed to a very restricted time schedule within little more than a month of the original target date owing to the unsparing efforts of many on the railway, with contractors and with the electricity supply undertakings.

The measurement of frequencies in the range 10,000 to 50,000 Mc/s

Frequencies up to about 50,000 Mc/s can be measured in terms of a standard frequency by means of the apparatus described. The unknown frequency is compared, by the heterodyne process, with that of a harmonic of an auxiliary oscillator, the frequency of which is adjustable about 3 000 Mc/s and measured by means of a frequency-meter previously described. The method is capable of an accuracy of the order of 1 part in 106, but the present sources of frequencies of the order of 104 Mc/s are not stable to this degree even with the highest practicable stability of operating voltages. For example, several low-power oscillators with frequencies in the region of 25 000 Mc/s were found to vary in frequency by as much as 1 part in 104 during periods of 15 min, even under very stable conditions of power supply and temperature. This instability of the unknown frequency imposes a practical limitation on the narrowness of the band-width of the components used for the detection of the heterodyne frequency. In the present design the accuracy is limited thereby to about 5 parts in 105.The apparatus has been applied to an investigation of an absorption wavemeter of the resonant cavity type, for a similar region of frequency, oscillating in the H11n mode. It was found that although the first half-wavelength may differ by as much as 5% from the value calculated from simple wave-guide theory, the subsequent half-wavelengths agree with this value within the accuracy of measurement. The frequency of resonance may be calculated from the measured value of wavelength with an accuracy of 2 parts in 104, but the same wavemeter can be calibrated in frequency and thereafter used as a single-reading instrument with an accuracy of 3 parts in 105.

Electric Drives for Steam-Electric Generating-Station Auxiliaries

For several years there has been an increasing trend toward all-electric drives for steam-station auxiliaries on account of the recognized advantages in flexibility, convenience, low operating cost, and comparable investment cost. Substantial economies in first cost also have been obtained along with further improvements in flexibility through the use of transformers as the sole means of station power supply. Gratifying reliability of performance has been achieved by co-ordinating design, backed by extensive tests, including momentary interruptions of station power supply, and has been incorporated in approximately 500,000 kw of modern plants of the 850-pound 900-degrees-Fahrenheit powdered-fuel-fired unit type. Operating experience has demonstrated the over-all reliability and economy of all-electric drives for station auxiliaries and of the use of transformers as the sole source of station power supply.

Sources of error in the efficiency determination of rotating electric machines

This paper treats of the sources and effect of errors entering into the determination of the power efficiency of rotating electric apparatus. It is shown that where the efficiency is determined by the so-called method of “summation of separate losses” the effect of possible errors in measurement is much less than when determined by the input-output method. In the input-output method of efficiency determination all measurements enter directly into the result, so that errors in them have a maximum effect. Attention is called to the different classes of errors likely to arise, viz., purely instrument errors, observation of reading errors, and errors due to changes in the operating condition of the machine under test. Particular stress is laid on observation errors, these probably being especially large under commercial operating conditions, due to excessive swinging of meter pointers. This swinging of meter pointers may be considerably reduced under special conditions of power supply and loading, and fairly consistent efficiencies then obtained. It is this necessity of operating under special conditions and observing all precautions possible in the layout and conduct of an input-output test that entirely offsets its apparent simplicity. It is next shown that, while the efficiency as determined by the loss method is not the true operating efficiency, it can be so modified by certain factors, depending upon the type of machine, as to approach very closely to that value — much closer, in fact, than the average input-output test. The probable relative accuracies are illustrated in Fig. 1. In consideration of the equivocal results usually obtained, and in view of the laboratory methods of testing required for making accurate input-output tests, the writers do not feel that that method is to be recommended