Leakage Variation Research Articles

Exact and Heuristic Approaches to Input Vector Control for Leakage Power Reduction

Leakage power consumption is an increasingly serious problem in very large-scale integration circuits, especially for portable applications. Two novel approaches to leakage power minimization in static complementary metal-oxide-semiconductor circuits that employ input vector control (IVC) are investigated. The authors model leakage effects by means of pseudo-Boolean functions. These functions are linearized and incorporated into an exact (optimal) integer linear programming (ILP) model, called virtual-gate ILP, which analyzes leakage variation with respect to a circuit's input vectors. A heuristic mixed-integer linear programming (MLP) method is also proposed, which has several advantages: it is faster, its accuracy can be quickly estimated, and tradeoffs between runtime and optimality can easily be made. Furthermore, the MLP model also provides a way to estimate a lower bound on circuit leakage current. The proposed methods are used to generate an extensive set of experimental results on leakage reduction. It is shown that average leakage currents are usually 1.25 times the minimum, confirming the effectiveness of IVC. The heuristic MLP approach is shown to be approximately 13.6 times faster than the exact ILP method, whereas finding input vectors whose power consumption is only a few percent above the optimum. In addition, the lower bound estimated by the MLP model is also within a few percent of the optimal value

A process variation compensating technique with an on-die leakage current sensor for nanometer scale dynamic circuits

This paper describes a process compensating dynamic (PCD) circuit technique for maintaining the performance benefit of dynamic circuits and reducing the variation in delay and robustness. A variable strength keeper that is optimally programmed based on the die leakage, enables 10% faster performance, 35% reduction in delay variation, and 5times reduction in the number of robustness failing dies, compared to conventional designs. A new leakage current sensor design is also presented that can detect leakage variation and generate the keeper control signals for the PCD technique. Results based on measured leakage data show 1.9-10.2times higher signal-to-noise ratio (SNR) and reduced sensitivity to supply and p-n skew variations compared to prior leakage sensor designs

PVT-Aware Leakage Reduction for On-Die Caches With Improved Read Stability

Effectiveness of previous SRAM leakage reduction techniques vary significantly as the leakage variation gets worse with process and temperature fluctuation. This paper proposes a simple circuit technique that adaptively trades off overhead energy for maximum leakage savings under severe leakage variations. The proposed run-time leakage reduction technique for on-die SRAM caches considers architectural access behavior to determine how often the SRAM blocks should enter a sleep mode. A self-decay circuit generates a periodic sleep pulse with an adaptive pulse period, which puts the SRAM array into a sleep mode more frequently at high leakage conditions (fast process, high temperature) and vice versa. An 0.18-/spl mu/m 1.8-V 16-kbyte SRAM testchip shows 94.2% reduction in SRAM cell leakage at a performance penalty less than 2%. Measurement results also indicate that our proposed memory cell improves SRAM static noise margin by 25%.

Effect of Ti-rich TiN as a Co-salicide capping layer for 0.15 um embedded flash memory devices and beyond

This work is aimed at the practical effect of Ti-rich TiN as a Co-salicide capping layer on Gate-Induced Drain Leakage (GIDL) variation on High Voltage (HV) transistors in embedded Flash memory devices. It is reported that Ti-incorporating capping layer into Co film may reduce GIDL of HV transistor dramatically by ∼2 order magnitude of leakage at V dd > 8 V of drain bias, resulting in better yield and reliability performance. This is due to the removal of contaminated silicon oxide from the reaction between diffused Ti and interfacial contaminated oxide at the Co/Si interface during salicide process. I–V measurement to define the leakage behavior and transmission electron microscopy (TEM) with element mapping analysis to investigate the Co/Si interface of S/D junction area have been carried out. Furthermore, we verified that Ti-rich TiN layer with the advantages of both Ti and TiN film could suppress GIDL with a larger process window due to the minimization of the sensitivity of Co-salicide process to Si-surface condition as well as provided a good junction leakage uniformity and contact resistance ( R c), concurrently.

Unified functional tolerancing approach for precision cylindrical components

Current geometric dimensioning and tolerancing (GD&T) standards dictate that the geometry of a cylindrical manufactured part should be characterized in terms of its roundness, straightness, cylindricity and diameter. However, standards define the form errors using maximum peak-to-valley values – a very simplistic geometric description. As a result, measurements based on GD&T definitions for manufactured parts are ineffective for identifying and diagnosing error sources in a manufacturing process. This paper introduces a new tolerancing scheme for cylindrical parts and its application to functional tolerancing for diesel engine components. The new tolerance definition method is based on Legendre and Fourier polynomials for modelling and characterizing typical geometric errors found in machined cylindrical parts. As the tolerance parameters in the new tolerancing scheme represents the whole profile characteristics of the part geometry, they provide a direct link to part function and error sources of manufacturing processes. This paper describes the Legendre and Fourier polynomials-based tolerancing method. Typical machining errors of cylindrical parts in precision turning and grinding processes are analysed and modelled using the new tolerancing method. Application of the new tolerancing method is illustrated with an example of functional tolerancing a production diesel engine component, which shows that the new tolerancing method is effective for the specification and control of fuel leakage variation in diesel engine component design and manufacturing.

Geothermal Exploration Using Surface Mercury Geochemistry: ABSTRACT

Shallow soil mercury surveys are an inexpensive and effective exploration tool for geothermal resources. In a geothermal system at depth, mercury is leached from the country rock and transported to the surface by the geothermal fluids. The mercury is fixed by clays and organic material in the soil above the geothermal system and can be detected by analyzing the near-surface soil. Surface mercury surveys can be used in regional reconnaissance to discriminate prospective from nonprospective areas. Closely spaced mercury surveys over individual prospects typically enhance the structural understanding of the prospect and show which structures are important as migration pathways. The use of probability graphs greatly enhances the interpretation of mercury geochemical data. Probability graphs have a logarithmic ordinate scale versus a cumulative percentage abscissa scale. This graph is arranged such that a typical lognormal population plots as a straight line on the graph. Deviations from a straight line show deviations in the data from a standard lognormal population distribution. The mercury data are easily plotted on the graph and can be evaluated visually. Anomalous and background populations can be separated consistently even when considerable overlap occurs between populations. In Nevada and California, soil mercury surveys have detected up to four distinct mercury populations in one area. These populations are related to background End_Page 952------------------------------ over different bed-rock types and to variations in leakage from the geothermal system at depth. An interpretation of the mercury populations in light of the available geologic and structural characteristics of a prospect can significantly increase the understanding of the geothermal resource. End_of_Article - Last_Page 953------------

A High-Sensitivity Particle Spectrometer for the Measurement of Polar-Cap-Absorption Events

A hybrid particle spectrometer possessing high-sensitivity and high-time resolution for the measurement of precipitating protons, electrons, and alpha particles during Polar-Cap-Absorption (PCA) events has been successfully operating in space aboard the OV1-18 satellite since 23 March 1969. Detection of protons in the energy range 1.2 to 46 MeV and integral above 70 MeV, electrons in the range 0.4 to 1.9 MeV and alpha particles in the range 7 to 20 MeV is performed with sensitivities as high as 0.1 particle/cm2-sec and with a dynamic intensity range of six decades through the use of a transmission solid-state detector in conjunction with a total-energy, plastic-scintillation detector. Acceptable pulses from each detector, as determined by various combinations of coincidence logic, are analyzed with separate 15-channel pulse-height analyzers of the analog-to-digital type. A detailed description of the spectrometer, including a unique biasing technique which maintains a constant potential across the solid-state detector, independent of leakage variations due to temperature and radiation damage, will be given. Some typical characteristics of the particles measured during several PCA events will also be presented.

Leakage Rejection in Beam-Switched CW Radars

This paper is directed to the problem of transmitter-receiver leakage rejection in CW and FMCW radars which employ stepped-scanning antennas. An IF carrier-elimination filter has been devised and analyzed which provides leakage-rejection capabilities limited only by leakage variations during stationary beam positions. Leakage rejection is provided by coherently reducing the signal to zero IF, rejecting the leakage components by a combination synchronous switch and high-pass filter, and remodulation onto a second IF carrier. The filter operates in a linear manner. Positive and negative senses of Doppler signals are retained. The spectrum of the input signal is faithfully reproduced in the output with the exception of a sharp notch at the input carrier frequency. In one configuration, the minimum notch bandwidth is limited by the on-time of each beam, and is approximately equal to one-half the reciprocal of this on-time. A more complex arrangement removes this restriction, permitting a minimum notch width which is limited only by the cutoff frequency of a high-pass RC filter. The simpler configuration has been used with the AN/APN-118 Doppler Navigation Radar, a system which was developed under contract with the U. S. Signal Corps, Fort Monmouth, N. J., by the Sperry Gyroscope Company.

Pulse Amplifiers Using Transistor Circuits

Transistor circuits simplify the design of pulse amplifiers because of their essentially linear gain characteristics. The low heat dissipation of such circuits permits small packages. The variations in transistor gain and leakage can be minimized by converting the high single stage gain to stability through the use of emitter feedback. Linearity and response to fast-rise pulses is shown for specifiic scintillation amplifier circuits.