Application of source biasing technique for energy efficient DECODER circuit design: memory array application

Researchers have proposed many circuit techniques to reduce leakage power dissipation in memory cells.If we want to reduce the overall power in the memory system,we have to work on the input circuitry of memory architecture i.e.row and column decoder.In this research work,low leakage power with a high speed row and column decoder for memory array application is designed and four new techniques are proposed.In this work,the comparison of cluster DECODER,body bias DECODER,source bias DECODER,and source coupling DECODER are designed and analyzed for memory array application.Simulation is performed for the comparative analysis of different DECODER design parameters at 180 nm GPDK technology file using the CADENCE tool.Simulation results show that the proposed source bias DECODER circuit technique decreases the leakage current by 99.92％ and static energy by 99.92％ at a supply voltage of 1.2 V.The proposed circuit also improves dynamic power dissipation by 5.69％,dynamic PDP/EDP 65.03％ and delay 57.25％ at 1.2 V supply voltage.     

Random error effects in matched MOS capacitors and current sources

Explicit formulas are derived using statistical methods for the random errors affecting capacitance and current ratios in MOS integrated circuits. They give the dependence of each error source on the physical dimensions, the standard deviations of the fabrication parameters, the bias conditions, etc. Experimental results, obtained for both matched capacitors and matched current sources using a 3.5-/spl mu/m NMOS technology, confirmed the theoretical predictions. Random effects represent the ultimate limitation on the achievable accuracy of switched-capacitor filters, D/A converters, and other MOS analog integrated circuits. The results indicate that a 9-bit matching accuracy can be obtained for capacitors and an 8-bit accuracy for MOS current sources without difficulty if the systematic error sources are reduced using proper design and layout techniques.     

New approximation technique for current distribution in microstrip array antennas

To reduce the number of unknowns in the moment method solution for microstrip array antennas consisting of complex shaped but identical elements, the current distribution of each element is approximated by the distribution of an isolated single element. The so computed coupling shows excellent agreement with an exact calculation and leads to a tremendous decrease in computation time.<>     

The use of current sources in wire moment-method analysis and thefeed-network interaction with an array

Discusses the 1.8 MHz transmitting phased array antenna of Christman (2000). The present author presents an NEC-4 analysis of the BOP (both arrays fed out of phase) and BIP (both arrays fed in phase) cases. Antenna radiation patterns are shown     

Soft breakdown as a cause of current drop in an MOS tunnel structure

The effect of electric stress on current-voltage characteristics of Al/SiO₂/p⁺-Si MOS diodes with a tunnel-thin (2.5–3.0 nm) insulator was studied at constant current and constant voltage. Under constant-voltage stress, the current increase related to soft breakdown was followed in several cases by an abrupt drop in current. Typically, the drop occurs at a high bias, and it may be a specific manifestation of a soft breakdown. At strong nonuniformity of the SiO₂ thickness, the effect can be significant even if the breakdown is localized within a rather small area.     

Profiling generation lifetime in an MOS capacitor using a multistep constant-capacitance technique

This paper describes a method to obtain the depth profile of generation lifetime in a semiconductor using a MOS capacitor. The capacitance is kept constant at a number of values in deep depletion, and the resulting gate voltage transient measured. This consists of a series of ramps. The profile of the generation lifetime is obtained from the slopes of the ramps and the values of capacitance through which the capacitor is stepped.     

CASTAM: A process variation analysis simulator for MOS LSI's

A simulator named CASTAM, which includes both process and device models, has been developed to predict MOS process variations through the analysis of variations in electrical characteristics of fabricated MOS devices using the Monte Carlo method. Analysis accuracy using the simulator is examined. Investigation shows that process parameter variations can be estimated with an error of less than 10 percent if an appropriate set of device characteristic items is chosen. Wafer inspection data for a CMOS pilot line can be analyzed with this simulator, and the main cause of threshold voltage variation pinpointed. Predictions derived from the analyzed results have been confirmed using experimental data. This shows that analysis using CASTAM is sufficiently reliable.     

High-frequency analysis of an array of line sources on a truncatedground plane

A uniform high-frequency solution is presented for the field radiated at finite distance by a semi-infinite beam-scanning array of magnetic line sources located on a perfectly conducting half-plane. The field is represented in terms of Floquet waves plus their relevant singly and doubly diffracted rays, which arise from both the end of the array and the edge of the half-plane. This representation is uniformly valid also when transition conditions from propagating to evanescent Floquet waves occur. Furthermore, it provides a simple and attractive physical interpretation and is found numerically very effective, due to the fast convergence of the Floquet wave expansion for the field     

Analysis of an array of line sources above a finite ground plane

A simplified analysis which gives insight into and physical interpretation on the radiation mechanism of an array of line sources above a finite ground plane is presented. Computations have been restricted to an array of two line sources since data are available for comparison. Results on the variation of the maximum field intensity, the angle of maximum field intensity, and the field intensity at the axis of the counterpoise as functions of the size of the ground plane are presented. Variations of the maximum field intensity and the angle of maximum field intensity as functions of the distance of the source above the ground plane are also illustrated. These data become very important in the design of antennas for aircraft navigation taking into account the presence of the finite counterpoise which otherwise could lead to erroneous designs.     

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 5/spl times/ 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 1.9-10.2/spl times/ higher signal-to-noise ratio (SNR) and reduced sensitivity to supply and p-n skew variations compared to prior leakage sensor designs.     

Relationships for the drift and diffusion components of the drain current in an MOS transistor

It is shown that, by taking into account the current-continuity equation, analytical expressions for both the drift and the diffusion components of the drain current in an MOST can be derived. Also, these current components, which can be expressed as a function of the surface potential values at the source and at the drain ends of the channel, are reported against the voltages applied to the device.     

Experimental evaluation of an array technique for zenith to horizon coverage

An experimental study of a new array concept with application to providing low cost efficient antennas with hemispherical coverage for aircraft to satellite communication links is described. The combined array-surface wave antenna consists of 64 waveguide elements scanned conventionally except at endfire. At endfire the array is shorted to become a corrugated surface-wave antenna and excited by an eight-element feed to provide a directional beam near the horizon. The array is rotated to give hemispherical coverage.     

Investigation of an array technique for robotic seam tracking ofweld joints

A noncontact optical preview sensing technique for possible application to a robotic seam tracking system is presented. This technique uses a structured laser illumination source: a SELFOC lens array (SLA) coupled to a fiberoptic and a phototransistor (photodetector) array. The experimental results with the SLA and fiberoptic array demonstrate the feasibility of linear fiberoptic array sensing of the weld joint. The intensity profiles acquired by the array were such that when combined with suitable data processing software routines, the sensing technique was able to provide satisfactory measurements of joint width and location of the centerline. An experiment demonstrates the viability of the approach for tracking of a weld seam. A clear profile containing the expected features was obtained at each cross-sectional location as the joint was traversed     

Analysis of a dual-frequency array technique

This paper describes the radiating properties of a new element for a dual-frequency phased array that operates over two frequency bands separated by about an octave. The analysis considers the array element excited by two waveguides for high-frequency operation, and includes an evaluation of the element radiation properties at both frequency bands. The analysis of radiation is carried out for the case ofH-plane scan, which is expected to be the most severe test of the element's scanning behavior. Computed results indicate that the structure radiates efficiently within the two bands and operates free from anomalous behavior over substantial scan angles. These results demonstrate the feasibility and practicality of the basic concept.     

色噪声环境下信源数目估计的线性插值法

为了减轻加性色噪声对信源数目估计性能的影响,本文提出了一种基于相干矩阵特征值分布曲线线性插值的信号检测方法.构造适当的代价函数,避免了对数似然函数的使用,该方法对色噪声协方差矩阵特征值分散具有稳健性,同时具有较低的计算复杂度和适用于相关甚至相干源等优点.其有效性由大量的计算机仿真结果得到了验证.     

Mechanism of stress-induced leakage current in MOS capacitors

Stress-induced leakage current (SILC) is examined both below and above the voltage at which the preexisting Fowler-Nordheim tunneling current dominates. Based on these results, it is argued that SILC is the result of inelastic rather than elastic trap-assisted tunneling. This clarification explains the well-known thickness dependence of the SILC at low fields that has identified it as a scaling limitation for nonvolatile memory tunnel oxide. It also explains a newly observed different thickness dependence at high fields and facilitates modeling of the electric field/voltage and trap density dependencies of the SILC     

New technique for measuring the threshold voltage in MOS devices

The present paper describes an experimental method that can be used to measure the threshold voltage in MOS devices in the form of transistors or capacitors. The proposed method is based on the detection of the non-steady-state/steady-state transition of the surface potential at the oxide–semiconductor interface of a MOS device, when it is swept from depletion to inversion regions. This detection is carried out as follows: a set of current versus gate signal frequency measurements, for different voltage amplitudes, is performed. The frequency values corresponding to the maximum measured current (optimum frequency) f_m, are read. Several gate voltage versus optimum frequencies (f_m–V_G) curves are plotted for gate voltage values ranging from 0.2 to 3 V with a 0.1 V step increment. The (f_m–V_G) curves are found to undergo an abrupt change of slope at a specific gate voltage value. The value of threshold voltage is extracted from the critical points of the former curves. Experiments have been carried out on different devices. The measured values of threshold voltage are found to be in good agreement to those obtained by the conventional I_D–V_GS and simulation methods as well as that supplied by the device manufacturer.     

DOA estimation method of weak sources for an array antenna under strong interference conditions

The concept of a preserving source orthogonality and characteristic beam is defined according to an array data model. It is proven theoretically that the corresponding eigenvectors maintain the preserving orthogonality when the powers and the angle intervals between the signals are large. The theory is then applied to the direction of arrival (DOA) estimation for the array antenna in the presence of strong interference. A novel DOA estimation algorithm based on the elimination of the eigenvectors of interference is proposed. The simulation results and comparison of the jamming jam method (JJM) algorithm show that the proposed algorithm does not require the position of the interference source to be known. Moreover, its interference suppression ability and statistical estimation performance are superior to those of the JJM, and thus, it is more suitable for low SNR and small angle intervals.