A simple circuit structure implementing digital-to-analog data conversion function is presented. The proposed digital-to-analog converter utilizes the inherent characters of single-electron tunneling which consist of the periodic voltage oscillation and the ability of counting the number of trapped charges. It produces an analog output voltage for a given digital input. We proposed the device structure performing the weighted summation of inputs, which is converted into an analog voltage by the proposed sensing circuit. Monte Carlo simulation results give us the clear performance of the 3-bit digital-to-analog conversion function and the effect of temperature, capacitance variations, and background charge fluctuations. Moreover, we examined the possibility of extending a N-bit digital-to-analog converter with the proposed scheme.

We prepared alkoxide solutions to fabricate SrBi2Ta2O9 (SBT) ferroelectric capacitors with IrO2 electrodes. In this process, to minimize excess bismuth, the Sr : Bi : Ta mole ratio was kept at 0. 9 : 2. 1 : 2. 0, i. e. , nearly stoichiometric. Three types of solution - mixed-only (MIX), complexed (COMP), and hydrolyzed (HYD) - were used. The HYD capacitor had low absolute leakage current, 10-7 A/cm2 order, and good saturation properties to 6 V. When voltage was applied to each capacitor at 2 to 6 V, MIX and COMP capacitors showed only partial hysteresis loops due to a high leakage current, reflecting the I-V characteristics. These results are probably due to film density caused by metaloxane network bonding. A fatigue endurance test was conducted using cycling of polarization switching at 6 V using the HYD capacitor with IrO2 electrodes. Slight changes were, however, observed in hysteresis loop configuration, but good hysteresis properties were kept up to 1. 04 1012 cycles. We compared SBT ferroelectric thin films fabricated with Pt electrodes and with IrO2 electrodes. Scarcely any difference due to SBT in the XRD pattern was seen, depending on the substrate material. We found that the use of IrO2 electrodes had the effect of decreasing the crystallization temperature. On Pt and IrO2 electrodes, the two films have surface morphology quite different from that of the rod-like structure wellknown for SBT films prepared using a metal 2-ethylhexanate solution. Their surfaces show a similar morphology with relatively large, closely packed grains. A comparison of the I-V characteristics after reannealing showed that the capacitor with IrO2 electrodes had a higher leakage current than that with Pt electrodes. The leakage current was probably due to the density of the film and interface between the SBT film and electrodes.

Pb(ZrxTi1-x)O3 (PZT) thin films were prepared on various electrodes. When Ir system materials were used as electrodes, fatigue properties of PZT thin films were improved. Moreover, in the case of the PZT thin film on an Ir/IrO2 electrode, not only fatigue but imprint properties were clearly improved. We could find these improvements were caused by good barrier effect of IrO2 from secondary ion mass spectroscopy (SIMS) analysis. By applying these Ir system electrodes, we fabricated stacked capacitors on polycrystalline silicon (poly-Si) plugs. In spite of high temperature thermal processing, we found poly-Si plugs were ohmically connected with the bottom electrodes of the capacitors from hysteresis measurements and I-V characteristics, and could greatly expect them for practical use.

In this paper, we propose a new structure of the frequency domain adaptive filter (FDAF). The proposed structure is based on the modified DFT pair which consists of the FIR filters, so that un-delayed output signal can be obtained with stable convergence and without accumulated error which are problems for the conventional FDAFs. The convergence performance of the proposed FDAF is examined through the computer simulations in the adaptive line enhancer (ALE) comparing with the conventional FDAF and the DCT domain adaptive filter. Furthermore, in order to improve the error performance of the FDAF, we propose a composite algorithm which consists of the normalized step size algorithm for fast convergence and the variable step size one for small estimation error. The advantage of the proposed algorithm is also confirmed through simulations in the ALE. Finally, we propose a reduction method of the computational complexity of the proposed FDAF. The proposed method is to utilize a part of the FFT flow-graph, so that the computational complexity is reduced to O(N log N).

An improved numerical computation model is presented to calculate the metal-ferroelectric-semiconductor field effect transistor (MFSFET) characteristics with a sufficiently large gate area which can be applied for large drain voltages. In the presented model, the polarization of the ferroelectric gate insulator is inhomogeneous and treated as a variable along the channel. We have calculated electrical properties of SrBi2Ta2O9/Si MFSFETs and demonstrate that the conventional model, in which the polarization of the ferroelectric gate insulator (Pd) is treated as a constant, overestimate the drain current when the drain voltage is large. In addition, effects of the ratio of remanent polarization to spontaneous polarization (Pr/Ps ratio) of the ferroelectric film on the transistor characteristics are discussed.

We have applied hot-carrier circuit-level simulation to memory peripheral circuits of a few thousand to over 12K transistors using a simple but accurate degradation model for reliability verification of actual memory products. By applying simulation to entire circuits, it was found that the location of maximum degradation depended greatly upon circuit configuration and device technology. A design curve has been developed to quickly relate device-level DC lifetime to circuit-level performance lifetime. Using these results in conjunction with a methodology that has been developed to predict hot-carrier degradation early in the design cycle before TEG fabrication, accurate total-circuit simulation is applied early in the design process, making reliability simulation a crucial design tool rather than a verification tool as technology advances into the deep sub-micron high clock rate regime.

In this paper, Wavelength Division Multiple access (WDM) ring is proposed for interconnection in workstation clusters or parallel machines. This network consists of ring connected routers each of which selectively passes signals addressed in some particular wavelengths. Other wavelengths are once converted to electric signals, and re-transmitted being addressed in different wavelengths. Wavelengths are assigned to divisors of the number of nodes in the system. Using the regular WDM ring with imaginary nodes, the diameter and average distance are reduced even if the number of nodes has few divisors. It provides better diameter and average distance than that of the uni-directional torus. Although the diameter and average distance is worse than that of ShuffleNet, the physical structure of the WDM ring is simple and the available number of nodes is flexible.

This paper describes an automatic region segmentation method which is detectable nuclei regions from hematoxylin and eosin (HE)-stained breast tumor images using artificial organisms. In this model, the stained images are treated as virtual environments which consist of nuclei, interstitial tissue and background regions. The movement characteristics of each organism are controlled by the gene and the adaptive behavior of each organism is evaluated by calculating the similarities of the texture features before and after the movement. In the nuclei regions, the artificial organisms can survive, obtain energy and produce offspring. Organisms in other regions lose energy by the movement and die during searching. As a result, nuclei regions are detected by the collective behavior of artificial organisms. The method developed was applied to 9 cases of breast tumor images and detection of nuclei regions by the artificial organisms was successful in all cases. The proposed method has the following advantages: (1) the criteria of each organism's texture feature values (supervised values) for the evaluation of nuclei regions are decided automatically at the learning stage in every input image; (2) the proposed algorithm requires only the similarity ratio as the threshold value when each organism evaluates the environment; (3) this model can successfully detect the nuclei regions without affecting the variance of color tones in stained images which depends on the tissue condition and the degree of malignancy in each breast tumor case.

A formal necessary and sufficient condition on the general Petri net reachability problem is presented by eliminating all spurious solutions among known nonnegative integer solutions of state equation and unifying all the causes of those spurious solutions into a maximal-strongly-connected and siphon-and-trap subnet Nw. This result is based on the decomposition of a given net (N, Mo) with Md and the concepts of "no immature siphon at the reduced initial marking Mwo" and "no immature trap at the reduced end marking Mwd" on Nw which are both extended from "no token-free siphon at the initial marking Mo" and "no token-free trap at the end marking Md" on N, respectively, which have been both effectively, explicitly or implicitly, used in the well-known fundamental and simple subclasses.

In this paper, we discuss ferroelectric materials suitable for a metal ferroelectric metal insulator semiconductor FET (MFMIS FET). It is important for a ferroelectric material to have a low dielectric constant to enable the application of sufficient electric field to a ferroelectric layer. Films of Sr2Nb2O7 (SNO) and Sr2(Ta1-xNbx)2O7 (STNO) were prepared by the sol-gel method on Pt/IrO2 electrodes for an MFMIS FET. The ferroelectricities of STNO films were confirmed in the range of x=0. 1-0. 3. In case of x=0. 3, the largest remanent polarization was obtained in the hysteresis loop. The remanent polarization and the coercive field are 0. 5 µ C/cm2 and 44 kV/cm, respectively. The film had a low dielectric constant (ε=53). It is considered that the characteristics of STNO thin films are suitable for MFMIS FET.

In indoor optical channels, intersymbol interference (ISI) due to multipath propagation prevents high data rate transmission. In this paper, a new Optical Multi-Wavelength Modulation technique has been investigated for improving the quality of transmission. In this technique, parallel transmission is used, which lowers the data rate per channel and thus reduces the effects of ISI. Furthermore, parallel coding is used in predetermined parallel branches, so that coding can correct errors without changing the system data rate. Simulation results show that a combination of these methods can achieve high quality transmission without reduction of the total data rate.

Sr0. 7Bi2. 3Ta2O9(SBT) films are drawing attention as fatigue-free materials. We prepared an SBT film containing discontinuous crystals in the Bi-layered compound using a misted deposition method. In comparison to films prepared by the spin-on method, leakage current was low and spontaneous polarization is high but saturation performance was low. The low saturation performance seems attributable to the inclusion of discontinuous crystals in the Bi-layered compound, while the low leakage current may be explained by the films smaller, denser particles, which form a film without voids, resulting in higher uniformity. The misted deposition method has advantages of finer grain size and higher uniformity.

This paper presents a routing methodology and a routing algorithm used in designing Gb/s LSIs with deep-submicron technology. A routing method for controlling wire width and spacing is adopted for net groups classified according to wire length and maximum-allowable-delay constraints. A high-performance router using this method has been developed and can handle variable wire widths, variable spacing, wire shape control, and low-delay routing. For multi-terminal net routing, a modification of variable-cost maze routing (GVMR) is effective for reducing wire capacitance (net length) and decreasing net delay. The methodology described here has been used to design an ATM-switch LSI using 0. 25-µm CMOS/SIMOX technology. The LSI has a throughput of 40 Gb/s (2. 5 Gbps/pin) and an internal clock frequency of 312 MHz.

This paper proposes a new methodology for diagnosing transistor leakage faults with information on IDDQ and logic values at primary output lines. A hierarchical approach is proposed to identify the faults that do not exist in the circuit through comparing their IDDQ and logic behaviors predicted by simulation with observed responses. Several techniques for handling intermediate faulty voltages in fault simulation are also proposed. Further, an approach is proposed to generate diagnostic vectors based on IDDQ information. In addition, a method for identifying IDDQ equivalent faults is proposed to reduce the time needed for diagnostic vector generation and to improve diagnostic resolution. Experimental results show that the proposed methodology often confines diagnosed faults to only a few gates.

A system combining multicarrier modulation and adaptive modulation in which a suitable level of quadrature amplitude modulation (QAM) is selected for each subcarrier and time-slot, is proposed for high-bit-rate and high-quality digital land mobile communications. The advantages of the system are a mode in which information cannot be transmitted under adverse propagation conditions and a buffer memory to limit a transmission delay time. If the allowable delay time is small, such as in voice and video transmissions, the system tends to have a poor bit error rate (BER) because of the forcible QAM-level selection. Our new selection scheme improves the BER for small transmission delay time. Suitable distribution of the delay time among subcarriers is obtained by using the scheme where the QAM-level of each subcarrier is chosen collectively using the number of data bits stored in memory. Computer simulation of the systems BER performance showed that the system could provide a noticeable BER improvement over frequency-selective fading channels as well as flat Rayleigh fading channels. The QAM-level selection scheme was also effective for a low maximum Doppler frequency and a small memory size. The system could thus attain about 25-fold improvement in BER at Es/N030 dB compared to the multicarrier/16QAM system. It also attained about 60-fold and 3. 5-fold improvement in BER at fd=10Hz compared with the system with multicarrier/16QAM and without the QAM-level selection scheme, respectively.

In this paper, we give a new approach to the computation of primary decomposition and associated prime components of a zero-dimensional polynomial ideal (f1,f2,. . . ,fn), where fi are multivariate polynomials on Z (the ring of integer). Over the past several years, a considerable number of studies have been made on the computation of primary decomposition of a zero-dimensional polynomial ideal. Many algorithms to compute primary decomposition are proposed. Most of the algorithms recently proposed are based on Groebner basis. However, the computation of Groebner basis can be very expensive to perform. Some computations are even impossible because of the physical limitation of memory in a computer. On the other hand, recent advance in numerical methods such as homotopy method made access to the zeros of a polynomial system relatively easy. Hence, instead of Groebner basis, we use the zeros of a given ideal to compute primary decomposition and associated prime components. More specifically, given a zero-dimensional ideal, we use LLL reduction algorithm by Lenstra et al. to determine the integer coefficients of irreducible polynomials in the ideal. It is shown that primary decomposition and associated prime components of the ideal can be computed, provided the zeros of the ideal are computed with enough accuracy. A numerical experiment is given to show effectiveness of our algorithm.

In this work, a new algorithm for tracking the directions-of-arrival (DOA's) of moving targets by introducing a linear approximation is proposed. The targets are assumed to move with constant angular velocities within a short time and emitting continuously narrow-band signals that impinge on an array of sensors. Therefore the trajectories of targets can be approximated by linear functions of time, which consist of the DOA's and the angular velocities, within the short time. In the condition that the number of targets is known and the outputs vector of the sensors including the additive white complex Gaussian noises is observed continuously, a cost function which consists of the squared residual error vectors is defined. The estimation of the DOA's and the angular velocities of targets is performed by minimizing this cost function. By estimating both the DOA's and the angular velocities at the same time, the proposed algorithm is able to improve the tracking performance for rapidly moving targets. In computer simulations, the performance of the proposed algorithm is compared with the ESPRIT method, which is one of the typical subspace methods with super resolution.

Process algebras with name passing have been proposed for concurrent mobile processes. They can be suitable to describe dynamical changes of connections among processes. To describe mobile communication or mobile computing systems, however, it is necessary to consider locations at which processes run. We propose a description method to design mobile communication systems using a concurrent calculus in this paper. The concept of a field is introduced to model locality of communication. An extension of π-calculus with a field is proposed. The extension does not include locality represented by a field while most related works treat locality within their languages. A field is given when behavior of a target system is verified in a particular environment. The aim of the extension is to verify and to test connectivity between processes under various geographical constraints. This method could be design-oriented in this context. Equivalence relations with/without location in this calculus are also discussed.

RZ signal transmission in an anomalous region with periodic dispersion compensation is examined by a straight-line experiment in terms of the compensation ratio, the signal power, and the pulse width. The optimum condition enables single-channel 20-Gbit/s RZ signal and two-WDM-channel 20-Gbit/s signals (40-Gbit/s in total) to be transmitted over 5,520 km and 2,160 km, respectively. Numerical simulations with the assistance of a basic theory enables analysis of the experimental results. It is shown that the balance between the waveform distortion and the remaining Gordon-Haus jitter determines the optimum conditions to achieve the longest transmission distance. Excess dispersion compensation results in waveform distortion, while insufficient compensation causes a greater amount of remaining jitter. Moreover, spectrum deformation during propagation is experimentally and numerically clarified to have a large effect on the transmission performance, especially for WDM transmission.

It is important to test the various kinds of interconnect faults between chips on a card/module. When boundary scan design techniques are adopted, the chip to chip interconnection test generation and application of test patterns is greatly simplified. Various test generation algorithms have been developed for interconnect faults. A new interconnect test generation algorithm is introduced. It reduces the number of test patterns by half over present techniques. It also guarantees the complete diagnosis of multiple interconnect faults.