High-frequency capacitance-voltage (C-V) characteristics of buried-channel MOS capacitors with a structure of subquarter-micron pMOS have been measured and analyzed, emphasizing transient behavior. The C-V characteristics, including transient behavior, of buried-channel MOS capacitors that have a counter-doped p layer at the surface of n substrate are very similar to those of surface-channel MOS capacitors of n substrate if the counter-doped layer is shallow enough to be fully inverted at large positive bias. As gate voltage is decreased, equilibrium capacitance for inversion (accumulation for the counter-doped layer) reaches a minimum value and then slightly increases to saturate, which is peculiar to buried-channel capacitors. The gate voltage for minimum capacitance, which has been used to estimate the threshold voltage, changes dramatically by illumination even in room light. Net doping profiles of n-type dopant can be obtained from pulsed C-V characteristics even for buried-channel capacitors. For MOS capacitors with thinner gate oxide (5 nm), steady-state C-V curve is not an equilibrium one but a deep depletion one at room temperature. This is because holes are drained away by tunneling through the thin gate oxide.

In ATM networks Connection Admission Control (CAC) is a key part of traffic control but several challenging problems still remain. One is how to assign sufficient bandwidth fast enough to achieve real-time CAC. Although solutions to the bandwidth assignment problem have been proposed, they require a lot of calculations depending on the number of VCs and on the number of different VC types. Therefore, it is difficult to apply these solutions to real-time CAC decisions, This paper presents a cell-loss ratio evaluation algorithm that takes the peak and the average cell rates as inputs, and providers the upper-bound of the cell-loss ratio. The most remarkable characteristic of this algorithm is that it does not require exhaustive calculation and its calculation load is independent of the number of VCs and the number of different VC types. Using this approximation, we propose a real-time CAC. The experimental results show that call processing of the proposed CAC using a processor, whose pertormance is almost the same as that of a processor in a conventional PBX, terminates within several milliseconds.

A novel technique for evaluation of charge build-up in semiconductor wafer processing such as ion implantation, plasma etching and plasma enhanced chemical vapor deposition by using the breakdown of MOS capacitors with charge collecting electrodes (antenna) is proposed. The charge build-up during high beam current ion implantation is successfully evaluated by using this technique. The breakdown sensitivity of a MOS capacitor is improved by using a small area MOS capacitor with a large area antenna electrode. To estimate charge build-up on wafers quantitatively, the best combination of gate oxide thickness, substrate type, MOS capacitor area and antenna ratio should be carefully chosen for individual charge build-up situation. The optimum structured antenna MOS capacitors which relationship between QBD and stressing current density was well characterized give us very simple and quantitative charge build-up evaluation. This technique is very simple and useful to estimate charge build-up as compared with conventional technique by suing EEPROM devices or large area MOS capacitors.

A voltage-mode resonant forward converter with capacitor-input filter is proposed, and its static and dynamic characteristics for both half-wave type and full-wave type are revealed by analysis and experiment. As a result, this converter has prominent features of simplicity of circuit configuration, isolation between input and output and high stability.

This paper describes our newly developed intelligent sensor system which comprises two eyes and four ears on a movable head. It can acquire its dynamical visual and auditory image of its surrouding 3-D environment while showing humanlike behavior naturally and autonomously. The most important feature of the sensor system is in an autonomous and optimum sensory architecture of it. This enables the sensor to achieve 1) repid (5 ms) and accurate (2 deg) auditory localization, 2) rapid (0.5 s/65536 pixel) extraction of visual motion in marginal view, 3) rapid (several TV frames' time) eye movement and binocular fixation to a suddenly appeared object, 3) rapid (0.1 s/4096 pixel) extraction of 3-D object profile and image features, which is activated by its own auditory localization and motion detection. We describe in this paper the several key items for realizing this sensor.

Recently, some speech recognition methods using fusion of visual and auditory information have been researched. In this paper, a study on the mouth shape image suitable for fusion of visual and auditory information has been described. Features of mouth shape which are extracted from gray level image and binary image are adopted, and speech recognition using linear combination method has been performed. From results of speech recognition, the studies on the mouth shape features which are effective in fusion of visual and auditory information have been performed. And the effectiveness of using two kinds of mouth shape features also has been confirmed.

This paper presents a simple and efficient method for estimation of parameters useful for textured image analysis. On the basia of a 2-D Wold-like decomposition of homogenenous random fields, the texture field can be decomposed into a sum of two mutually orthogonal components: a deterministic component and an indeterministic component. The spectral density function (SDF) of the former is a sum of 1-D or 2-D delta functions. The 2-D autocorrelation function (ACF) of the latter is fitted to the assumed anisotropic ACF that has an elliptical contour. The parameters representing the ellipse and those representing the delta functions can be used to detect rotation angles and scaling factors of test textures. Specially, rotation and scaling invariant parameters, which are applicable to the classification of rotated and scaled textured images, can be estimated by combining these parameters. That is, a test texture can be correctly classified even if it is rotated and scaled. Several computer experiments on natural textures show the effectiveness of this method.

NAND-structured trench capacitor cell technologies for 256 Mb DRAM and beyond have been developed. The NAND-structured cell has four memory cells connected in series. The cell size can be reduced to 56% of the conventional cell. A substrate plate trench capacitor cell was adapted to this layout. The NAND-structured trench capacitor cell can achieve sufficient storage capacitance within the restricted capacitor area. A sufficient capacitance of 40 fF was achieved when the size and depth of trench were 0.5 µm and 5.0 µm, respectively. The most important point for realizing the NAND-structured trench capacitor cell is how to reduce the leakage current from the storage node. There are two main sources; one is the leakage current to the neighboring cells, the other is the leakage current to Pwell. These leakage currents have been investigated. An experimental 256 Mb DRAM with the NAND-structured cell was fabricated using the 0.4 µm design rule. The chip size is 464 mm2, which is 68% of a conventional DRAM of the same design rule. This is the result of the reduction of the memory cell area by the NAND-structured cell and the introduction of the open-bit-line arrangement.

Switched-capacitor chaotic neurons fabricated in a full-custom integrated circuit are used to investigate the behavior of 2- and 3-neuron chaotic neural networks. Various sets of parameters are used to visualize the dynamical responses of the networks. Hysteresis of the network is also demonstrated. Lyapunov exponents are approximated from the measured data to characterize the state of each neuron. The effect of the finite length of data and the rounding effect of data acquisition system to the computation of Lyapunov exponents are briefly discussed.

The Double-Sided Rugged poly Si (DSR) technology has been developed for high density DRAMs. The DSR technology was achieved using transformation of rugged poly Si caused by ion implantation. The DSR can increase the surface area of the storage electrode, because it has rugged surfaces on both upper and lower sides. The 2-FINs STC (STacked Capacitor cell) with DSR was fabricated in the cell size of 0.72 µm2, and it is confirmed that the DSR can increase the surface area 1.8 times larger than that of smooth poly Si. It is expected that 25 fF/bit is obtained with a 300 nm-thick storage electrode. These effects show that sufficient capacitance for 256 Mb DRAMs is obtained with a low storage electrode. It is confirmed that there is no degradation in C-V and I-V characteristics. Moreover, the DSR needs neither complicated process steps nor special technologies. Therefore, the DSR technology is one of the most suitable methods for 256 Mb DRAMs and beyond.

In this paper, bifurcation and chaotic behavior which occur in simple looped MOS inverters with high speed operation are described. The most important point in this work is to change a nonlinear transfer characteristic of a MOS inverter to the nonlinearity generating a chaos. Three types of circuits which include four, three and one MOS inverters, respectively, are proposed. A switched capacitor (SC) circuit to operate sampling holding is added in the loop in each of the circuits. The bifurcation and chaotic behavior have been found along with a variation of an external input, and/or a sampling clock frequency. The bifurcation and chaotic behavior of the proposed simple looped MOS inverters are verified by employing SPICE circuit simulator as well as the experiments. For the first type of four looped CMOS inverters, Lyapunov exponent λ which has the positive regions for the chaotic behavior can be calculated by use of the fitting nonlinear function synthesized from two sigmoid functions. For the second type of three looped CMOS inverters and the third type of one looped MOS inverter, the nonlinear charge/discharge characteristics of the hold capacitor in the SC circuit is utilized efficiently for forming the nonlinearity generating the bifurcation and chaotic behavior. Their bifurcation can be generated by the sampling clock frequency parameter which is controlled easily.

Feasibility of 20 Gbit/s single channel transoceanic soliton transmission systems with a simple EDFA repeaters configuration has been studied. Both a simple and versatile soliton pulse generator and a polarization insensitive optical demultiplexer, which can provide a almost square shape optical gate with duration of full bit time period, have been proposed and demonstrated by using sinusoidally modulated electroabsorption modulators. The optical time-division multiplexing/demultiplexing scheme using the optical demultiplexer results in drastic improvement of bit error rate characteristics. We have experimentally confirmed that the use of alternating-amplitude solitons is an efficient way to mitigate not only soliton-soliton interaction but also Gordon-Haus timing jitter constraints in multi-ten Gbit/s soliton transmission. Timing jitter reduction using relatively wide band optical filter bas been investigated in 20 Gbit/s loop experiments and single-carrier, single-polarization 20 Gbit/s soliton data transmission over 11500 km with bit error rate of below 10-9 has been experimentally demonstrated, using the modulator-based soliton source, the optical demultiplexer, the alternation-amplitude solitons, and wide-band optical filters. Obtained 230 Tbit/skm transmission capacity shows the feasibility of 20 Gbit/s single channel soliton transoceanic systems using fully practical technologies.

The polarization dependence of femtosecond soliton-soliton interactions is investigated in detail. When the polarization direction of two solitons is orthogonal, the soliton interaction can be reduced in comparison to that for parallel polarization. The soliton self-frequency shift (SSFS) is still observed even in the orthogonal condition, but the quantity of the SSFS is much smaller than in the parallel condition. A stronger soliton interaction is observed between two solitons in an in-phase condition, than in an out-of-phase condition. The largest SSFS occurs in-phase with parallel polarization. The polarization dependence of femtosecond soliton interaction in a distributed erbium-doped fiber amplifier (DEDFA) is also investigated. It is shown that when the optical gain of the DEDFA is given adiabatically, the input pulse separation at which the first soliton occurs is less with orthogonal polarization. This is because the soliton pulse width is reduced due to the adiabatic soliton narrowing caused by the optical amplification.

Ultrashort pulsed-beam propagation in a Kerr-type bulk medium is studied theoretically through classical and quantum field solutions of a higher-order nonlinear Schrödinger equation, which is valid for transversely localized femtosecond pulses in an anomalous dispersion regime. Quantum-mechanical stability analysis via a Hartree approximation to interacting bosons shows that within a certain range of a parameter the solitary wave could be stabilized even in the three-dimensional transverse space-time. This feature admits of an exotic route to multidimensional solitons.

A new device consisting of an optical pulse generation section and pulse coding section monolithically integrated on a single-chip has been developed. The pulse generation section consists of a multiple quantum well (MQW) electroabsorption modulator integrated with an MQW DFB laser. The modulator operates at large-signal modulation and low voltage (from 2 to 3-V DC bias with a 3.2-V peak-to-peak RF signal). The second modulator is operated independently as a pulse encoder. An approximately transform-limited optical pulse train, whose full width at half maximum (FWHM) in the time domain is less than 17-ps and spectral FWHM is 28-GHz, is obtained with a repetition frequency of 10-GHz. Compressive strain is introduced in both InGaAsP quantum wells in order to obtain efficient device characteristics. These include a low threshold current (18-mA) for the laser, and low driving voltage (30-dB for 3-V swing) and high-speed operation (over 12-GHz for a 3-dB bandwidth) for the modulators. Demonstrations show that this new device generates short optical pulses encoded by a pseudo-random signal at a rate of 10 Gbit/s. This is the first time 10 Gbit/s modulation has been achieved with a multi-section electroabsorption modulator/DFB laser integrated light source. This monolithic device is expected to be applied to optical soliton transmitters.

In this paper, the dispersion characteristics of magnetostatic surface waves (MSSW) in a nonlinear gyromagnetic medium are analytically investigated. Assuming the nonlinearity as the first order perturbation in permeability tensor of the gyromagnetic medium, the perturbation technique based on the multiple scale method is used to deduce the nonlinear dispersion relations for the MSSW. It is observed that for a given propagation constant of the MSSW the frequency decreases with microwave power. It is also observed that group velocity decreases, and as a consequence, delay time increases with power of the microwave. By evaluating the dependence of frequency on power and variation of group velocity on propagation constant within the accuracy of the perturbation theory, it is confirmed that the conditions for formation of bright soliton are not satisfied for the MSSW.

We propose two methods to fuse auditory information and visual information for accurate sppech recognition. The first method fuses two kinds of information by using linear combination after calculating two kinds of probabilities by HMM for each word. The second method fuses two kinds of information by using the histogram which expresses the correlation of them. We have performed experiments comparing the proposed methods with the conventional method and confirmed the validity of the proposed methods.

We predict that chemical waves can propagate as a guided mode in a reaction-diffusion system that consists of two regions with different wave speeds. In comparison with electromagnetic waveguides, unique features of the guided chemical waves can be seen in their dispersion characteristics. Conditions for supporting lowest-loss guided waves are discussed.

A capacitor-error-free SC voltage inverter with zero sensitivity to element-value variations is proposed. By virtue of the capacitor-error-free property, this SC voltage inverter is free from the capacitor mismatch. The performance of this SC voltage inverter has been confirmed from both the simulation and experiment.

Advanced Traveller Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) require real-time traffic data to observe and control the trafic flow. Still, there is a lack of proficient traffic monitoring systems. One method to collect such data is using particular equipped vehicles, called probes, transmitting experienced travel times to base stations which in turn are connected to a traffic control center. In this paper we analyse the performance of a radio network for collecting real-time traffic data from probes. The results reveal that random transmission of traffic reports is a (spectrum) efficient, inexpensive and flexible method for collecting road traffic data that can provide reliable traffic monitoring.