This paper describes a new approach towards the performance-driven layout for analog LSIs. Based on our approach, we developed an automatic performance-driven layout system LIBRA. The performance-driven layout has an advantage that numerical evaluations of performance requirements may exactly specify layout requirements so that a better layout result will be expected with regard to both the size and the performances. As the first step to the final goal, we only concern with the DC characteristics of analog circuits affected by the placement and routing. First of all, LIBRA performs the sensitivity analysis with respect to process parameters and wire parasitics, which are major causes for DC performance deviations of analog LSIs, so as to describe every perfomance deviation by its first order approximation. Based on the estimations of those performance deviations, LIBRA designs the placement of devices. The placement approach here is the simulated annealing method driven by their circuit performance specification. The routing of inter-cell wires is performed according to the priority of the larger total wire sensitivities in the net by the maze router. Then, the simple compaction eliminates the empty space as much as possible. After that, the power lines optimization is performed so as to minimize the ferformance deviations. Finally, an advantage of the performance improvement by our approach is demonstrated by showing a layout result of a practical bipolar circuit and its excellent performance evaluations.

We have developed a 64-neuron electrically trainable BiCMOS analog neuroprocessor based on 3-layered PDP networks with a feedforward time as short as 10 µs which is equivalent to the operation speed as high as 108 multiplications per second. A crucial point in this development is application of a dynamic refreshment technique to a weighting circuit. A sufficiently long retention time of the synapse weight has thereby been attained, leading to a practical operation of the neuroprocessor.

The aim of this article is to show the effectiveness of exploiting separability in numerical analysis of nonlinear systems. Separability is a valuable property of nonlinear mappings which appears with surprising frequency in science and engineering. By exploiting this property, computational complexity of many numerical algorithms can be substantially improved. However, this idea has not been received much attention in the fields of electronics, information and communication engineerings. In recent years, efficient algorithms that exploit the separability have been proposed in the areas of circuit analysis, homotopy methods, integer labeling methods, nonlinear programming, information theory, numerical differentiation, and neural networks. In this article, these algorithms are surveyed, and it is shown that considerable improvement of computational efficiency can be achieved by exploiting the separability.

Mechanism for radiation phenomenon caused by a finite-length transmission line is discussed. Coupling of an external wave to a transmission line has been studied by using a circuit concept because of a TEM transmission. Since the relationship between coupling and radiation is reciprocal, radiation can be treated by using the circuit concept. It is shown that the equations obtained by using the field theory are quite coincident with those by the circuit theory. From the resultant, it can be concluded that the radiated fields are composed of those by the line current of TEM and the terminal currents. A method for an application of the circuit concept to radiation due to a trace on a printed circuit board is studied by comparing the experimental results.

A current source with current switches (switched current source) is widely used in various analog ICs. One of its typical application is data converters. This paper describes an analysis of the transient behavior of a switched current source. The analysis has clarified conditions and causes of overshooting in the output waveform. The analysis also clarifies dependence of the settling time on parameters. The waveform heavily depends on time constant and initial charge at the internal node where current source and current switch are connected. They can cause the overshooting and limit the settling time. A phenomenon of acceleration of the settling time and an influence of the charge coupling through current switches are also discussed. A chart mentioned in this paper is useful for the initial design and the improvement of switched current sources.

By close analogy of annealing for solids, we devise a new algorithm, called APS, for the time evolution of both the state and the synapses of the Hopfield's neural network. Through constrainedly random perturbation of the synapses of the network, the evolution of the state will ignore the tremendous number of small minima and reach a good minimum. The synapses resemble the microstructure of a network. This new algorithm anneals the microstructure of the network through a thermal controlled process. And the algorithm allows us to obtain a good minimum of the Hopfield's model efficiently. We show the potential of this approach for optimization problems by applying it to the will-known traveling salesman problem. The performance of this new algorithm has been supported by many computer simulations.

The subject of the paper is to propose a simple O(|V|+|E|) algorithm for finding all 3-edge-components of a given undirected multigraph G=(V, E). An 3-edge-connected component of G is defined as a maximal set of vertices such that G has at least three edge-disjoint paths between every pair of vertices in the set. The algorithm is based on the depth-first search (DFS) technique. For any fixed DFS-tree T of G, cutpairs of G are partitioned into two types: a type 1 pair consists of an edge of T and a back edge; a type 2 pair consists of two edges of T. All type 1 pairs can easily be determined in O(|V|+|E|) time. The point is that an edge set KE(T) in which any type 2 pair is included can be found in O(|V|+|E|) time. All 3-edge-components of G appear as connected components if we delete from G all edges contained in type 1 pairs or in the edge set KE(T).

Serious failures of the latest electronic equipments occur easily due to electrostatic discharge (ESD) , which can be caused frequently by the electrification phenomena of human-body walking on the floor. The number of the above damaging incidents has significantly been increasing with an increased use of integrated semiconductor elements with lower operation power. The most effective measures against the ESD consist in preventive ones, which are to obtain dynamic behaviors of the electric charge before the ESD happens, thereby preventing the charge accumulation. From this point of view, this paper describes new approaches for measurement of the static electricity directed toward preventing the ESD. First, a two-dimensional measurement method for visualizing charge distributions is described. This principle is based on visualizing the potential distribution induced in the array electrodes from the electrostatic fields. For showing usefulness of the visualization measurement, a prototype was built and attempts were made on the visualizations for the static electricity distributions of charged bodies. Second, a potential calculation of the human body charged by walking on the floor is described. A model was shown for analyzing the human-body potential on the floor, and the theoretical equation for describing the potential attenuation process was derived in the closed form in the Laplacian transformation domain. In order to obtain the typical half-life of the human-body potential, numerical computations were performed using a reverse Laplacian transformation. The experiments were also conducted for confirming the validity of the computed results. Finally, a new method is described for estimating dynamic behaviors of the occurrence charges of the human body electrified by walking-motions. Statistical measurements of the charges and potentials were made for the fundamental walking-motions specified here. The pace transitions of the potentials due to continuous walking and stepping were also measured and their results were explained from the electrification properties for the fundamental walking-motions.

The subject of the paper is to analyze time complexity of the minimum axiom set problem (MASHC) in the Horn clause propositional logic. MASHC is defined by "Given a set H of Horn clauses and a query Q, all in propositional logic, such that Q is provable over H, find an axiom set of minimum cardinality, HH, with respect to Q, where Q is provable over H if and only if Q can be shown to be true by repeating Modus Ponens starting from clauses of H under the assumption that all of them are originally assumed to be true". If Q is provable over H then H is called an axiom set (with respect to Q). As stated in the definition of MASHC, detecting if Q is provable over H is required. This leads us to a problem, called the provability detecting problem (PDPHC), defined by "Given a set H of Horn clauses and a query Q in propositional logic, determine if Q is provable over H". First an O(σ) algorithm BFSHC for PDPHC is given based on the breadth-first search, where σ is the formula size of a given set of Horn clauses. For MASHC, it is shown that the problem is NP-complete, and an O(σ) approximation algorithm FMAS is given. Its experimental evaluation is also presented.

We propose a new distributed signal (analog or digital) transmission system which has the immunity against the noisy channel. An information signal in transmitter is distributed by distributor and the distributed signal is transmitted. Received signal is reconstructed by the inverse distributor in receiver. In this system, an impulsive interference noise which disturbs the transmission signal in the channel passes decoder only, and this interference noise is distributed by the inverse distributor while the transmitted signal is reconstructed. Some appended signals make it possible to estimate the noise components which inversely distributed with the Fourier transformation as the distributor. Basing upon this principle, the transmission system will have an ability to suppress the impulsive interference, and the channel will have high noise immunity. The construction of receiver which can eliminate the impulsive noise is derived.

ATM cross-connect systems, which will be used for provisioning virtual paths (i.e. logical direct connections between exchanges) in future broadband transport networks, simplify network configuration and yield increased routing and capacity allocating flexibility. This paper describes the design of a large capacity ATM cross-connect system that has a multi-stage network structure which requires only one type of switch module. The capacity of the proposed system can be easily increased without service interruptions. To realize cell sequence integrity, a time stamp is added to the self-routing tag. Required time stamp length and efficient module size are discussed.

New methods are needed for accessing very large information services. This paper proposes the use of a user model neural network to allow better access to a news service. The network is constructed on the basis of articles read, and articles marked as rejected. It adapts over time to better represent the user's interests and rank the articles supplied by the news service. Using an augmented keyword search we can also search for articles using keywords in conjunction with the user model neural network. Trials of the system in a USENET news environment show promising results for the use of this approach in information retrieval.

Suppose that there are terminals on two concentric circles, Cin and Cout, with Cin inside of Cout. We are given a set of nets each of which consists of a terminal on Cin and a terminal on Cout. The routing area is the annular region between the two circles. In this paper, we present an O(nk-1) time algorithm for testing whether the given net set is k-layer routable without vias, where k2 and n is the number of nets.

This paper is concerned with the stress simulation of a LOCOS structure during not only oxidation but also the subsequent cooling down based on viscoelastic stress modeling. A viscoelastic model is successfully applied to the oxide, nitride and silicon substrate for a LOCOS structure. Thermal stress is also taken into account during the cooling down process. The viscoelastic deformation problem of all the three materials for the LOCOS structure are solved by a two-dimensional finite element method. It is the first time to show that the stress values after cooling down to room temperature are much higher than those right after oxidation. It is also shown that varying the cooling down rates results in the different stress values after cooling down.

In this paper, a three part algorithm is employed to obtain stable convergence during stress dependent oxidation simulation using the finite element method is presented. By introducing (1) a reduced integration formulation, (2) an averaging procedure for the mid-side node velocities at the Si/SiO2 interface, and (3) a three-node element to discretize the oxidant diffusion equation, major improvements in achieving stable convergence are realized during stress dependent oxidation simulation. This technique is generally applicable for an oxidation simulator using the finite element method.

We have developed a new model to analyze the thermal failure mechanism due to electrical-over-stress (EOS) for two-dimensional planar pn-junction structures where the failure power is proportional to about 1/5 power of the failure time. We adopted a pseudo two-dimensional numerical simulation method where a pn-junction diode is divided into small elements and represented by a circuit network composed of many minute resistors and diodes. The failure mechanism studied by Wunsch and Bell, that is one of many studies for one-dimensional pn-diodes, is not valid for the case of two-dimensional pn-junction, such as a planar type junction. On the contrary, the failure mechanism was found to be much correlative with the junction structure, especially the impurity concentration in the substrate in the two-dimensional case. When the impurity concentration in the substrate is high enough (e.g. Nsub1017[cm-3]), the breakdown occurs at the whole junction. The heat transfer is one-dimensional and the failure power is proportional to about 1/2 power of the failure time, which is well known results reported by many researchers: e.g. Wunsch &Bell. On the other hand, when the impurity concentration in the substrate is low enough (e.g. Nsub1016[cm-3]), the breakdown occurs locally at the junction edge. The heat transfer is two-dimensional and the failure power is in proportion to about 1/5 power of the failure time.

The objective of this paper is to provide an overview of the recent developments in the area of speech processing and in particular in the fields of speech coding and speech recognition. The speech coding review covers DPCM coders, model-based vocoders, waveform coders, and hybrid coders. The hybrid coders are described in some detail since they are the subject of current research. Our treatment of speech recognition techniques concentrates on the methodologies for voice recognition and the progress made in speaker independent recognition. In addition, we describe the efforts towards commercial deployment of this technology.

This paper presents a new method for estimating lattice parameters of a system with additive white noise. A new lattice structure filter is used to reduce the effect of additive white noise, and then, an overfitting lattice filter is proposed to obtain the ARMA parameters by using the estimated lattice parameters with additive white noise.

This paper proposes a technique for designing two-dimensional (2-D) digital filters approximating an arbitrary magnitude function. The technique is based on 2-D spectral factorization and rational approximation of the complex exponential function. A 2-D spectral factorization technique is used to obtain a recursively computable and stable system with nonsymmetric half-plane support from the desired 2-D magnitude function. Since the obtained system has an exponential function type transfer function and cannot be realized directly in a rational form, a class of realizable 2-D digital filters is introduced to approximate the exponential type transfer function. This class of filters referred to as two-dimensional log magnitude approximation (2-D LMA) filters can be viewed as an extension of the class of 1-D LMA filters to the 2-D case. Filter coefficients are given by the 2-D complex cepstrum coefficients, i.e., the inverse Fourier transform of the logarithm of the given magnitude function, which can be efficiently computed using 2-D FFT algorithm. Consequently, computation of the filter coefficients is straightforward and efficient. A simple stability condition for the 2-D LMA filters is given. Under this condition, the stability of the designed filter is guaranteed. Parallel implementation of the 2-D LMA filters is also discussed. Several examples are presented to demonstrate the design capability.

Low-field mobilities and velocity versus electric field relations are among the key input parameters for drift-diffusion simulations of field-effect and bipolar transistors. For example, most device simulations that treat scattering from ionized impurities contain mobilities or velocity versus field relations based on the Born approximation (BA). The BA is insensitive to the sign of the charged impurity and is especially poor for ionized impurity scattering because of the relatively strong scattering of long-wavelength carriers, which have low energies, and therefore violate the validity condition for the BA. Such carriers occur at high symmetry points in the Brillouin zone and are critical for device behavior. There has been a tendency in the past to assume that majority and minority mobilities are equal. This assumption can lead to incorrect interpretations of device data and thereby misleading design strategies based on such simulations. We have calculated the majority electron and minority hole mobilities in GaAs at 300 K for donor densities between 51016 and 11019 cm-3 and the majority hole and minority electron mobilities for acceptor densities between 51016 and 11020 cm-3. We have included all the important scattering mechanisms for GaAs: acoustic phonon, polar optic phonon, nonpolar optic phonon (holes only), piezoelectric, ionized impurity, carrier-carrier, and plasmon scattering. The ionized impurity and carrier-carrier scattering processes have been calculated with a quantum mechanical phase-shift analysis to obtain more accurate matrix elements for these two scattering mechanisms. We compare the total scattering rate for majority electrons due to ionized impurities based on exact phase shifts and on the BA used by Brooks-Herring. We also present additional data that show the differences between the exact phase-shift analyses and the BA for majority electron scattering rates as functions of carrier energy and scattering angle. These results show that the calculated low-field mobilities are in good agreement with experiment, but they predict that at high dopant densities minority mobilities should increase with increasing dopant density for a short range of densities. This effect occurs because of the reduction of plasmon scattering and the removal of carriers from carrier-carrier scattering because of the Pauli exclusion principle. Some recent experiments support this finding. These results are important for device modeling because of the need to have reliable values for the minority mobilities and velocity-field relations.