Search

In order to obtain higher membrane performance in the concentration of bioethanol and dehydration of organic solvents, porous poly[1-(trimethylsilyl)-1-propyne] (PTMSP) and porous chitosan membranes, respectively are applied to a temperature-difference controlled evapomeation (TDEV) method in which a temperature difference between the feed solution and the membrane surroundings is established. Pressure treated porous PTMS membranes showed a high ethanol concentration performance with a high permeation rate and porous chitosan membranes also showed a high dehydration performance in TDEV. Membrane performances through these porous membranes in TDEV are discussed from the viewpoints of physical structure of membranes and permeants.

Average position of electrons along thickness direction in a Coulomb island in an n-channel Si single-electron transistor is estimated by analyzing the back-gate voltage dependence of peak voltage (defined as the gate voltage giving a drain current peak) as a function of peak number. It is found that the accuracy of estimated average position is better than 0.5 nm and that the average position fluctuates as the peak number increases.

TlFe2Se2-δ was synthesized by a self-flux method with excess amount of selenium. Elemental analysis using energy-dispersive X-ray spectroscopy estimates the deficiency δ at about 0.5. The magnetic susceptibility reveals an antiferromagnetic transition at TN ≈ 475 K. The resistivity exhibits a semiconducting behavior with an activation energy, EA = 0.04 eV. There is a clear anomaly in the resistivity at TN, indicating a strong interplay between magnetism and electric conduction.

Introduction: During laparoscopic cholecystectomy, an enlarged field of vision increases safety and precision, but surgeons often encounter bleeding that can cause difficulties. It is important to prevent and control arterial bleeding from Calot's triangle and the liver bed that results from injury to the deep branch of the cystic artery (DBCA). However, no previous reports have mentioned the layer between the gallbladder and liver through which the DBCA runs. Materials and Surgical Technique: To determine this layer, we investigated the histological findings from consecutive thin-slice (3 mm) blocks in six cases (three cadavers and three patients who underwent extended cholecystectomy). Results: The subserosal layer of the gallbladder wall can be divided into an inner (ss-i) layer, which consists of abundant vasculature and some fibrous tissue, and an outer (ss-o) layer, which consists of abundant fat tissue. DBCA runs through the ss-o layer, far from the ss-i layer in Calot's triangle, and runs toward the gallbladder body and ramifies into several branches that flow into the ss-i layer. Discussion: If the gallbladder is dissected in the layer close to the ss-i layer, as in our standardized procedure, the subbranches of DBCA are transected at the border of the ss-i layer, and most of the DBCA is left within the ss-o layer in Calot's triangle and the liver bed. Knowledge of the anatomy of DBCA is useful to avoid and stop bleeding from the deep part of Calot's triangle and the liver bed.

An efficient voice-over-IP (VoIP) support at the wireless access point (AP) of a wireless LAN (WLAN) remains a challenge for the last-mile wireless coverage of IP networks with mobility support. Due to the limited bandwidth that is available in WLANs, an accurate analysis of the voice capacity in such networks is crucial for the efficient utilization of their resources. The available analytical models only provide the upper and lower bounds on voice capacity, which may significantly overestimate or underestimate the WLAN's capability of supporting VoIP and, thus, are not suitable for the mentioned purpose. In this paper, we focus on the voice capacity analysis of a wireless 802.11(a/b) AP running the distributed coordination function (DCF). In particular, we show that by incorporating the clients' spatial distribution into the analysis, we are able to develop a new analytical model for a much more accurate estimation of the average voice capacity. By properly exploring this spatial information, we further propose a new scheme for AP placement such that the overall voice capacity can be enhanced. The efficiency of the new voice capacity model and the new AP placement scheme is validated through both analytical and simulation studies.

We investigate the hole transport in p-channel field-effect transistors doped with boron, at low temperatures (6–28 K). In transistors with a relatively large dimension, we observe the acceptor-mediated hopping and carrier freezeout, both of which are strongly influenced by the gate bias. In nanoscale transistors, these features turn into single-charge tunneling, i.e., the trapping/detrapping of single holes by/from individual acceptors. The statistics of the appearance of the modulation in a few ten samples indicates that the number of acceptors is small, or even just one, indicating that what we have observed is single-charge-transistor operation by a single-acceptor quantum dot.

Summary A characteristic feature of allergic rhinitis (AR) is the production of allergen-specific IgE antibodies. It is widely accepted that the induction of antigen-specific type 2 CD4+ helper cells (Th2) is a key event in this disease. Allergen-specific T cell–B cell interaction is indispensable for the induction of human IgE synthesis. Th2 cells also cause influx and activation of eosinophils, mast cells and basophils. Th2 cytokine-inducing cells play a major role in AR; this is known as the ‘Th2 paradigm’. In this review, we examine the Th1/Th2 cell dysregulation of AR and discuss new treatment approaches to improve this dysregulation.

The scheme of vertical stacking has caught much interest in the design of ultra high-speed communication switches for the past a few years. In particular, the scheme can greatly facilitate the effort of constructing all-optical photonic switches in the event that a banyan network structure is adopted. A vertically stacked photonic banyan (VSPB) network can preserve the good properties of the banyan network structures, such as the small depth and absolute loss uniformity; on the other hand, it introduces a significant increase in the hardware cost. Extensive research efforts have been addressed in determining the minimum number of stacked copies (planes) required for a nonblocking VSPB network. However, very few of them focused on the performance of the VSPB networks in terms of blocking probability. Therefore, in this paper, we study the blocking behavior of the VSPB networks and propose a corresponding analytical model under the random routing strategy. The proposed analytical model is designed to fully explore the property of symmetry in banyan network structures, and can calculate the blocking probability of a VSPB network stage by stage in a recursive manner such that the combinatorial explosion problem is avoided. To verify the proposed model, we conduct extensive simulations, in which the results indicate that our model can accurately describe the blocking behavior of VSPB networks under the random routing strategy and it agrees with the conditions of strictly nonblocking VSPB networks. We find that the proposed analytical model can deeply investigate into the inherent relationship between blocking probability and network hardware cost in terms of the number of planes; as a result, a quantitative guidance for initiating a graceful compromise between blocking probability and hardware cost can be developed based on the analytical model. Our analysis results also show that the hardware cost of a VSPB network can be dramatically reduced by simply allowing a negligible nonzero blocking probability in most of the practical cases. This fact will solidly contribute to the network switch architecture design and enable more practical applications of VSPB networks.

The gain characteristics of longitudinal discharge F2 lasers were investigated. The discharge tube consisted of a ceramic pipe of an inner diameter of 5 mm and a length of 15 cm with two metallic electrodes at each end, and with a special preionization electrode. When the tube was used as an oscillator, a laser output energy of 100 μJ was obtained at 1 atm total pressure with an excitation density of 1.5 MW/cm3. The time resolved gain measurement of the F2 laser was made in the oscillator–amplifier configuration, and the peak value of the gain coefficient was estimated to be 11% cm−1. The numerical analysis of the discharge circuit was made to estimate discharge resistances, inductances and currents in the excitation circuit.

We report on the superconductivity in FeSe samples, which were prepared from Fe and Se powder, synthesized by different sintering temperatures (Ts) from 573 K to 1173 K at intervals of 100 K. According to observation of the surface of the resulting samples using a scanning electron microscope (SEM), the grain-size increases from ∼1 μm (573 K) to ∼50 μm (1173 K) with raising Ts. These polycrystalline samples with Ts ⩾ 773 K, composed almost entirely of the tetragonal FeSe phase, although small amounts of the hexagonal FeSe phase were detected by X-ray diffraction (XRD) measurements. These samples indicated the negative susceptibility in magnetization, which gave estimates of the onset T c on ∼ 7 – 9 K , respectively. The sample for Ts = 873 K showed the maximum value of T c on .

The Haptic Cooperative Virtual Workspace (HCVW), where users can simultaneously manipulate and haptically feel the same object, is beneficial and in some cases indispensable for training a team of surgeons, or in application areas in telerobotics and entertainment. In this paper we propose an architecture for the haptic cooperative workspace where the participants can kinesthetically interact, feel and push each other simultaneously while moving in the simulation. This involves the ability to manipulate the same virtual object at the same time. A set of experiments carried out to investigate the haptic cooperative workspace is reported. A new approach to quantitatively evaluate the cooperative haptic system is proposed, which can be extended to evaluate haptic systems in general.

Shubnikov–de Haas oscillations have been investigated in Silicon-on-insulator MOSFET's with silicon film thicknesses down to 3 nm. The lifting of the valley degeneracy may reach 20 meV. This anomalous valley splitting is tentatively attributed to a combination of a higher quantum confinement and a rough back interface.

The condition for a direct band gap in Si quantum wires is investigated within the effective mass theory for wires coherent in every direction perpendicular to the wire direction. The condition is calculated using the equivalent condition that the minimum energy of the one-dimensional sub-bands of electrons is at the Γ-point, because holes always have a minimum energy at this point. It is shown that only Si quantum wires on the {100} plane can have a direct band gap. In particular, 〈100〉-oriented Si quantum wires have a direct band gap regardless of their cross-sectional shape. For wires other than 〈100〉-oriented ones, the condition of a direct band gap for rectangular, elliptic, triangular and trapezoidal cross-sectional shapes is investigated, assuming that the confinement potential is infinitely high in order to have the condition determined only by their cross-sectional shape and direction independently of their cross-sectional size. In all cases, wires have a direct band gap when the ratio of wire height (size perpendicular to the {100} plane) to width (size parallel to the {100} plane) decreases, and 〈110〉-oriented wires have the largest ratio of height to width for a direct band gap.

A very small Si single-electron transistor (SET) was fabricated by converting a one-dimensional Si wire on a SIMOX substrate into a small Si island with a tunneling barrier at each end by means of pattern-dependent oxidation. The conductance characteristics of the device are very stable and do not change after thermal cycles between low and room temperatures. The temperature and voltage dependence of the cotunneling current measured with high accuracy are analyzed in comparison with inelastic cotunneling theory.

OBJECTIVES: Vocal cord abductor paralysis (VCAP) is a life threatening complication which may cause nocturnal sudden death in patients with multiple system atrophy. However, the early diagnosis of VCAP is often difficult to make on routine laryngoscopy performed during wakefulness, as stridor, which is the sole symptom of VCAP in the early stage, develops only during sleep. The aim was to investigate laryngeal dysfunction in patients with multiple system atrophy while awake and asleep. METHODS: Seven patients with multiple system atrophy with nocturnal stridor and five control patients were studied. Vocal cord movement was analysed by laryngoscopy while the patients were awake and also during sleep induced by intravenous diazepam. RESULTS: When awake, for the seven patients with multiple system atrophy normal movement of the vocal cords occurred in three, mild abduction restriction in three, and paradoxical movement in one. When asleep, however, all showed obvious paradoxical movement with high pitched inspiratory stridor. In controls, there were no differences in the vocal cord movement between wakefulness and sleep. From these findings, VCAP could be divided into four stages: stage 0 (normal) with normal vocal cord movement during both wakefulness and sleep, stage 1 (mild VCAP) with normal movement during wakefulness and paradoxical movement during sleep, stage 2 (moderately severe VCAP) with abduction restriction during wakefulness and paradoxical movement during sleep, and stage 3 (severe VCAP) with an almost midline position for the vocal cords during both wakefulness and sleep. CONCLUSIONS: Laryngoscopy during sleep can disclose subclinical VCAP, making an early diagnosis of VCAP in patients with multiple system atrophy. Stage 2 of VCAP seems to be a suitable stage for tracheostomy in patients with multiple system atrophy.

In the allergic mucosa, there is a significant increase in numbers of CD25+ cells and activated eosinophils. To determine whether a link exists between the activated T-lymphocytes and tissue eosinophils in nasal allergy, we studied CD25+ cells in the nasal mucosa and compared the levels of soluble IL-2 receptor (sIL-2R) both in the serum and the nasal secretions, and further investigated expression of CD11b on eosinophils in the nasal lavage fluids and peripheral blood of patients with nasal allergy. We also examined the effects of the culture supernatant of Con A- and IL-2-activated T-lymphocytes on CD11b expression on eosinophils in the present study. The concentration of sIL-2R in the nasal secretions from patients with Japanese cedar pollinosis (JCP) was significantly higher than that from normal subjects (p < 0.01). The sIL-2R level was significantly higher in the nasal secretions than in the sera in patients (p < 0.01), and CD11b expression on eosinophils from nasal hvage fluid was significandy higher than that of eosinophils from peripheral blood of the same individuals (p < 0.01). The activated T-lymphocytes promoted eosinophil activation with upregulation of CD11b in vitro, and eosinophils in the nasal secretions from patients significantly expressed more CD11b in vivo. These results indicate that activation of T-lymphocytes is linked to eosinophil activation in nasal allergy.

To investigate soluble IL-2 receptor (sIL-2R) levels in nasal allergy, the sera and nasal secretions from patients with nasal allergy and from healthy subjects were subjected to a double-epitope enzyme-linked immunosorbent assay. Significant elevation of sIL-2R concentrations in the sera and nasal secretions was observed in the allergy patients (n = 26) compared with those of healthy subjects (n = 9). IL-2R-positive (CD25+) cells were observed in the crust formed in an allergic nasal mucosa. The concentration of sIL-2R in the sera correlated neither with the eosinophil count of the peripheral blood count nor with clinical severity. The concentration of sIL-2R in the nasal secretions was significantly higher compared with that in the sera from allergic patients (p < 0.01), whereas no significant difference was observed between sIL-2R levels in the sera and nasal sections from normal subjects. These findings indicate that sIL-2R plays an essential role in allergic processes by regulating IL-2R-positive cells recruited into the nasal mucosa.

In order to elucidate the mechanisms responsible for the excimer formation kinetics in a discharge-pumped KrF laser, the time-resolved densities of Kr ∗ atoms, an F - ion and an electron in the discharge plasma have been measured by means of an interferometric method and an absorption method. On the basis of these experimental data, the formed density of the KrF ∗ excimer is calculated. It is experimentally elucidated that in a He buffer a degree of contribution of the neutral and ion channels for the excimer formation is almost equal, and in a Ne buffer that of the ion channel is an order of magnitude larger than that of the neutral channel.

In recent years, many countries have experienced an increase in the prevalence of allergic rhinitis. No effective approach is currently available to prevent the onset of symptoms in allergic individuals. Pranlukast, a leukotriene receptor antagonist with a good safety and efficacy record for the management of allergic inflammation, may be appropriate for early intervention in the management of pollinosis.To investigate the efficacy of pranlukast as an early intervention in the control of cedar pollinosis.In a double-blind comparative study, pranlukast (n = 102) or placebo (n = 91) was administered to cedar pollinosis patients immediately before the start of the dispersion season and continued for 4 weeks. Subsequently, pranlukast was administered to all patients for 2 weeks until the end of the cedar pollen dispersion season (mid-March). All patients were carefully monitored for severity of nasal symptoms, symptom scores, medication scores, symptom-medication scores, and quality of life (QOL).Compared with placebo, therapy with pranlukast before and during the dispersion of cedar pollen in these patients significantly improved nasal symptoms (paroxysmal sneezing, rhinorrhea, and nasal congestion), symptom scores, and symptom-medication scores. The drug also significantly reduced deterioration of QOL, and improved nasal symptoms and QOL throughout the dispersion period.Administering pranlukast immediately before the beginning of cedar pollen dispersion is effective in reducing symptoms of allergic rhinitis throughout the dispersion period.

Despite the benefits those communities FM radio broadcasting services provide to their listeners, more than half of the community stations in Japan are struggling financially. This situation has arisen because the Internet has attracted advertising revenue away from radio broadcasting channels. One way to revive local FM radio broadcasting is by adding new representation function to radio signals. It is designed for many listeners to share the same information simultaneously. On the other hand, while the Web provides a variety of content, its ability to broadcast is inferior to that of TV or radio broadcasting. Combining radio broadcasting and the WWW provides a new broadcasting media. The control signals used for accessing the Web are put onto radio sound by using Acoustic OFDM technology. We developed and evaluated such a broadcasting system.

A method to analysis the performance of arbitrary cross section rib waveguide is proposed in this paper. In this method, effective-index method (EIM) and transfer matrix method are used and the results are precision but the process are simple and convenient.

We investigate transport in phosphorus-doped buried-channel metal-oxide-semiconductor field-effect transistors at temperatures between 10 and $295\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. We focus on transistors with phosphorus donor concentrations higher than those previously studied, where we expect conduction to rely on donor electrons rather than conduction-band electrons. In a range of doping concentration between around 2.1 and $8.7\ifmmode\times\else\texttimes\fi{}{10}^{17}\phantom{\rule{0.3em}{0ex}}{\mathrm{cm}}^{\ensuremath{-}3}$, we find that a clear peak emerges in the conductance versus gate-voltage curves at low temperature. In addition, temperature dependence measurements reveal that the conductance obeys a variable-range-hopping law up to an unexpectedly high temperature of over $100\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. The symmetric dual-gate configuration of the silicon-on-insulator we use allows us to fully characterize the vertical-bias dependence of the conductance. Comparison to computer simulation of the phosphorus impurity band depth profile reveals how the spatial variation of the impurity-band energy determines the hopping conduction in transistor structures. We conclude that the emergence of the conductance peak and the high-temperature variable-range hopping originate from the band bending and its change by the gate bias. Moreover, the peak structure is found to be strongly related to the density of states (DOS) of the phosphorus impurity band, suggesting the possibility of performing a spectroscopy for the DOS of phosphorus, the dopant of paramount importance in Si technology, through transport experiments.

This paper proposes a new algorithm to measure relevance among Web pages (RWP) using a hybrid method of hyperlink analysis and content analysis. Here we used a new approach to Web searching where the input to the search process is not a set of query terms, rather the URL of a page, and the output is a set of related Web pages. A related Web page is one that addresses the same topic as the original page. Here, the proposed algorithm first uses only the connectivity information in the Web (i.e., the links between pages) and then the content of pages. To evaluate the performance, the algorithm is compared with existing algorithms. Experimental results show that RWP outperforms existing algorithms to find relevant Web pages. RWP increases the search efficiency effectively and enhances the application area of Web related research.

Crosstalk-free pruned optical banyan networks on vertical stacking scheme (namely, EP-VSOB networks) has been proposed in the literature for faster connection establishment that can be used in optical cross-connect. The routing algorithm provided with the networks has optimal time complexity, O(log/sub 2/N). In that architecture, the number of pruned planes has always been considered as /spl radic/N (or /spl radic/2N when log/sub 2/N is odd), and a few extra planes (regular banyan) has been added with this pruned planes. The switch architecture has very low blocking probability with considerably lower cost and high speed. In this paper we study the blocking behavior of a generalized architecture of pruned optical banyan networks in which the number of pruned planes can be 2/sup x/, where 0/spl les/x/spl les/log/sub 2/N in addition to the variable extra planes. This generalization helps us find the desirable tradeoff between different constraint and performance metrics. Our simulation results show that for some given performance requirements (e.g. cost, speed or blocking probability) we can choose a network that has lower switch count compared to /spl radic/N -plane pruned crosstalk-free optical banyan networks. For example, to ensure the blocking probability to be less than 0.02, previously we would choose a pruned network of 32 pruned-planes and 1 extra plane (a regular banyan); however, our simulations results show that a network of 16 pruned-planes and 2 extra-planes is enough to ensure the same performance requirement. It is notable that, the hardware cost can be decreased significantly by choosing the alternative combination of pruned and extra planes. We believe our results provide more flexibility in choosing a particular EP-VSOB network satisfying given requirements.

In this paper, we consider the problem of dynamic lightpath protection in survivable WDM networks with single link failure model. Our work concerns in how to dynamically determine a protection cycle to establish a dependable lightpath with fault-tolerance requirement. This problem is identified as NP-complete, thus a heuristic for finding near optimal solution with reasonable computation time is usually preferred. Inspired from the principle of ant colony optimization, we develop in this paper an ant-based mobile agents algorithm for this problem with improved blocking performance. To enable the new ant-based algorithm, we propose to use on each network node both a routing table that contains a set of feasible cycles between source destination nodes and also a pheromone table for mobile agents. By keeping a suitable number of mobile agents in a network to continually and proactively update the cycles in a routing table based on the current network congestion state, the routing solution of a connection request can be obtained based on simply a local searching with a reasonable computation time. Extensive simulation results upon the ns-2 network simulator show that our new algorithm can achieve a significantly lower blocking probability than the promising algorithm for dynamic lightpath protection with a comparable computation complexity.

This paper will cover a 2500-gate bipolar array with 80ps delay, which uses a macro cell design and 1μ rules. A 7.5ns 16b multiplier has been realized.

${\mathrm{SiO}}_{2}/{\mathrm{S}\mathrm{i}/\mathrm{S}\mathrm{i}\mathrm{O}}_{2}$ quantum wells fabricated on SIMOX silicon-on-insulator substrates are examined in the quantized Hall regime. An 8 nm quantum well behaves as a single layer of two-dimensional electrons at accessible gate voltages. By using front and back gates, the wave function in the confinement direction can be shifted continuously between two ${\mathrm{SiO}}_{2}/\mathrm{Si}$ interfaces formed through different processes. We find that this results in a continuous evolution of the valley splitting which is asymmetric with electrical gate bias. Wider quantum wells show bilayer behavior where the valley splitting is different in each layer, demonstrating that its control shown by the 8 nm well arises due to the different properties of the two interfaces. Estimates of the valley splitting are made through Landau level coincidences and activation energies. The coincidence between Landau levels of opposite spin, opposite valley, and like cyclotron indices at $\ensuremath{\nu}=6$ shows anticrossing behavior.

The task of human written decomposition is based on the pair of original documents and its summary to define these components in a summary sentence come from somewhere in the document. This task aims to satisfy three requirements as follows: 1) Whether it is constructed from cutting and pasting? 2) Which components in the sentence come from the original document? 3) Where in the document do the components come from? The result of a decomposition program is considered as training data and data evaluation for reduction and combination steps in cut and paste summarization system. We propose a method to enhance the accuracy of decomposition task through checking position and semantic measure for each word within a summary sentence. The model we used in the paper is extended from the hidden Markov model described by Hongyan Jing and K.R. MacKeown, (1999). Experiment results in the DUC data shows that the proposed method is efficient.

Interconnection networks play a crucial role in the performance of massively parallel computers. Hierarchical interconnection networks provide high performance at low cost by exploring the locality that exists in the communication patterns of massively parallel computers. A hierarchical torus network (HTN) is a 2D-torus network of multiple basic modules, in which the basic modules are 3D-torus networks that are hierarchically interconnected for higher level networks. The static network performance of the HTN has already been studied and has been shown to be good. Dynamic communication performance has been evaluated under uniform traffic patterns but not under a nonuniform traffic, such as matrix transpose traffic patterns. In this paper, we present a deadlock-free routing algorithm for the HTN using 3 virtual channels and evaluate the network's dynamic communication performance under matrix transpose traffic, using the proposed routing algorithm. We evaluate the dynamic communication performance of HTN, H3D-mesh, TESH, and mesh networks by computer simulation. We find that the dynamic communication performance of HTN is better than that of the H3D-mesh, TESH, and mesh networks.

Discusses a high speed off-line defect compensation scheme for trained multi-layer neural networks implemented in WSI devices. Since the partial retraining scheme utilizes the redundancy of neural networks, no additional circuits are needed. The performance of the partial retraining scheme is compared with that of a back-propagation algorithm on a face image recognition problem.

In this paper, multi-resolutional optical flow estimation using a gradient-based method with local optimization is proposed. The method computes image motions in a fine resolution at points where image displacements are small, and in a coarse resolution at points where image displacements are large. Considering the effect of a low-pass filter that is applied to make the coarse resolutional image, some parameters are set for each resolution as follows: (1) size of a local window where optical flow is assumed to be constant is enlarged as resolution is decreased; (2) threshold of the smaller eigenvalue of the Hessian of image is determined by the power of white noise, impulse response of the low-pass filter and derivative operator. The proposed method is tested and discussed on synthetic and real image sequences. We find an optimal resolution for velocity to estimate optical flow in sequences where white noise is added.

An approach to solving reliability problems due to voltage tolerance in submicron devices is described which involves lowering the operating voltage using an on-chip voltage conversion system. The masterslice has an on-chip voltage converter, TLL-compatible I/O circuits and uses advanced 0.8- mu m BiCMOS technology. A cross-sectional view of the BiCMOS device, which consists of CMOS transistors with simple n-well structure and an n-p-n bipolar transistor, is shown. The masterslice has been applied to a digital signal processing circuit. The chip contains 20 k gates, including four multiplier macrocells and random logic circuits. In the random logic circuits, which consist of double-size transistors, the packing density is 240 gate/mm/sup 2/, and the average delay is 600 ps for a two-input NAND gate with FO=3 and 1-mm wiring length. In the multipliers, 660 gate/mm/sup 2/ packing density and 450 ps average delay for 2-input NAND gate with FO=3 are attained. >

An ultra-high-speed GaAs macrocell array is described which uses a three-level series-gate low-power source-coupled FET logic (LSCFL) as a basic circuit and a 0.4- mu m-gate flat-gate self-aligned implantation for n/sup +/-layer technology-2 (FG-SAINT-2) as a fabrication technology. The chip consists of 50 macrocells and is the equivalent of 250 gates. A typical propagation delay of unloaded ring oscillators and a typical toggle frequency of 1/4 frequency dividers fabricated on the macrocell array are 30 ps and 7.5 GHz, respectively. The basic cell is composed of three-level series gate LSCFL using all-differential signals; this circuit has twice the speed of a single-ended SCFL because it involves only one-half logic swing with the same noise margin. To verify the LSI performance, a 2*2 asynchronous transfer mode (ATM) switch element (150 equivalent gates) was fabricated on the macrocell array. The measured waveforms of the switch at 2 Gb/s are shown. The equivalent critical path gate number of the chip is 10 between flip-flops; therefore an average gate delay time of 50 ps is obtained. >

A high-density and quick-turnaround macrocell design method for custom VLSIs is applied to a 500 k-transistor protocol control chip, resulting in a density of about 4000 transistors/mm/sup 2/ using 0.8- mu m BiCMOS technology. An automated adaptive macrocell and a short-time custom VLSI design methodology were developed to make the logic and physical design more adaptable by offering greater variety of bit width, word length, circuit type, and signal terminals. The adaptive macrocell generation procedure consists of a logical description and a physical description with minimum information on the composition of complete macrocells, suitable for all specific uses. The variables providing adaptability are parameterized in this procedure, which is hierarchically described by network information among leaf cells or submacrocells, together with their topological placement information, permitting the adaptive macrocell to be generated automatically. An example of an ALU (arithmetic logic unit) circuit generated as a data-path submacrocell is shown. To verify the effectiveness of the proposed method, various kinds of macrocells were generated and fabricated using the 0.8- mu m, double-metal BiCMOS technology. A packet communication control circuit supporting X.25-based layer 2 and 3 protocols, which was designed by this method, is presented. >