This paper proposes a new environment for high-level VLSI design specification validation using "Algorithmic Debugging" and evaluates its benefits on three significant examples (a protocol processor, an 8-bit CPU, and a Prolog processor). A design is specified at a high-level using the structured analysis (SA) method, which is useful for analyzing and understanding the functionality to be realized. The specification written in SA is transformed into a logic programming language and is simulated in it. The errors (which terminate with an incorrect output in the simulation) included in the three large examples are efficiently located by answering junt a few queries from the algorithmic debugger. The number of interactions between the designer and the debugger is reduced by a factor of ten to a hundred compared to conventional simulation based validation methodologies. The correct SA specification can be automatically translated into a Register Transfer Level (RTL) specification suitable for logic synthesis. In this environment, a designer is freed from the tedious task of debugging a RTL specification, and can concentrate on the design itself. This environment promises to be an important step towards efficient high-level VLSI design specification validation.

High performance I/O circuits for fast memory devices such as Synchronous DRAMs were studied. For a TTL interface, the effect of capacitive loading must increase as I/O speed is increased, and signal termination is required for frequencies over 100 MHz. For this reason, industry-proposed alternative interface approaches such as GTL and CTT were investigated using experimental test devices. The results showed that open-drain type drivers have a problem; as the frequency increases, the high-level output voltage becomes degraded. In contrast, a push-pull driver T-LVTTL (Terminated Low Voltage TTL), developed as an implementation of the CTT interface specification, was found to be suitable for high-speed data transfer. A high-speed bus driver circuit connecting an impedance element in series to the stub is proposed as an application of T-LVTTL. Simulated results showed that this scheme greatly improves the signal integrity of memory bus systems; the operating frequency could very well be the highest among several schemes discussed as candidates for the post-LVTTL standard interface.

This paper discusses pulse responses of multi-conductor transmission lines terminated by linear and nonlinear subnetworks. At first step, the circuit is partitioned into a linear transmission lines and nonlinear subnetworks by the substitution voltage sources. Then, the linear subnetworks are solved by a well-known phasor technique, and the nonlinear subnetworks by a numerical integration technique. The variational value at each iteration is calculated by a frequency domain relaxation method to the associated linearized time-invariant sensitivity circuit. Although the algorithm can be efficiently applied to weakly nonlinear circuits, the convergence ratio for stiff nonlinear circuits becomes very small. Hence, we recommend to introduce a compensation element which plays very important role to weaken the nonlinearity. Thus, our algorithm is very simple and can be efficiently applied to wide classes of nonlinear circuits.

We introduce a generalized cln grammar (gclng), a generalization of a completely linearly nested context-free grammar (clncfg), of which variables are partitioned linearly and each rule satisfies similar conditions as those of clncfg related to its partition. We show that the class of languages generated by gclng's coincides with the class of quasi-rational languages, and consider the inclusion relations between languages generated by gclng's and those generated by clncfg's.

A beam adaptive frame for finite-element beam-propagation analysis is proposed. The width of the frame can be adapted itself to either the guiding structure or the propagating beam in optical circuits, so the size of the computational window can be reduced.

In a hybrid coder which employs motion compensation and discrete cosine transform (MC-DCT coder), up to 90% of bits are used to represent the quantized DCT blocks. So it is most important to represent them with as few bits as possible. In this paper, we propose an efficient method for encoding the quantized DCT blocks of motion compensated prediction (MCP) errors, which adaptively selects one of a few scanning patterns. The scanning pattern selection of an MCP error block is based on the motion compensated images which are always available at the decoder as well as at the encoder. No overhead information for the scanning patterns needs to be transmitted. Simulation results show that the average bit rate reduction amounts to 5%.

A new approach to implement queues for controlling ATM switch LSI is presented. In many conventional architecture, external FIFOs are provided for each output link and used to manage the address of the buffer in an ATM switch. We reduce the number of FIFOs by using a self-timed queue with a search circuit that finds the earliest entry for each output link. Using this architecture, number of the FIFOs is reduced to 1/N, where N is the switch size. Delay priority and multicasting can be supported without doubling the number of the queues. This new queue can also be utilized as an ATM switch by itself. Evaluation chip was fabricated using 0.5-µm CMOS process technology. Inter-stage transfer speed over 500 MHz and cycle time over 125 MHz was obtained. This performance is enough for a 622-Mbps 1616 ATM Switch.

In real life, our sence of social reality is supported by the institutional basis, group/interpersonal basis, and belief/schema basis. In networked life, in contrast, these natural and ordinary bases are not always warranted because of a lack of institutional backup, the fragility of the group or interpersonal environment, and the noncommonality of our common sense. In order to compensate for these incomplete bases, networkers ar seeking adaptive communication styles. In this process, there emerge three types of communication cultures. One is the name-card exchange" type. This type is realized by communicating our demographic attributes verbally, which is useful for reality construction of the institutional basis. The second is the ideographization" type. In this type, the content of customary nonverbal communication is creatively transformed into various pseudo nonverbal or para-linguistic expressions, which strengthen fragile interpersonal relationships. The last type is the verbalian" type. This type never depends on the interpersonal or institutional basis. The networked reality is constructed solely in the attempt for common sense development among members. By analyzing the content of messages exchanged in four public groups called Forums," the author found that patterns of communication are transformed in a manner adaptive to each Forum's reality. Thier adaptation modes are different and depend on the types of communication culture every Forum pursues. This is contrarty to the psychologists' tendency to assume that there must be common characteristics or rules valid throughout all of the electronic communication situations.

We present a new multi-layer over-the-cell channel router for standard cell layout design using simulated annealing. This new approach, STANZA-M consists of two key features. The first key feature of our router is a new scheme for simulated annealing in which we use a cost function to evaluate both the total net-length and the channel heights, and an effective simulated annealing process by a limited range to obtain an optimal chnnel wiring in practical time. The second feature of our router is a basic layer assignment procedure in which we assign all horizontal wiring inside a channel to feasible layers by considering the height of channel including cell region with a one dimensional channel compaction process. We implemented our three-layer cannel router in C language on a Solbourne Series 5 Work Station (22 MIPS). Experimental results for benchmarks such as Deutsch's Difficult Example and MCNC's PRIMARY1 channel routing problems indicate that STANZA-M can achieve superior results compared to the conventional routers, and the process times are very fast despite the use of simulated annealing.

Genetic algorithms have been shown to be very useful in a variety of search and optimization problems. In this paper, we propose a modified genetic channel router. We adopt the compatible crossover operator and newly designed compatible mutation operator in order to search solution space more effectively, where vertical constraints are integrated. By carefully selected fitness function forms and optimized genetic parameters, the current version speeds up benchmarks on average about 5.83 times faster than that of our previous version. Moreover the total convergence to optimal solutions for benchmarks can be always obtained.

When we design a human interface of a computer-mediated communication (CMC) system, it is important to take a socio-behavioral approach for understanding the nature of the human communication. From this point of view, we conducted experimental observations and post-experimental questionnaires to investigate communicative characteristics in a teleconference using Fujitsu Habitat" visual telecommunication software. We experimentally held the following three kinds of small-group conferences consisting of five geographically distributed participants: (a) teleconference using a visual telecommunication system (Fujitsu Habitat"), (b) teleconference using a real-time keyboard telecommunication system of NIFTY-Serve and (c) live face to face physical conference. Analyses were made on (1) effects of the media on utterance behaviors of conference members, and (2) satisfaction of conference members with communicative functions of the media. Satisfaction was measured by a seven-level rating scale. We found that participants in a telconference held by using Habitat showed significant differences in contents of utterances and the rating of satisfaction with nine communicative functions compared with those of conferences held by using a real-time keyboard telecommunication system and a live face-to-face conference. These results suggest some features that could facilitate multi-participant on-line electronic conferences and conversations.

This paper describes an adaptively weighted code division multiplexing (AW-CDM) system, in other words, power controlled spread-spectrum multiplexing system and describes its application to hierarchical digital broadcasting of television signals. The AW-CDM, being combined with multi-resolutional video encoder, can provide such a hierarchical transmission that allows both high quality services for fixed receivers and reduced quality services for mobile/portable receivers. The carrier and the clock are robustly regenerated by using a spread-spectrum multiplexed pseudorandom noise (PN) sounder as a reference in the receiver. The PN reference is also used for Rake combining with signals via different paths, and for adaptive equalization (EQ). In a prototype AW-CDM modem, three layers of hierarchical video signals (highs: 5.91Mbps, middles: 1.50Mbps, and lows: 0.46 Mbps) are divided into a pair of 64 orthogonal spread-spectrum subchannels, each of which can be given a different priority and therefore a different threshold. In this case, three different thresholds are given. The modem's transmission rate is 9.7Mbps in the 6MHz band. Indoor transmission tests confirm that lows (weighted power layer I), middles (averaged power layer II), and highs (lightened power layer III) are retrievable under conditions in which the desired to undesired signal ratios (DURs) are respectively 0dB, 8.5dB, and 13.5dB. If the undesired signals are multipaths, these performances are dramatically improved by Rake combining and EQ. The AW-CDM system can be used for 20-30 Mbps advanced television (ATV) transmission in the 6-MHz bandwidth simply by changing the binary inputs into quaternary or octonary inputs.

When a new digital broadcasting system is introduced for the viewers, it is important to be able to include new services and system aspects. That is to give the viewers new experiences and meet the demands they might have in the future. To fulfil the viewers expectations, is a key for success for the introduction of new service and product. It is equally important to look at the long term perspective and have the possibility to gradually develop the digital broadcasting systems we establish today. A fully integrated multimedia system is a hybrid of different media services, distribution paths and display object. The pros and cons of each of them must be examined and each of them used where best suited. This will probably give a more complex media world with fuzzy borders between what is broadcasting, packaged media and what is the on-line information society. In order to balance this, any new digital multimedia system needs to be developed with an open architecture, based on generally agreed standards and possibly follow a non-proprietary approach. IDUN, a prototype system for multimedia broadcasting, is on its way to fulfil these requirements. IDUN combines the powerful point to multi-point emission, domestic data storage and computer processing with the telecommunication network. It is feasible to introduce it in the analogue world of today but could better be utilised in a fully digital future. Some possible services are further proposed. Some of them with a tight relation to what a broadcaster already produces, which could give an evolutionary transfer to the new digital world.

The double-stage threshold-type foreground-background congestion control for the common-store queueing system with multiple nonpreemptive priority classes is proposed to improve the transient performance, where the numbers of accepted priority packets in both foreground and background stores are controlled under the double-stage threshold-type scheduling. In the double-stage threshold-type congestion control, the background store is used for any priority packets, and some parts of the background store are reserved for lower-priority packets to accommodate more lower-priority packets in the background store, whereas some parts of the foreground store are reserved for higher-priority packets to avoid the priority deadlock. First, we derive the general set of coupled differential equations describing the system-state, and the expressions for mean system occupancy, throughput and loss probability. Second, the transient behavior of system performance is evaluated from the time-dependent state probabilities by using the Runge-Kutta procedure. It is shown that when the particular traffic class becomes overloaded, high throughputs and low loss probabilities of other priority classes can be obtained.

A programmable clock generator, based on a phase-locked loop (PLL) circuit, has been developed with 0.5 µm CMOS triple-layer Al interconnection technology for use as an on-chip clock generator in a 300-MHz video signal processor. The PLL-based clock generator generates a clock signal whose frequency ranges from 50 to 350 MHz which is an integral multiple, from 2 to 16, of an external clock frequency. In order to achieve stable operation within this wide range, a voltage controlled oscillator (VCO) with selectable low VCO gain characteristics has been developed. Experimental results show that the clock generator generates a 297-MHz clock with a 27-MHz external clock, with jitter of 180 ps and power dissipation of 120 mW at 3.3-V power supply, and it can also oscillate up to 348 MHz with a 31.7-MHz external clock.

OFDM (Orthogonal Frequency Division Multiplexing) is a useful digital modulation method for terrestrial digital broadcasting systems, both for digital TV broadcasting and digital audio broadcasting. OFDM is a kind of multicarrier modulation and shows excellent performance especially in multipath environments and in mobile reception. Other advantages are its resistance to interference signals and its suitability for digital signal processing. When each carrier of the OFDM signal is modulated with DQPSK, we call it DQPSK-OFDM. DQPSK-OFDM is a basic OFDM system, which is especially suitable for mobile reception. This paper describes how a DQPSK-OFDM system works and shows several experimental and simulation results. The experimental results mainly concern the performance of the DQPSK-OFDM system relative to various disturbances such as multipath (ghost) signals, nonlinearity of the channel, and interference from analog signals. The transmission characteristics of DQPSK-OFDM are investigated and the basic criteria for the system design of DQPSK-OFDM are discussed.

This paper presents a heuristic floorplanning method that improves the method proposed by Vijayan and Tsay. It is based on tentative insertion of constraints, that intentionally produces redundant constraints to make it possible to search in a wide range of solution space. The proposed method can reduce the total area of blocks with the removal and insertion of constraints on the critical path in both horizontal and vertical constraint graphs. Experimental results for MCNC benchmarks showed that the quality of solutions of the proposed method is better than [7],[8] by about 15% on average, and even for the large number of blocks, the proposed method keeps the high quality of solutions.

A timing-driven global routing algorithm is proposed that directly models the path-based timing constraints. By keeping track of the critical path delay and channel densities, and using novel heuristic criteria, it can select routing paths that minimize area as well as satisfy the timing constraints. Using bipolar-specific features, this router can be used to design LSI chips that handle signals with speeds greater that a gigabit per second. Experimental results shows an average delay improvement of 17.6%.

Video compression technologies such as MPEG have enabled the efficient use of video data in the computer environment. However, the compressed video information still has a huge amount of data compared with the other media such as text, audio, and graphics. Therefore, it is very important to handle the video information in a networked database for the efficient use of resources like storage media. Furthermore, in the networked database, its retrieval methods including search and delivery become the key issues especially for the video information which requires a large network bandwidth. In this paper, a video browsing method using an automatic fast scene cut detection for networked video database access is described. The scene cut is defined as the scene change frame and is detected by temporal change in interframe luminance difference and chrominance correlation which are obtained from spatio-temporally scaled image directly extracted from the MPEG compressed video without any complex processing of video decoding. The detected scene change frames are further investigated to exploit the relationship between the scene cuts and are classified in order to make a hierarchical indexing. These results of detection are stored as an scene index file using the MPEG format. The simulation results are also presented for several test video sequences to show that these methods have enabled the efficient video database construction and accessing.

A multi-stage noise-shaping (MASH) A/D converter combining an RC-integrator and a digital correction technique for high accuracy is described. Using 1.2-µm BiCMOS technology, we developed an A/D converter for digital audio with an S/N ratio of over 100 dB. This paper discusses the principles of MASH technology with an RC-integrator, the technique for correcting RC variation, and the experimental results obtained with a fabricated chip.