Large-scale integration (LSI) microchips are widely used in many types of modern electronic products including electric appliances, cellular phones, toys, electronic games, and automobiles. The electromagnetic interference (EMI) noise produced by these micro devices can cause significant operational problems in other devices in the system. Some methods that have been proposed for such analysis estimates the EMI noise characteristic through transistor-level power simulation. However, in these methods, transistor-level circuit simulation is performed by combining the power-supply impedance model and the power-supply source model. In general, transistor-level simulators are too slow for practical application-specific integrated circuit (ASIC) design. In this paper, a total solution for reducing EMI noise in LSI microchips was presented. The proposed design methodology integrates fast and accurate estimation, reduction, and verification. The method was successfully applied to the design of a 32-bit microprocessor, achieving a 2-dB noise reduction in the FM frequency band and 10-dB reduction at 1 GHz. The proposed design methodology is a powerful solution for LSI designers as a tool for minimizing EMI noise and achieve higher levels of reliability for the microelectronic products.

InGaP/GaAs HBT with novel ledge coupled capacitor (LCC) structure has been proposed and demonstrated for the first time. The LCC employs an extrinsic InGaP ledge layer as a capacitor parallel to the base resistor. This configuration enables feeding RF signals directly into the base without passing them through the base resistor. With the fabricated HBT, no increase of leakage current between emitter and base electrode was observed. The maximum oscillation frequency (fmax) of the HBT was improved by 10 GHz as compared with an HBT without the LCC.

A high-speed high-resolution sample-and-hold amplifier (SHA) is designed for time-interleaved analog-to-digital converter applications. Using the techniques of precharging and output capacitor coupling can mitigate the stringent performance requirements for the opamp, resulting in low power dissipation. Implemented in a standard 0.25 µm CMOS technology, the SHA achieves 80 dB spurious-free dynamic range (SFDR) for a 1.8 Vpp output at 100 MHz Nyquist sampling rate. The SHA occupies a die area of 0.35 mm2 and dissipates 33 mW from a single 2.5 V supply.

At the initial stage of developing parallel machines, a software monitor, which manages communication between host computers, program loading and debugging, is necessary. However, it is often a cumbersome job to develop such a monitoring system especially when the target takes a parallel architecture. To solve this problem, we developed an integrated monitor system called "Pot". "Pot" consists of a system runs on the host computer and simple code on a target machine. In order to reduce the development costs, the program on a target machine is as simple as possible while "Pot" on the host computer itself provides various functions for system development.

This paper describes an experimental study on resonant properties of the plasma-wave field-effect transistors (PW-FET's). The PW-FET is a new type of the electron devices, which utilizes the plasma resonance effect of highly dense two-dimensional conduction electrons in the FET channel. Frequency tunability of plasma-wave resonance in the terahertz range was experimentally investigated for sub 100-nm gate-length GaAs MESFET's by means of laser-photo-mixing terahertz excitation. The measured results, including the first observation of the third-harmonic resonance in the terahertz range, however, fairly deviate from the ideal characteristics expected for an ideal 2-D confined electron systems. The steady-state electronic charge distribution in the MESFET channel under laser illumination was analyzed to study the effect of insufficient carrier confinement on the frequency tunability. The simulated results support the measured results. It was clarified that an ideal heterostructure 2-D electron confinement is essential to assuring smooth, monotonic frequency tunability of plasma-wave resonance.

A framework is described for a peer-to-peer information exchange system, and a collaborative information retrieval (IR) scheme for the system is proposed. The aims of the system include smooth knowledge and information management to activate organizations or communities. Conventional server-centric systems are weak because they create information-providing bottlenecks. Accordingly, the proposed framework targets the collaborative inter-working of personal repositories that accumulate per-user information, and accept and service requests. Issues concerning the framework are addressed. One issue is the retrieval of information from another's personal repository; the retrieval criteria of a system are tightly personalized for its user. The system is assumed to employ a vector space model with a concept-base as its IR mechanism. The vector space on one system is very different from that on another system. Another issue is the automated control of the information-providing criteria. This paper presents solutions to the first problem. To achieve IR that provides satisfactory results to a user requiring information from another's personal repository, we need vector space equalization to compensate for the differences in the vector spaces of the personal repositories. The paper presents a vector space equalization scheme, the automated relevance feedback scheme, that compensates the differences in the vector spaces of the personal repositories. We implement the scheme as a system and evaluate its performance using documents on the Internet.

In this paper a digital frequency domain RFI (Radio Frequency Interference) cancellation scheme for DMT (Discrete Multitone) based VDSL (Very high speed Digital Subscriber Line) systems is presented. The proposed algorithm has been optimized and characterized in terms of complexity and performance. Optimizations were also performed from an implementation point of view by deducing key dependencies among our RFI model coefficients that let us drastically reduce the size of the memories involved. System simulations showed the effectiveness of the canceller: in terms of VDSL performance parameters such as bit rate, the optimized cancellation scheme recovers almost totally the performance degradation due to RFI.

The design, fabrication, and characterization of monolithic analog phase shifters based on barium-strontium-titanate (BST) coated sapphire substrates with continuously variable 180and 360phase-shift ranges are presented. The phase shifter using a single series resonated termination can provide 180phase shift with the chip area of 4 mm 4 mm. A double series resonated termination in a parallel connection can reach over 370phase shift with better than 6.8 dB-loss at 2.4 GHz. Also, an all-pass network phase shifter composed of only lumped LC elements was described here. This phase shifter demonstrated 160phase shift with an insertion loss of 3.1 dB 1 dB and return loss of better than 10 dB at 2.4 GHz. The total size of the phase shifter is only 2.4 mm 2.6 mm, which is the smallest reported BST phase shifter operating at S-band, to the best of the authors' knowledge.

This paper focuses on the investigation of RoF link noise influence in an ubiquitous antenna system, which is composed of multiple radio base stations (RBSs) deployed over the service area, central control station (CCS) and radio-on-fiber (RoF) link that connects RBSs to the CCS. The ubiquitous antenna system is capable of receiving multiple mobile terminals simultaneously operating at the same frequency channel by making effective use of joint detection. However, in the ubiquitous antenna system, since signals are transmitted from RBSs to CCS via the RoF link, the noise generated at the RoF link, such as relative intensity noise, inter modulation distortion, optical shot noise and thermal noise, may become dominant factors degrading the performance. The performance evaluations considering optical link noise is given by computer simulations. Computer simulation results show that more than 19 dB of RoF link Eb/N0 is required for achieving sufficient performance.

This paper proposes an ROF ubiquitous antenna architecture for the wireless CDMA system. The proposed system separates each component of independent signals passing through the multipath in radio and optical links, which are gathered at passive double star link, by using RAKE reception and the macrodiversity effect is obtained. Theoretical analysis shows that the proposed system improves BER performance by 22 dB and reduces the transmission power and its control range by 19 dB.

We have thoroughly investigated the effect of on-chip decoupling capacitors on the simultaneous switching noise (SSN) and the radiated emission. Furthermore, we have successfully demonstrated an efficient design method for on-chip decoupling capacitors on an 8-bit microcontroller without increasing the die size, which results in more than 10 dB of suppressed radiated emission.

A new analog correlator circuit is proposed for direct sequence code division multiple access (DS-CDMA) demodulator. The circuit consists of only 16 switches, 4 capacitors and 2 level shifters. Control sequence requires only three clock phases. Simulation with code length of 127 reveals that the proposed circuit has a good ability to cancel off the charge error and dissipates 3.4mW at 128MHz. The circuit had been designed using a 0.6µm CMOS process. The area of 256µm 245µm is estimated to be 9 times smaller compared to other reported equivalent analog correlators.

This paper presents an innovative 155Mb/s burst-mode laser transmitter chip, which was designed and successfully demonstrated, and contains several new subsystems: a digitally programmed current source, programmable up to 120mA with a resolution of 0.1mA, a fast but accurate intermittent optical level monitoring circuit, and a digital Automatic Power Control (APC) algorithm. This generic and intelligent chip was developed in a standard digital 0.35µm CMOS process. Extensive testing showed a high yield and algorithm stability, as well as excellent performance. During initialization, when the transmitter is connected to the Passive Optical Network (PON) for the first time, maximum three Laser Control Fields (LCF) are needed, with a length of 17bytes (0.88microsecond at 155Mb/s), to stabilize the laser output power. In this short time, the chip can regulate the launched optical output power of any FSAN (Full Service Access Network) compliant laser diode to the required level, even in the extreme circumstances caused by outdoor operation or by battery backup operation during power outages. Other tests show that the chip can further stabilize and track this launched optical power with a tolerance lower than 1dB over a wide temperature range, during the burst mode data transmission. The APC algorithm intermittently adjusts the optical power to be transmitted in a digital way, starting from loosely specified but safe preset values, to the required stable logic "1" and "0" level. No laborious calibration of the laser characteristic curve and storage of the calibration values in lookup tables are needed, nor any off-chip adjustable component. The power consumption is significantly reduced by disabling inactive circuitry and by gating the digital high-speed clock. Although this laser transmitter was developed for FSAN PON applications, which are standardized at a speed of 155Mb/s upstream, the design concept is quite generic and can be applied for developing a wide range of burst mode laser transmitters, such as required for Gigabit PON systems or other TDMA networks.

It is found that the supercontinuum spectrum is generated from cross-phase modulated soliton pulses which are propagated through a dispersion-flattened/decreasing fiber with low birefringence. The cross-phase modulation is achieved by exciting two orthogonally polarized modes in a birefringent fiber and the effect of input azimuth of linearly polarized pulses is discussed theoretically and numerically.

We have exploited a high-power-tolerant variable optical attenuator (VOA) based on the fused fiber coupler in the all-fiber structure. A newly designed VOA employs the external modulation by forcing an axial stress in the tapered region of the fused fiber coupler. In the tapered region, the axial stress changes the refractive index of silica glasses resulting in a change in the coupling coefficient of the coupler. In this paper, we explain the principle of the novel device, VOA, and the optimized fabrication of the fused fiber coupler for the attenuation. The changes of the transmission spectrum for the coupler and the optical power spectrum for pump laser diode (LD), whose center wavelength is 1.47µm, versus the axial displacement were verified by experiment. The possibility of the wavelength uniformity less than 1dB over the range of 1460-1500nm was also obtained by another coupler under a different fabrication condition. The polarization-dependent loss (PDL) at 1.47µm wavelength was 0.65dB for a maximum displacement of 150µm. The designed device has an attractive feature of another output port of the coupler available as a monitoring tap. The device showed a high attenuation above 34dB and an insertion loss below 0.15dB. The all-fiber structure can provide less alignment, which in turn provides a high power tolerance. This novel design, moreover, has a simple and cost-effective structure.

An ultra-small (0.4 0.4 mm2) radio frequency identification (RFID) chip named µ -chip has been developed for use in a wide range of individual recognition applications. The chip is designed to be 0.06 mm thick so that it can be applied to paper and to thin paper-like media, which have been used widely in retailing to create certificates that have monetary value, as well as to token-type devices. The µ-chip has been designed and fabricated using 0.18 µm standard CMOS technology with 3-layer aluminum metallization. The chip has a 128-bit memory. The memory data is easily read by applying a 2.45 GHz microwave radio frequency identification circuit technique. The minimum operating voltage of the chip's digital circuits is 0.5 V. This chip has attached to a thin-film external antenna. The chip terminals are connected to the antenna by an anisotropic conductive film (ACF). This type of structure results in a 0.15 mm thin transponder. The maximum communication distance between the µ -chip and a reader is 300 mm at a reader power of 300 mW.

In this paper, we propose the CMOS implementation of neuron models for an artificial auditory neural network. We show that when voltage is added directly to the control terminal of the basic circuit of the hardware neuron model, a change in the output firing is observed. Next, based on this circuit, a circuit that changes with time is added to the control terminal of the basic circuit of the hardware neuron model. As a result, a neuron model is constructed with ON firing, adaptation firing, and repetitive firing using CMOS. Furthermore, an improved circuit of a neuron model with OFF firing using CMOS which has been improved from the previous model is also constructed.

This paper describes a method for assessing the structural integrity of International America's Cup Class (IACC) yachts using a fiber optic distributed strain sensor. IACC yachts are made of advanced composite materials designed for high stiffness and lightness, however, a number of critical accidents have occurred during sailing. So we developed a health monitoring system and applied it to two Japanese IACC yachts to measure the distributed strain by using an optical fiber sensor installed in their hulls. We then estimated the three-dimensional distributed strain and compared the results with simulated data obtained by finite element analysis (FEA) to confirm the designed strength of these yachts.

This paper introduces a way to realize high-pass, band-stop and all-pass transfer functions using two-integrator loop structure consisting of loss-less and lossy integrators. The basic circuit configuration is constructed with five Operational Transconductance Amplifiers (OTAs) and two grounded capacitors. It is shown that the circuit can realize their circuit transfer functions by choosing the input terminals, and that the circuit parameters can also be independently set by the transconductance gains with the proportional block. Although the basic circuit configuration has been known, it seems that the feature for realizing the high-pass, the band-stop and the all-pass transfer functions makes the structure more attractive and useful. An example is given together with simulated results by PSPICE.

Recently, information display equipment such as a navigation system has often come to be installed in a vehicle, and a variety of useful information has been offered to the driver by voice and images while driving. The necessity of improving safety when the driver receives such information has come to be stressed. As one of the means of solving this problem, we can develop a system that presents the driving and road conditions information such as a lane changing car to the driver by using a warning sound. The purpose of our study is to clarify the effectiveness of an auditory display that uses spatial sounds on such a system. An experiment for measuring the driver's reaction time and eye movements to LED lighting during actual driving has been carried out to investigate whether the spatial sound can quicken the driver's operation and decrease human error. We evaluated the effectiveness by two measures, average reaction time and the number of largely delayed reactions. We considered that the average reaction time corresponds to the quickness of the driver's operation, and the number of largely delayed reactions corresponds to the probability of human error. As a result of the experiment, the use of directional sound clearly showed better performance than the use of monaural sound and no sound in the number of largely delayed reactions. Moreover, we analyzed the factors involved in delay of the reaction by the results of eye movement measurements. Consequently, it has been found that directional sound can decrease the number of the largely delayed reactions, which lead to an accident during actual driving.