bluuebunny/crossref_metadata_2025 huggingface dataset:
Performance analysis of the integrated train access scheme under light and medium load
Authors: Hayashida Yukuo
Published: July 2007

The integrated train access scheme is an access scheme integrating synchronous traffic and asynchronous traffic based on the train concept. It has a feature that an upper limit can be bounded on the train ring rotation time by limiting the number of asynchronous frames that can be connected to the train running on the ring network. Furthermore, it can also have the feature of round‐robin scheduling. An approximating analysis by a polling model is made to clarify the traffic characteristics of this integrated train access scheme under medium and light load. As a result of simulation studies, it has been found that this analysis shows a good approximation.
Design of multilayer wave absorber for oblique incidence using the point frequency matching method
Authors: Aoyagi Takahiro , Shimizu Yasutaka
Published: July 2007

The desirable characteristics of the wave absorber are such that it has good absorbing characteristics not only for the normal incidence but also the oblique incidence and that it has an effective absorbing capability for any polarization.

In this paper, a program is developed for design of a multilayer wave absorber for the oblique incidence by means of the point frequency matching method and subsequently a design is carried out. It was successful in designing a broadband wave absorber for which the reflection coefficient is less than a certain value at frequencies above a certain design frequency once an incident angle and a polarization are specified for an obliquely incident TE or TM wave.

To study both the frequency characteristics and the incident angle dependence of the designed wave absorber, contour maps were developed. By means of the contour maps, the absorbing characteristics of the wave absorber were studied. It was confirmed that good results can be obtained for oblique incidence.
Electromagnetic environmental measurement system employing frequency level selective process
Authors: Masugi Masao , Takagi Kusuo , Ideguchi Tsuyoshi , Satoh Masaji
Published: July 2007

This paper describes a method of measuring quasi‐stationary electromagnetic waves, whose level, generation time, radiation points, and rates of the incidents are not always constant. Those quasi‐stationary waves radiated from the amateur radio, the land mobile station, and so on, sometimes cause electromagnetic interference (EMI) and are rather difficult to detect. the frequency and the electromagnetic field level of those waves can be detected effectively by frequency domain measurements using a high‐resolution spectrum analyzer. This measurement system detects EMI waves whose peak level is above a threshold line set in the specific frequency range. Measurements were also carried out in urban areas to investigate the environment for citizen‐band. Results indicate that there is a close relationship between the occurrence rates and the human activities. This system is useful for detecting the cause of EMI and establishing countermeasures against electromagnetic waves.
Proposal of coherence multiplexed optical communication system using balanced receiver and its application for space transmission
Authors: Takeda Shinichi , Tsukamoto Katsutoshi , Morinaga Norihiko
Published: July 2007

Various types of theoretical studies and experimental work are being performed on coherence multiplexed systems in which multiplexing of the signal light is done by using the time incoherence of a semiconductor laser light. In this paper, the balanced receiver that uses the balanced mixer type photodetector is proposed for coherence multiplexed communication system and signal‐to‐noise power ratio (SNR) and bit‐error rate are theoretically derived. Moreover, the application of a coherence multiplexed system for space transmission is studied and the system which transmits reference light and signal light by polarization multiplexing is proposed. Moreover, the polarization diversity balanced receiver that is presented can remove the effect of polarization mismatch between the transmitter and receiver. Since both of the proposed systems are removed, then a signal‐signal beat noise (a large problem in conventional receiver using single photodetector) creates a drastic improvement in the SNR. Moreover, theoretical analysis of the receiver using an optical amplifier is performed and it is shown that there is an optimum value of spectral linewidth for obtaining the maximum SNR.
High‐density pin‐board matrix switch and its crosstalk characteristics
Authors: Inagaki Shuichiro , Kanai Tsuneo , Hosokawa Shigefumi
Published: July 2007

The purpose of this study is to realize the automated main distribution frame (MDF), which is indispensable in the new installation and transfer of the telephone set. the switching element, which is the key component in the matrix connection, as well as its crosstalk characteristics, are investigated. the following results are obtained: (1) systems based on various switching elements are compared, and it is shown that the pin‐board matrix is the best in the sense of the adaptability at the present stage. A detailed structure of the pin‐board matrix is proposed; (2) the effects of the shielding layer, the frequency and the defined route (insertion position of the pin) on the crosstalk characteristics of the single pinboard matrix switch is analyzed experimentally; and (3) a method is proposed and established for the probabilistic analysis of the pin‐board matrix switch with the threestage link connection.

The proposed method of analysis is applied to the automated MDF. It is shown that the probability that the overall crosstalk does not satisfy the specification of the 320‐kbit/s time‐compression multiplexing transmission lines is very small (1.2 × 10‐5). In other words, it is shown that the automated MDF can accommodate the 320‐kbit/s time‐compression multiplexing transmission lines.
Fast convergence PLL synthesizer with initial phase difference
Authors: Iritani Tadamitsu , Kuge Junzo , Oie Takahiro
Published: July 2007

A PLL synthesizer with a short frequency switching time applicable to frequency hopped spread spectrum (FH‐SS) communications is proposed in this paper. Switching output frequencies at high speed is difficult in a conventional PLL because of the low‐pass filters in the loop. In contrast to this, a sample hold‐type phase comparer that does not require a low‐pass filter is used in the proposed PLL. In addition, an output frequency is converged instantaneously by giving an initial value to the PLL during frequency switching. an initial value corresponding to each frequency can be obtained from a phase difference of the normal state of the PLL at the same frequency as that of the preceding cycle because the frequency transition of the propagation wave of FH‐SS communications is cyclical. Analysis of the errors of the proposed PLL show that the maximum error is the phase lag of VCO that occurs when an initial value is given. It is difficult to increase the hopping frequency because the switching time is shortened. While it is difficult to increase the hopping frequency since the PLL response is delayed when the PLL time constant is large, the effect of this error is slight. A method for compensating for the error due to this phase lag is proposed here. In addition, it is shown that this method allows the hopping frequency to be increased up to one‐third of the reference frequency.
A unified solution to mixed loss and delay systems with partial preemptive priority
Authors: Niu Zhisheng , Kawai Takehiro , Tadokoro Yoshiaki , Akimaru Haruo
Published: July 2007

This paper proposes a new priority scheme called partial preemptive priority (PPP) for mixed loss and delay system to satisfy very different individual performance requirements of loss (delay‐sensitive) traffic and delay (loss‐sensitive) traffic. the PPP scheme is a generic priority scheme which includes all the conventional priority schemes, e.g., preemptive priority (PP) and movable boundary (MB), as well as nonpriority (NP), schemes as special cases. By using the matrix‐analytic method, a unified matrix‐geometric solution to the mixed loss and delay priority systems with phase‐type Markov renewal process (PH‐MRP) inputs is derived. Numerical examples also are presented to demonstrate the effectiveness of the PPP scheme.
Multiple‐symbol differential detection for differentially encoded amplitude modulation signals and its application to 16DAPSK
Authors: Suzuki Toshinori , Mizuno Toshio
Published: July 2007

This paper addresses a multiple‐symbol differential detection scheme for 16 DAPSK. At the outset, conventional differential detection of 16 DAPSK is scrutinized analytically. As a result, it is seen that the energy penalty of differential amplitude detection compared with ideal coherent detection is larger than that of phase detection. Then, to improve the overall performance of 16 DAPSK, an MLSE algorithm is proposed for a large C/N as well as a suboptimum algorithm. Both allow multiple‐symbol differential amplitude and phase detection. Their performances also are evaluated through computer simulation.
Propagation characteristics of whistler‐mode signals from low‐frequency decca transmitter
Authors: Iwata Akira , Tanaka Yoshihito , Nishino Masanori
Published: July 2007

To resolve the propagation characteristics of low‐ frequency (LF) radio waves in the low latitude magneto sphere, the navigation radio signal (transmitting frequency of 85.725 kHz, 1.2 kW CW) from Biei Decca station in Hokkaido (geographical latitude: 43.60°N, geograph ical longitude: l42.45°E, magnetic latitude: 37.20°N) was observed at Birdsville. Australia (geographical latitude: 25.83°S, geographical longitude: 139.33°E, magnetic longitude: 37.08°S), which is the magnetic conjugate point. From the analysis of the intensity, Doppler spectrum and polarization of the magnetospheric propagation wave, the following characteristics were obtained. (1) the magnetospheric wave, which is below the detectable level during daytime, appeared around sunset and disappeared immediately after sunrise. (2) at sunset, the width of the Doppler spectrum spreading is rather narrow and the polarization is a right‐handed elliptical one. This suggests a propagation in a few ducts. (3) During the night, the width of the Doppler spectrum spreading is rather wide and the polarization is a right‐ handed elliptical one close to linear. the intensity is higher when the sustaining duration of the magneto‐ spheric propagation wave is longer. This suggests a propagation within several chamber‐type ducts, which are repeatedly generated and eliminated within a rather short period. From the calculation of the loss of the ionospher ic transmission, difference is suggested in the duct emission mechanism of the magnetospheric duct propagation at the sunset and at night.
Staggered superposed transmission of narrow band‐ limited spread spectrum multiple access signals and multicarrier high‐speed signals
Authors: Sugiyama Takatoshi , Kubota Shuji , Kazama Hiroshi , Kato Shuzo
Published: July 2007

This paper proposes a staggered superposed transmission scheme of narrow band limited spread spectrum multiple access (SSMA) signals and multicarrier high‐ speed signals. to lessen degradation due to mutual interference between SSMA signals and multicarrier high‐ speed signals, SSMA signals are set between two high‐ speed signal channels. Moreover, a band‐limitation filter in the transmission side and an interference‐suppression filter in the receiving side whose bandwidths are narrower than Nyquist bandwidth of spreading code chip‐rate are employed. the proposed scheme decreases SSMA signal transmission power and increases the number of SSMA channels.
Method of estimating bit‐error rate due to transverse lightning surge
Authors: Motomitsu Tamio , Yamane Hiroshi , Hattori Mitsuo
Published: July 2007

The longitudinal lightning surge appearing on the telecom cable between the pair of conductors and ground is changed into the transverse lightning surge between the conductors due to conversion characteristics of the system. the transverse lightning surge overlaps the signal voltage and causes bit errors. In this paper, the longitudinal and transverse lightning surges are deter mined. Using these lightning surges, a new method of estimating bit‐error rate oy simulation (numerical calculation) is proposed. Time domain and frequency domain parameters obtained by actual measurement of lightning surge are used in the simulation. Using this method, bit‐ error rate due to lightning surge can be evaluated easily. Moreover, it can cope with the changes in the telecom system and is superior to the conventional method of evaluating the bit‐error rate using actual lightning surges.
Antidisturbance characteristics in a distributed digital signal transmission system using orthogonal transform codes and recovery of signal with the estimation method
Authors: Uh Yoon , Sone Susumu , Takagi Tasuku , Kang Hyunkoo
Published: July 2007

The spatial distribution method using orthogonal transformation of signal is proposed and studied for its effectiveness in a new digital communication system having high immunity to impulse interferences. This method is based on the time domain consideration that spatially spread information can be recovered even if part of the information is destroyed by a pulselike disturbance. Computational investigations on the application of the distributed signal transmission method to the base‐ band digital signal transmission when discrete Fourier transform (DFT), discrete cosine transform (DCT), and Walsh‐Hadamard transform (WHT) are used as the signal distributor are covered in this research. It is also shown that the estimation of an erased symbol at the receiver is possible using an estimation method.
Spectral domain analysis of a proximity feed polarimetric microstrip antenna
Authors: Miyazaki Toshiyuki , Itoh Kiyohiko
Published: July 2007

As a form of feeding the microstrip antenna, there is a method of exciting the patch via a gap from the semiinfinite feed line. In this scheme, the polarization plane can be switched by changing the stub length. Due to the effect of the feed line on the input and polarization characteristics and to the expected strong coupling by the surface wave through the gap, the rigorous analysis by the conventional method has not been possible.

In this paper, the operating principle of the present model is presented. In addition, a model of the current basis on the feed line is proposed including the scattering by the patch. Further, by means of the spectral domain method, the input and polarization characteristics are analyzed rigorously. the behavior of the polarization is shown analytically when the frequency and the stub length are varied.
Micro mass axis alignment device with piezoelements for optical fiber and its application to optical connection
Authors: Aoshima Shin‐Ichi , Kubota Manabu , Yabuta Tetsuro
Published: July 2007

Fusion mass‐splice devices for optical fibers have been developed for splicing fiber ribbons. However, these devices use only V‐grooves to align the optical fiber axes. Thus, axis misalignment errors easily occur due to the following reasons: (1) accurate design of a V‐groove is difficult; and (2) optical fibers have core eccentricity. These both cause an increase in splice loss.

We first proposed here some types of axis alignment device that can independently align individual optical fibers. Next, axis alignment experiments were performed with the designed device. Experimental results indicated that it will be possible to align a fiber core axis of 0.1‐μm order precision by using feedback control. The axis alignment range is approximately 20 × 20 μm. The proposed axis alignment device was applied to the fusion mass‐splice device by a researcher from another company. Average splice loss was 0.05 dB for four fiber ribbons of 1.55‐μm DSF. These results show that the proposed device has enough performance for the fusion mass‐splice device. Finally, we proposed a device for low‐loss optical coupling between an optical waveguide plate and optical fibers.
Estimations and evaluations of radiation patterns of personal handy phone systems by numerical electromagnetics code‐2 (NEC2)
Authors: Saitoh Hirotaka , Omiya Manabu , Itoh Kiyohiko
Published: July 2007

To verify that the electromagnetic analysis system NEC2 is effective for the development and design of the second generation digital cordless telephone investigated for use in the frequency band of 1.9 GHz. Two types of personal handy phone models with metal housing and plastic housing were fabricated and measurement and analysis by NEC2 were carried out for radiation patterns. The analysis results were found to agree with the measured results in regard to the absolute gain and shape. For the metal housing model, examples of the procedures were presented for modeling the housing by wire grids or surface patch elements. It was shown that the analysis results agree well with the measured results. It was also found that the radiation pattern of the plastic housing model is only slightly affected by the housing material. By realizing the installed circuit as an analytical model, estimations and evaluations of the radiation pattern are possible by means of NEC2. As a result, NEC2 is effective for the analysis of the radiation pattern of personal handy phone systems at 1.9 GHz.
Characteristics of whistler wave normal distributions at the exit of low‐latitude duct
Authors: Nakamura Yoshikatsu
Published: July 2007

According to the direction‐finding observation of whistler at low latitudes, the whistlers come from a narrow region of the zenith and exhibit morphology at ionospheric exits. When ionospheric transmission characteristics of the very low‐frequency (VLF) radio wave emitted to the ground from the magnetic field‐aligned duct due to the irregularity of the ionosphere are computed, or when the results of the VLF direction‐finding observation on the ground are discussed, distribution of the wave normal of the radio wave at the duct exits is important.

Here, the wave‐normal distribution of the VLF whistlers at the duct exit, namely the wave normal of the VLF whistlers at each part of the duct exit, is computed by means of the two‐dimensional ray tracing based on the duct propagation model assuming low latitudes. It was found that there are two kinds of wave‐normal distributions, i.e., upward and downward. The cause of the generation of the two kinds of distributions was clarified qualitatively by the duct‐propagation theory. Also, the factors for various characteristics of the wave‐normal distributions at the duct exit were investigated. Especially, for the downward wave‐normal distributions, there is a region at the center of the duct where the wave normals are directed vertically downward due to the effect of the vertical gradient of the ionosphere applied in the duct. This region contributes to the transmission of the whistler to the ground.
Rectangular loop antenna for circular polarization
Authors: Murakami Yuichi , Yoshida Akimasa , Ieda Kiyokazu , Nakamura Takashi
Published: July 2007

It is shown here that a rectangular unloaded one wavelength loop antenna works as a circularly polarized antenna. Its operating principle is presented. The current distribution on the loop of this antenna can be controlled by the ratio of the major and minor sides. It is a single‐feed antenna with the simplest configuration. The current distribution of this antenna can be decomposed to the traveling wave mode currents for the forward and backward waves. Based on this fact, the condition for the circular polarization is derived in terms of the current value at the center of each side of the loop and the effective length. Based on the investigation of the realization method for this condition, a circularly polarized antenna off‐center‐fed at a corner of the loop was actually designed and the various characteristics, such as axial ratio and the directivity, were derived. From this study, it is found that a good circular polarization can be obtained with the antenna height within a range near 0.13λ from the reflector. Validity of the theoretical results is confirmed by experiment.
Tri‐reflector antennas eliminating cross‐polarized component based on beam‐mode analysis
Authors: Furuno Takayoshi , Urasaki Shuji , Katagi Takashi
Published: July 2007

The offset‐type antennas have efficient and desirable wide‐angle radiating characteristics in comparison to the rotationally symmetric parabola antennas and Case‐grain antennas because there is no blocking due to the primary radiator, subreflector, and supporting members. However, in the microwave relay link, the two orthogonal polarizations are used so that the cross‐polarized component generated by the asymmetric reflector is a problem.

To resolve this problem, the tri‐reflector offset antenna is used which is constructed such that the cross‐polarized component generated by the main and subre‐flectors are cancelled in the geometrical optics manner. When such an antenna is used at low frequencies, the electromagnetic field distributions are different from those conceived by the geometrical optics so that the cross‐polarized component cannot be eliminated completely. To improve this discrepancy, the beam‐mode expansion method has been used for optimization of the cross‐polarization characteristic by successive calculations. Since this method takes into account the phase, improvement is better than the geometrical optics. However, the method is not convenient for perspective for optimization and is difficult in completely eliminating the cross polarization.

In this paper, the cross‐polarization elimination condition is derived by taking into account the phase of the cross‐polarized component generated by the reflector. The shape of the reflector system satisfying this condition is presented and the design method is described. Further, it is shown that the derived condition is a geometrical relationship not related to the frequency.
Hybrid clock synchronization: Condition for the existence of steady state in a ring network
Authors: Yahata Haruki
Published: July 2007

In the clock synchronization of the closed area network (such as local area network (LAN) and metropolitan area network (MAN)) to the wide area network, it is advantageous to use the hybrid synchronization from the viewpoint of reliability, where the master‐slave synchronization is applied at several points from the wide area network, and the mutual synchronization is applied within the closed area network.

This paper considers the case where the hybrid synchronization is applied to the ring‐type area network and derives the condition for the existence of the stable phase state. When the synchronization circuit is a two‐input complete integrating second‐order PLL with the sinusoidal or equilateral triangular phase comparator characteristic, the sufficient condition for the existence of the stable phase state of the whole network is that the ratio of the gain for the mutual synchronization to the gain for the master‐slave synchronization is less than 1 in at least one PLL. When the synchronization circuit is the incomplete integrating PLL, the sufficient condition is that the above gain ratio is less than a certain limit in at least one PLL, and the ratio is above the inverse of that limit in other PLL, where the limit is less than 1 and is determined by the difference between the input frequency from the wide area network and the center frequency of PLL as well as the magnitude of the gain. The above properties are shown theoretically and are verified also by computer simulation.
Optical fiber cable extension method applicable to the large demand distribution
Authors: Morita Hideyo , Tsujino Masayuki , Ikeuchi Noriyuki
Published: July 2007

Optical access networks are important for developing an information infrastructure. When an optical fiber is first introduced, the demand generated varies greatly so an optical fiber cable extension method to address this is necessary. This paper uses the concept of fixed fiber and common fiber, both of which are used in the conventional method as the base, α, and proposes a new method to find the optimal extension amount to meet the large demand deviation. First, a method for determining the amount of common fiber extension that satisfies the required reliability with respect to the fixed‐fiber extension is introduced. Next, a simulator to simulate the extension of both the fixed and common fiber is developed to determine the total cost for the various fixed‐fiber extension parameter. Using this procedure, an optimal amount of fixed‐fiber and common‐fiber extension is found as parameters such as average demand and standard deviation. The proposed method is then shown to produce more economical planning than the conventional method.
Fan‐beam forming for a linear antenna with exponential‐tapered amplitude distribution
Authors: Konishi Yoshihiko , Ohtsuka Masataka , Matsunaga Makoto , Urasaki Shuji
Published: July 2007

As a fan‐beam forming method for a line source having an exponential‐tapered amplitude distribution simulating the linear array antenna or a linear antenna with a traveling‐wave feed such as in the multifilar helical antenna, this paper investigates a method in which the entire source is divided into n : 1 and the excitation phase in the 1/(n + 1) portion is π shifted. First, the fan‐beam forming method is studied analytically for a linear source with an exponential‐tapered amplitude distribution so that the equation needed for realizing a fan beam is derived. Next, in the case where a fan beam is formed for the determined coverage angle (angle θ = 30–60°) from the zenith, the relationship between the total length LT of the source and the coverage gain is studied. It is shown that the coverage gain can be improved by forming a fan beam. It is shown also that there exists an optimum value of the total length of the source maximizing the coverage gain for a given coverage area. Further, by using a bifilar helical antenna, a fan‐beam forming experiment is carried out. It is confirmed that a fan beam close to the computed value can be formed and the coverage gain can be improved although there exists asymmetry in the measured radiation pattern.
Two‐dimensional numerical analysis for high electron mobility transistors (HEMTs)
Authors: Yoshida Jiro , Kurata Mamoru
Published: July 2007

A two‐dimensional numerical model has been developed for the analysis of operation of a high electron mobility transistor (HEMT) based on the AlGaAs/GaAs heterojunction. In this model, the basic equations are formulated under the assumption that the band structure is continuous and Boltzmann statistics are applicable. Further, it is assumed that the velocity‐electric field curve of the two‐dimensional electron gas system is identical to that of the bulk GaAs. The calculations have been performed for the device with a 1 μm gate length and the following results have been made on the operating mechanism of the HEMT. 1 In the short‐channel HEMT, the electron velocity saturates in the channel directly below the drain‐side edge of the gate electrode and as a result the current also saturates. 2 In the HEMT operated in the saturation region, an electron accumulation region is formed in the GaAs layer below the drain‐side edge of the gate electrode. In this region, the current flow significantly extends into the bulk GaAs from the heterojunction interface. 3' A strong electric field concentration occurs in this region and the major portion of the applied drain voltage is sustained by this region. This concentration is limited in an extremely narrow region.
Built‐In ECC techniques for LSI memories
Authors: Yamada Junzo , Mano Tsuneo , Date Shigeru
Published: July 2007

Built‐in Error Checking and Correcting (ECC) is essential for megabit level dynamic MOSRAMs to reduce an alpha parcle‐induced soft error rate. As the one‐bit per multicell ECC method makes a one‐bit item of information from multiple memory cell items of information, a one‐bit per three‐cell method and a one‐bit per two‐cell method are proposed. Next, encoding methods for items of memory cell information on an identical word‐line, namely, the bidirectional parity method and the Hamming code method are proposed and their logical structures are clarified. The advantages and disadvantages of these techniques are compared from the viewpoints of memory overhead, error correcting time and the soft error rate. As a result, it is shown that an ECC method using a bidirectional parity code is best suited for a built‐in ECC applicable to megabit level dynamic RAMs.
A time‐dependent and two‐dimensional device analysis of CMOS structures
Authors: Odanaka Shinji , Wakabayashi Mutsuko , Ohzone Takashi , Takemoto Toyoki
Published: July 2007

Latchup phenomena are becoming important problems for increased density CMOS integration. Here, a 2‐dim device simulator is used for transient analysis of latchup phenomena in CMOS structures. The dynamic characteristics of the latchup turn‐on process due to parasitic MOSFET or direct forward biasing are investigated. From this, difficulties for scaling the n‐well CMOS structure, and the design of latchup resistant CMOS devices are considered. Also discussed will be the effectiveness for device design of applying two carrier 2‐dim device simulators to large area devices with complex shapes, such as typified by the CMOS structure.
Two‐dimensional modeling based on boltzmann transport equation for ion implantation
Authors: Takeda Tadao , Yoshii Akira
Published: July 2007

A highly accurate analysis method based on the two‐dimensional Boltzmann transport equation is proposed for ion implantation. In this method, the ion energy and traveling angle distributions are quantized so that the analysis of the diffusion and scattering terms in the Boltzmann transport equation is simplified. Also, the degradation of the analysis accuracy due to the above quantization can be avoided by newly introducing the packet beam model. To show the validity of this method, As+ and P+ ion implantation into Si and SiO2 substrates is analyzed and the results are compared with the experimental data. Consequently, the calculated impurity distributions agree well with the experimental results and hence this agreement indicates the high‐accuracy of the method. Also, the ion‐irradiation‐region dependence on the impurity distribution is successfully shown. From the energy deposition and subsequent heat generation in the substrate by ion‐irradiation, it is indicated that the thermal impurity diffusion toward the substrate surface is possible. Moreover, it is indicated that the channeling effect must be considered for the low‐energy, P+ ion implantation. Finally, the deviation of the SiO2 stopping cross section from Bragg's rule is obtained using this method.

Thus, using this method, the ion implantation can be analyzed so accurately that complex and fine structured devices can easily be designed.
Epitaxial growth of gaas on ge/si substrates by mocvd
Authors: Okamoto Kotaro , Yukawa Teizo , Asano Yasanori
Published: July 2007

Ge was deposited on n‐type (100) Si substrates by electron beam evaporation and it became clear that to obtain good morphology of a single‐crystal Ge layer, the conditions of crystal growth should be maintained as follows: pressure should be less than 10‐6 Pa, the temperature range should be 400‐500°C, and the growth rate should be kept less than 7 Å/s. Moreover, in the growth of GaAs, it was found that we can obtain an epitaxial layer of monocrystalline n‐type GaAs if we use the MOCVD method in which trimethyl gallium (TMG: (CH3)3 Ga) and arsine (As H3) are used, silane (SiH4) is used an an n‐type doping gas, the temperature range is 590 to 670°C, the mole ratio of As H3/TMG is 10 to 24, the mole ratio of Si H4/TMG is 2‐5 × 10‐3, and the growth rate is kept below 0.4 μm/min. Zn diffusion is done on n‐type* p‐n junctions, and the resulting light‐emitting diode was observed to have electroluminescence at the peak wavelength of 897 nm at room temperature. In the case of GaAs/Ge/Si structure, the thermal expansion coefficients of Si and GaAs are different and tension is produced so the spectrum shifts to the longer wavelength. Moreover, if the thickness of the GaAs layer becomes less than 5 μm, then cracks are produced.
Finite‐element analysis of periodically perturbed piezoelectric waveguides
Authors: Mitobe Seiichi , Koshiba Masanori , Suzuki Michio
Published: July 2007

The propagation velocity of the acoustic wave can be reduced in a periodic acoustic waveguide (periodic waveguide) on which a periodic perturbation is added along the propagation direction of the acoustic wave. The passband and stopband appear in the dispersion characteristics (Brillouin diagram). The structure is used widely for the delay line, filter, reflector and resonator. The design of these devices made of periodic waveguides requires the Brillouin diagram. The objective of this paper is to develop a method that can be used to derive the Brillouin diagram of the periodic piezoelectric waveguide receiving an arbitrary mechanical or electrical perturbation. A method based on the finite element method is proposed and its formulation is presented. Further, for the periodic waveguide used as a reflector, the stopband width and the shift of the center frequency are calculated. These are important parameters for the design of the reflector. The groove reflector and the metal strip reflector are analyzed and the results are found to agree well with the experimental values.
High‐sensitivity analysis of impurities in gaas using multi‐element‐doped gaas standard samples
Authors: Kurosawa Satoru , Homma Yoshikazu , Yamawaki Masataka , Tanaka Tohru
Published: July 2007

In order to improve the quality of GaAs crystal, it is indispensable to conduct ultramicroanalysis of impurities in GaAs. For the analyses in this paper standard samples were made by adding a certain amount of impurities which can adequately be detected by chemical analyses. Using these samples, the SSMS, SIMS and chemical analysis methods are examined. The results are: (1) three chemical analysis methods (FLAA, ICP and colorimetric methods) are examined and permit a detection limit of 0.05 ∼ 5 ppm and a CV value of ±30%. (2) For the SSMS method, a process for making a specimen electrically conductive by applying a vacuum‐evaporated silver film is introduced. Comparing this result with those obtained by the chemical methods, a relative sensitivity factor is found which permits determination of the absolute value and it is possible to conduct analysis with detection limits of 10 ∼ 30 ppb and CV value of ±30%. (3) For the SIMS method, the secondary ionization yields for B, Al, Si, S, Cr and Mn are obtained, by comparison with the results of chemical analysis, which makes absolute quantitative analyses of these elements possible. The accuracy of quantitative analysis in which ion‐implanted specimens were used for the standard samples is confirmed.
High‐rate syntheses of high tc superconducting nbcxn1‐x films by hollow‐type target sputtering
Authors: Yamamoto Hiroshi , Ishii Koichi , Tanaka Masaichi
Published: July 2007

A new high‐speed sputtering method using a hollow target is proposed. Its model analysis and experimental examination are carried out. As a result, it has been shown that a high‐speed film synthesis without damages from high‐energy particles is possible. This is not only because the plasma discharge is confined inside the target resulting in high density, but also because the particles sputtered from the target inner wall lose considerable energy due to collisions. In the actual experiments, by argon sputtering a small hollow cylindrical Nb target with inner wall area of 33 cm2, a high deposition rate of more than 200 nm/min has been obtained despite a very simple electrode configuration. Furthermore, as a result of applying this method to the NbCxN1‐x film formation by reactive sputtering with nitrogen, it has been verified that a high‐speed film synthesis with more than 60 nm/min is possible. In addition, a high‐quality film with superconducting critical temperature of 17.7 K in the composition range of x = 0.1–0.3 can be obtained. Moreover, this film shows a peculiar preferential growth in the (200) plane on a high‐temperature substrate.
Judgment of outlying observations in automatically measured SI wafer inspection data
Authors: Aoki Yukio , Toyabes Tooru , Shimada Shozo , Sato Shoji
Published: July 2007

Research and development of LSIs require rapid evaluation of the characteristics of fabricated devices. For this purpose automatic measurement systems have been developed in various laboratories. Some outlying data unavoidably exist in the data collected by the automatic data acquisition system, and it is necessary to judge the outliers in data processing. In this paper two algorithms to judge outliers are examined and one new algorithm is presented. They applied for Si wafer inspection data collected automatically. The three algorithms are the outlier judgment method proposed by Grubbs, the judgment method using Mahalanobis's distance and the method combining the principal component analysis method with the latter method. The conclusions are as follows:

Grubb's method is easy to use for one kind of measured items

Mahalanobis's method is useful for several kinds of measured items and is especially effective when they are correlated

The combination of the principal component analysis method and the method by Mahalanobis's distance is useful in saving manpower for routine judgment of the same data produced in the same line for several measured items.
Radiation from a circular bend of step‐index single‐mode fibers
Authors: Morita Nagayoshi , Tanaka Toshiaki , Kumagai Nobuaki
Published: July 2007

The problem of radiation from a uniform bend of step‐index single‐mode fibers is analyzed in detail. Unlike the previous methods of approximate evaluation of the bending loss of fibers, a strict analysis of the radiated electromagnetic fields is performed. A detailed study of the electromagnetic fields, radiated in the neighborhood of the junction of straight and bend portions, which have not been studied fully so far, is performed here. The radiated field is expressed in integral form, using the mode field on the curved surface circumscribing the core in the cladding, and the far field expressions are determined using the stationary phase method. From these results, many factors that had not been clarified before such as the degree of contribution of mode field components and radiated power, the direction of travel of radiated light, and radiation patterns, etc., are evaluated in detail in addition to the evaluation of radiation losses with greater precision. Moreover, the numerical examples for the radiation from the starting portion of a bend in the curved fiber, and the radiation patterns in the fiber cross‐section plane when radiation is uniform, are also shown.
Relationship between losses under a large flux excitation and small signal loss factors tanδ in magnetic cores for high frequency use
Authors: Sakaki Yo , Sato Toshiro
Published: July 2007

For the evaulation of magnetic core losses in a high‐frequency region, the small‐signal parameter tan δ or the relative loss coefficient tan δ/μs, which are a small‐signal parameter in the region of an initial permeability, has been used. The magnetic cores for transformers or reactors have recently been used at a frequency greater than 100 kHz, and with a magnetic flux density far greater than the initial permeability, due to the demands of miniaturizing switching power supplies. This paper examines the relationship between the large‐signal loss of magnetic cores and their tan δ in a frequency range of 1 kHz to 1 MHz. It was found that the large‐signal loss has poor correlations with a small‐signal parameter, such as tan δ or tan δ/μs. ‘A loss‐evaluation parameter’ ζ = tanδ/μs (1 + tan2δ) was newly introduced. It is shown that the large‐signal eddy‐current losses of most magnetic cores at a frequency greater than 100 kHz can be estimated with a high accuracy by using this parameter; ζ is expected to be a useful parameter for evaluating the losses of cores for power applications at a frequency greater than 100 kHz.
Improvement of the spatial resolution of ultrasonic imaging using the holographic technique
Authors: Ikegami Masiki , Yamamoto Tsuyoshi , Aoki Yoshinao
Published: July 2007

In the conventional synthetic aperture technique the antenna directivity is assumed to be wide enough that sufficient phase information can be obtained with antenna scanning. This assumption is made in the experimental studies as well. With a sharp antenna directivity, however, sufficient phase information cannot be obtained and the reconstructed image obtained by the conventional synthetic aperture technique has poor resolution. On the other hand, if the real aperture technique is employed, an image of improved quality can be obtained with a sharp antenna directivity and the resolution increases as the directivity becomes sharper. The present paper deals with the case of directivity which is too sharp for the synthetic aperture technique and too wide for the real aperture technique. Theoretical and experimental studies are made on ultrasonic imaging by using the modified synthetic aperture technique for this case. Specifically, the actually measured point spread function is used in the synthetic aperture technique and it is confirmed that a higher resolution can be obtained in this way than by the conventional synthetic or real aperture technique.
Switched‐capacitor realization of a fourier analyzer using integral feedback capacitance circuit
Authors: Sasaki Itsuo , Okabe Kaoru , Yoneda Shojiro , Kasai Tamotsu
Published: July 2007

The technique of forming a discrete Fourier transform (DFT) circuit with an analog circuit has numerous attractive features not available in the DFT circuit with a digital circuit. For example, frequency analysis can easily be carried out and real time processing is possible. The switched‐capacitor (SC) circuit has recently been considered suited for MOSIC of analog circuits. In this paper, a DFT circuit is constructed with an SC circuit in an analog format so that circuit integration is possible. For SC realization of a DFT circuit, an integral feedback capacitance circuit has been proposed for a signal processing circuit. This circuit makes use of the feedback capacitance terminal voltage of an integrator made of an operational amplifier. It is used for the SC sample‐and‐hold circuit and the SC multiplier and adder. This SCDFT circuit has been fabricated with discrete components and the operating principle has been confirmed.
Magnetostriction of co‐based alloy films for magnetic recording
Authors: Matsuoka Morito , Naoe Masahiko , Hoshii Yoichi
Published: July 2007

This paper evaluates the magnetostriction in various kinds of Co–based alloy sputtered film for magnetic recording, especially Co film and Co–Cr film for vertical magnetic recording, Co–Cr–M film containing a third element (Fe, Ta and Zr) and Co–Pt film with large face–angle ratio. The result shows that evaluation of the magnetostriction is useful as measure of the extent of stress–induced demagnetization in a medium for magnetic recording and also in prediction of the microscopic structural changes peculiar to Co–based alloys, where α(fcc) high–temperature phase is mixed in the film by α–ϵ transition. Consequently, it is concluded that the evaluation of demagnetization is useful for evaluation of Co–based alloy film medium. By simultaneously measuring the magnetostriction and the stress–induced demagnetization one can determine the value of λc, which is one of the magnetostrictive constants in C–oriented film and has been difficult to determine by other methods.
Method for measuring the glossiness of curved surfaces using charge‐coupled‐device line sensor
Authors: Aida Teizo , Serikawa Seiichi , Tamura Hiroyuki , Kugisawa Hideo
Published: July 2007

The method for measuring the glossiness of a plane object is regulated in JIS Z 8741. However, no method has been established for the glossiness of a curved surface. For instance, the psychological glossiness Gph to humans depends on the radius of curvature of the object even if the material and the surface finish are identical. However, the conventional physical glossiness is almost unrelated to Gph. A system for measuring the indistinctness‐degree glossiness GID has been fabricated with a light source, an optical system (lens and slit), and charge‐coupled‐device (CCD) line sensor. This equipment has been used to measure GID of metal spheres of various radii, enamel‐coated spheres, and a spherical pearl of 8 mm diameter. In all samples, a strong correlation with a correlation factor more than 0.88 has been observed between GID and the psychological glossiness GID. From this fact, it has been found that GID is effective as a physical glossiness of a curved surface with a relatively large glossiness such as the curved surface of a metal body, painted body and spherical pearl. On the other hand, GID is not suited for a curved surface with a low glossiness such as paper and plastic or for a highly glossy metal surface with a mirror finish.
Josephson threshold logic circuit and its application
Authors: Harada Yutaka , Hatano Yuji , Yamashita Kunio , Kawabe Ushio
Published: July 2007

This paper proposes a Josephson threshold logic circuit, which is best suited to high‐speed operations. Using the proposed circuit, the adder can be constructed by four Josephson elements. The scale of the circuit can be reduced both in the number of circuits and the number of logic stages, compared with the conventional Josephson logic circuits. The circuit is shown to be useful in the realization of the high‐speed and highly integrated adders and multipliers. Then it is demonstrated that the Josephson threshold logic circuit can be constructed by the magnetically coupled interferometer element, the current‐injection interferometer element and the direct‐coupled element. A typical circuit construction is shown with the adder as an example. To verify the correct operation of the Josephson threshold logic circuit, a 1‐bit adder by magnetically coupled interferometer elements was constructed by Nb‐Pb alloy process, and the operation of the circuit was verified.
Realizations of simulation inductors using mutators with differentiators
Authors: Tanno Yorimoto , Watanabe Masato , Member Shingo Isozaki, Associate
Published: July 2007

Many methods of simulating inductors and capacitors have been proposed for the integration of electronic circuits. By using mutators, excellent simulation capacitors and inductors can be obtained with simple circuit configuration. This paper describes the realization of frequency‐independent simulation inductors using mutators. A mutator is an active two‐port linear network for transforming one type of nonlinear element into another type. There are three classes of mutators: L ‐ R mutator, C ‐ R mutator, and L ‐ C mutator. The relationships pertaining to an L ‐ R mutator are classified into four types. A new approach is proposed to realize a type‐2 L ‐ R mutator and a type‐4 L ‐ R mutator with R, C and operational amplifiers using a differentiator configuration. The principle of the simulation inductors by those circuits is presented. This simulation inductor is characterized by the independent adjustment of its inductance and Q, and variable L which changes linearly with the value of a resistor.