bluuebunny/crossref_metadata_2025 huggingface dataset:
Indoor propagation calculation taking into account antenna patterns using geometrical optics method
Authors: Uehara Kazuhiro , Seki Tomohiro , Kagoshima Kenichi
Published: July 2007

An algorithm to compute the effects of the radiation patterns and polarizations of arbitrary transmit and receive antenna is added to the conventional geometrical optics analysis procedure to study indoor propagation delay characteristics. A method is presented in which the angular information needed for the calculations of the foregoing in a rectangular room can be derived easily from the geometrical nature of the room. By moans of the present procedure, the delay wave suppression effect of a narrow‐beam antenna in a multipath propagation environment is shown quantitatively. For instance, in the case where both transmit and receive antennas are omnidirectional, the delay spread can be reduced to almost one‐tenth if a pencil beam with a half‐power beamwidth of 30° is used. By means of these results, a design procedure for antenna half‐power beamdwidth and the polarization was developed for realization of high‐transmission quality in an indoor high‐speed wireless data communication.
Reachability analysis for communication service specification descriptions in global state transition rules
Authors: Sato Masakazu
Published: July 2007

This paper discusses fundamental characteristics in reachability analysis of communication service specifications defined by means of production rules. In the conventional service specifications, reachability has been analyzed within a finite number of communication processes. However, it is necessary to deal with infinite processes to verify state reachability of the global transition description of the production rules. If the reachability state as a reachable subglobal state constructed with a number of processes is defined, the size of the reachability state set depends on the number of processes at the initial state. In general, the system is analyzed on the assumption of an infinitive number of processes to verify reachability. This paper presents the relationship between the size of the reachable set and the number of processes in the system. It also shows the existence of the upper bound of the reachable state set and a method to obtain the minimum number of processes that gives the upper bound of the reachable set. This study makes it possible to analyze the reachability of an infinite number of processes by a reachability problem of finite number of processes.
Frequency agility radar with doppler processing
Authors: Maeda Seiichi , Sueda Hachirou , Itoh Toshiharu
Published: July 2007

In the frequency agility radar in which the transmit frequency of the radar can be changed at an ultrahigh speed, not only is excellent electronic counter countermeasure (ECCM) performance obtained but also improvement of the detection probability of the object with a fluctuating reflection cross section is expected. However, in the conventional‐type radar, the frequency is modified at a high speed so as to change the entire pulse. However, the standard Doppler process is not possible.

In this paper, in order to add a Doppler processing function to a frequency agility radar, the clutter is suppressed with one pulse and the obtained object signal is integrated coherently. The method and the simulation results are presented.
Air traffic control data tables for conflict alert system
Authors: Miura Akira , Morikawa Hiroyuki , Mizumachi Moriyuki
Published: July 2007

The conflict alert system was developed for air traffic control to detect and warn of the danger of aircraft collisions. This paper presents a configuration for air traffic control data tables that increases the efficiency of the conflict alert system, which was devised to predict what instructions to give for preventing collisions. Air traffic control data tables are constructed mainly from air route data and aircraft data. The aircraft are controlled by the air route unit, and all data as well as the relationships between the data (i.e., between aircraft, between aircraft and air routes, etc.) are updated continually in real time for the data tables in question. As a result: (1) the relationship between the aircraft and the air route can instantly be grasped, thereby improving the accuracy of the course prediction for the aircraft; and (2) when judging if two aircraft are possibly in conflict, the efficiency of the conflict detection process can be improved by rapidly being able to grasp the relative relationships of aircraft on adjacent air routes and the relationship between the leading and last aircraft on the same course. The feasibility of the points (1) and (2) is demonstrated through computer simulation.
Performance of modulation‐level‐controlled adaptive modulation systems
Authors: Otsuki Shinya , Sampei Seiichi , Morinaga Norihiko
Published: July 2007

The multivalued quadrature amplitude modulation (QAM), such as 16 QAM, is a very useful technique in land mobile communication since a high‐speed transmission can be realized without enlarging the transmission band. The technique has a problem, however, in that it is not robust against the decrease of the received signal level due to fading or the effect of the delayed waves, which easily deteriorates the transmission quality. To solve such a problem, this paper proposes an adaptive modulation system where the number of modulation levels is adjusted according to the condition of the channel. In the proposed system, the instantaneousC/N0and the delay spread are estimated as the condition of the channel, using a method based on time division multiple access/time division duplex (TDMA/TDD).

When the channel is in a good situation, a highspeed transmission is executed using a larger number of modulation levels such as 256 QAM. When the channel is in a bad condition, a modulation method with a small number of modulation levels, such as quadraphase‐shift keying (QPSK), is used, which is robust against the noise or the delayed waves. By this scheme, it is possible to realize a high‐speed transmission without deteriorating the transmission quality, compared to the conventional system with the fixed number of modulation levels. The transmission performance is evaluated by a computer simulation, and it is shown that a high‐speed transmission can be realized without deteriorating the transmission quality, compared to the QPSK system, in the uniform Rayleigh fading condition as well as in the situation containing delayed waves.
Coefficient‐based adaptive transform coding scheme
Authors: Hamada Takahiro , Matsumoto Shuichi
Published: July 2007

A coefficient‐based, adaptive, orthogonal transform coding scheme is proposed to enhance the performance of interframe DPCM/orthogonal transform coding which has currently become the mainstream coding method in use for video signals. In this proposed scheme, the widely used block‐based inter‐ and intracoding modes are supplemented by introducing a new coding mode, the “mixed mode,” that has the characteristic of optimally controlling prediction and quantization on an orthogonal transform coefficient basis. Based on a statistical model of the video signal, it is shown that the prediction coefficients and quantizer of the proposed scheme can be theoretically optimized. Results from computer simulations on real images show that in terms of an objective evaluation measure (weighted signal‐to‐noise ratio) that reflects properties of the human visual system, that a performance gain of 4.6 dB over the H.261 standard is obtained and 3.4 dB gain over MPEG is obtained. From the perspective of subjective evaluations, it is shown that it is possible to greatly reduce block noise, of course, in exchange for some resolution degradation from mosquito noise.
Fault location on optical amplifier submarine transmission systems
Authors: Sumida Masatoyo , Amemiya Masaki , Furukawa Shin‐Ichi , Tanaka Kuniaki
Published: July 2007

This paper addresses some solutions to overcome the problems that arise when optical time domain reflectometry (OTDR) is applied to optical amplifier submarine transmission systems. It designs a backscatter path that feeds the backscattering into the opposite line without causing any degradation in the main signal transmission. This paper proposes a new modulation format, FSK‐ASK, and confirms that the proposed approach can both eliminate optical surge generation and improve OTDR performance. An FSK‐ASK OTDR is applied to an 890‐km commercial amplifier submarine transmission system with a 90‐km span. Field trials successfully demonstrate that the OTDR can locate a fault in all spans with a spatial resolution of 1 km after averaging the sum of 220measurements. The FSK‐ASK OTDR proves to be very useful in maintaining a reliable submarine transmission system because it can locate subtle fiber anomalies along the entire length from a terminal end.
Link control method for improving packet transmission efficiency for store and forward communications by LEO satellites
Authors: Nakayama Tsuyoshi , Hamamoto Naokazu
Published: July 2007

For a communication system using LEO satellites, a simpler method that will improve link transmission efficiency is indispensable in cost reduction. A new link control method is proposed to improve packet transmission efficiency for store and forward communication systems using LEO satellites. With this method, the throughput is improved by controlling the request of user terminals by the control packets from a satellite allocating slots for information packets in reserved frames of variable length. Performance of the proposed method is evaluated by computer simulation; the result has revealed that the method improves the throughput twice as much as the variable calling rate slotted ALOHA system.
A method of designing feed‐array excitation coefficients for array‐fed reflector‐type reconfigurable beam antennas
Authors: Naito Izuru , Chiba Isamu , Makino Shigeru , Mano Seiji
Published: July 2007

Reconfigurable beam antennas are suitable for on‐board antennas from the point of view of frequency reuse, satellite power utilization, and flexibility for traffic demand variation. In this paper, an efficient design method of the feed‐array excitation coefficients for array‐fed reflector‐type reconfigurable beam antennas is proposed. The feed‐array is composed of several subarrays, and only amplitude between subarrays is controlled to achieve reconfigurability. Excitation coefficients of subarrays and amplitude between subarrays are determined efficiently by the proposed design method. The method is verified by a design example for an international communications satellite application.
Numerical analysis of self‐focusing effect caused by inhomogeneity of microwave energy density in ionosphere
Authors: Shinohara Naoki , Matsumoto Hiroshi , Shklyar David R.
Published: July 2007

In this paper, the results of numerical analysis based on the theoretical analysis of the self‐focusing effect when a microwave beam propagates through the ionospheric plasma from the solar power station (SPS) to the ground are shown. The self‐focusing effect of the microwave beam is either caused by the plasma heating by the microwave beam or caused by the spatial gradient of the electromagnetic beam intensity. In this paper, the latter case is discussed. Since the microwave frequency used in the SPS is six orders of magnitude higher than the maximum collision frequency in the ionosphere, the theory used in this paper assumes a collisionless plasma and is derived from Maxwell's equations and the equation of motion. The self‐focusing effect of the microwave beam predicted by the theory is determined by five parameters: plasma density and temperature; microwave frequency; intensity; and the spatial gradient of intensity. In this paper, based on the results of the numerical analysis of the theoretical equations, the self‐focusing effect under the parameters related to the microwave beam used in the energy transmission of a future SPS is described.
Evaluation of pseudonoise sequence in time spread pulse position modulation/code division multiple access systems
Authors: Date Toshitaka , Zhou Xuping , Oka Ikuo , Fujiwara Chikato
Published: July 2007

To evaluate the processing gain performance of the binary maximal‐length sequence (m sequence), the Gold sequence and the Kasami sequence in a time spread pulse position modulation/code division multiple access (PPM/ CDMA) system, the merit factors of these sequences are calculated and a lower bound on the processing gain of a time spreading filter is derived using the merit factors. It is shown that, under the condition that the sequence length is large, the merit factor of the m sequence approaches 3, the merit factors of the Gold sequence and the Kasami sequence approach 1, the m sequence having the strongest impulse noise resistibility. Furthermore, the cross merit factor between two pseudonoise sequences is defined as a parameter expressing the capability of suppressing multiple access interference. It is shown that the cross merit factors of m sequences, synchronous Gold sequences, and good synchronous Kasami sequences approach 3, and the cross merit factor of bad synchronous Kasami sequence having the strongest multiple access interference suppression capability and the bad synchronous Kasami sequence having almost no multiple access interference suppression capability.
Evaluating the performance of the dynamic bandwidth reservation method using link utilization information in automatic transfer mode local area networks
Authors: Wakamiya Naoki , Murata Masayuki , Miyahara Hideo , Ikeda Chinatsu
Published: July 2007

With the improvement of the speed of computers in recent years, there is required a local area network (LAN) that can realize a high‐speed broadband communication. For this purpose, asynchronous transfer mode (ATM) LANs based on ATM technique is considered important.

This paper considers the bandwidth reservation control as a means of traffic control in ATM LAN and evaluates the performance by simulation. The evaluation is made for the following methods of congestion control: ACK/NACK method, based on the ACK/NACK signal which is returned when the bandwidth reservation succeeds/fails; the dynamic ACK/NACK method, which is an improvement so that the control can be adapted to the traffic load; and control method based on the link information from the switch.

It is shown for the single‐stage switching network that the dynamic ACK/NACK method has a better performance when the traffic is low but the control method based on the link information has the highest performance when the traffic is high. It also is shown for the three‐stage switching network that the control method based on the link information has the highest performance.
Bit‐error rate performance of block‐coded modulation systems under rayleigh fading
Authors: Okada Minoru , Hara Shinsuke , Morinaga Norihiko
Published: July 2007

A block‐coded modulation (BCM) system estimating the complex amplitude variations of a channel by Kalman estimation is proposed and evaluated in this paper. A differential BCM system estimating a channel equivalently by differential encoding, on Rayleigh fading channels, is also presented here. To evaluate the propagation characteristics of the proposed BCM systems accurately, the upper bounds of the bit‐error rate (BER) of BCM are derived, considering the estimation error of the complex amplitude variations of a propagation channel; the BER characteristics of the systems on Rayleigh fading channels are analyzed by the derived upper bounds of the BER and computer simulation. Analyses show that the upper bounds derived are effective in evaluating the BER characteristics of the BCM systems when there are channel estimation errors and the proposed BCM systems operate effectively even when channel estimation errors exist.
Large‐capacity optical communication systems
Authors: Nakagawa Kiyoshi
Published: July 2007

Along with widened and diversified social activities, there is an increasing demand for transmission capacity including voice, data, video and yet‐to‐evolve new business and entertainment markets. Studies are performed in ultrahigh‐speed optical modulation/demodulation circuits and transmission characteristics of rare earth doped fiber amplifiers which satisfy the requirements needed in widening the repeater‐span and increasing the transmission speed. It has become possible to realize ultrahigh‐speed 10 Gbit/s transmission systems with the capacity of about 130,000 telephone channels. In these systems, besides the flexibility in their transmission bit rate and new forms of installation, maintenance and operation, it is considered that the new technology will contribute to a great evolution in future optical communication networks and equipment. A prospective on a next‐generation large‐capacity optical communication techniques also is given.
128‐channel, 480‐km optical frequency division multiplexing transmission employing 0.98‐μm pumped erbium‐doped fiber amplifiers and a gain equalizer
Authors: Oda Kazuhiro , Fukutoku Mitsunori , Toba Hiromu , Kitoh Tsutomu
Published: July 2007

In optical frequency division multiplexing (FDM) transmission systems using optical amplifiers, the transmission distance is limited mainly by gain‐tilt of erbiumdoped fiber amplifiers (EDFAs), accumulations of the ASE noise, and crosstalk due to the four‐wave mixing (FWM). Especially when dispersion‐shifted fibers are used, the transmission distance is limited by the decrease of the allowable input level to the fiber due to the FWM. It is shown here that a 0.98‐μm pumped EDFA has a smaller gain‐tilt accumulation and is suitable for optical FDM transmission. Level diagram is designed taking into account the ASE noise and the FWM crosstalk accumulation; the relationship between fiber‐EDFA input level and the receiver sensitivity is investigated. A 128‐channel optical FDM transmission experiment with 10‐GHz spacing was carried out, and it is demonstrated that all channels can be successfully transmitted through 480 km of dispersion‐shifted fiber with a power penalty of less than 1 dB by using a tunable gain equalizer.
20‐gb/s optical transmitter and receiver using sige integrated circuits
Authors: Tezuka Hiroshi , Fukuchi Kiyoshi , Takeuchi Takeshi , Soda Masaaki , Suzaki Tetsuyuki , Hashimoto Takasuke , Sato Fumihiko
Published: July 2007

A 20‐Gb/s optical transmitter and a receiver with 3R functions is developed for ultrahigh‐speed optical communication systems for future multimedia communications. Integrated circuits (ICs), such as preamplifiers, differential amplifiers, D‐type flip‐flop (D‐F/F), and selectors with a 20‐Gb/s operating speed have been developed using the SiGe process as key components of the optical transmitter and receiver. A waveguide pinphotodiode with very low capacitance is used to realize a wide bandwidth. A front‐end module with a bandwidth of 16 GHz and a gain of 43 dBQ has been achieved using the preamplifier IC and the waveguide pin‐photodiode (PD). A 20‐Gb/s optical transmitter and a receiver is fabricated using the developed SiGe. ICs, high‐speed optical devices, and a receiver sensitivity of −23 dBm are obtained.
Study of shape control for modular mesh antenna
Authors: Shimizu Masashi
Published: July 2007

As the satellite‐borne antenna becomes larger, the degradation of the electrical performance due to thermal deformation on the orbit becomes more problematic. The necessary reflector surface accuracy is determined by the operating frequency regardless of the antenna aperture size. On the other hand, mesh antennas often are used as a satellite‐borne antenna due to weight‐and‐containing requirement.

In comparison to the conventional solid mirrors, the mirror surface deformation is known to be larger for the mesh antennas. Hence, it is necessary to control the mirror surface in order to maintain the performance of the mesh antenna.

In this paper, the backprojection procedure to derive the mirror surface shape from the antenna pattern measurement is used for the mirror surface shape sensor. A closed‐loop reflector surface control is proposed in which an ultracompact pulse motor installed in the mirror surface for adjusting the cable length is used as an actuator. Instead of measuring the far‐field pattern on the ground base station, an experimental system is constructed for near‐field measurement with a near‐field scanner.

The deformed mode is created intentionally which reflects the results of the thermal deformation analysis on the orbit, and a mirror surface control experiment is carried out. It is demonstrated that, by the proposed method, the mirror surface error can be reduced from 2.0 mm RMS to 0.38 mm RMS and the sidelobe level can be improved by 2.0 dB while the directive error can be corrected.
Multicarrier trellis‐coded eight‐phase shift keying system using frequency hopping
Authors: Okawa Koichi , Sasase Iwao
Published: July 2007

A multicarrier trellis‐coded eight‐phase shift keying (8‐PSK) system using a frequency hopping (FH) technique is proposed to improve bit‐error rate (BER) performance in digital land mobile communications. In general, a trellis‐coded modulation (TCM) system is employed with interleaving in multipath fading environment; by contrast, in the proposed system, an FH technique is employed to disperse the influence of successively received weak signals due to multipath fading with small delay, i.e., without interleaving process. The BER performances of the proposed system are investigated by computer simulation. It is found that, although there is no improvement in diversity order by applying the FH technique, there is an improvement in energy efficiency as compared with a multicarrier trellis‐coded 8‐PSK system in a Rayleigh fading channel. It is also found that the performance of the proposed system is not affected by the fade rate of the channels, i.e., the proposed system is effective even under slow fading conditions. It is shown that the performance of the proposed system is affected by the number of hopping frequency; moreover, there is an optimum number of hopping frequency, which depends on the span of dominant error event path of the multiple trellis code employed. Therefore, it is found that the proposed system is effective in the case in which the processing delay time is restricted, such as mobile speech communications.
Analysis of stationary oscillations on josephson circuit
Authors: Kanasugi Akinori , Morisue Mititada
Published: July 2007

Due to its strong nonlinearity, computer simulation has been used in most cases to analyze the Josephson circuit. Thus, it is difficult to obtain the general prospect for the solutions and their errors are apt to accumulate. This paper proposed an analytical method to solve the stationary oscillation, produced in such a circuit with any higher harmonic components, and the calculated analytical results show a good agreement with those of computer simulation. A method is proposed to obtain solutions based on the combined concepts of the Fourier analysis and harmonic balance method, assuming in advance that the stationary oscillation solution includes any higher harmonic components. The stationary oscillation solutions produced in the captioned circuit can be analyzed with good results. This method is applicable to the analysis of any nonlinear circuits other than the Josephson circuit.
An evaluation of leakage inductance for toroidal core transformers
Authors: Ueda Yoshinori , Muto Hiromichi , Koshiba Tsuneori
Published: July 2007

The effect of winding configuration on leakage inductance of a toroidal core transformer for electronic pulse‐drive circuits is investigated. Theoretical expressions for the effect of wire diameter, conductor spacing of primary and secondary windings, winding pitch, number of turns and core dimensions are derived. It is found that: (1) winding capacitance can be reduced without increasing the leakage inductance by applying an insulation coating to the core; (2) the leakage inductance is simply proportional to the number of turns; (3) a core of square cross‐section can reduce the ratio of leakage inductance to excitation inductance; (4) leakage inductance decreases with decreasing conductor spacing of the pair wire and with increasing diameter; (5) and the leakage inductance decreases with decreasing winding pitch and, in the case of a dense winding, it is less than that of a sparsely wound coil by as much as a value proportional to log (4/3). The experiments in which the above results were obtained were in good agreement with calculated values.
Distributed index formation of planar microlens
Authors: Chiba Takashi , Oikawa Masahiro , Iga Kenichi , Misawa Shigeyoshi
Published: July 2007

Finding the distributed index formation in the fabrication of planar microlens is important in realizing the optimization of the conditions controlling the distribution as it determines the optical properties. The system is modeled under the assumption that the penetration of the metal dopant ions follows the drift‐diffusion equation. Before this equation is solved, the diffusion constant and the mobility of metal ions in a glass substrate are measured. It is found that the diffusion constant is strongly dependent on the ion concentration. Based on these findings, the drift‐diffusion equation is analyzed numerically to find the concentration distribution in the planar microlens. It is found that the thermal diffusion with a strong concentration dependence contributes significantly to the formation of concentration profile without a tail.
Measuring method of active impedance of crystal oscillator circuits
Authors: Toki Masahiro , Tsuzuki Yasuo , Mitsuoka Teruyoshi
Published: July 2007

Although crystal oscillators are used widely in such electronic devices as communication equipment and measuring apparatus, it is not possible to determine if the circuit oscillates or how the adjustment must be made until the crystal is connected to the circuit. To remedy this situation and to improve the design method for the crystal oscillators, a method has been developed for measuring the two‐terminal impedance of the active circuit seen from the crystal terminal or the equivalent capacitance when negative resistance of a specific value is obtained. In principle, a known resistance is connected in series with the crystal terminal so that negative resistance is cancelled. Then the resultant pure capacitance is measured with a bridge circuit. A measurement system consisting of a bridge circuit which is controlled by a computer has been constructed. Representative oscillator circuits have been measured. It is found that a usable frequency range can be found from the measured frequency characteristics of the excitation current and the equivalent capacitance, and that the static capacitance of the active circuit seen from the crystal terminal can be adjusted to a desired value via an adjusting capacitance.
Multistable circuit using Λ‐shaped negative resistance devices and its application to frequency divider
Authors: Sekine Yoshifumi , Suyama Masatoshi
Published: July 2007

New voltage‐controlled negative resistance devices, Λ‐shaped negative resistance devices, are combined with Zener diodes and resistors to form a unit circuit. These unit circuits are connected in parallel to create circuit configurations that cannot be realized by previous voltage‐controlled negative resistance devices. This circuit exhibits multipeak characteristics and realizes a multistable circuit and a frequency divider

In previous multipeak characteristics, the current peak increases with the voltage. In the present multipeak characteristics, the current peak can be set independetly. A multistable circuit has been constructed with the present structure, analyzed, and its characteristics found. The voltage of the stable point can be varied independently and the number of stable points can be varied with the gate voltage of the Λ‐shaped three‐terminal negative resistance device. When the multistable circuit is used for construction of a frequencey divider, the reset circuit can also be made simply with the Λ‐shaped negative resistance device. In addition to the 1/n divider, an arbitrary rational ratio divider can be fabricated by addition of a feedback loop.
Basic fuzzy logic circuit formed by using p‐MOS current mirror circuits
Authors: Yamakawa Takeshi , Miki Tsutomu , Ueno Fumio
Published: July 2007

Modern digital computers have great numerical calculation ability, but processing of fuzzy information is poor in terms of effectiveness and cost. Consequently, hardware systems peculiar to fuzzy information processing are anxiously awaited. This paper proposes a basic fuzzy logic circuit formed by using p‐MOS current mirror circuits, discusses the zero‐error condition and verifies their operations by the semicostom fuzzy logic IC designed in a standard Al‐gate p‐MOS technology

The distinctive features of the proposed fuzzy logic circuits are:

any fuzzy logic functions can be implemented with one kind of master slice (Bounded‐Difference array);

variations of process parameters affect the electrical characteristics of the logic circuits very little;

the basic logic cell is accurate;

the current mode design facilitates the algebraic sum only by Al‐wiring; and

these fuzzy logic circuits can be useful in binary logic and multiple‐valued logic

The basic fuzzy logic cell described here will be a candidate for a logic circuit of Fuzzy Computer in the near future.
Displacement sensors and displacement signal coding circuits using twisted and bent dual‐core fiber
Authors: Taya Hiroyuki , Noda Ken‐Ichi , Kimuras Tadashi , Seki Yohsuke
Published: July 2007

Displacement and twist sensors are constructed by providing twist and/or bend to the dual‐core optical fiber composed of two parallel single‐mode fibers. A circuit is also presented which can produce the coded signal output for the displacement or twist. More precisely, theoretical analysis is made for the twist sensor, which is obtained by twisting the bent central part of the bothend fixed dual‐core optical fiber, and the displacement sensor, which is obtained by displacing the twisted central part of the both‐end fixed dual‐core optical fiber. It is shown that satisfactory sensitivity and the linearity in input‐output characteristics are realized. Then the basic characteristics are measured experimentally. The change of the phase difference due to the length difference of the two cores with twist and bend were measured. The result is in good agreement with the theory. Then as an application to the digital circuit, the principle is investigated to realized ΔM coding of the signal by vibrating the twisted dual‐core optical fiber in the perpendicular direction. Theoretical and experimental investigations are made on the initial rotation and twist, optical coupling to the fiber and the mechanical strength against shear stress due to twist. This will be the problem in practical applications.
A proposal of various recursive switched capacitor filters using a single OP‐Amp and experimental results
Authors: Kudo Michio , Hayashibes Rinpei
Published: July 2007

A simple structure filter design technique which uses a first‐order passive circuit and a switched‐capacitor integrator as a negative feedback element is shown to be applicable to a wide variety of second‐order filters. The circuit features less power consuption, fewer component count and less cost. These features are not offered by switched‐capacitor filter designs proposed to date. Transfer function of the filter is analyzed. High Q‐factor bandpass filter design is developped and Q‐factor within approximately 50 ˜ 60 is obtained in the audio‐frequency region. It is demonstrated that local integration of the circuit can realize double Q‐factor and sensitivities of center frequency and Q‐factor can be decreased within one‐half. Improved low‐pass and high‐pass filter design which preserve the wide‐flat sharp transition response curve is proposed and the desired band‐eliminating filter consisting of the combination of them is also shown. Dynamic range of the input signal amplitude, which would be insufficient in current switched‐capacitor filter designs, is improved to have 60 to 70 dB. The effect of the driving pulse waveform on circuit operation is studied further.
A method for improving convergence in a power semiconductor device analysis program
Authors: Sakai Tatsuo , Shimada Yuuki , Katoh Kuniharu
Published: July 2007

A new simulation technique for analyzing power semiconductor devices is presented in this paper. In this technique, quasifermi potentials are used as variables for current continuity equations and the upwind differential scheme is used for discretizing the current continuity equations after linearization according to Gummel's method. With this technique, it is possible to analyze the high bias condition of a device using a relatively rough mesh. A detailed design of breakdown voltage can be created since carrier generation and recombination are taken into account. The efficacy of this technique is confirmed by comparing the simulation results obtained using this new technique to assess the lateral MOSFET model with those obtained using a model reported previously. Analyses of 600 V‐ and 40 V‐ VD‐MOSFET using this new technique are carried out, and it is shown that the new technique is effective for modeling power semiconductor devices.
Fabrication of SiO2‐TiO2 glass planar optical waveguides by soot deposition process
Authors: Yasu Mitsuho , Kawachi Masao , Kobayashi Morio
Published: July 2007

This paper concerns the soot deposition fabrication of SiO2‐TiO2 planar optical waveguides using a starting material of SiO4‐TiO4. Two different methods are investigated: thermal oxidation using a CVD tube and direct flame hydrolysis using a torch. The resulting structures and their optical propagation losses are compared to arrive at the main results of this research as summarized below

(1) The flame of hydrolysis process is superior to thermal oxidation CVD both in terms of the optical quality and producibility

(2) The flame hydrolysis process permits fabrication of guides with arbitrary distribution of index of refraction for step and graded index, as well as single‐mode guides, and with optical losses of ˜0.1 dB/cm

The SiO2‐TiO2 waveguides achieved through this research, either in their obtained thin‐film structure or with additional microfabrication as necessary, will be valuable in the realization of various optical waveguide circuit functions.
Influence of arc discharge types on contact resistance
Authors: Sawa Koichiro , Asakawa Akira , Uekis Tadao , Miyachi Kunio
Published: July 2007

The state of the breaking contact can be steady arc, showering arc or no‐discharge depending on the circuit condition, even if the same current is cut off. These types of discharge are concerned not only with the wear of the contact, but also with the contact resistance. In this paper, using the automatic measuring instrument for contact resistance developed by the authors, the relation between types of arc discharge and the contact resistance is examined, mostly for the silver and palladium contacts. As a result, it is seen that the silver contact in steady arc condition has a fairly high contact resistance (50 ˜ 100 m Ω) with a large variance. On the other hand, the palladium contact in steady arc condition and the palladium and silver contacts in showering arc condition are relatively stable with low contact resistance. These properties are related to the erosion of contact surface by the arc. It is seen from the observation of surface by SEM that the contact resistance of the silver contact in steady arc is affected greatly by the surface film, while a metallic contact is maintained in the palladium contact. In the showering arc condition, both silver and palladium contacts maintain the metallic contact, with the measured contact resistance being in good agreement with the calculation by the theory of spreading resistance.
High rate preparation of C‐axis oriented aln films by reactive sputtering
Authors: Matsuoka Morito , Naoe Masahiko , Hoshi Yoichi
Published: July 2007

Highly oriented AlN film has been formed at a high rate of a Targets Facing Type Sputtering (TFTS) method which has reduced substrate bombardment by various high energy particles. The relation between its crystal structure and the formation condition has been studied in detail. As a result, C‐axis oriented AlN film can be obtained for a wide nitrogen gas pressure range of 0.2 ‐ 10 mtorr at a relative low substrate temperature of around 400°C. In particular, at a low pressure of 0.5 ‐ 2 mtorr, C‐axis oriented film with good surface smoothness can be formed. Also, higher film deposition rate results in improved film orientation, and a good orientation with ΔO50 of 1.9° (σ002 of 0.9°) can be obtained at a rate of 0.6 μm/h even for a thin film of 0.2 μm thickness. Furthermore, it has been found that the orientation degrades with bias application to the substrate, and that a high‐orientation AlN film can be obtained by the TFTS method because of the suppression of substrate bombardment by high‐energy particles. From the forementioned results, to obtain a good quality C‐axis oriented AlN film with good orientation and surface smoothness, the necessity of using a sputtering method, such as the TFTS method, has been shown. In this case, particles with sufficient energy to destroy the film do not bombard the substrate, and sputtering particles themselves reach the substrate with an appropriate energy (several eV).
Realization of multiport D‐R mutator and its application to high‐pass filters
Authors: Ikeda Katsuji , Tomita Yasushi , Ishimoto Hidetaka
Published: July 2007

Active RC circuits using gyrators as active elements can be applied to the realization of inductorless filters which inherit the superior transmission characteristics of LC filters. However, equivalent transmission characteristics can also be obtained by the application of D ‐ R mutators that simulate frequency dependent negative conductance defined as Y = s2D. Gyrators can be constructed from operational amplifiers used as voltage‐current transducers or negative impedance converters. In this paper, a multiport D ‐ R mutator is realized in the way that the capacitance takes the place of the resistance of multiport gyrator, which is constructed by negative impedance converter using current conveyors as voltage‐current transducer. It is shown that a multiport D ‐ R mutator obtained in this way can then be applied to the realization of a high‐order, high‐pass filter; the excellent measurement results are also presented. It is shown that the realized high‐pass filter has few passive elements in comparison with those derived using methods based on operational amplifiers, the filter characteristic can be easily tuned by grounded passive elements, and the proposed active elements are particularly efficient for the realization of high‐order, high‐pass filters.
Coaxial‐line type microwave plasma CVD system to fabricate SiN films
Authors: Kato Isamu , Kohyama Yusuke , Noguchi Kazuto
Published: July 2007

This paper considers the fabrication of silicon nitride films by means of the vapor phase deposition with a microwave glow discharge. With a cavity‐type coaxial line microwave discharge tube, a plasma has been confined in a desired space and the film has been fabricated successfully outside the plasma. Hence, the substrate is not damaged nor heated by plasma bombardment. Fabrication has been successful with the substrate at room temperature. The deposition rate depends on the location of the substrate table. When the table is sufficiently far away so that an almost uniform film thickness is obtained for a substrate 6 cm in diameter, the deposition rate is 2 to 7 Å/s with the microwave power of 100 W. Depending on the fabrication conditions, the optical energy gap varies from 2 to 5 eV. Then the color of the film (∼l μm) changes from brown to transparent.

A new method has been proposed for finding the Si/N ratio and the film density from the measurement of the infrared absorption spectrum and the index of refraction. Based on the computed results, the film quality has been studied. When the flow rate of SiH4 gas is kept sufficiently small, a sufficiently strong transparent film can be fabricated with the Si/N ratio of 0.75 and the density of 2.3 g/cm3. When the substrate temperature is increased, the film density is increased and the deposition rate is reduced. It is found that the reduction of the deposition rate is due to that of the adsorption rate of the radicals.
A multiinput type converter for an uninterruptible dc power supply
Authors: Koyashiki Tohru , Ogata Tsutomu
Published: July 2007

Low‐power uninterruptible dc power supplies have been used widely. These are powered by several types of power sources with differing voltages, e.g., commercial ac power sources as well as batteries. A multi‐input‐type converter is developed to simplify circuit configuration and realize a low‐loss power system.

This paper presents a method of designing a multiinput transformer as well as the operation principle of a multiinput‐type uninterruptible power supply and the circuit technology required for it. The power supply can be realized if the transformer primary winding‐turn ratio is designed considering the input voltage variation range and the voltage‐drop in the transformer primary circuit. The fact that the switching‐duty ratio must be changed drastically and that the switching transistor loss is inclined to increase in a multiinput‐type converter causes some problems. It is shown that the application of a collector current proportional drive circuit to the forward‐type converter or a base resistor switching circuit to the flyback‐type converter is effective in reducing the converter loss and the converter can be simplified by using most of the converter circuits in common.
Application of two‐frequency nonlinearity measuring method to contacts
Authors: Minowa Isao , Akiyama Jun , Kanno Makoto
Published: July 2007

It is known that electric contacts, as well as resistors and capacitors, exhibit nonlinearity in their voltage‐current characteristics, although very slight. With the oxidation and contamination on the surface of a contact, the nonlinearity increases with the contact resistance. From such a viewpoint, a proposal has been presented to utilize the nonlinearity in estimating the degradation of contact. In that proposal, the third‐order distortion is detected as the measurement of the nonlinearity. In this study, the two‐frequency method is employed, where a current composed of two frequencies is passed through the contact and the distortion voltage at another frequency is detected. A higher sensitivity than the past method was obtained. By this system, the contact resistance as well as the distortion voltages from second‐ to sixth‐orders can also be measured maintaining the same contact state. To examine the effectiveness of the method, gold‐plated contacts and other kinds were measured. The spectrum features from the second to the sixth distortion can be measured. This provides new information not obtained from the third distortion only. This will be a new method for describing the contact characteristics in the future.
Speech prosthesis system for laryngectomees using “electropalatograph” and a small keyboard
Authors: Muraki Shigeru , Sugie Soboru
Published: July 2007

We have been working on a speech prosthesis system for the past three years. This system utilizes the electromyograph of the laryngectomee who is unable to speak. The detection of the electromyograph, however, involves a number of problems such as noise and electrode attachment. This paper reports on the development of a system which can discriminate and produce a number of monosyllabic speeches from the contact pattern between the tongue and the palate in cooperation with the input from a simple keyboard. A device, called the electropalatograph, detects the contact pattern between the tongue and the palate. The matching between the detected pattern and the preregistered template is examined. Based on the time‐course of the best‐matched template and the input from the simple keyboard, the intended monosyllable is determined. The result drives the speech synthesizer to produce the speech. In the evaluation experiment, 82.4 percent of 63 monsyllables were uttered correctly. Furthermore, the score tended to improve with the training of the patient.
A three‐dimensional process simulator and its application to submicron VLSI's
Authors: Onga Shinji , Taniguchi Kenji
Published: July 2007

A three‐dimensional process simulator TRIP for submicron electron device fabrication was developed. TRIP includes, as the process models, the ion‐implantation model, diffusion/oxidation model, and etching model. In the diffusion model, Fick's second equation is discretized by seven‐point difference in the three‐dimensional space. The oxidation‐enhanced diffusion (OED) effect in the oxidizing atmosphere is taken into consideration is determining the diffusion coefficient. The OED effect at the mask corner in LOCOS is extended into three dimensions. The fabrication process of a junction is used to examine the accuracy of TRIP. It was seen as a result that the accuracy is practically satisfactory. Examining the problems in the process design for a submicron MOS device using TRIP, the impurity dilution effect and impurity crowding effect are found as problems peculiar to the three‐dimensional process.
A consideration of discharge phenomena generated in E cross B devices
Authors: Tanizuka Noboru
Published: July 2007

Since discharge phenomena are generally complex, a systematic method of interpreting them will be useful for their applications. This paper offers an interpretation of discharge phenomena from the viewpoint of flow, transformation and distribution of energy by taking E cross B devices. The results are useful for designing this type of device. The device constant, k × erB2/8U2, was introduced, where r2 is the radius of the outer electrode, U2 is the electrode voltage, B is the axial flux, and k has a dimension of mass. The energy transformation efficiency, \documentclass{article}\pagestyle{empty}\begin{document}$ \eta = 2h^{ - 2} \sqrt {1 - h^2} \left({1 - \sqrt {1 - h^2}} \right) $\end{document} was found, where \documentclass{article}\pagestyle{empty}\begin{document}$ h = \sqrt {m/k} $\end{document}, and m is the mass of charge (the intermediate charge) which transforms the electrostatic potential energy into the discharge energy. It was found experimentally that this type of device discharges when h < 1. This agrees with the theory that a discharge occurs (0 < n < 1) when h < 1; 1 − n indicates the rate of the kinetic energy (which is the cause of the temperature rise in the device) when the charge m collides with the electrode. It is predicted that the closer the h to zero, the closer the n to 1 and the more effective the discharge.