bluuebunny/crossref_metadata_2025 huggingface dataset:
CR Low frequency tuned amplifier circuit with high selectivity
Authors: Ieyasu Kenzo , Kurokawa Susumu
Published: July 2007

The conductance of the reactance circuit used in the tuning circuit of the CR tuned amplifier is a function of frequency with negative minimum value. If the external parallel resistance to the tuning circuit is reduced so that a high selectivity is obtained, the conductance becomes negative at a frequency other than the resonance frequency and the circuit will oscillate. We have obtained a stable high‐gain tuned amplifier with high selectivity by selecting the values of resistor and capacitor in the voltage phase‐shift circuit so that the conductance of the tuning circuit is minimum at the resonance frequency. The amplifier with the resonance frequency of 10 kHz fabricated according to this design method exhibits the maximum selectivity of about 700 and the voltage gain of about 100 dB. These values agree well with the computed values. The rate of change of the resonance frequency for the temperature has been made rather small with the use of circuit components with small temperature coefficients. However, the rate of change of the gain (and hence selectivity) is extremely large. With the use of an ac resistive circuit with a positive temperature coefficient consisting of PTC thermistors and transistors, the rate has been reduced to the extent tolerable in the practical temperature range.
One‐dimensional table look‐up model for sub‐μm MOS transistors
Authors: Matsuo Hitoshi , Yokomizo Gooichi , Masuda Hiroo , Hagiwara Takaaki
Published: July 2007

A highly accurate one‐dimensional table model has been developed for an MOS transistor simulation used in a circuit simulation necessary for the VLSI design. The usefulness of the model for the circuit simulation has been tested. Traditionally, the one‐dimensional table model has been used in the area where high precision is not required, such as the timing simulators. It is not sufficient for simulation of a high‐precision circuit and the accuracy has been a particular problem for the MOS transistor of submicron level. In the new one‐dimensional table model, the two‐dimensional effect of the drain and gate electric fields is included and only two one‐dimensional tables are added. The model can be applied to a high‐precision circuit simulation. This model has been applied to three devices with the effective channel length of 0.66 ∼ 2.30 μm fabricated in different processes. It was found that the maximum of the average relative error within the practical voltage range is 3.87% which corresponds to the acuracy four times that in the conventional model. Increase of the error for the variation of the substrate voltage is especially small. It has been demonstrated that the present one‐dimensional table model is a transistor model capable of high‐precision circuit simulation.
A current conveyor II realized by Mosfets and its application to switched capacitor filters
Authors: Gotō Naoki , Nishio Makoto , Suzuki Tokio
Published: July 2007

From the viewpoint of intergration, a MOSFET configuration is superior to the previous current conveyors (CC) consisting of an operational amplifier and/or bipolar transistors

In this paper, a current conveyor II (CC II) is composed of an operational amplifier and MOSFETs. It was clarified that the current transfer ratio from X terminal (input) to Z terminal (output) of CC II can be put to variable Ki., not to 1, because the MOSFET is a voltage‐controlled device. As a case of application, a switched capacitor (SC) integrator is realized with our proposed CC II and its transfer characteristic is studied theroretically and experimentally. Then, by applying this SC integrator to a Biquard‐type bandpass switched capacitor filter (SCF), it turned out that the electric capacitor of the SCF can be reduced largely and the SCF integration is superior in this regard.
Printing properties of two‐color laser beam printer
Authors: Hoshi Nobuyoshi , Anzai Masayasu , Akimaru Susumu , Komatsu Isamu
Published: July 2007

In operation of a laser beam printer to print a two‐color image with one rotation of a photoconductive drum by twice exposing the negative and reversal development of the image undesirable color mixing occurs. This is due to the fact that the first color toner is mixed into the second color developer by the magnetic brush of the printer and the mixed first toner is developed with the second color toner. This paper describes a method of inhibiting the color mixing by reversing the electrostatic charge polarity of the mixed toner so that it can be separated. It is possible to reverse the charge polarity of the first color toner mixed into the second color developer by utilizing its friction against the second color toner in a developing process which uses the same carrier for the first and second color developers. The mixed toner with its charge polarity reversed is separated from the second color toner by the electric field of the electro‐static latent image during its developing and remains on the nonimage part of the photoconductor, being finally removed with the photoconductor.
High‐speed logic circuits combining bipolar and CMOS technology
Authors: Masuda Ikuro , Nishio Yoji , Ikeda Takahide
Published: July 2007

It has been verified that a new LSI concept with high speed and low power consumption can be realized by combining bipolar and CMOS technology inside a basic unit circuit. This paper proposes a combined basic circuit that is of the high‐speed logic type. It is theoretically and experimentally evaluated to show that specified performance can be obtained, and some effective applications are analyzed. Using the circuit model, the relatioship between the performance of logic cicuit and the basic characteristics of the devices are analyzed, and the collector current vs. fT characteristics of bipolar device is shown to be important. Ring oscillators are fabricated for the two concrete circuits, and the speed and power conssumption are evaluated. The fabrication uses a newly developed Bi‐CMOS 2 μm technology which has buried layer and a small‐sized emitter for bipolar device with good high frequency characteristics. As a result, with a standard load and operation frequency, the delay of 0.7‐0.8 ns, and the power consumption of 0.15‐0.25 mW are obtained. By applying this logic circuit to gate arrays and memories, twice the speed of a CMOS can be realized with the same amount of power consumption.
Linearization of a light emitting diode for analog baseband video transmission
Authors: Nakamura Masaru , Nitta Koichi , Komatsubara Tadashi , Okajima Masaki , Ozeki Takeshi
Published: July 2007

Nonlinearity compensation is very important when using an LED source for video transmission. In general, wideband negative optoelectronic feedback makes a high‐quality, low‐distortion, adjustment‐free light source possible. However, when attempting to apply this technique to the LED, a stable feedback loop design is difficult to achieve because of the poor coupling efficiency between the LED and the external photodetector. We have resolved this problem via a monolithic integration of the LED and PD, and realized a low‐distortion LED by the addition of an external negative feedback circuit. The LED, PD composite device is a hybrid fabricated with LPE for the LED and MOCVD for the PD. A signal transmission efficiency of 2 percent was achieved between the LED and PD. This is more than an order of magnitude larger than the efficiency attainable with conventional discrete components, and rivaling what can be done with an LD. Evaluation of the video transmission quality showed an improvement in the differential gain and phase from 8 percent and 2.5° to 1 percent and 0.5°, and also automatic compensation was available for line and frame slope and improved frequency response flatness in the passband. With this method of LED distortion reduction, the conventional predistortion or frequency compensation circuits and their adjustments are no longer necessary, and a low‐cost, high‐quality LED source becomes possible.
Video frequency active filters using balanced‐type NICs
Authors: Kumazawa Masazumi , Yanagisawas Takeshi
Published: July 2007

Most proposed methods of constructing active filters are limited to the audio‐frequency band. This paper describes an LC simulation type video‐band active filter using the excellent high‐frequency characteristics of the balanced‐type negative‐impedance converter (NIC)

After describing the construction method of a balanced‐type NIC, the nonideal components which affect the characteristics of the filters are analyzed. A dc‐bias method for a gyrator using the proposed NIC is also shown. Taking the 4th‐order BPF and the 5th‐order LPF as examples, a method of constructing video‐band active filters and a method of filter compensation are shown. These methods require fewer active elements than usual and utilize npn transistors alone so that they are suitable for monolithic ICs. The results of the experiments using standard transistor‐arrays with simple compensation agree well with the theory in the frequency band up to 10 MHz.
Five‐layer structure electroluminescent devices prepared by RF sputtering
Authors: Mikami Akiyoshi , Ando Keiichi
Published: July 2007

Five‐layered electroluminescent (EL) devices having an active ZnS:TbF3 layer sand‐wiched by an insulating layer and a low‐resistive Ta2O5 layer were produced, and luminous characteristics were investigated. It was found that these devices provide high brightness and luminous efficiency compared with the conventional three‐layered El devices, as well as low driving voltage. This is because the low‐resistive layer between the active layer and the insulating layer is important in improvement of crystallinity of the active layer, increase of conduction carriers in the active layer, and improvement of device breakdown voltage which enables a thinner insulating layer compared to the three‐layered structure. Bright green electroluminescence exceeding 1000 cd/m2 at 90 V and threshold voltage of 68 V have been obtained under 5‐kHz sinusoidal voltage excitation.
Improved pulse‐width‐modulation D‐A converter
Authors: Yoshida Takashi , Nakagawa Masao , Tsunogaes Toshio
Published: July 2007

With all of the recent technological advances in electronics, the problem of interfacing between digital and analog signals is of great importance. Many different principles for Digital‐to‐Analog Converters (DAC) exist; this paper proposes a new Pulse Width Modulation (PWM) type DAC. With conventional PWM DACs only a simple circuit is needed to realize high resolution; however, the necessary Low Pass Filter (LPF) at the output makes them unsuited for high‐speed operation. Accordingly, we consider here a PWM DAC in which the PWM pulse is separated into component pulses to allow the LPF cutoff frequency to be raised for higher‐speed operation. In this Separated Pulse Width Modulation (SPWM) DAC technique there is no need to convert serial digital input into parallel, so the circuitry can remain simple. Here we report on the principle of the SPWM method, the DAC design philosophy, and on experimental confirmation of its performance.
A new cut of quartz for SAW devices with extremely small temperature coefficient by leaky surface wave
Authors: Shimizu Yasutaka , Tanaka Masafumi
Published: July 2007

SAW devices are widely used as delay lines, oscillators and filters. Their characteristics are mainly determined by the SAW propagation characteristics on the piezoelectric substrate. This paper seeks to find a cut that produces better characteristics than those of the conventional Rayleigh wave. Theoretical and experimental investigations are conducted for the characteristics of leaky surface waves propagating on a quartz substrate. As a result, an extremely desirable cut is identified which is a θ = 14.7° cut from a rotated Y‐cut X‐propagation substrate. This cut has a zero temperature coefficient, the variation of the delay time is less than ±10 ppm over a wide temperature range of −20 ˜ 80°C, the propagation loss is only 2.6 × 10−3 dB/λ and the propagation velocity of about 3940 m/s is much higher than that of an ST cut. This new cut is considered to be sufficiently practical for application to various SAW devices.
A two‐dimensional reliability simulator (2P/IMPAC) and its application to LDD MOS devices
Authors: Onga Shinji , Wada Masashi , Konaka Masami
Published: July 2007

A new two‐dimensional reliability simulator 2P/IMPAC has been developed in which a two‐dimensional process simulator and a two‐dimensional device simulator for inspecting the substrate current are combined in a file link method. In the process simulator part, lithography, oxidation, diffusion, ion implantation, film deposition and etching are modeled. Hence, the impurity profile and the fabricated device shape can be derived. In the device simulation part, the Poisson equation and the current continuity equation are solved simultaneously with a repetitive numerical method based on the results of the process simulation, and the electrical characteristics of the MOS device can be calculated. This system is used for finding the relation between the electrical characteristics and the process parameters of the n− region formation in an LDD (Lightly Doped Drain) device from the viewpoint of longterm reliability of MOS devices.
Seed crystal in growth of KDP single crystal for optical harmonic generation
Authors: Shimomura Osamu
Published: July 2007

A large single‐crystal KDP with a radius larger than 35 cm is needed in laser fusion as a conversion device of the laser wavelength to a shorter one. Since the growth speed of KDP single crystal is slow and hence a long time is required for growth, reduction of the growth time is important. The orientation of the seed is studied for both Type I and Type II of the phase matching. For the (001) and (101) plates, it has been found that less weight of the crystal is needed for a desired crystal plate from the seed of (101) plate than (001) plate in the range of θm > 23.7° for Type I and θm > 11.6° for Type II where θm is the phase matching angle. It has also been found that the growth time can be reduced with a (101) plate regardless of θm. For example, in the case of SHG of a glass laser at λ = 1.06 μm, the growth is only 54.4% for Type I and 33.8% for Type II with a (101) plate as a seed compared to a (001) plate.
Static analysis of a resistor‐load‐type D2 CMOS (dual depletion CMOS) associative memory cell by using the state diagram method
Authors: Yoshida Masahiro , Yoneyama Masao
Published: July 2007

In addition to functions required for conventional RAM cells, an associative memory cell requires a function for interrogating its input information and memory information. These requirements increase the number of components per bit, and create the problem of increased cell area when the components are integrated. This paper proposes a new associative memory cell using dual depletion CMOS (D2 CMOS) devices which have fewer components per bit than conventional associative memory cells so that they are more suitable for an integration. By using “the state diagram method,” the static characteristics of the cell were analyzed. The conditional equations of the load resistance which makes the cell functional as an associative memory were obtained and the memory characteristics examined. The writing characteristics involving the conditions for the shift of a state and the writing voltage also were analyzed. In addition, the reading characteristics and the interrogating characteristics were examined. The results of the analyses agree fairly well with the results of the simulation using the circuit analysis programme SPICE 2.
Two‐dimensional mode analysis of a Raman‐type free‐electron laser using a TM pump wave
Authors: Kondo Harufusa , Shiozawa Toshiyuki , Ishido Yoshinari
Published: July 2007

We consider a two‐dimensional Ramantype free‐electron laser composed of a relativistic electron beam with arbitrary thickness drifting in a parallel plate waveguide. For the Raman‐type free‐electron laser specified, we analyze the case where the pump wave is an electromagnetic wave of the TM mode, comparing with the case of the TE pump wave. First, we derive the coupled mode equations relating the scattered wave and the electron plasma wave. By imposing the boundary conditions at the beam surface upon the solutions to the coupled mode equations, we find the dispersion relation for these waves, from which we obtain the spatial growth rate for them. Then, we investigate in detail the frequency and growth rate of the scattered wave, with the aid of numerical illustrations. For the case of the TM pump wave, the boundary conditions at the beam surface and the coupled mode equations in the electron beam become much more complicated than those for the case of the TE pump wave. As a result, the growth rate of the former case shows a considerably different behavior as compared with the latter case. In particular, we can obtain a greater growth rate for the case of the TM pump wave. In addition, the TM pump wave is found to be more advantageous for suppressing the oscillation of higher‐order modes because we can reduce the separation between conducting walls of the waveguide for this case.
On radiation from a relatively sharp bend of step‐index single‐mode optical fibers
Authors: Morita Nagayoshi , Tanaka Toshiaki , Kumagai Nobuaki
Published: July 2007

The problem of radiation from a uniform bend of a step‐index single‐mode fiber is theoretically investigated with the emphasis on derivation of a rigorous expression of the radiation field. The expression for radiation can be applied to a relatively sharp bend in which the modal field profile in the fiber cross section at the bend is different from the one in the straight section. Theoretical equations for the radiation pattern and the radiation loss are also given. Numerical examples for these quantities are shown in comparison to those obtained by neglecting the change of the field due to the bend. The application limit of the present expression for the radiation field is studied from the point of the geometrical optics. It is shown that the present results are applicable if the radius of curvature is more than 0.5 ∼ 1 cm when the wavelength is 1.55 μm and the core diameter is 9.8 μm.
High resolution polysiloxane electron resist
Authors: Naraoka Kiyotake
Published: July 2007

In electron beam lithography, patterning of submicron geometry is not easy because of electron beam backscattering from the underlying substrate. To solve this problem, the use of multilayer resist structure of irradiation dose correction is inevitable. In this work, the electron beam exposure characteristics of polysiloxane resist which is promising as an upper resist in two‐layer resist systems are examined. It has been found that for the polysiloxane resist with molecular weight of several 10,000, the film thickness is increased in the exposed area by exposure alone. The reason for this increase has been found to be the swelling due to the penetration of liquid‐state polymer with molecular weight of less than 10,000 ‐ 20,000 into the network crosslinking structure formed by the exposure. Therefore, a polymer with molecular weight (μMn) of 200,000 is appropriate for a practical polymethysiloxane resist, with sensitivity of 0.3 μC/cm2 (10 keV). This resist can resolve 1 μm line and space, and is promising for submicron fabrication.
Driving conditions and signal treatment method of the buried channel CPD image sensor
Authors: Kozono Toshiyuki , Matsuda Yuji , Senda Koji , Terakawa Sumio , Takamura Tohru , Kunii Takao
Published: July 2007

This paper examines the CPD (charge priming device) ‐ type solid‐state image sensor (MN8210), which has the image size of 2/3 inch, 398 (H) × 496 (V) pixels and horizontal overflow drain structure. Discussions are made on the driving and signal processing methods, which are effective in improving the vertical transfer efficiency and the noise characteristics. By injection driving using externally injected charge, the vertical transfer efficiency can be improved up to 95 percent, independently of the signal magnitude. By using the CDS (correlated double sampling) signal treatment method, the low‐frequency noise component generated in FDA (floating diffusion amplifier) is reduced by approximately 5 dB. By the signal treatment method which picks up only the photosignal component in the two output, waveforms noise reduction of 3 dB could be achieved.
Dynamic characteristics of the push‐pull dc‐dc converter
Authors: Shoyama Masahito , Harada Koosuke
Published: July 2007

Push‐pull dc‐dc converters are used widely as large‐capacity power supplies for electronic equipment. Previously, the authors have shown that when the transformer magnetizing current in this converter is not negligible, there are six modes of operation determined by the relation between the reactor and the transformer magnetizing currents. They have analyzed the steady‐state characteristics for each mode of operation. This paper considers the analysis of the dynamic characteristics for each mode of operation for small perturbations around the steady‐state operating point. Transfer functions for four of the six modes of operation were derived based on a new model with the ripples of the transformer and the reactor magnetizing currents taken into account; they were shown to be of the first‐order delay system. It turns out that in two of these four modes of operation the reactor current is continuous and by using these modes, a highly stable converter with small output voltage ripple for a relatively large load current can be realized.
Characteristics of a single‐mode fiber beyond the cutoff frequency of the LP11 mode
Authors: Hiratani Yuji , Kawakami Shojiro
Published: July 2007

To clarify the basis of the concept of effective cutoff wavelength useful for design of single mode optical fibers, this paper discusses theoretically and experimentally the mode conversion effect due to fluctuation of the fiber structure in addition to the difference of the attenuation constants of the modes. In the two‐mode region, the scattering matrix elements of the optical fiber are measured with respect to the power of the LP01 and LP11 modes. Based on the measurement, the wavelength dependence of the mode conversion coefficient h and the mode attenuation αi are determined.

Next, the multimode dispersion and excess loss of the two‐mode system with mode conversion are related to the parameters h and αi and the significance of the effective cutoff wavelength is discussed. It is found that at frequencies slightly beyond the theoretical cutoff for the measured sample fiber the difference of attenuation constants of two modes is substantial. In addition, since the mode conversion coefficient is small, the degradation of the transmission characteristics due to the higher order mode is reduced, resulting in the effective single mode transmission line. Also found is the condition to be satisfied by h and αi so that the desired transmission characteristics (dispersion and loss) are realized with a necessary length of fiber.
Effect of the heat treatment of tife amorphous alloy thin films
Authors: Konishi Ryösuke , Imai Hiroshi , Ishibe Shoichi , Harada Hisamochi , Sasakuras Hiroshi
Published: July 2007

TiFe, which is well known as an oxygen occlusion alloy, was fabricated by using a composite target of Ti and Fe with sputtering. The composition and structure of TiFe alloy thin‐films were analyzed by using XPS, Mössbauer, x‐ray diffraction and electric resistance measurements. The results show that they are amorphous alloy thin‐films consisting of 38 to 45 Ti at %. The TiFe amorphous alloy thin‐film was heat‐treated in ultra‐high vacuum (2 × 10−9 Torr) at 450°C for one hour; then the change was investigated by measuring its depth profile with XPS. It was found that Ti precipitated and Fe decreased in the film surface after the heat treatment, and, at the same time, Fe increased in the lower layer; and that TiFeOx was formed internally in a part of the layer.
Measurement of surface coupling coefficients between nematic liquid crystals and various substrates
Authors: Kuwahara Michio , Onnagawa Hiroyoshi , Miyashita Kazuo
Published: July 2007

There are still problems not fully solved concerning the characteristics and magnitude of interaction between liquid crystals and the surfaces of substrates. It is thought that the number of electrodes in a matrix display device can be increased and its display panel can contain a memory function by the weak boundary‐coupling effect (i.e., by reducing the coupling of the liquid crystal and the substrate surface). Thus, it is necessary to investigate the strength of the coupling between liquid crystals and the surfaces of various substrates. The coupling strength is measured by curve fitting of the electrostatic capacitance–applied voltage characteristic (the C ‐ V characteristic) of a nematic liquid crystal cell. In this method the measured result of the C ‐ V characteristic is compared with the result of calculation in which the surface coupling coefficient is used as parameter. Two kinds of surface treatment (i.e., oblique vacuum‐evaporation of silicon monoxide and rubbing after coating with polyvinyl alcohol film) are investigated. The nematic liquid crystals used in this study are phenyl cyclohexane‐based. The coupling coefficient is of the order of 10−3 J/m2. When the temperature is raised, the coupling coefficient decreases.
Equivalent‐circuit model analyses of the dv/dt characteristics of a complex pnpn switch circuit
Authors: Suzuki Masayoshi , Sagawa Akio , Izaki Naoyuki , Kawakami Hideaki
Published: July 2007

This paper describes a complex pnpn switch (thyristor) circuit which offers high noise‐immunity and high gate‐sensitivity at the same time. The circuit has a protection transistor which short‐circuits the gate and cathode of the thyristor instantaneously when a noise enters. This has a critical slew rate of about 1000 V/μs (= 200 V/0.2 μs) at a gate‐trigger current of 0.1 mA. However, it is found that the thyristor makes a false turn‐on when the storage time of the protection transistor is shorter than the gate recovery time of the thyristor. This phenomenon is designated “a turn‐off time racing false ignition.” To analyze this phenomenon, an equivalent circuit of the complex pnpn switch circuit is proposed. It is found that no false turn‐on occurs when the anodecathode voltage of the thyristor is lower than the dynamic blocking voltage VF.
Effects of metallic‐grating upon leaky saw propagating on 36° YX‐liTaO3
Authors: Hashimoto Ken‐Ya , Yamaguchi Masatsune , Kogo Hiroshi
Published: July 2007

Propagation characteristics of leaky SAW under a metallic‐grating structure (grating mode) on 36° YX‐LiTaO3 (36‐LTO) are analyzed and compared with experimental results. First, the velocity dispersion and attenuation for the grating mode are theoretically analyzed. The results show that although the velocity dispersion is similar to that for an SAW, the stopband width of the grating changes with the electrical boundary of the grating. The attenuation depends on how strongly the grating mode couples to bulk waves and leaks its energy into the bulk. The interaction of the grating mode with slow shear waves is markedly weak on 36‐LTO. Hence, the attenuation due to bulk wave radiation is negligible at frequencies where the grating mode couples only to slow shear waves. However, the attenuation increases at frequencies slightly higher than the stopband, where the grating mode strongly couples to fast shear waves. Next, transmission and reflection characteristics are experimentally investigated about the stopband of a metallic‐grating fabricated on 36‐LTO. The results are in good agreement with the theoretical prediction.
Vector variational analysis of the guided modes in the three‐dimensional anisotropic optical waveguides
Authors: Ohtaka Masato , Kobayashi Takao
Published: July 2007

The guided wave characteristics in a three‐dimensional dielectric optical waveguide containing anisotropic materials must be investigated by vectorial analysis. Such analyses are extremely complicated if non‐diagonal terms are contained in the dielectric tensor or more than two anisotropic materials are involved. In this paper the guided modes are analyzed by a variational method in the case where the dielectric tensor contains nondiagonal elements of the transverse components. First, a new variational expression and trial functions suitable for analysis of the guided mode in these waveguides are derived. Next, numerical calculations are performed for a rectangular dielectric waveguide in which both the core and the substrate are made of anisotropic materials. With these calculations, we investigate the effects of the directions of the multiple principal axes on accuracy of the propagation constant near the lower limit, coupling of the guided modes and directions of the electromagnetic vectors. It is found that there are tight hybrid modes and weak hybrid modes. In the case of weak hybrid modes the electromagnetic vectors are straight and almost parallel to the principal axes. On the other hand, in tight hybrid modes the electromagnetic vectors bend significantly and the vector direction is rotated as the normalized frequency is varied.
Acceptance angles of four‐wave parametric upconverters
Authors: Koyanagi Kojiro , Mishima Teruhito , Sakuraba Ichiro
Published: July 2007

In the four‐wave parametric upconverter based on isotropic alkali‐metal vapor which is considered useful as an infrared detector, the acceptance angle characteristics of the infrared ray have been studied theoretically in the case of angle phase matching (or pump phase matching) in which a phase matching is taken by way of small angular difference of two pumping light beams. It is found that various acceptance angle characteristics such as single‐peak, double‐peak, and multi‐peak characteristics can be obtained by adjustment of two pumping light angles, if the collinear phase mismatch is negative due to anomalous dispersion of the metal vapor. The collinear phase mismatch is defined as the magnitude of wave vector of the sum frequency minus the sum of the magnitudes of the wave vectors of two pumping beams and the infrared beam. A flat and broad acceptance angle is obtained in the case of tangential phase matching. It is also found that an optimum state as an image upconverter with a high conversion efficiency and a large acceptance angle exists in the four‐wave parametric upconverter of the two‐photon resonance excitation type in which a large conversion efficiency has been expected.
Design for a single‐mode optical fiber switch
Authors: Kishimoto Ryozo
Published: July 2007

Because of its low loss and broadband characteristics, the optical communication system with single‐mode fibers is promising for long‐distance large‐capacity communication and subscriber video transmission systems. These systems require optical switching techniques for upgrading and for expanding applications. In this paper, with a view to establishing a method for design of a single‐mode optical fiber switch, an optical collimating system employing a focusing rod lens is analyzed by means of a beam mode expansion method. Next, the characteristics of the optical collimating system, the characteristics of a large matrix optical switch collimating system and the displacement, which is important in the optical circuit, are discussed. Finally, a method of construction and test results are described for a 1 × 3 single‐mode fiber optical switch employing a parallelogram prism. A single‐mode optical fiber switch with insertion loss of 0.4 dB and switching reproducibility of less than 0.1 dB is realized. The results confirm the validity of the design method of single‐mode optical fibers.
Silver migration suppression effects of the 2,4‐diamino‐6‐vinyl‐s‐triazine compounds
Authors: Kamagata Kazuo , Kawatas Shunichi , Yamada Toshiaki
Published: July 2007

Silver is used widely as an electrode material. It is well known that the silver used in ceramic substrates, paper/phenol resins, and glass cloths/epoxy resin‐laminated boards, tends to migrate when subjected to an electric potential difference under a high temperature/humidity environment, causing a reduction in insulator resistance and ultimately short‐circuiting. This phenomenon arises from the ionization and resulting migration between silver electrodes in the presence of water and an electric potential difference. A known method of inhibiting silver migration is to apply an epoxy resin coating to the substrate surface. It has been determined that an epoxy resin coating containing intermolecular compounds of isocyanuric acid and 2,4‐diamino‐6‐vinyl‐s‐triazine having an s‐triazine ring within the molecule, is substantially more effective in suppressing silver migration than are epoxy resin coatings not containing those compounds. It has also been confirmed that 2,4‐diamino‐6‐vinyl‐s‐triazine easily forms a complex in combination with silver ions in the water. When water droplets containing this compound are discharged onto bare silver electrodes, the amount of time it takes for shorts to occur is significantly greater than when water devoid of the compound is used. On the basis of these observations, it is conjectured that 2,4‐diamino‐6‐vinyl‐s‐triazine is responsible for suppressing silver migration.
Focusing grating for integrated optical‐disk pickup devices
Authors: Ura Shogo , Suhara Toshiaki , Nishihara Hiroshi , Koyama Jiro
Published: July 2007

Optical‐disk pickup heads have been constructed with microoptics. Great improvement in producibility and reduction of weight and size are expected by replacing the pickup head with integrated optics. Such an integrated optic device can be constructed by a focusing grating coupler (FGC) which focuses an optical guided wave onto a point in space. This paper describes the theoretical and experimental examinations of the fundamental characteristics of the FGC for the integrated optical disk pickup device. The theoretical analyses show the feasibility of an FGC having a focus spot width larger than the diffraction‐limited value only by 3 percent and the efficiency of 60 percent, by optimizing the device parameters. The analyses of the imaging of the optical system show that the tracking error and the focusing error of a disk can be detected as the displacement of the focal point of the back‐coupled optical guided wave. By fabricating FGCs by an electron‐beam etch method, the focus spot widths were measured to be 3 μm for the laser diode and 1.4 μm for the He‐Ne laser, while the diffraction‐limited values are 1.4 μm and 1.1 μm, respectively, and the imaging relation was confirmed. The efficiency was measured to be 40%. It is necessary for the pickup operation and was confirmed experimentally that the reflected light from the focal plane is coupled back into the waveguide through the FGC.
Analysis of switched capacitor power supplies using finite element method
Authors: Ueno Fumio , Inoue Takahiro , Iida Hitoshi , Oota Ichirou
Published: July 2007

A switched capacitor (SC) power supply with a low output power can be made highly efficient, small and lightweight. The finite element method is a numerical technique superior in adaptability and convergence; however, its application to electronic circuits is yet to be explored. In this paper, the finite element method is used as a time domain algorithm for transient and steady‐state analysis of a step‐down, low‐output SC power supply. In the case where the on‐resistances of P‐channel MOS switches and N‐channel MOS switches are not equal, such transient characteristics as the overshoot and rise time of the output voltage and such steady‐state characteristics as the steady output voltage, efficiency and ripple voltages are analyzed. It is found that the parasitic inductance of the wiring reduces the power supply efficiency. Although the results agree well with those by the Hamming method, the computation time is shorter in the finite element method. It is confirmed that the finite element method is efficient for analysis of the problem described by state equations.
Effect of doping carbon in an electromagnetic wave absorber rubber ferrite
Authors: Naito Yoshiyuki , Mizumoto Tetsuya
Published: July 2007

Ferrite, a ferromagnetic material in the form of sintered ferrite and rubber ferrite, is used for electromagnetic‐wave absorbers. However, there is a certain limit to reducing the thickness of the electromagnetic wave absorber using ferrite. For obtaining thin rubber‐ferrite electromagnetic‐wave absorbers, carbon is added to them and their electromagnetic‐wave absorbing characteristics are examined. The results show that the thickness can be reduced to about 30 percent by adding the order of 1 to 10 percent (volume ratio) of carbon to ferrite. The reduction of the thickness of the absorber also reduces its weight. The mixing of carbon is highly effective in reducing the weight of the absorber, since the specific gravity of carbon is smaller than ferrite. This paper presents the electromagnetic‐wave absorption characteristics of carbon‐added rubber ferrite.
Driving method for pnpn switch with dv/dt protection circuit
Authors: Suzuki Masayoshi , Sagawa Akio , Izaki Naoyuki , Kawakami Hideaki
Published: July 2007

A gate driving method is proposed for a pnpn switch with noise protection capability. In relation to a dv/dt protection circuit, on‐and‐off tests of the switch have been carried out so that the operative and inoperative regions due to switch potentials are determined. If the circuit of the driving current source is of a series‐control type, there is an inoperative (nonfiring) region of about 1 V in terms of cathode potential. In a parallel control‐type circuit, driving is possible in all regions because the currents overlap at the time of switching each gate. On the other hand, in the on‐and‐off switch experiment, it is confirmed that only the combination of a parallel control driving‐type circuit and of a dv/dt protection method by a diode can operate correctly regardless of the switch potential.
Analysis of the electromagnetic fields at the facets of optical fibers and dielectric rod antennas
Authors: Toyoda Ichihiko , Matsuhara Masanori , Kumagai Nobuaki
Published: July 2007

The electromagnetic fields at the facets of optical fibers were analyzed by using a three‐dimensional model, unlike a conventional slab waveguide which is a two‐dimensional model. A closed‐type waveguide model of an optical fiber was analyzed by using the eigenmode expansion method, since the radiation mode in an open‐type waveguide (such as an optical fiber) is difficult to treat and compute numerically. The radiation pattern at the facet was obtained by applying the stationary‐phase method to the electromagnetic field. The radiation pattern of the electromagnetic field of a dielectric rod antenna was also analyzed via the same method, since this is a pattern at the facet of a dielectric cylindrical waveguide. Numerical examples of the reflected and transmitted powers in various cases were shown.
A method for real‐time adaptive cancelling of power‐line noise by microprocessor
Authors: Kubo Hiroshi , Uematsu Hitoshi , Takemoto Akira , Nakagawa Takeshi
Published: July 2007

This paper describes a method of cancelling the periodic noise induced from the power‐line during measurement, using the LMS algorithm and the adaptive periodic noise canceller synchronized to the power‐line frequency. To simplify the analysis, a modelling is made whereby the signal is a random variable and the noise is periodic, containing fundamental and a large number of harmonic components with the power‐line frequency as the fundamental component. A parameter for evaluating the noise cancelling performance of the adaptive periodic noise canceller is derived analytically. It is shown that the processing can be performed without multiplication, without degrading the performance. Then a fast algorithm is proposed for adaptive periodic noise cancellation, which can reduce drastically the computational complexity, thereby degrading the performance little. By applying the algorithm, the realtime processing by a microprocessor is realized with a sampling rate of several kilohertz. Finally, a discussion is made of the effect of digital implementation on the performance, and it is shown that the cancellation of the power‐line interference by the fast algorithm is practically useful.
Frequency characteristics of CR double‐tuned amplifier circuits
Authors: Kurokawa Susumu , Kohno Tadashi , Ieyasu Kenzo
Published: July 2007

In the CR single‐tuned amplifier in general, it is difficult to realize high selectivity and high amplification when a high tuning frequency is specified. We succeeded in reducing the body effect by using a high‐frequency, field‐effect transistor as the reactance transistor and grounding the CR tuned circuit which is a load to the driving circuit. When a double‐tuned amplifier is constructed by cascading such a circuit in two stages, the frequency bandwidth can be enlarged. A stable amplifier was realized with the center frequency of 455 kHz and voltage gain of approximately 80 dB. This paper analyzes the frequency characteristics of such a CR double‐tuned amplifier circuit, deriving the formula for realizing the required double‐hump characteristics. When a single‐hump characteristic is composed by aligning the double‐tuned amplifier to the same tuning frequency, the selectivity is increased by approximately 55 percent compared with the characteristics of the singletuned amplifier, together with a considerable improvement in the roll‐off characteristics. An experimental circuit was constructed. The measurement of the frequency characteristics agreed well with the result of calculation. The double‐tuned amplifier circuit can be applied to the IF amplifier of the receiver.
An integrated‐optic disk pickup device
Authors: Ura Shogo , Suhara Toshiaki , Nishihara Hiroshi , Koyama Jiro
Published: July 2007

This paper describes the proposal, design and fabrication, as well as the experimental results of an optical disk pickup constructed with integrated‐optics using thin‐film waveguides. This integrated‐optic device is constructed with a focusing grating coupler, a guided‐wave beam splitter and a photodiode array on an Si substrate which is coupled to a semiconductor laser. The focusing grating coupler and the guided‐wave beam splitter were fabricated by the electron beam direct writing method. The focus spot width of the fabricated device was measured to be close to the diffraction limited value, and the reflected light was detected as photocurrents of the photodiodes. It was confirmed that the device has a capability of detecting focusing/tracking errors.
Architecture of fiber optic broadband interactive distribution system
Authors: Yamagata Jun , Takemoto Kenji , Okada Kenji
Published: July 2007

The ideal situation in constructing a broadband communication network is that all kinds of services are provided by a single network. Such a structure is not necessarily advantageous at the present state of technology. From such a viewpoint, the best approach would be first to construct an economically‐optimum system, mostly considering the CE type broadband distribution service, which is estimated to have the highest demand, and gradually extend the network for other services. This paper first describes that the configuration combining the star‐type subscriber link and the tree‐type trunk lines is economical and has the functional expandability. Next another configuration is considered, in which the optical fiber is used for the subscriber link and the frequency division switch is used for the channel selections in the conversion of network topology. It is shown that the system is the optimum from the viewpoint of the cost per subscriber. By applying the notion of the cross‐contact switch, it is shown that the proposed system can be extended to the CE type video retrieval service and EE type transmission service. The optical distribution system will be utilized effectively in the future new media, providing the basis for the broadband communication network.
Analysis of the electro–optic polarizer having parallel electrodes on the same surface
Authors: Fujii Katunori , Iida Yoshinao
Published: July 2007

Electro‐optic effect elements have attracted special interest recently and these generally have parallel electrodes on the same surface. Therefore, the electric field is not uniform and has complicated distribution. Moreover, knowledge of the electric field distribution is important to the element design, and the authors analyzed the case of the interdigital electrodes. However, the analysis of the electric field of the parallel electrodes was not investigated satisfactorily.

This paper analyzes the electric field of the parallel electrodes for many varieties of electrode dimensions and the element thickness with the conformal representation. Moreover, the character of the electro‐optic polarizer having the parallel electrodes is discussed. The analysis result has clarified the relations between the electrode dimension: i.e., the element thickness and the half‐wave voltage. Further, the results are clarified as follows. For the first electro‐optic effect, the transmitting light is generally uniform between the electrodes (about 95% electrode distance). However, for the second electro‐optic effect, the uniform transmitting light can be obtained when the thickness of the element is about 0.2 × D −0.25 × D, where D is the distance between the outside electrodes.
Effect of the Si‐SiO2 interface state density and the charge in the SiO2 film on the electrical properties in Pt–diffused MOS structure
Authors: Kato Hideo , Shibata Yasuo , Kuwano Hiroshi
Published: July 2007

The effect of Pt‐diffusion on the electrical properties in the Pt‐diffused MOS structure has been investigated. In these structures, the Pt‐diffusion ambient has a direct effect on the electrical properties;, the samples which were Pt‐diffused in oxygen ambient show a large positive flatband voltage shift, and those which were Pt‐diffused in nitrogen ambient show little flatband voltage shift but have a memory effect. We measured the dependence of flatband voltage on the oxide thickness and evaluated the distribution of the Si‐SiO2 interface state density. We also measured the oxide charge density. From these experimental results, we show that the large shift of the flatband voltage is caused mainly by the charges generated within the oxide film and that the Si‐SiO2 interface state density distribution varies reversibly according to the memory effect.
Numerical analysis of silicon–clad planar optical waveguides
Authors: Kumagami Hiroshi , Koshiba Masanori , Suzuki Michio
Published: July 2007

The results of the numerical calculations related to the propagation characteristics of silicon‐clad planar optical waveguides are presented. The finite‐element method is used for the calculations. First, the propagation characteristics of TE modes in waveguides of silicon layer/dielectric core/homogeneous dielectric substrate are investigated. The results are compared with those of the exact solution to confirm the correctness of the present method. In this case, the phase and attenuation constants both oscillate periodically with the silicon thickness. Then, the TM modes are analyzed and it is indicated that the propagation constants are different from those of the TE modes and that propagation constants do not necessarily oscillate periodically with the silicon thickness. Whether or not the oscillations are present depends on the refractive‐index difference between the dielectric core and the silicon layer. Next, to reduce the propagation losses of the silicon‐clad planar optical waveguides with interesting characteristics, the new structures of silicon layer/inhomogeneous dielectric substrate or silicon layer/dielectric buffer layer/ inhomogeneous dielectric substrate, are proposed. It is shown that the propagation losses of these silicon‐clad planar optical waveguides expressed in decibels, are reduced by one order of magnitude compared with the previous planar waveguides.