bluuebunny/crossref_metadata_2025 huggingface dataset:
Design of a low‐power universal literal circuit
Authors: Tsuhako Shin‐Ichiro , Afuso Chushin , Zukeran Chotei
Published: July 2007

In the universal literal circuit (ULC) previously proposed, since the two threshold values of the literal circuit are variable by external control signals, four‐valued logic circuits have attracted considerable attention. However, to realize LSI, there was room for improvement from the viewpoint of power consumption.

In this paper, as a literal, with the other characteristics remaining the same, a new low‐power ULC circuit with power consumption decreased by 1/285 is proposed. Also, the threshold voltage variation due to the body‐effect of MOS transistors, having a critical influence on the level discrimination characteristics of the circuit, is solved by introducing body‐effect compensating transistors. Moreover, by SPICE simulation, it is verified that the low‐power ULC works satisfactorily.
Electro‐optic effect of phase‐transition liquid crystals separated by polymer network
Authors: Fujikake Hideo , Takizawa Kuniharu , Kikuchi Hiroshi
Published: July 2007

A new light‐scattering liquid crystal device of chiral nematic liquid crystal dispersed in three‐dimensional polymer network is proposed. The liquid‐crystal device has been fabricated, and its fundamental electrooptic properties have been examined. Each cholesteric domain of focal conic texture, whose helical axis orients randomly but is fixed by a polymer wall, exhibits phase transition to nematic phase by an applied voltage. Therefore, the device has a high‐speed response (less than 500 μ ms) and high contrast ratio (100 : 1). Also, the device can perform as a stable gray‐scale memory because of its multidomain structure. It has an advantage of self‐supported structure, ease of fabrication of a large‐size device, and no requirement of sealing gap; thus, it is applicable for a full‐color projection display and a high‐speed, large‐area light shutter.
Evaluation of surface structure of cadmium arachidate langmuir‐blodgett films with atomic force microscope
Authors: Shibata Miki , Kataoka Akio , Okada Hiroyuki , Onnagawa Hiroyoshi , Miyashita Kazuo
Published: July 2007

In this paper, an atomic force microscope (AFM) observation is attempted for the surface structure of the cadmium arachidate Langmuir‐Blodgett (LB) film. The measurement region is on the order of micrometers and the vertical resolution is on the order of nanometers for the deposited film surface of one to five layers. Different surface structures were observed in the LB films with the hydrophobic tail at the surface and those with the hydrophilic head at the surface. The LB films with the hydrophobic tail at the surface are stable. The molecular area derived from the molecular image of the AFM was identical to 0.2 nm2 estimated from the μ‐A curve even if the deposition ratio is 0.7 to 0.8. There was no correlation between the surface orientation direction and the dipping direction.

The LB film with the hydrophilic head at the surface has an unstable layered structure. Although the surface structure immediately after deposition is a flat layer of monomolecular films, it changes easily to a step structure associated with the bilayer structure of cadmium arachidate. This structure is considered to be caused by local peeling off of the film molecules deposited on the substrate and deposition to the surface with the hydrophilic head. The structural change observed by the AFM was in good agreement with the one due to the overturning model proposed by Honig.
Optical odor sensors using potential‐sensitive dye coatings
Authors: Yamakawa Shinzo
Published: July 2007

There have been many reports on odor recognition sensors based on multichannel semiconductor gas sensors but few on odor recognition using an optical fiber sensor.

Using a fiber‐optic sensor array with potential‐sensitive dye coatings, this paper investigates a sensing system to recognize odor by an optical spectral pattern. The edges of a fiber were coated with films consisting of potential‐sensitive dyes and silicone resin to form a transmission‐type fiber‐optic sensor. When these sensors are exposed to organic vapor odorants, the absorption spectra of the dyes changed, depending on the differences of odorants, indicating that this type of sensor array can be used as an odor‐recognition sensor.

Selecting six dyes from 16 dyes, a six‐channel optical fiber sensor array was fabricated. The changes of absorption spectra of dyes were measured and data were processed by a computer. Response patterns to organic vapors were measured and it was confirmed that pattern recognition could be achieved.
GaAs‐pin/ferroelectric liquid crystal spatial light modulator (GaAs‐pin/FLC‐SLM) and its applications
Authors: Hashimoto Masashi , Kitayama Ken‐Ichi , Ishibashi Shigeki , Fukuda Yukio
Published: July 2007

A spatial light modulator GaAs‐pin/ferroelectric liquid crystal spatial light modulator (GaAs‐pin/FLC‐SLM) was developed in which a GaAs photodiode is used as a photodetector, and a ferroelectric liquid crystal is used as a modulator. In the present device, write‐in with visible light and a transmission‐type readout at infrared are possible. Other characteristics of this device include a high‐speed operation due to the use of a ferroelectric liquid‐crystal and no need for erasing light due to the use of a pin diode.

In this paper, the configuration of the SLM is presented and the operating principle is explained by means of an operation model. Next, experimental examples as a switching device are described. Also, several examples of the system applications are presented.

The first example is a self‐routing crossbar switch. In this switch, the 1.3‐μm signal light is switched by providing a header at a different wavelength to a connected output port. the present SLM is used as an optical switch section. the experimental results of the present switch with 2 × 2 ports are reported.

The second example of the system application is an optical parallel processor which is based on the accumulative threshold characteristic of the present SLM. By means of this characteristic, logic operation is possible for time series parallel optical signals. It is presented that the sequential operation system can be constructed in a much simpler configuration. the experimental results for configuration of the principle are added.
A waveguide bandpass filter made of high‐permittivity ceramics
Authors: Dong Ying , Kubo Hiroshi , Hano Mitsuo , Awai Ikuo
Published: July 2007

A rectangular waveguide was formed with ceramics having a high relative permittivity of 93. This waveguide is divided into two in the E‐plane. This structure was used for the design and fabrication of a bandpass filter of small size and light weight which can be surface mounted. Inductive strips are formed on the E‐plane so that the center frequency of the one‐half wavelength resonator and the coupling coefficient between the resonators are adjusted. Further, by choosing a structure in which the filter is connected directly from a microstrip line, the structure is miniaturized.

In the design, first the dimension dependence of the characteristic values of the composite resonators, e.g., the center frequency and the coupling coefficient, was found experimentally. Then a general filter theory was applied. Further, the characteristic values of the resonator were studied theoretically so that the dimension dependence can be explained qualitatively.
Fabrication and characterization of superconducting weak links with InAs/(AlGa)SB heterostructure
Authors: Maemoto Toshihiko , Yoh Kanji , Inoue Masataka
Published: July 2007

A superconducting weak link device using InAs/(AlGa)Sb heterostructure has been fabricated, and its electrical property has been characterized for applications to high‐performance superconducting transistors. the semiconductor layers consist of InAs/(AlGa)Sb heterostructure with high mobility and high electron density; the superconducting electrodes consist of Pb alloy superconducting thin films.

InAs/(AlGa)Sb heterostructure was grown by molecular beam epitaxy. the superconducting electrodes were formed by thermal evaporation, and the superconducting weak link device was fabricated using a lift‐off process and wet etching.

The film thickness of the InAs quantum well layer was 150 Å, and the thickness of the lead alloy superconducting thin film was 2000 Å. the current density and linear current density at 4.2 K for the device length of 0.3 μm were 3 × 104 − 105 A/cm2 and 4.5 − 15 mA/mm, respectively, and the IcRn product was estimated to be ∼2 mV. Therefore, the current density and IcRn product in superconducting weak link devices using InAs/(AlGa)Sb heterostructure were estimated to be sufficiently large and its potential for superconducting devices has been confirmed.
Fabrication and electrical characterization of InGaAs MISFET using ultrathin Si interface control layer
Authors: Xie Yong‐Gui , Suzuki Satoshi , Sawada Takayuki , Hasegawa Hideki
Published: July 2007

A recess gate depletion‐type InGaAs MISFET has been fabricated by using a thick photo‐CVD SiO2 outer layer and on ultrathin MBE Si interface control layer (Si ICL) after HF treatment of air‐exposed InGaAs surface treated by HF. After optimum annealing of the MISFET at 350°C in hydrogen atmosphere for 1 hr, a significant increase of the transconductance was obtained and with a very stable drain current. Maximum effective mobility of 3850 cm2/V.s and a transconductance of 61 mS/mm for a gate length 6 μm were achieved.

Based on the observed dependence of gate length on the transconductance, it is found that transconductance as much as 250 mS/mm can be expected for 1 μm gate length even after considering the velocity saturation effect. A drain current drift was controlled below 5 percent after 104 s after a gate step voltage was applied.

The performance obtained in the present study is comparable to that of photo‐CVD SiO2/Si ICL/InGaAs MISFET fabricated in an in‐line process in ultrahigh vacuum. the result clearly demonstrates that an HF treatment of air‐exposed InGaAs surface is useful for a MISFET device process.
Electrical properties of crystallized semiinsulating polycrystalline silicon films
Authors: Cho Wonju , Takeuchi Yuji , Kuwano Hiroshi
Published: July 2007

The electrical characteristics of the crystallized semiinsulating polycrystalline silicon (SIPOS) film were studied, and its electrical conduction was investigated. It is found that the electrical characteristics of the SIPOS film can be explained by the thermionic emission mechanism. Since the oxygen concentration in the film is higher, the band gap is wider and the resistivity and activation energy are increased. By considering the segregation effect of phosphorus, the surface density of grain boundary traps of the crystallized SIPOS film was derived and the relationship was clarified between the oxygen concentration and the surface density of traps. As the oxygen concentration is increased, the surface density of traps increases. the electrical characteristics of the SIPOS film can be explained better if a Gaussian distribution rather than a single level is assumed for the energy of the grain boundary trap.
Some characteristics of switching contacts riveted on the tips of both supporting arms arranged partially in parallel
Authors: Kubono Takayoshi , Mogami Masahiko
Published: July 2007

To a relay with supporting arms in which only the tips with electrical contacts are parallel, AgCdO electrical contacts with Au flash are installed as a normally open contact pair. Within the circuit with dc 30 V ‐ 10 A and a resistive load, it is used as the make‐only, the break‐only, and the make‐and‐break contact pair. the electrical characteristics at each make and break and the contact surface damage after 100 thousand operations were measured.

In the sample electrical contact pair with the tips of supporting arms in parallel, it is demonstrated by experiments that arc damages (roughness and black and brown contaminant) occur at the center of the contact surface.

The arc trace at the make‐only electrical contact is the narrowest in comparison with two other switching operations and is a milky metallic color surface with many infinitesimal irregularities. In the case of the break‐only and make‐and‐break contacts, large irregularities exist at the center of one of the electrode surfaces. A thick black and brown contaminant exists in this part and surroundings. Also, contact sticking occurred in all samples of make‐only contacts but not in the break‐only contacts.

The black and brown contaminant between the contact surfaces prevents locking and increases the contact resistance and the variation width so that they cause a longer duration in the breaking arc.
Realization of current‐mode biquadratic filter using CC IIs with current followers
Authors: Ikeda Katsuji , Tomita Yasushi
Published: July 2007

This paper proposes the circuit configuration of a current‐mode biquadratic filter which uses a pair of four‐terminal active‐current conveyors (CFCC II) consisting of a current follower attached to a second‐generation current conveyor (CC II). the circuit is composed of one current adder and two current integrators. This configuration is capable of synthesizing arbitrary current‐mode second‐order transfer functions by changing the conditions (grounding or connecting) at the output terminals of the CFCC IIs.

Each of the proposed filters has high output impedance so they can be cascaded directly. Moreover, ω0 and Q0 is determined from the ratio of passive elements, and the element sensitivity is even lower than 0.5. Since all the passive elements are grounded, this configuration is very advantageous to IC fabrication. Again, the effect of imperfection of CFCC II on the transfer function is studied and it is found that ω0 is influenced by the current conversion factor of CFCC II and Q0 is affected by the imperfection of the integrator. Moreover, it is shown that the operating frequency limits of the filter are determined by the permissible change of Q0. Each type of filter actually is synthesized, and the useful operation is confirmed by experiments.
Numerical method for calculating surface current density on three‐dimensional smooth scatterers
Authors: Ikuno Hiroyoshi , Gondo Michizo , Nishimoto Masahiko
Published: July 2007

This paper shows that the surface current density can be calculated by using approximate total tangent magnetic vector fields which are expressed by finite number of linear combination of tangent vectors of spherical wave functions. Sampling points are determined by considering the property of associated Legendre functions and trigonometrical functions. By setting a number of sampling points to twice the largest mode number, a computer‐aided algorithm is obtained. the accuracy of the solutions is checked and the polarization dependence of the surface current densities is clarified.
Coupling efficiency of two anisotropic single‐mode slab waveguides butt‐joined via a gap
Authors: Sawa Shinnosuke , Masuchi Toshio
Published: July 2007

The fundamental characteristics of the coupling efficiency between two anisotropic slab waveguides with different configurations butt‐joined via a gap are analyzed in the case of a TM mode incidence by means of a single‐mode slab waveguide model made of equatorial dielectric tensor. the electromagnetic field in the gap is represented by a combination of the forward elementary plane wave propagating from the incident side to the output waveguide and the backward elementary plane wave propagating in the opposite direction.

By applying the boundary conditions, the power transmission and reflection coefficients in the guided‐wave system are computed. Further, the effects of the lateral misalignment and inclination between the wave‐guides and the index of refraction and spacing of the gap on the coupling efficiency are studied based on the numerical results. an optimum condition to maximize the coupling efficiency is obtained.
A study of high‐temperature superconducting field‐effect transistors
Authors: Kobayashi Takeshi
Published: July 2007

The MIS field effect has been confirmed in superconductors by effectively using a low carrier density in oxide high‐temperature superconductors. Based on this principle, a superconductor field effect transistor has been created. the experimental device uses an MIS diode and MISFET with Au/(100)SrTiO3/(001)YBaCuO structure grown by selective heteroepitaxy. the drain current could be decreased and increased by positive and negative gate fields. When cooled below the critical temperature, both the superconducting critical current and the flux‐flow resistance were modulated by the gate field. By approximating the high temperature superconductor with a degenerate semiconductor band model and introducing the Bardeen‐Stephen magnetic flux resistance and the flux‐creep concept, the operation mechanism of the superconductor MISFET can be explained.
A 5‐ns 32 K ×8/×9 bi‐CMOS TTL SRAM with alternated bit line load architecture
Authors: Ohbayashi Shigeki , Shiomi Toru , Matsuo Ryuichi , Sumi Tadashi , Honda Hiroki , Ishigaki Yoshiyuki , Uga Kimiharu , Ishida Masahiro , Kohno Yoshio
Published: July 2007

An ultrahigh‐speed 32 K ×8/×9 TTL bi‐CMOS SRAM with a 5‐ns standard access time was developed using a five‐layer polysilicon/two‐layer aluminum 0.6‐μm bi‐CMOS process with 4.2 × 5.6‐μm24‐M SRAM‐class small‐size memory cells, ultrahigh capacity, self‐aligned bipolar electrodes with 18.5‐GHz cutoff frequency and 0.6‐μm/0.7‐μm (nMOS/pMOS) gate‐length MOS transistors. This fast access time was achieved by using center power pin‐out to reduce output noise, a major problem in the TTL SRAM, together with alternated bit line load architecture, a memory array architecture well suited to center power pin‐out. Also used were a bit‐line load circuit for rapid precharging of the bit line and a high‐speed wired‐OR column‐sensing circuit.
Simulation for the current density distribution in a contact spot
Authors: Minowa Isao , Nakamura Mitsunobu
Published: July 2007

Contact components have been used widely for switches, relays, and connectors. Although they have a simple structure, they are very reliable, having low resistance at on‐time and high resistance at off‐time, and are relatively immune against external noise. As a result, there has been a constant increase in demand for such components. However, because the contact surface may get contaminated, oxidized, or damaged over a long period of time or just through many cycles of usage, they may fail in conduction. Thus, very little information is available as to the relation between the surface state and the conductive phenomenon.

The electric conductivity has been studied in conjunction with the surface state using a finite element method. A current density distribution inside a contact spot was calculated. As a result, when the resistivity of the contact spot is small, the current was found not to distribute uniformly throughout the spot area but increases at the corners of the spot when the spot shape is square. This means that the electric conductivity is proportional to the circumference length of the spot. On the other hand, as the resistivity of the spot increases, the current density at corners and circumferential regions decreases gradually and finally becomes uniform in its distribution over the entire spot region. In this case, the electric conductivity is shown schematically and quantitatively to be proportional to the area.
Fabrication of NB‐based Josephson junctions using low‐energy ion beam cleaning
Authors: Usami Koichi , Park Chan Hun , Moriya Masataka , Kobayashi Tadayuki , Goto Toshinari , Matsui Seiichi
Published: July 2007

Tunneling junction Josephson devices with an Nb/NbOx/Pb structure were fabricated using Nb‐based superconducting films deposited by the biased‐sputtering method. Prior to forming the junction, 100 to 400 eV low‐energy Ar ion beam cleaning was employed instead of RF sputter‐cleaning which has conventionally been used.

An etching condition suitable for cleaning the junction was obtained experimentally by evaluating the relationship between the gap parameters obtained from the I—V characteristic and etching energy. It was found that since energy control was easy in ion beam cleaning, the etching could be carried out under optimum conditions. Also, when ion beam cleaning was used, the increase in the gap voltage and the current spikes in the I—V characteristic were much less than when RF sputtercleaning was used. Using ion‐beam etching under controlled energy, the junction could be cleaned with minimum damage, resulting in the improvement of the Josephson device properties.
Analysis of dynamic behavior of an open‐boundary Čcerenkov laser
Authors: Horinouchi Katsuhiko , Shiozawa Toshiyuki
Published: July 2007

On the basis of the energy conservation relation between an electromagnetic wave and electron beam, the dynamic behavior of an open‐boundary Čerenkov laser is analyzed theoretically. Specifically, the power growth for the electromagnetic waves, the decrease in the beam drift velocity and its effect due to the growth of the electromagnetic wave, and the improvement in the growth characteristics by varying the permittivity of the dielectric constituting the waveguide are examined. First, it is shown that, since the growth of an electromagnetic wave causes the drift velocity of the electron beam to decrease and keeps the beam and wave out of the synchronism, the spatial growth rate at the frequency initially set decreases gradually and the growth of the electromagnetic power is prevented.

Next, to keep the synchronism of the electron beam and electromagnetic wave, the permittivity of the dielectric waveguide can be increased gradually in the direction of wave propagation in accordance with the decrease in the beam drift velocity. This is shown to suppress the decrease in the spatial growth rate due to the decrease in the beam drift velocity and to improve the growth characteristics of the electromagnetic wave.
Magnetoelastic waves in yttrium iron garnet film
Authors: Yukawa Toshinobu , Tsutsumi Makoto
Published: July 2007

The principle of the method for excitation of magnetoelastic waves by a nonuniform magnetic field is described. In addition, the distribution of the nonuniform magnetic field appearing in the thin film by the demagnetization effect is obtained. Next, by using a yttrium iron garnet (YIG) thin film with a thickness of 100 μm and 5 × 15 mm2, an experiment of the magnetoelastic wave was carrid out at 3.5 GHz. the experimental results including the delay characteristics of the magnetoelastic wave have been compared with theoretical results. Also, the loss characteristics are studied experimentally from the viewpoint of dependence on the crystal axis. the minimum value of the loss of the magnetoelastic wave is 50 dB and the loss per delay of 1 μs is 30 dB when the crystal axes are oriented in 〈112〈.
Method of designing high‐efficiency UHF‐band monolithic multistage FET amplifier using harmonic terminating technique
Authors: Takagi Tadashi , Ikeda Yukio , Hashimoto Tsutomu , Nakajima Yasuharu
Published: July 2007

A design method is described for a high‐efficiency FET amplifier. First, a method is proposed to derive an optimum load impedance for the second harmonic and the fundamental waves by means of the second harmonic injection load‐pull method and the fundamental wave load‐pull method. Then, to realize the resulting load impedance, a small harmonic terminating circuit is studied which consists of a short phase‐adjustment transmission line and a second harmonic parallel resonant circuit made of lumped elements. Also, a method is shown for determining the FET gate width for each stage to maximize the efficiency of the multistage amplifier including the driver stages. the UHF monolithic four‐stage FET amplifier fabricated using this design method has exhibited a saturated output power of 31 dBm and a maximum drain efficiency of 63 percent.
New compact bandpass filters using λgo/4 coplanar waveguide resonitors and a method for suppessing these spurious responses
Authors: Noguchi Yasumasa , Ishii Junya
Published: July 2007

The bandpass filters installed in digital mobile communication equipment are required to have characteristics with low spurious responses over the broadband. In this paper, a bandpass filter with low spurious response based on a coplanar waveguide resonator (CPW‐BPF) is proposed which can be applied for MIC and MMIC and its characteristics are discussed. the suppression of the spurious responses is accomplished in this paper by the following method.

First, a coplanar waveguide resonator filter is realized. Next, the resonator length is reduced to less than one‐twentieth of the wavelength at the center frequency. Finally, lumped capacitors are added to these reduced resonators in parallel and after that adjusted so that the desired bandpass characteristics are realized. This reduced CPW resonator can be considered approximately as an “L” near the center frequency of the passband. Therefore, by adding in parallel a capacitor, an “LC” resonator can be formed. As the result, the spurious responses concerning the resonant frequency are suppressed.

The three‐stage CPW‐BPF fabricated by the proposed method has the center frequency of 1.0 GHz in the passband and a bandwidth of 100 MHz and can suppress the spurious responses to −40 dB up to 7.5 GHz and to −30 dB up to 12.0 GHz.
Measurements of dielectric constants and surface resistance for millimeter and submillimeter wavelength region using Josephson effect
Authors: Kawakami Akira , Wang Zhen , Komiyama Bokuji
Published: July 2007

Josephson junctions with microstrip resonators fabricated. By observing the current steps caused by the mutual interaction between the high‐frequency current due to the ac Josephson effect and resonator, the dielectric constants of the dielectric thin films (a‐Si, SiO, and SiO2) and surface resistance of an Nb thin film at 4.2 K in the millimeter and submillimeter wavelength region were evaluated. As a result, it was found that this method was effective in determining the dielectric constant and surface resistance.

In the device used, a Josephson junction was placed at the center of the microstrip resonator. the resonator length was varied from 217 to 2740 μm, the measurements were carried out at a frequency ranging from about 30 to 310 GHz, while the device was biased with dc voltage. the relative dielectric constants of the materials were rather independent of the frequency, where Ωa‐Si = 14.5 ± 0.5, ϵSiO 5.5 ± 0.4, and ϵSiO2 = 4.4 ± 0.4. the surface resistances of the Nb thin films were 1 to 6 mω when the frequencies were 70 to 180 GHz.
Optimization of via‐hole shape using quasi‐3‐D topograpy simulation
Authors: Abe Tetsuya , Tazawa Satoshi , Saito Kazuyuki
Published: July 2007

Deposition and etching rates exhibit localized change in via‐holes because the incoming particles are shielded in three‐dimensional (3‐D) topography (shadowing effect). to investigate this problem, quasi‐3‐D topography simulation is applied, approximating the shape of the via‐holes in LSI using rectangular or elliptical functions. In this simulation, parameter fitting is carried out easily using the results obtained in actual processes. By this three‐step method, the fabrication of via‐holes for electrical contact is optimized.

The parameters for the etching processes applied to form a via‐hole and those for the metal deposition rate after etching were extracted without affecting each other. Then the cross‐sectional profile of a via‐hole is determined to ascertain which is the thickest deposited metal film. Finally, the etching condition under which a hole is formed with the profile described in the foregoing is investigated. This method is examined in the sputterdeposition of metal, showing that a via‐hole having a vertical wall in the upper section and a tapered wall in the bottom area is the most suitable for good metal depo sition.

When the via‐hole is formed by reactive ion etching of an insulating film, a via‐hole having the profile described in the foregoing can be formed by varying the etching rates of the photoresist and insulating film three times.
Highly efficient UHF‐band Si power MOSFET for RF power amplifiers
Authors: Yoshida Isao , Katsueda Mineo , Ohtaka Shigeo , Maruyama Yasuo , Okabe Takeaki
Published: July 2007

A low‐voltage/high‐efficiency Si power MOSFET has been developed for power amplifiers in mobile wire less telephone. Using submicrometer metal gate and self‐aligned drain contact structures, the on‐voltage and the output capacitance were reduced and the cutoff frequency was increased. As a result, compared with the conven tional device, the power‐added efficiency was increased by 10 percent. the power‐added efficiency was 60 percent at 1.5 GHz when the output power was 1 W.

With 50‐kHz offset in digital modulation, leakage power between adjacent channels of 50 dBc, and output power of 0.8 W, the power‐added efficiency was 53 percent.

It was confirmed that the Si MOSFET had an excellent linear power amplification characteristic in the ultrahigh‐frequency (UHF) band.
A direct conversion receiver employing a frequency multiplied digital phase‐shifting demodulator
Authors: Hasegawa Makoto , Mimura Masahiro , Takahashi Kazuaki , Makimoto Mitsuo
Published: July 2007

Radio data receiver systems are being made smaller with lower power consumption and higher performance. Integrated circuits (IC) can be fitted into a direct conver sion receiver, but this has not yet been found practical because it is difficult to ensure the performance. A novel architecture is proposed for the wideband frequency shift‐keying (FSK) quadrature demodulator, which is called the frequency multiplied digital phase‐shifting demodulator; and it has been used in a receiver. This demodulator has been adopted as an IC for low bit rate FSK radio equipment such as paging receivers, it is confirmed that the direct conversion receiver has the required sensitivity, distortion, and power consumption; and its usefulness is demonstrated.
A surface‐mountable ceramic 3‐dB directional coupler
Authors: Takasugi Atsunori , Kitoh Ryozo , Awai Ikuo , Hano Mitsuo
Published: July 2007

In the lossless symmetric reciprocal four port represented by the directional coupler, it is possible to cal culate an invariant from the measured results of thesparameters. As a result, an integrated directional coupler was fabricated with high‐permittivity ceramic waveguide (DEW: dielectric E‐plane waveguide) and a coupling of 3 dB was obtained.
Finite‐element analysis of two‐dimensional chirowaveguides
Authors: Maruyama Shinji , Koshiba Masanori
Published: July 2007

The finite element formulation for three‐dimensional (3‐D) chirowaveguides cannot be applied to 2‐D ones because all components of the electromagnetic field in chiral media, even if a 2‐D system is considered, are coupled. In this paper, the finite element formulation is described for the analysis of 2‐D chirowaveguides. to show the validity of the present formulation, numerical results are shown for homogeneous chirowaveguides and are compared with exact solutions. Furthermore, to demonstrate the applicability of the present approach, chirowaveguides with graded chirality admittance profiles are investigated.
Gain characteristics of Pr3+‐doped fluoride fiber amplifier
Authors: Yamada Makoto , Shimizu Makoto , Ohishi Yasutake , Kanamori Terutoki , Sudo Shouichi , Temmyo Jiro
Published: July 2007

Using the high‐efficiency Pr3+‐daped fluoride fiber and the high‐output LD module and an optimization of amplifer setup, a high‐gain LD pumped Pr3+‐doped fluoride fiber amplifier is developed. the noise characteristics and the temperature dependence are studied in detail and the following results are obtained.

the noise figure of the Pr3+‐doped fluoride fiber amplifier is 3.4 dB. However, the noise figure increases with the signal wavelength in the region of signal wavelength larger than 1.3 μm due to the effect of the base level absorption and signal light‐excited absorption.

the temperature dependence of the amplifier characteristics is caused by the change of luminescence life of1G4by the change of nonradiating transition probability from1G4level to3F4level. As the fiber temperature is reduced, the signal gain increases monotonically while the noise figure decreases at a signal wavelength over 1.31 μm and the saturation output decreases.
Optical power monitor for two‐beam laser diodes using electric operational circuits
Authors: Shinoda Masahisa , Satoh Yasuyuki , Karaki Morihiro , Kime Kenjiro , Ishii Mitsuo
Published: July 2007

This paper presents a method for monitoring individual laser beams from an array‐type, two‐beam laser diode with two emission points in one laser chip using an electric operational circuit. the characteristics of the two‐beam monitoring system are evaluated by experiment. This system analytically monitors optical output powers on the principle that the two laser beams are received at different ratios by a photodiode having two detecting surfaces located near the laser facet. the main feature of the system is the possibility of signal separation using a simple circuit configuration and adjustmentfree arrangement of the photodiode.

Evaluation of a trial two‐beam monitoring circuit has revealed that a gain deterioration of 3 dB is exhibited at 1 MHz. Crosstalk, which represents the degree of signal separation, depends on frequency and is ‐54 dB at 10 kHz and ‐23 dB at 1 MHz, exhibiting excellent separation characteristics. These results can be used without problems in optical disk drives incorporating two‐beam laser diodes. Thus, they demonstrate the effectiveness and practicality of the proposed system.
A new method for measuring absorption losses in an infrared optical fiber
Authors: Ishiwatari Hiromasa
Published: July 2007

Pressure‐extruded infrared optical fiber is a polycrystalline structure with grain sizes of 30 to 70 μm, and it exhibits a large amount of attenuation. the attenuation due to scattering is more than one‐half the total attenuation and is induced by the residual strain, surface roughness, and grain boundary defects. In the investigation of loss mechanisms, it is indispensable to measure separately the different losses such as absorption loss and scattering loss. Since the scattering loss can be measured by an integrating sphere sliding along the fiber axis, the absorption loss is obtained by the subtraction of the scattering loss from the total loss.

This paper proposes a new method for directly measuring the absorption loss, and experiments using this method were carried out. the method is based on the thermal expansion associated with temperature rise due to the absorption. It is shown that the absorption loss can be evaluated by measuring the time response of the elongation of the fiber in which the laser power is absorbed. In addition a new measuring method for the heat transfer coefficient of the fiber also is proposed.

Using these methods, the absorption and scattering losses of KRS‐5 optical fiber were measured. the results indicate that the scattering loss is about 1.5 times larger than the absorption loss.
Influence of optical rotary power on optical voltage sensor using BGO crystal
Authors: Ohtsuka Masao , Shimomura Teruo
Published: July 2007

Bismuth germanium oxide (Bi12GeO20) is an optical rotary power (ORP) crystal; and, when used in longitudinal voltage sensors, its performance is influenced by such rotary‐power performance. That is, as the ORP angle Φ is increased, the sensor sensitivity |m| is decreased. Here, the relation between ORP angle Φ and sensitivity |m| of the longitudinal voltage sensor is investigated and the corresponding equation is derived. Further, by changing the crystal thickness. the ORP angle Φ is varied between 20 and 80 degrees and the measured sensitivities of the voltage sensor are compared against the calculated results. it is found that agreement is quite good between the calculated results based on the derived equation and the measured data.

with the existence of ORP, the method of suppressing its degrading effects upon the sensitivity is devised and the effectiveness of the method is verified experimentally. Finally, based on the results of the present investigations, the conditions for direct vectorial addition of the measured quantities via the optical sensor are determined and the voltage relative to the ground of the three‐phase circuits are processed optically as the addition of three vectors. As a result, it is verified experimentally that the zero‐sequence voltage can be measured with high accuracy.
Bonding mechanism between Sn‐Sb solder and evaporated multilayers
Authors: Kurihara Yasutoshi , Saito Ryuichi
Published: July 2007

This paper discusses the behavior of metal and the bonding mechanism at the interface between Sn‐Sb solder and an evaporated Al‐Cr‐Ni‐Ag multilayer used for bonding a silicon chip to a substrate. As the treatment temperature increases, alloying among Ag, Ni, and Cr and diffusion of Al toward the metal surface are accelerated. the multilayer is composed of a mixture of the forementioned metals. When soldering is carried out, Ag and Ni disappear from the interface and the solder has direct contact with the Cr layer. Even in this case, the adhesion is still secure.

After soldering, the Cr layer at the interface contains metals in the multilayer and solder compositions and the Sb‐based intermetallic compound is formed at the interface. the adhesion force between the Sn‐Sb solder and Cr layer is determined by the diffusion of metals to the Cr layer and the formation of the intermetallic compound.
Novel recording method employing direct ink heating: Thermal rheography
Authors: Yamaguchi Hiroyuki , Matsuki Makoto , Saitoh Takashi
Published: July 2007

A new heat‐aided recording method, thermal rheography, which employs no ink film is proposed. With this method, a paste ink is directly heated and melted through a porous thermal‐print head, upon which it passes through holes engraved in the heating elements. Since the recording process uses no ink film, the operational cost is low and the need for a film‐feed mechanism is eliminated.

To realize this method: 1) the relation between paste ink composition and recording characteristics; and 2) the construction of porous thermal‐printing‐head are investigated. the method can attain according density 1.0 with energy 30 mI/mm2, compatible with G3 thermalsensitive paper recording.
Synthesis, properties, and molecular structure analysis of Sio2 thin films prepared by Sol‐Gel method
Authors: Maekawa Sachiko , Okude Kojiro , Ohishi Tomoji
Published: July 2007

SiO2 thin films were prepared by the sol‐gel method. the properties of the films such as film thickness, etching rate in hydrofluoric acid, Vicker's hardness, and the effect of the thermal treatment on the molecular structure were investigated. As a result, it was found that the etching resistance and hardness were improved as the treatment temperature increased. These changes in the properties were related to the density and water content in the film.

The molecular structure analysis by the 29Si solid‐state NMR and Raman spectroscopy revealed that the unstable distorted Si‐O‐Si bonds formed in the solution were broken and stable straight Si‐O‐Si bonds were formed during the high‐temperature treatment. As the number of the stable Si‐O‐Si bonds increases, the hardness and density of the films increases.
Circuit theoretical approach for the quantum wells and periodic potentials
Authors: Sanada Hirofumi , Nagai Nobuo , Ohtani Naoki , Miki Nobuhiro
Published: July 2007

circuit‐theoretical treatment has been investigated as a systematic and easy method to obtain a guideline for the analysis and design of energy levels by quantum wells and minibands by periodic potentials. the existing circuit‐theoretical approach considers only the case in which the wave function is continuous in the heterointerface under an effective mass approximation.

In this paper, by means of the interface matrix which represents general boundary conditions at the heterointerface, a method for circuit‐theoretical analysis is presented for the energy level and the miniband of quantum wells and periodic potentials made of various materials. It is shown that the eigenenergy level and the complex eigenenergy level in the quantum well structure can be formulated in terms of the real and complex frequencies. As numerical examples, the quantum wells made of GaAs/AlxGa1‐xAs and InAs/GaSb are considered and the relationship of the eigenenergy level and the complex eigenenergy level to the well structure is shown. By means of the repetition parameters in the circuit theory, numerical examples are given for the minibands by GaAs/AlxGa1 ‐xAs and InAs/GaSb due to the periodic potential.
A method of analyzing negative resistive and equivalent capacitance of CMOS crystal oscillators
Authors: Toki Masahiro , Fuchisawa Takashi
Published: July 2007

A method is investigated for an analysis of the level characteristics of the two‐port active impedance in a CMOS quartz crystal oscillator circuit used widely as a clock source of electronic devices. As a result, it was found that the negative resistance and the equivalent capacitance for arbitrary circuit parameters can be analyzed in relation to the characteristics of the CMOS‐IC itself over a small signal to a large steady‐state signal.

The analysis is useful for discussions of initiation of the oscillation in addition to the investigations as to up to what frequency the oscillation takes place definitely with a sufficient small signal negative resistance and to what the resonator current is under the steady‐state oscillation.
Integrated wideband amplifier for three‐channel video signals
Authors: Sano Yuji , Ohsawa Michitaka
Published: July 2007

A three‐channel integrated wideband video IC with the possibility of application in high resolution display of 1M pixel was developed.

This paper reports first the construction of a wideband voltage amplifier circuit in which a wide output signal dynamic range is obtained. With respect to the construction of this circuit, by compensating for the nonlinearity of the bipolar transistor and the logarithmic compression of the signal voltage, an attempt is made to expand the dynamic range. Moreover, by using an opposite‐phase current to cancel the negative resistance component appearing in the input impedance when compensating for the nonlinearity, it was attempted to flatten the frequency characteristic.

With the present circuit construction, by overcoming the process limitation of low‐voltage tolerance, it was possible to ensure wideband characteristics in excess of 140 MHz. In addition, the wideband suppression method of signal crosstalk appearing between channels as side effects of tracking characteristic improvement due to three‐channel integration is reported.

By suppressing the influence of common impedance and the differential transmission of each signal, it was possible to suppress lower than ‐43.6 dB the crosstalk between channels below 100 MHz. By the development of this IC, the miniaturization and lowering of cost of high‐resolution display and the improvement of adjustment accuracy and stability characteristics could be achieved.
Backplane power source capability
Authors: Sugiura Nobuaki
Published: July 2007

A backplane is attached to a subrack into which equipment is mounted. Each subrack has a different function and can handle different types of equipment. the backplane is used as a power source for printed circuit boards installed in the subrack. the backplane power source capability is determined by the number of power and ground inner layers, the copper sheet thickness of the inner layer, and the copper sheet area.

An equivalent circuit model of the backplane power source is set up to study the heat balance conditions during backplane power source operation. the heat balance is related to the generation, conduction, and radiation of heat. Using this model, the power source capability related to the different backplane structures is simulated and the results are compared. the results showed that the 2‐mm grid press‐in pin alignment is better than the 2.54‐mm stagger grid alignment. the backplane power source capabilities and structural parameters also are determined.
Twin‐counter digital‐loop preset frequency synthesizer (TC‐DLPS)
Authors: Tarusawa Yoshiaki , Yamao Yasushi , Nojima Toshio
Published: July 2007

A twin‐counter digital‐loop preset frequency synthesizer (TC‐DLPS) is proposed which is a newly developed form of the phase‐locked loop (PLL) frequency synthesizer having high‐speed frequency switching and small size with low power consumption. the phase detector of the TC‐DLPS consists of two counters, i.e., a high‐speed counter and a low‐speed counter, which yields a highly sensitive phase detection with low power consumption and the time constant of the loop can be decreased. Moreover, the voltage‐controlled oscillator (VCO) can be preset precisely at the time of frequency switching. In this way, the frequency‐switching time can be reduced to one‐tenth compared to the conventional PLL synthesizer.

The operation of the TC‐DLPS is explained and the possibility of reducing the PLL time constant is shown by the transient analysis of the linear transfer function. Moreover, the frequency‐switching characteristics of the prototype circuit are shown in the 800‐MHz band.
Noise characteristics of long‐wavelength monolithically integrated pin‐FETS
Authors: Akahori Yuji , Ikeda Mutsuo , Kouzen Atsuo , Itaya Yoshio
Published: July 2007

The noise characteristics of a monolithically integrated pin‐FET were analyzed using the circuit simulator SPICE. This device consists of InGaAs p‐i‐n photodiodes (PDs) and In GaAs‐channel junction field‐effect transistors (JFETs). the equation for the metal‐semiconductor field‐effect transistor (MESFET) model of the SPICE simulator is modified to fit the noise characteristics of the fabricated InGaAs channel JFETs. Then the noise parameters are extracted by fitting the simulation results to the measured noise characteristics of the pin‐FET. the sensitivity degradation caused by the noise from the two noise sources in the monolithic pin‐FETs is analyzed by circuit simulations using these noise parameters. the noise sources considered in this analysis are the load FET at the common‐source amplifier stage and the level‐shift diodes introduced to provide the operation with a single power supply.

Finally, the measured sensitivity differences among the channels of the fabricated four‐channel pin‐FET array are analyzed and it is shown that they agree with the simulation results when the flicker noise is proportional to 1/f0.8 where f is the frequency. This simulation technology is useful for analyzing the noise factors that dominate the noise characteristics and can be used to predict the sensitivity when designing monolithic photo‐receivers.
Mode‐field‐converting fiber for coupling to photonic devices
Authors: Yanagawa Hisaharu , Ono Takahiro , Oyobe Akira
Published: July 2007

A mode‐field‐converting (MFC) fiber is proposed to reduce mode‐field mismatch loss which is produced when an optical fiber and a photonic device chip are butt‐coupled to each other. an MFC fiber is fabricated by fusion‐splicing a specially designed device‐compatible fiber with an ordinary transmission‐line fiber and by heating the spliced point to form an index‐and‐dimensional taper. Also proposed is an elliptic‐mode‐field (EMF) fiber which is composed of an elliptic core and two claddings to yield a highly elliptic mode field.

An EMF fiber with an ellipticity of 2 and MFC fibers with the EMF fiber were fabricated experimentally and the lowest conversion loss of 0.09 dB was obtained. the MFC fiber was designed for coupling to a semiconductor optical switch and achieved shape conversion. Arrays of eight MFC fibers also were fabricated, and the lowest loss was 0.11 dB with a size conversion ratio of 2. the MFC fiber array was designed for coupling to a high‐Δ silica waveguide. Those loss values around 0.1 dB were sufficiently lower than the corresponding initial mode‐field mismatch losses of 0.7 and 1.7 dB; and, thus, the loss reduction effect of an MFC fiber was confirmed experimentally.