bluuebunny/crossref_metadata_2025_split huggingface dataset:
A waveguide bandpass filter made of high‐permittivity ceramics
Authors: Dong Ying , Kubo Hiroshi , Hano Mitsuo , Awai Ikuo 
Published: July 2007

AbstractA 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

AbstractA 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

AbstractA 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

AbstractThe 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

AbstractTo 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

AbstractThis 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

AbstractThis 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

AbstractThe 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

AbstractThe 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

AbstractAn 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

AbstractContact 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

AbstractTunneling 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

AbstractOn 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

AbstractThe 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

AbstractA 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

AbstractThe 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

AbstractJosephson 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

AbstractDeposition 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

AbstractA 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

AbstractRadio 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.