bluuebunny/crossref_metadata_2025_split huggingface dataset:
Millimeter‐wave AlGaAs/InGaAs heterojunction finite‐element monolithic microwave integrated circuit oscillators
Authors: Funabashi Masahiro , Ohata Keiichi , Onda Kazuhiko , Inoue Takashi , Hosoya Ken'Ichi , Maruhashi Ken'Ichi , Kuzuhara Masaaki 
Published: July 2007

AbstractV‐band and Ka‐band oscillators have been developed using monolithic microwave integrated circuits (MMICs). The active elements employed are AlGaAs/InGaAs heterojunction finite element transmitters (FETs) with a 0.15‐μm T‐shaped gate. The oscillators were designed with a series feedback circuit with capacitive stubs at the FET source side for generating negative resistance and a resonance circuit at the gate side.MMIC prototypes have power outputs of 4.5 dBm for a V‐band oscillator (fosc= 50.5 GHz) and 6.7 dBm for a Ka‐band oscillator (fosc= 30.6 GHz). The phase noise for the V‐band oscillator is ‐97 dBc/Hz (1 MHz off‐carrier), which is relatively small for a free‐running oscillator.
A tunable oscillator using magnetostatic forward‐volume wave resonator with wide strip transducer
Authors: Asao Hideki , Oh‐Hashi Hideyuki , Ohwada Tetsu , Members Osami Ishida 
Published: July 2007

AbstractIt is shown theoretically and experimentally that a tunable oscillator without spurious oscillations can be obtained by using a magnetostatic forward‐volume wave resonator with wide strip transducers. First, the equivalent circuit of a rectangular resonator is presented and the unloaded Q and the external Q are expressed in terms of the dimensions and the material constants of the resonator. By means of this expression, the condition is derived for selective excitation of the dominant mode and for suppression of the higher‐order modes. A 5‐GHz tunable oscillator using this resonator was fabricated. It was demonstrated that stable oscillation characteristics without spurious oscillations can be obtained.
Analysis of frequency characteristics of dielectric waveguide discontinuities using finite difference‐time difference method
Authors: Taira Midori , Morita Nagayoshi 
Published: July 2007

AbstractThe frequency characteristics of several discontinuous shapes in a dielectric slab waveguide have been studied numerically by means of the finite difference‐time difference (FD‐TD) method. First, an excitation method of the incident mode field suitable for the FD‐TD calculations is presented in detail and the numerical accuracy of the method is discussed. For the step and bent discontinuities, the transmission and reflection coefficients derived by the FD‐TD method are compared with rigorous values. It is confirmed that sufficient accuracy is guaranteed. Next, for the discontinuities such as step, gap, slope, crank, axial offset, and sharp bend, the frequency dependence of the transmission coefficient is studied; both amplitude and phase are investigated. Finally, with a simple model of the quadriphase‐shift keying (QPSK) modulated wave, the discontinuity transmission characteristics are examined.
A loaded‐line phase shifter with series transformers
Authors: Matsunaga Makoto , Katagi Takashi 
Published: July 2007

AbstractA series transformer‐type loaded‐line phase shifter is proposed in which an impedance transformer is connected in series with a main line. The circuit configuration, a design method, and the test results are described. First, the matching condition and the relationship between the circuit parameters and the required phase shift are shown in the case where the switching semiconductor devices have dissipated. In addition, a design method is presented which determines the loss balance between the two‐phase states and the frequency dependence of the phase shift at the center frequency. The semiconductor loss characteristic to this phase shifter is expressed in terms of the figure of merit (switching cutoff frequency) of the semiconductor device for switching. The peak power handling capability of the phase shifter determined by the breakdown voltage is studied.Based on these investigations, a 90‐degree PIN phase shifter was designed by the present method in the L band. The loss balance at the center frequency was 0.22 dB, and the phase‐shift error was less than 4 degrees at the relative bandwidth of 8 percent. These values are close to those in the design. Hence, the effectiveness of the present phase‐shifter format and the design method was confirmed.
A fin line diode switch with coupled strip conductors
Authors: Matsunaga Makoto 
Published: July 2007

AbstractA design method and experimental results of a new‐type fin line diode switch using coupled strip conductors as matching elements are described. A diode and the strip conductor electromagnetically coupled with fin line are connected in shunt. By introducing coupled conductors, the forward biased diode impedance can be made low but the reverse biased diode impedance is high; so the broad band characteristic of the fin line switch with only one diode can be realized. In this switch, in order to get the greatest bandwidth, the parameters of the microstrip line switch consist of the strip conductor, the dielectric substrate, and fin conductors are uniquely determined. The validity of the design method is verified by measuring the experimental single and two‐stage SPST switches at W‐band.
Finite‐difference beam propagation method using the oblique coordinate system
Authors: Yamauchi Junji , Shibayama Jun , Nakano Hisamatsu 
Published: July 2007

AbstractUntil now, the rectangular coordinate system has been used mainly for the analysis of optical beam propagation. Hence, when a tilted waveguide is analyzed, the core shape is expressed by a stepped approximation which causes the quantization error so that the error accumulates as the field propagates.In this paper, with a view to overcome this problem, the finite‐difference beam‐propagation method is proposed in which the oblique coordinate system is employed. To confirm the effectiveness of the method, the propagation error of the fundamental mode is evaluated by the model mismatch loss in a tilted step index slab waveguide. It is found that the mode mismatch loss is kept low as the quantization error in the rectangular coordinate system is now eliminated. Further, as an example of application of this method, an optical waveguide bend is analyzed and the effects of coherent coupling are investigated. It is pointed out that the computational region can be made narrower in this method compared with that required in the rectangular coordinate system.
Estimation of higher‐order modes using prony's method in the finite difference‐time difference method
Authors: Hyodo Ken‐Ichi , Sasaki Masahiro , Kashiwa Tatsuya , Tagashira Hiroaki 
Published: July 2007

AbstractOne of the characteristics of the finite difference‐time difference (FD‐TD) method, which is a three‐dimensional time domain analysis technique for the electromagnetic field, is its ability to obtain broadband frequency characteristics by one calculation if the pulse response waveform is Fourier transformed. However, in the system where higher‐order modes may be generated, it is not possible to obtain the frequency characteristics with this procedure. A new method to cope with this problem is proposed here. This method consists of the conventional Fourier transform and Prony's method used in signal processing. The proposed method can be applied to a system containing an arbitrary number of modes. In this paper, as an example, the method is applied to a waveguide discontinuity problem so that the validity and effectiveness of the method are confirmed.
Vector finite‐element method based on use of hybrid edge elements and its application to three‐dimensional electromagnetic waveguide‐discontinuity problems
Authors: Nomura Yoshinori , Tsuji Mikio , Shigesawa Hiroshi 
Published: July 2007

AbstractAs a method for eliminating the spurious solution in the finite element analysis of three‐dimensional waveguide discontinuity problems, the use of linear edge elements is most effective. However, the shape of the element has been limited to rectangular blocks and tetrahedral bodies.In this paper, a vector finite element method using triangular‐prism elements is proposed and a formulation for three‐dimensional waveguide discontinuity problems is carried out based on this method. The present triangular‐prism elements can be used with a mixture of different edge elements so that the element division can be made highly efficient. The numerical examples demonstrate that the spurious solutions can be eliminated by using the triangular‐prism elements as other edge element methods and also the hybrid use of edge elements provides a substantial reduction in the number of unknowns compared to the conventional analysis of using only one type of edge element.
TE‐TM mode switching in tensile‐strained quantum‐well lasers induced by an electric field
Authors: Ogawa Matsuto 
Published: July 2007

AbstractBy inserting a strain into the active layer of quantum‐well lasers, the functionality of the laser can be improved. Regarding the valence band structure of the strained quantum‐well laser with an external electric field applied, a multiband‐effective‐mass theory is developed in which the band‐mixing effect of the valence band including the spin‐split off interaction is taken into account herein. Further, the present method is applied to the gain calculation of the TE and TM modes in a strained quantum well laser. As a result, it is found that the switching operation from the TE mode to the TM mode of the induced emission is possible with an external electric field.
A new pipelined decoder of error‐correction codes for a sync‐out data sequence of digital VTRs
Authors: Nakase Junko , Doi Nobukazu , Nakatomi Toshiji 
Published: July 2007

AbstractThe error‐correcting decoder is designed assuming that the input data have a constant data length. In the case of digital video technology recorders (VTR), however, there is a possibility that the length of the playback data sequence changes by desynchronization.This paper proposes an independent reset‐type error‐correcting decoder that can cope with the playback data sequence with varying data length. In the independent reset method, the signal indicating the end of processing in the operational block composing the pipeline is used as the reset signal for the operational block in the next stage. By this mechanism, a sufficient time for the operation is secured for each operational block, even if the data length of the input data varies.By applying the proposed method to the D2 digital VTR system, the miscorrection probability is examined. It is then shown that the miscorrection probability can be decreased compared to the conventional method, both in the normal and the special playback.Using the proposed independent reset method, the error‐correcting LSI decoder based on the Reed‐Solomon code is constructed. LSI is shared by the decoding processes of the inner and the outer codes of D2 system. LSI is designed so that up to 4 Bytes can be corrected for both random error and erasure corrections. The additional circuit complexity due to the independent reset mechanism is several percent of the whole LSI.
Analysis of a very low‐level DC current amplifier with allowance for the distributed ground capacitance of a high‐ohmage feedback resistor
Authors: Nakamura Ikuo , Shimoji Toshihiko , Nakada Tsuyoshi , Higa Hiroki 
Published: July 2007

AbstractWhen the response speed of a very low level dc current amplifier is increased with a shield, especially with a shielding pipe of small diameter, distortion of its output waveform increases. To elucidate the phenomenon, the new concept of distributed ground capacitances, in addition to the stray capacitances across the terminals of the high‐ohmage resistor, is taken into consideration for the circuit analysis. This paper shows that the output waveforms of the very low level dc current amplifier are distorted when Cin < KCa (where Cin, K, and Ca are the effective input capacitance, the amplification of the high‐input‐resistance amplifier and the distributed capacitance to ground, respectively) and that the distortion on its output waveforms is mainly caused by Ca.
Optical soliton switching and coupled‐soliton propagation in three‐core fiber nonlinear directional couplers
Authors: Sotobayashi Hideyuki , Fujii Yoichi 
Published: July 2007

AbstractOptical switching by nonlinear directional coupler has the problem of waveform collapse. It is known that using optical soliton pulse can avoid large waveform collapse.In this article, numerical analysis was performed for optical switching characteristics of optical soliton coupling and propagation by three‐core fiber nonlinear directional couplers. As a result, in case where multiple optical soliton pulse signals were input, it is possible to change the switching characteristics (phase‐controlled switching) by controlling relative phase difference between signals. The concept of coupled soliton in coupled nonlinear waveguide was proposed and the formation condition was discussed.
Analysis of electromagnetic fields using the finite‐difference time‐domain method in a microwave oven loaded with high‐loss dielectric
Authors: Iwabuchi Koji , Kubota Tetsuo , Kashiwa Tatsuya , Members Hiroaki Tagashira 
Published: July 2007

AbstractThere are few examples for three‐dimensional electromagnetic analysis for a high‐loss dielectric water load which has one of the highest relative permittivities of 80.4 among food items placed in a microwave oven. In this paper, the three‐dimensional finite‐difference time‐domain (FD‐TD) method is used for the analysis of the electromagnetic field inside the water load. In the fundamental investigation using the high‐loss dielectric loaded rectangular waveguide, it is confirmed that the FD‐TD numerical results with Yee's cell pitch which is set at about one‐tenth the wavelength reduced within the dielectric, agree almost with the exact solution based on the transmission theory. After the confirmation of the validity, the electromagnetic field within a water load placed on a metal turntable is analyzed. The water load has a cylindrical shape with a diameter of 64 mm and a height of 80 mm. As a result, the reduction of heating unevenness by the turntable can be predicted visually and quantitatively. In this analysis, the steady‐state solution can be obtained after 300 iterations while the heating pattern is stabilized after 100 to 200 iterations.
The influence of interdiffusion of metals in an evaporated multilayer metallization on the adhesion of an Sn‐Sb solder
Authors: Kurihara Yasutoshi , Hosokawa Takashi , Saitoh Ryuichi 
Published: July 2007

AbstractThe influence of heat treatment of Al‐Cr‐Ni‐Ag multilayer metallization on the nonuniform wetting of an Sn‐Sb solder was investigated. The goal was to obtain highly reliable semiconductor power devices by improving solder adhesion. Increase in thermal resistance after thermal fatigue testing is attributed to the nonuniform wetting of the solder to the semiconductor chips, which caused thermal stress to concentrate on the wetted regions and promoted the selective cracking of these regions. The heat treatment of the multilayer metallization at 500°C caused Al (the bottom layer) diffusion to the surface of the Ag layer. Al exposed to the surface prevented uniform wetting of the solder and caused poor wetting.
Optical time‐division multiplexing scheme for fiber‐optic millimeter‐wave radio system
Authors: Harada Hiroshi , Komaka Shozo , Tsukamoto Katsutoshi , Morinaga Norihiko 
Published: July 2007

AbstractIn fiber‐optic millimeter‐wave radio systems using conventional subcarrier multiplexing (SCM) scheme intermodulation distortion caused by the nonlinearity of electrooptic conversion is a serious problem in signal transmission. Laser diodes used as light sources have difficulties handling very high millimeter‐wave frequency due to their limited modulation bandwidth. A new fiberoptic millimeter‐wave radio system proposed here can provide higher received carrier‐to‐noise ratio (CNR) than the SCM scheme and also eliminate the effect of intermodulation distortion. In the proposed system, radio signals are sampled and transmitted through a fiber‐optic link using a time‐division multiplexing (TDM) scheme but maintaining the analog information of the radio signal. Since a radio frequency pulse train with TDM format is transmitted on the fiber‐optic link, it is easy to modulate directly the laser diode and no intermodulation distortion will be produced. The theoretical analysis results on transmission performance show that the received CNR of the proposed scheme is about 7 to 10 dB better than that of the SCM scheme.
Short‐time reproduction characteristics of the parametric magnetic tape recorder
Authors: Karasawa Koichi , Member Yorimoto Tanno , Mikoshiba Takashi 
Published: July 2007

AbstractA parametric magnetic reproducing head consists of a reproducing head and a time‐variable capacitor connected in parallel. It is a flux response‐type head. The amplitude of the output voltage is independent of the signal frequency and proportional to the signal field. In this paper, magnetic tape recorder configuration and characteristics for low‐frequency signals with this head are described. It is also reported that this recorder is suitable for long‐time recording and short‐time reproduction. It is clear that it has excellent characteristics at a low‐frequency range and is very useful for the application of long‐time recording and short‐time reproduction of an ultralow‐frequency signal.
Electron wave propagation in potential structures with δ‐type potentials
Authors: Sanada Hirofumi , Ren Jie , Nagai Nobuo 
Published: July 2007

AbstractWith the recent advances in fine‐structure fabrication technology for semiconductors, it is now possible to fabricate a potential structure in which the wave nature of the electrons can be utilized. The wave phenomena caused in such structures are important as they become the operating principle of the device making use of the quantum effect. Therefore, much research has been carried out for the behaviors of the electron waves in potential structures with various shapes.In this paper, the behavior of the electron waves in a one‐dimensional potential including a δ‐type potential is analyzed by means of the equivalent circuits. In addition, the synthesis of the transmission characteristics by making use of this method is investigated. By carrying out synthesis of the resonant levels in a single barrier structure and a structure containing δ‐type potentials in a double barrier, the resonant characteristics are compared with those obtained from the conventional double barrier and quadruple barrier. Further, a synthesis of an electron wave filter is studied by means of a structure made of δ‐type potentials placed regularly in a flat potential. It is shown that a similar transmission characteristic can be synthesized with a simpler synthesis procedure than the method in which a multilayer combination of quarter‐wavelength layers is used.
Calculation of electrostatic field in an electrophotographic development zone
Authors: Imada Hiroshi , Kiwakim Hisatomo 
Published: July 2007

AbstractIt is important to measure the electrostatic field in the electrophotographic development zone in designing copying machines. Since this zone is of a complex structure, no measurement method has been established and, hence, it is difficult to analyze this zone.In this paper, new equations to obtain the electrostatic potential and field in the development zone are obtained. In formulating the equations, it is assumed that the electrophotographic development zone was composed of four layers, that is, an electrically conductive substrate, a photosensitive layer, a development space, and a development electrode. For analysis, a charge distribution having a figure similar to a resolution test chart was assumed to be present on the photosensitive surface. In addition, an image charge which satisfies the boundary condition was taken into account.Using this method, the electrostatic potential and electric field distributions in the development zone could be evaluated when a square wave‐shaped charge with an arbitrary spread and charge density distribution was applied. Of course, this method could be applied to the case where the charge had an arbitrary shape. Moreover, this method is more precise than the finite element method. In addition, the software for this method can easily be developed and the calculation time is extremely short.
Development of single‐layer positive resist process for electron beam direct writing technology
Authors: Yamaguchi Hidenori , Sakamizu Toshio , Murai Fumio , Shiraishi Hiroshi , Hayakawa Hajime , Hasegawa Keiko , Okazaki Shinji 
Published: July 2007

AbstractA single‐layer resist process using a high resistivity positive resist by solubility reversal (PSR) for electron beam direct writing is described. Conventional PSR designed for mask creation is found to have inhomogeneous dissolution characteristics due to a side effect during the stage of deprotection reaction. To overcome this problem, the efficiency of dissolution inhibition is improved by controlling the composition of base resin materials. Using an optimized base resin structure, 0.4‐μm contact window patterns were successfully delineated in a 1.6‐μm thick single‐layer with a sensitivity of 3.5 μC/cm2. The dry etching durability of a single‐layer PSR was also examined and a high level of dry etching durability for SiO2 etching was observed.
Theoretical determination of equivalent circuit parameters for natural single‐phase unidirectional surface acoustic wave transducers
Authors: Inagawa Kiyoshi , Hasegawa Koji , Koshiba Masanori 
Published: July 2007

AbstractThis paper proposes a method for theoretical determination of the circuit parameters in the equivalent circuit for the natural single‐phase unidirectional transducer (NSPUDT), which is one type of unidirectional surface acoustic wave interdigital transducers. The finite element method was used to find the upper and lower edge frequencies of the shorted and open‐ended gratings corresponding to the shorted and open electrical terminal of the NSPUDT, the potential standing wave distribution and the static capacitance per pair of NSPUDT, needed for determination of the circuit parameters. Due to the analysis method, the anisotropy of the substrate, the electrical perturbation effect, the acoustic perturbation effect, and the energy storage effect can be taken into account. Actually, the equivalent circuit parameters of the NSPUDT on an ST‐cut 25°X‐propagation quartz substrate were computed and the reflection and excitation characteristics of the surface wave were derived. From a comparison with the experimental values, the validity and usefulness of the present method is confirmed.