bluuebunny/crossref_metadata_2025_split huggingface dataset:
Infrared transmission loss increase of Germania—doped silica fiber caused by hydrogen and its mechanism
Authors: Ogai Mikio , Iino Akira , Matsubara Kunihiro 
Published: July 2007

AbstractThe increase in infrared transmission loss due to hydrogen has to be removed completely with good understanding of its mechanism before practical utilization of a 1.55‐μm window in germania‐doped silica fibers for a long‐haul optical transmission system. Many kinds of fibers with various compositions from different processes have been manufactured and subjected to hydrogen acceleration tests to solve this problem. From these studies, such alkali impurities as sodium and potassium have been found to have a negative effect on germania‐doped silica causing an increase of infrared transmission loss as well as phosphorus. Such alkalis exist in some of the natural silica tubes used widely as a supporting tube in the MCVD process or as a jacketing tube in the VAD and MCVD processes. Most of them have been found to be removed during the MCVD process, while residual alkali impurities in the jacketed tube have been found to migrate into the central part of the fiber during the fiber drawing process and form germania‐associated defects. These experiments show that removal of alkali impurities and phosphorus is essential in protecting germania‐doped silica fibers from the adverse effect of hydrogen and maintain a minimized transmission loss in the 1.55‐μm window with smaller excess loss than in the 1.3‐μm window. Electron spin resonance analysis has helped in understanding the behavior of phosphorus and alkali impurities and establishing a reaction model with hydrogen.
Analysis of the light—beam scattering and the sum and differential signal output by arbitrarily shaped pits and bosses
Authors: Funabiki Yuji , Kojima Toshitaka 
Published: July 2007

AbstractWhen the boundary element method is applied to an electromagnetic scattering problem in an open region, an infinite integral must be carried out if the scatterer has an infinite extent. If the incident wave is a beam wave, it exists in a narrow region centered around the illuminated region. However, although the surface current excited by this incident field decays quickly in the case of E‐wave incidence since the position is separated from the illuminated region, it is distributed in a broad range in the H‐wave incidence. In this paper, a method for evaluating such an integral over a broad region is applied to the problem of scattering by arbitrarily shaped pits and bosses. It is demonstrated that an analysis for the H‐wave incidence can be done with the same accuracy for the E‐wave. In conventional analysis methods, substantial numerical errors are unavoidable for the H‐wave case. In addition, an analysis is carried out for the output signal characteristics for the hypothetical signal detection system of an optical disk. A detailed study is carried out as to how the sum and difference signal output by rectangular trapezoidal and V‐shaped pits and bosses depend on the shape and dimensions of the pit and boss or the off‐axis shift (tracking misalignment) of the incident beam and the shift of the focus.
Microstrip—line split—ring resonators and their application to bandpass filters
Authors: Makimoto Mitsuo 
Published: July 2007

AbstractThe author has already reported a much more miniaturized split‐ring resonator compared with the existing one‐wavelength ring resonators by using microstrip lines and a prototype two‐stage tunable bandpass filter. In the present paper, basic characteristics and salient features of split‐ring resonators are summarized. Using a general‐purpose simulation program for analysis of microwave circuits, calculating methods of filter coupling parameters, derived by using generalized expression of inverters, were described. The design chart was constructed indicating the concrete steps for designing. Finally, a three‐stage filter for a 600‐MHz band based on the forementioned results was designed and fabricated, and its operational characteristics were presented. The experimental results agreed quite well with the results of a computer simulation. The validity of the present design method has been confirmed.The bandpass filters using split‐ring resonators have a suitable structure for a high‐frequency hybrid IC. They are considered to be applicable over a wide frequency band in UHF to SHF bands.
An optimized design for high‐performance megabit DRAMs
Authors: Kumanoya Masaki , Dosaka Katsumi , Konishi Yashuhiro , Yoshihara Tsutomu , Miyatake Hideshi , Ikeda Yuto , Furuta Isao 
Published: July 2007

AbstractActual guidelines for the techniques to be employed for high‐performance megabit DRAMs have been studied based on the performance analysis of conventional NMOS 1MDRAMs. It was found that for reduction of access time, use of word line Al shunt method + polycide bit line system based of three‐layered poly‐silicon process, reduction of I/O line capacitance and use of CMOS current mirror‐type preamplifier are effective. For reduction of current consumption, 1/2Vccprecharge of bit lines, 1/2 division operation of memory arrays, and use of CMOS process are confirmed to be effective. For battery backup, reduction of standby current was considered. It was found that intermittent operation of substrate bias generator is effective. For further improvement, use of LDD transistors is needed in which twin wells with divided wells are presumed.Based on the forementioned studies, CMOS 1MDRAMs were fabricated. The RAS access time at 5 V and 25°C was 50 ns with the current consumption of 28 mA (tc= 260 ns). Since the average standby current at refresh interval of 64 ms was 80 μA, battery backup is sufficiently possible in this high‐performance 1MDRAM.
Current‐voltage characteristics of all‐NbN nanobridges
Authors: Wang Zhen , Hamasaki Katsuyoshi , Yamashita Tsutomu , Matsui Toshiaki 
Published: July 2007

AbstractAll‐NbN nanobridges were developed for the thin‐film Josephson mixer in an integrated receiver for the detection of electromagnetic radiation. The transport mechanism of dc current and the product of the critical current‐normal state resistance were evaluated. As a result, it was found that when the thickness of an NbN film at the bridge section was (5 ∼ 7) ζ, bulk‐like non‐Josephson currents, which make the mixer design and operation analysis difficult, were superimposed on the critical current. The value of the non‐Josephson current was evaluted quantitatively by measuring the magnetic field dependence of the critical current. The non‐Josephson current due to the three‐dimensional effect of the current flowing through the bridge section was removed by Ar‐ion thinning of the NbN film at the bridge section. TheIJRNproduct was evaluated by using the true Josephson currentIJ.
Ultrabroadband amplifiers using hybrid circuits
Authors: Ito Yasushi 
Published: July 2007

AbstractThis paper describes the design, fabrication, and performance of hybrid distributed and lossy‐match amplifiers having a wide bandwidth. Two types of novelm‐derived low‐pass networks with a cutoff frequency of 22or greater than that of a conventionalm‐derived low‐pass network is proposed in order to achieve a wide bandwidth of the hybrid distributed and lossy‐match amplifiers. The distributed amplifier exhibits a gain of 6.0 ± 0.6 dB and a return loss of better than 10 dB over the 2 to 26.5 GHz band by using a novelm‐derived low‐pass network with a cutoff frequency 22times as high as that of a conventional network. On the other hand, the three‐stage lossy‐match amplifier shows a gain of 8.0 ± 0.6 dB and a return loss of better than 9 dB across the 2 to 32 GHz band by using a novalm‐derived low‐pass network with a cutoff frequency greater than 2 times as high as that of a conventional network.
Utilization of piezoelectric stiffened effects on impact printer heads
Authors: Yano Takeshi , Takahashi Sadayuki 
Published: July 2007

AbstractThe electromagnetic printer head has traditionally been used in the impact dot‐matrix printer based on the electromagnetic attractions. The traditional technique, however, is approaching its limit. To find a break‐through for this limit, efforts have been made to develop a printer head based on the piezoelectric effect. So far, however, there has not been realized a piezoelectric printer head with a better performance than that of the electromagnetic printer head. This paper discusses the direction to be aimed at by the high‐performance printer head based on the piezoelectric effect. The reported direction can be summarized as the use of the longitudinal stiffened piezoelectric effect, instead of the transversal piezoelectric effect considered in the past, as well as the use of the lever mechanism which is isolated structurally from the piezoelectric element, instead of the traditional bimorph structure. The first piezoelectric printer head for some commercial printer products has already been successfully fabricated based on the essential idea in this paper, indicating its practical usefulness.
Parallel‐running of two cylindrical cavity multiple‐device oscillators
Authors: Fukui Kiyoshi , Nogi Shigeji , Tanaka Satoshi , Ohishi Seiji 
Published: July 2007

AbstractAs a method to increase the number of devices while maintaining a high combining efficiency of the device output in a multiple‐device oscillator made of several devices in a cylindrical cavity, a parallel running of the multiple‐device cavities is studied. First, a differential equation is derived which describes the operation of a multiple‐device oscillator coupled with a transmission line. By means of this equation, a theoretical analysis is carried out for the mutual locking operation of a coupled system of two multiple‐device oscillators in which the unwanted modes are suppressed. Next, an experiment is carried out with two 8‐device TM020‐mode cylindrical cavity oscillators. As predicted from the theory, a parallel running characteristic is confirmed which is essentially identical to the one for two single‐device oscillators. The output combining efficiency exceeding 98 percent is obtained at the degree of coupling less than 0.3.Further, the cases of nonoscillation by short or open accident of one or two devices and power supply failure are studied in a multiple‐device oscillator and its parallel operation. The basic data related to output power reduction and frequency variation due to each of the three types of failure are provided.
The optimization of a DRAM CMOS row decoder circuit
Authors: Ozaki Hideyuki , Miyamot Hiroshi , Yamagata Tadato , Hidaka Hideto 
Published: July 2007

AbstractThis paper discusses a CMOS row decoder, which is indispensable to a VLSI DRAM. The factors involved in operational delay are analyzed and an investigation is done in order to be able to realize high‐speed operation, while maintaining the feature of low power consumption. The following structure was decided upon in order to achieve highspeed operation: the NAND gate of the CMOS row decoder is shared by more than one of the subdecoders. The size of the MOS transistors (MOST) which make up the gate is increased. In the size‐ratio of the p‐ and n‐channel MOSTs in the CMOS inverter of the next stage, the p‐channel MOST is made larger than in the usual design. A problem which arises from the unbalanced CMOS inverter is pointed out, and the optimization of the pre‐charge signal of the decoder is discussed in order to deal with this problem.For comparison, the optimized decoder circuit and an NMOS decoder are built into a IM DRAM test device, and their performances are compared. As a result of this test, it was verified that the operating current of the proposed CMOS row decoder is roughly 8 mA smaller than that of the NMOS circuit. The operational delay is negligible. By adopting the optimal precharge signal, a decoder circuit with a wide operational margin is realized.
Present status and future of silicon crystal technology for high‐performance silicon VLSI
Authors: Tsuya Hideki 
Published: July 2007

AbstractThis paper describes the present and future status of silicon crystal technology for high‐performance silicon VLSI. For 4 M to 16 M memory IC's, conventional technology must be developed further and the crystalline quality by gettering and wafer shape must be improved. The development of BiCMOS technology depends strongly on the improvement of epitaxial growth technology. A reduction in the device size causes problems in reliability and in the physical limit of the device performance.To overcome these problems, research and development of new crystal growth technologies are in demand. Among these technologies, the SOI (silicon on insulator) technology, selective epitaxial growth and molecular beam epitaxy will be the key technologies for high‐performance VLSI with ultrahigh speed, very large‐scale and ultramultifunctions.
SATURN: Device technology for high‐speed bipolar LSIs
Authors: Okita Yoshihisa , Shinozawa Masahiko , Umemura Yoshio , Yamaguchi Kazuo , Akahane Koji 
Published: July 2007

AbstractA new self‐alignment process technology SATURN (self alignment technology utilizing reserved nitride) has been developed in which the selective oxidation of polysilicon and the nitride films in this oxidation process are used for a number of objectives with a view to improve the operating speed of the bipolar devices. This method is characterized by the control of the emitter stripe width by the side wall spacer film thickness and the control of the distance between the emitter and the external base by the selective oxide film thickness are carried out independently. A process of optimization based on the forementioned control was carried out so that the small transistor with an emitter stripe width of 0.5 μm and a distance of 0.35 μm between the emitter contact and the base contact was realized. This resulted in a current gain of 66 and a cutoff frequency of 12 GHz. Further, this transistor was applied in the ECL circuit which resulted in the performance with the minimum propagation delay time of 88 ps in an inverter gate and the maximum dividing frequency of 3.5 GHz in a 1/8 divider.
Present status and future prospect of VLSI multilevel interconnection
Authors: Hazuki Yoshikazu , Ushiku Yukihiro , Matsuda Tetsuo , Kashiwagi Masahiro 
Published: July 2007

AbstractAs the degree of integration and speed of VLSI are advanced, the multilayered interconnection techniques become increasingly important. At the moment when the VLSI technology is advanced to 0.5 μm technology represented by 16 MDRAMs, electromigration by the high‐current density of Al interconnections and the stress migration by the stress from the interlayer insulating films are important in reliability of Al‐interconnections. Although the latter can be rectified by low‐temperature formation of the insulating films, the prevention of the former is still in a development stage. Since the spacing between the interconnections and the aspect ratio of the connecting hole increase, good planarization of the interlayer insulating films and buried planarization of the connecting holes are required.These problems can be resolved by directive deposition of the insulation films and selective CVD of W. Further, as the miniaturization and the number of interconnection layers are increased, the crosstalk noise of the device due to the interconnection capacitances becomes significant. It is necessary to reduce the film thickness of the insulating layer and the interconnection so that the interconnection capacitance is reduced. In this paper, first the present status of the fine multilevel interconnections, the problems and solutions are presented. Next, the necessity of reduction of the interconnection capacitance and the prospect of the multilevel interconnection in the future after the 0.5 μm generation are described.
Hot carrier effects in 0.5–μm–wide trench–isolated MOSFET's
Authors: Akamatsu Susumu , Hori Takashi , Fuse Genshu , Tsuji Kazuhiko 
Published: July 2007

AbstractWith the progress in the higher integration of devices, the trench‐isolation method to isolate devices has been developed, replacing the conventional LOCOS method. However, the degradation of MOSFET's formed by the trench‐isolation method due to the hot carrier effect has not been reported.In this study, to suppress the inverse narrow channel effect, narrow‐channel n‐channel MOSFET's with boron‐doped trench walls and a gate as narrow as 0.45 μm were fabricated, and the hot carrier effect in this device was then evaluated. In the evaluation, the dose and gate width were used as the parameters. It was found that although boron implantation to the trench walls is effective in suppressing the inverse narrow channel effect, the dose should be as low as possible to minimize the device characteristic degradation due to hot carriers. In the device with a submicron gate, the boron diffused from both trench walls and overlapped at the center of the gate, resulting in device degradation.
Structural dependence on device characteristics for sidewall base contact structure transistor
Authors: Washio Katsuyoshi , Nakazato Kazuo , Nakamura Tohru 
Published: July 2007

AbstractAlthough silicon bipolar transistors have realized high‐speed characteristics by the development of self‐aligned techniques, the miniaturization of each part of the device structure is important to realize further improvement in operation speed. This paper considers the width of the sidewall contact between a base polysilicon and single crystal silicon, which is a characteristic structural parameter for sidewall base contact structure (SICOS). Also, its effect on the transistor characteristics and ECL circuit characteristics is examined.As a result, it has been shown that the sidewall contact width determines the lateral diffusion length of the external base and affects the transistor characteristics concerning emitter‐base junction and external base‐intrinsic base link‐up. The transistor characteristics dependent on the separation between the external base and n+ buried layer is also clarified. As for the ECL circuit performance, the effect of structural parameters has been examined from the relation between its delay components and transistor characteristics, and the method for design optimization is shown.
Changes of characteristics in ain ceramics surface by laser irradiation
Authors: Takahashi Masaaki , Kurihara Yasutoshi , Yamada Kazuji , Kanai Kiyoshi , Kurihara Koichiro 
Published: July 2007

AbstractWhen a highly thermally conductive A1N ceramic is used as an electronic substrate, the fabrication processes, such as dicing, resistor trimming, etc., are essential. However, when an A1N ceramic is irradiated by a laser beam during the scribing and resistor‐trimming processes, the resistivity of the ceramic decreases or its values become nonuniform.After analyzing the laser‐irradiated area of the ceramic by X‐ray photospectroscopy and thin‐film X‐ray diffraction, a very small amount of metallic aluminum was detected in the irradiated area.To avoid this problem: (1) laser irradiation should be carried out under 02 atmosphere so that the precipitated aluminum becomes α‐Al2O3; or (2) the ceramic should be treated thermally after irradiation so that the precipitated aluminum becomes α‐Al2O3. Therefore, when thermal treatment cannot be carried out after irradiation in cases such as resistor functional trimming and dicing thin‐film metallized substrates, method (1) should be used. When post heat‐treatment can be adopted (for example, thick‐film metallization process after dicing), method (2) should be used.
Holographic reconstruction of NMR images in Fresnel transform technique
Authors: Yamada Yoshifumi , Ito Satoshi , Tanaka Kunio 
Published: July 2007

AbstractSince the signal obtained in the NMR Fresnel transform technique is given by an equation similar to that of the Fresnel diffraction equation in light, a technique in which the NMR signal in the Fresnel transform technique is recorded on a transparent film as a hologram and an image is reconstructed from such a hologram by using coherent laser light. Theoretical and experimental studies on such a technique are made in conjunction with the comparison between this technique and another technique in which the hologram is made from the NMR signal in the conventional Fourier imaging technique.The experiments show that considerably good quality images are reconstructed from the holograms in 16 shades of gray made from the signals in the NMR Fresnel transform technique since the dynamic range of the signal in this technique is small. This results in a quantization of the signal with little loss of the information, and the fringe pattern of the hologram is distributed widely over the hologram plane.The experiments show also that it is difficult to reconstruct good quality images from the holograms in 16 shades of gray made from the signals in the NMR Fourier transform technique. This is because most of the information of the image is lost by a quantization of the signal in such a small number of shades of gray since the dynamic range of the signal in the NMR Fourier transform technique is extremely large.It is shown also that the dynamic range of the signal can be decreased using a quadratic nonlinear field gradient in the pulse sequence in the NMR Fourier transform technique, and great improvement in the quality of the optically reconstructed image is obtained.
A study on sweeping and radiation hardness for high‐purity synthetic quartz
Authors: Shimoda Yoshio , Uno Takehiko 
Published: July 2007

AbstractTo increase the radiation hardness of a quartz resonator, the sweeping process of a quartz is essential. This paper describes the influence of sweeping on defects and impurity density, and radiation hardness of a high‐purity synthetic quartz. Sweeping converts an Al‐M+type defect to Al‐OH−defect, where M+is an alkaline ion. The change in the defect type progresses from the positive electrode side to the negative electrode side.After sufficient sweeping, Al‐OH−defects are located uniformly over the entire quartz. The density of the impurity M+, which is removed by sweeping, is almost the same as that of the newly formed Al‐OH−‐type defects. It was confirmed experimentally that M+was replaced with OH−.The frequency change of a swept quartz resonator due to radiation is 100 times smaller than that of an unswept quartz resonator. It is on the order of 10−8when irradiation was 106rad.
Analysis and application of switched‐capacitor transformers by formulation
Authors: Ueno Fumio , Inoue Takahiro , Umeno Tohru , Oota Ichirou 
Published: July 2007

AbstractThe operating characteristics of the switched capacitor transformer are formulated and analyzed by means of the state‐space averaging method for the three types: 1/2‐step‐down type, 2‐step‐up type, and polarity inverting type. The following conclusions are obtained:(1) The static characteristic is equivalent to that of a battery with the induced voltage of the input times the transformer ratio and the output resistance represented by the duty ratio and the on‐resistances of the switches.(2) Using switches having small on‐resistances and selecting a high duty ratio and the frequency five to ten times the natural frequency of the circuit, the output resistance can be made small and a high transforming efficiency of 80 to 90 percent can be realized.(3) The dynamic characteristic is a first order for the step‐down type and a second order for the step‐up and polarization inverting type in which no oscillation results with a feedback. In comparison with a switching converter using a reactor, the present structure is superior in stability. These conclusions were confirmed experimentally.Next, as an application of the switched‐capacitor transformer, a dc‐dc converter with a 12‐V input and a 5‐V output was constructed. As a method for regulating the output, an on‐resistance control was used instead of a conventional PWM control and a frequency control. The test results are excellent as: (1) the ripple of the output voltage is reduced to one‐tenth that for the PWM control, (2) the maximum output power is 50 W (10 A) and the efficiency is 80 percent for the specified input and output, and (3) the load response is excellent.