bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of surface‐acoustic‐wave reflectors on piezoelectric layered substrates and its application to resonators
Authors: Takeuchi Masao , Yamanouchi Kazuhiko 
Published: July 2007

AbstractThis paper discusses the layered substrate with excellent temperature characteristics and a large electromechanical coupling coefficient and its application to the surface‐acoustic‐wave resonator. Assuming that periodic perturbations are given to the free surface of the layer and to the boundary between the piezoelectric substrate and the layer, the reflection characteristics of the grating reflector are analyzed using the mode‐coupling theory and the perturbation theory. The magnitude relation and the superposition of the perturbation on the free surface and the perturbation on the free surface and the perturbation on the boundary of the piezoelectric substrate and the layer, as well as the superposition of the electrical and elastic perturbations are clarified. The dependence of the mode‐coupling coefficient of the mode‐coupling equation on the layer thickness is experimentally verified using SiO2/128°Y ‐ XLiNbO3substrate. It is seen that the experimental result agrees well with the prediction by the theory. Then, a one‐port resonator in 200 MHz band was constructed indicating that there exists a layer thickness, for which the first‐order temperature coefficient of frequency is zero, and a fairly small capacitance ratio (55) is obtained.
A floating track method for complete routing
Authors: Sone Tadashi , Nakabayashi Kiyoshi 
Published: July 2007

AbstractA “floating track” method is proposed for VLSI routing, which ensures a 100 percent connection ratio. This method automatically provides a connection path on the cells by using a line‐search algorithm and solves the problem of unconnected pin pairs by adding extra wiring tracks. Prevention rules and correction procedures are provided for the wiring shorts and disconnections caused by the track addition. Based on the distribution of the track addition requirement calculated from the location and status of the search line, a fast algorithm is developed for determining the location of the additional tracks. With this algorithm a number of unconnected pin pairs can be connected quickly without a penalty in chip size. The layout result of a 20‐Kgate 4‐layered VLSI confirms the usefulness of this method for designing high‐density multilayered VLSIs.
Reduction of dynamic RAM power dissipation by a multidivided data‐line structure
Authors: Kimura Katsutaka , Hori Ryoichi , Etoh Jun , Kawajiri Yoshiki , Itoh Kiyoo 
Published: July 2007

AbstractTo realize a highly integrated large‐capacity DRAM with megabit size, problems such as low S/N and increase of power dissipation due to the charge‐discharge of data‐lines must be resolved. As a possible step toward the solution, we have already proposed a multidivided data‐line system. The feature of the system is that it controls in common the input‐output information of the multidivided data‐lines by a single decoder‐output control‐line, and a senseamplifier and the common I/O‐line are provided between two adjacent divided data lines. However, a quantitative evaluation of the system has not been made sufficiently. From such a viewpoint, this paper presents a quantitative comparison of the system with other systems mostly from the viewpoint of the power dissipation. As a result, it is seen that the system can reduce the power dissipation to one‐third or less, compared with earlier systems. It is also seen that by introducing the hierarchical I/O‐lines and the interchanged connection of the decoder output‐line and the data line, a high‐speed, low‐noise system can be realized. The usefulness of the system is verified by the design and evaluation of the experimental 1 Mbit DRAM. The performance of the fabricated chip with the area 46 mm2is access time of 90 ns and power dissipation of 295 mW (cycle time 260 ns).
Some aspects of position‐sensitive photodetectors made of amorphous silicon
Authors: Ogita Masami , Kawamura Kazuhiko , Yamada Tsutomu , Yamamoto Tatsuo 
Published: July 2007

AbstractPosition‐sensitive photodetectors detect an illuminated position without using image scanning. A large area detector of dual‐axis tetralateral PSD has been fabricated using amorphous silicon for low cost. The effective area of the device was 9.6 × 9.6 mm2, the detection deviation within 2 mm from the center was 0.3 mm and the pulse response time was around 1.5 ms. The resistive divider layer using Pd and Mo thin films provided good results. The position‐sensitive characteristics were simulated numerically by using Lucovsky's equation and the result was in good agreement with the experimental result. The analytical results lead us to the conclusion that in case of two‐dimensional dual‐axis tetralateral PSD, the nonlinearity in the position coordinate of the measured signal is caused by the introduction of both coordinate components for illuminated position (x0,y0) to each signal potential components at thexoryaxis.
Power‐combining operation of window‐output cylindrical cavity multiple‐device structures
Authors: Nogi Shigeji , Fukui Kiyoshi 
Published: July 2007

AbstractIn a multiple device oscillator having a cylindrical cavity loaded with active devices in a ring‐like manner, a method is proposed in which the power‐combined output is extracted through a window on a side wall of the cavity. This paper reports on an analysis of operation and presents the experimental results. First, a modal analysis has been performed based on a lumped element model. To create a situation in which only the desired output mode (TM020) is stable, a condition of suppressing undesired modes is established for the case where the conductances for suppression of undesired modes are arranged: (A) in the direction of the current of the desired node on the cavity bottom plane; and (B) at the location of the zero electric field of the desired mode. It is shown that suppression of undesired modes is more feasible in the new structure than in the conventional probe output method. Next, corresponding experiments have been carried out for an eight‐element oscillator. It is shown that suppression method (B) can suppress the undesired modes with a lower loss than (A), and that (B) enables power combination of almost 100 percent under the complete suppression of undesired modes. By means of an experiment in which the same structure is used as a reflection amplifier, it is found possible to combine the input power and the available powers of each device. Since the window‐output oscillator/amplifier does not require a probe and is easily fabricated even for millimeter wave applications, it is considered very practical.
Design and evaluation of wafer transfer system for LSI production
Authors: Sakano Susumu , Kuroda Hisao , Asakawa Makoto 
Published: July 2007

AbstractAn automatic wafer transportation system has been developed that is suitable for the LSI fabrication line. Design objectives have been to achieve a flexible wafer routing and flexible line construction ensuring a high degree of cleanliness. The system consists of a computer‐controlled carriage system carrying wafer cassettes on a ceiling track, and standardized interface mechanisms installed on each equipment. This paper describes technical factors involved in the realization of flexible lines, and considers also fundamental track arrangement, carriage characteristics, a wafer‐routing control method, and low dust mechanisms.
Design of low–loss saw filters employing distributed acoustic reflection transducers
Authors: Kodama Toshikazu , Kawabata Hirokazu , Sato Hiroaki , Yasuhara Yoshihiko 
Published: July 2007

AbstractAs a means to reduce the loss in an SAW filter, the IDT (interdigital transducer) called the internal reflection‐type transducer has been studied extensively recently. This IDT is believed to be useful as a filter for video and broadband data transmission since it is simple in structure and has low loss over a broadband while its fabrication process and external circuit are simple. So far, the filter constructed with this IDT has had a large ripple in the passband due to a large spurious reflection. To alleviate this problem, a new distributed acoustic reflection transducer is proposed as an internal reflection type IDT in which suppression of the unwanted spurious reflection is possible over a broad frequency range. Next, the operation mechanism of this IDT is investigated and a first‐order design method is presented. It is pointed out that a low‐loss filter with an insertion loss less than 10 dB and spurious reflection suppressed by more than 45 dB can be realized with this IDT over a broad frequency range.
Analysis of broadside–coupled suspended strip lines with side–wall grooves
Authors: Wang Bai Yi , Yamashita Eikichi , Atsuki Kazuhiko 
Published: July 2007

AbstractCompared to microstrip lines, suspended strip lines have characteristics of low loss and weak dispersion and are being applied to millimeter‐wave circuits. Suspended strip line structures analyzed in the past have been limited to those which have the same substrate width as that of the outer conductor. However, in many practical cases, the side‐walls of the outer conductor have grooves to support a dielectric substrate. The authors have already proposed a quasi‐TEM wave analysis method based on a variational approach using the spline function for trial functions to estimate the effects of these grooves on the characteristics of single‐conductor suspended strip lines. This paper applies this method to characterize broadside coupled strip lines which are necessary to design millimeter‐wave directional couppiers and filters, and considers the effects of the grooves on characteristic impedance, propagation velocity, and coupling coefficient. The proper selection of spline knots is discussed to attain various characteristic constants with high accuracy.
A placement method based on logic circuit structure information
Authors: Takagi Shigeru , Nakabayashi Kiyoshi , Ishikawa Yuuzou 
Published: July 2007

AbstractLogic circuits for VLSI have become more and more attractive. This paper presents a new placement method reflecting such logic circuit structural features as signal flow direction and logically repeated structure in the chip layout. The placement steps are as follows. The logic synthesis system synthesizes multilevel Boolean expressions for the function block from their high‐level functional specifications and outputs a relative layout for these Boolean expressions. The Boolean expressions are then mapped into physical gates. Finally, the layout system determines the position of physical gates using the relative layout and the mapping information.
An evaluation of leakage inductance for a flat cable transformer with a circular cross–sectional core
Authors: Ueda Yoshinori , Koshiba Tsuneori 
Published: July 2007

AbstractWe have derived the relationship between the leakage inductance and the winding structure for an electronic transformer with a flat cable wound around a circular cross‐sectional core. It is found that: (1) the leakage inductance of a flat cable transformer with a circular cross‐sectional core is approximately identical to one with a square core cross‐sectional core. Next, the winding configuration of a multilayer winding flat cable transformer is classified into lap winding, turn‐up lap winding and twisted lap winding; (2) the leakage inductance is higher for the lap winding and the turn‐up lap winding than for the one layer winding, but the increase of the equivalent capacitance is minimal for the lap winding; (3) the leakage inductance is even smaller in the twisted lap winding than in the one layer winding; and (4) the leakage inductance per winding length does not increase in the flat cable transformer even if insulators are inserted between layers.Further, based on the leakage coefficient, the unit leakage constant is defined. It is found that: (5) the circular cross‐section core is superior to the square cross‐sectional core for a wider relative bandwidth and a restricted range of unit leakage constant; and (6) a wider relative bandwidth is more difficult to obtain as the core becomes smaller. These results agree well with experimental findings.
Hi‐bicmos 32‐bit execution unit
Authors: Hotta Takashi , Maejima Hideo , Iwamuar Masahiro , Kuri Kouzaburou , Ueno Masahiro , Masuda Ikurou , Hotta Atuo 
Published: July 2007

AbstractThe applicability of the Hi‐BiCMOS (High Performance Bipolar CMOS) technology to the 32‐bit execution unit has been researched to improve the function and speed of such processors as minicomputers CPUs. The HiBiCMOS technology enables MOS devices with performance comparable to pure CMOS LSIs and bipolar devices with performance comparable to pure bipolar LSIs to be combined on the same substrate. Device integrations comparable to CMOS LSIs have been achieved by the utilization of macrocells composed mainly of MOS circuits. Attempts have been made to speed‐up the macrocells by adding Hi‐BiCMOS circuits.In this paper, the feedback‐type smallamplitude precharge circuit is proposed and fabricated. This circuit affords precise bus voltage. Also, the carry propagation circuit that uses the bipolar sense amplifier to achieve the machine cycle of 25 ns is proposed. Consequently it is confirmed that the precharge circuit operates two times faster and the carry propagation circuit 3.3 times faster than pure CMOS circuits. Thus, one of the promising candidates for the ultrahigh‐speed one‐chip processors is shown.
Maximum available power gain of microwave‐transistor amplifier under large‐signal operation
Authors: Umeda Hiroyuki , Takahashi Kenichiro , Shiraga Yoshiaki 
Published: July 2007

AbstractBased on linear small‐signalSparameters, large‐signalSparameters are described in terms of the output of the amplifier. With the use of theseSparameters, the maximum available power gain under the large‐signal operation is discussed. The basic analysis method is based on the power chart representation of the input and output powers proposed by Linvill. The input and output powers are represented as points on two paraboloids. From the graphical relation of this parabola, the unconditional stability condition and the input and output matching condition can be formulated. The gain compression phenomena under the large‐signal operation is investigated. Next, with microwave GaAs MESFET's, the measured results of the large‐signalSparameters are shown, as well as the experimental results of the maximum available power gain by the effective load‐pull method. It is shown thatS21andS22of theSparameters have output power dependences of the quadratic form. It is also found that the theoretical maximum available power gain computed from the linear small‐signalSparameters and the nonlinear coefficient of the output power dependence agrees well with the experimental values measured by the effective load‐pull method.
Distributed fluid sensor using eccentrically cladded fibers
Authors: Yoshikawa Hiroshi , Sugata Akihiko , Watanabe Minoru , Ohno Yutaka 
Published: July 2007

AbstractTo increase the sensitivity of distributed gas or liquid sensors using the evanescent wave of optical fibers, methods such as making the fiber single‐mode and reducing its cladding thickness or removing it completely, can be considered. However, the core of the single‐mode fiber is only a few micrometers in diameter and, therefore, it becomes very difficult to preserve it without the cladding layer. On the other hand, increasing the cladding thickness will reduce its sensitivity. In this paper, the eccentrically cladded fiber is proposed as a means to increase the sensitivity without the need to reduce its diameter. The theoretical analysis and its experimental verification are carried out. As a result, it is shown that if the eccentricity is increased, the sensitivity will not decrease remarkably, even at large cladding diameters. Further, as experimental evidence of liquid detection, optical losses of a few decibels per centimeter were observed by attaching a liquid to the fiber. This indicated the possibility of highly sensitive distributed‐type sensors. Because of the good agreement of theoretically estimated radiation losses of W‐type fibers with experimental results, it is concluded that eccentrically cladded fibers can be designed to exhibit the desired sensing characteristics.
Comparison of characteristics between inverted and normal structure heterojunction bipolar transistors
Authors: Akagi Junko , Yoshida Jiro , Kurata Mamoru 
Published: July 2007

AbstractThe collector‐top heterojunction transistor (C‐top HBT) with inverted structure is expected to operate at a much higher speed than the emitter‐top heterojunction transistor (E‐top HBT) because the former has a smaller base‐collector junction area. In this paper, the merits of the C‐top HBT compared to the E‐top HBT in circuit applications were investigated by the simulation of ring oscillation characteristics, including dependence on fan‐out and interconnect line length, and the divide‐by‐four circuit characteristics. The influences of the emitter, base and collector resistances and the external base capacitance of the HBT's on the switching characteristics, and the divide‐by‐four circuit performance were also investigated. The degree of improvement was evaluated, using results of simulation over HBT's with the reduced base resistance and the external base capacitance.
Structure dependence of the short‐channel effect in GaAs MESFETs. Two‐dimensional device simulation
Authors: Hirose Mayumi , Ikawa Yasuo , Toyoda Nobuyuki 
Published: July 2007

AbstractThe structure dependence of the short‐channel effect in GaAs MESFETs has been investigated using a two‐dimensional device simulator. The short‐channel effect for 1‐μm gate length has been clarified as being due to the decrease in the potential barrier at the substrate region under the channel, especially toward the source. This decrease in the potential barrier increases the current injection into the substrate under the channel, and causes the threshold voltage and a decrease in theKvalue, which is one of the performance criteria of FETs. A structure with a thin source/drain n+layer, an offset structure with a small spacing between the gate electrode and the n+layer, and an LDD structure with an intermediately doped layer between the gate and the n+layer increase the potential barrier effect in the substrate compared to a conventional self‐aligned structure, thereby reducing the short‐channel effect. In addition, the formation of ap‐layer around the n+layer increases further this effect, resulting in an almost short‐channel affect free FET action down to 1–μ gate length.
Magnetically tuned microwave oscillator using the YIG film and its applications
Authors: Tsutsumi Makoto 
Published: July 2007

AbstractBased on the fact that the magnetostatic mode in a YIG thin film depends on the direction of a dc magnetic field, a frequency‐controllable oscillator is proposed. First, the dispersion and delay characteristics are analyzed theoretically for the magnetostatic wave in a YIG thin film magnetized in an arbitrary angle. Especially the delay characteristics have been analyzed both in terms of the group delay and the phase delay, and correlated with the oscillation frequency. Next, on both sides of a YIG thin film with a thickness of 13.6 μm and a size of 5 × 15 mm2, ten metal strips are evaporated at a pitch of 1 mm. The filtering characteristics of this Bragg reflection filter are then evaluated. Subsequently, this filter and an FET amplifier are combined to form an oscillator for 2 to 4 GHz. Measured results for the oscillation characteristics, output power and spectrum for different magnetic field directions are compared with theoretical results. Finally, as an application of this oscillator, a correlator is proposed and its operation is explained.
Electromagnetic wave absorbing properties of carbon‐rubber doped with ferrite
Authors: Naito Yoshiyuki , Yin Jifang , Mizumoto Tetsuya 
Published: July 2007

AbstractWhen ferrites are used for electromagnetic wave absorbers in the VHF and UHF bands we note their excellent properties such as their wider dynamic frequency bandwidth and their thinner thickness than that of lossy dielectric absorbers, which are due to their magnetic losses. However, there exists an upper frequency limit beyond which the frequency bandwidth of ferrite absorbers becomes narrower than that of lossy dielectric absorbers. In this paper we added ferrites to carbon‐rubbers and examined their characteristics as electromagnetic wave absorbers. We found through experiments that the relative bandwidth is widened more than twice by adding ferrites of only relative weight ratio 0.2 to rubber when the relative weight ratio of carbon to rubber is 1.1. Although we made measurements in the frequency range of 5 to 6 GHz, we expect the same effectiveness at higher frequencies.
On–chip multibit–test scheme for VLSI memories
Authors: Hidaka Hideto , Fujishima Kazuyasu , Kumanoya Masaki , Miyatake Hideshi , Dosaka Katsumi , Nishimura Yasumasa , Yoshihara Tsutomu 
Published: July 2007

AbstractTo reduce the time needed for testing VLSI memory chips, an on‐chip multibit‐test (MBT) scheme is proposed. The conditions for the test scheme and the relationship between the test mode and the memory array architecture (data bus structure, redundancy scheme, and so forth) are discussed. When the MBT mode is applied to the 1‐Mbit DRAM, the increase in the chip area and power consumption are minimized, and the test for a 256‐K bit device can be adopted to the memory array operating test. Using this technique, the time required for testing the device is reduced one‐half to one‐third.
Computer—aided estimation of refractive—index profile of optical waveguides from propagation—mode near field pattern
Authors: Sawa Shinnosuke , Ono Kazuo , Norimatsu Naoki , Kakemizu Kouji 
Published: July 2007

AbstractSeveral methods have been proposed for estimating the structural parameters of a waveguide from transmission characteristics of the guided mode. In this paper, a simple and effective method is proposed for estimating the index profile in the cross section of the optical waveguide. In this method the measured field distribution of the guided mode and that calculated from the assumed index profile are compared directly and the index profile is sought for which the two field distributions coincide. To confirm the validity of the method, numerical simulations have been carried out for several graded index slab waveguides. Even if the simplest step index profile is assumed as the initial guess of the profile, the index profile of the waveguide can be estimated with practically sufficient accuracy. In this method, no differential process is needed for the measured values nor a high‐degree smoothing operation. Hence, the method is expected to be superior to others in terms of noise tolerance.
Effect of dielectric constant on characteristics of transmission lines formed in multilayer ceramic circuit board
Authors: Hashimoto Kaoru , Niwa Koichi 
Published: July 2007

AbstractThe effects of the dielectric constant on the transmission characteristics of multilayer ceramic circuit boards were examined. Multilayer ceramic circuit boards were fabricated using various kinds of ceramic materials with different dielectric constants, and their characteristic impedances, crosstalk, and propagation delays were measured. Experimental results show that the lower the dielectric constant, the higher the characteristic impedance, with less crosstalk and propagation delay. Based on these results, lowering the dielectric constant of the board material is found to be essential for realizing higher‐density wiring, e.g., the reduction in the dielectric thickness and transmission line spacing in multilayer ceramic circuit boards.