bluuebunny/crossref_metadata_2025_split huggingface dataset:
A fast pull‐in PLL IC using two‐mode pull‐in technique
Authors: Sato Hideo , Kato Kazuo , Sase Takashi , Ikushima Ichiro , Kojima Shin‐ichi 
Published: July 2007

AbstractThe phase‐locked loop (PLL) circuit used in the timing recovery of high‐speed digital communications and high‐density digital recordings must have a fast pull‐in time and low jitter. One way to satisfy both characteristics is to use a two‐mode PLL in which the loop gain is switched in the pull‐in state and the steady state. However, in the PLL with a conventional procedure, the time constant of the loop filter cannot be reduced in the pull‐in state; hence the time for phase locking after frequency locking cannot be reduced.This paper proposes a method in which the time constant of the loop filter and the loop gain are both switched. The loop gain is switched by the gain of the smoothing filter to eliminate ripple in the output from the phase comparator while the time constant is switched by the resistor in the loop filter. This method realizes a pull‐in time one‐tenth that in the PLL with conventional two‐mode operation.A PLL IC using the forementioned method was fabricated by 2‐μm BiCMOS process technology. Its capture range was ±2 percent, the pull‐in time was 100 μs, and the noise bandwidth was 128 kHz in 64‐MHz operation.
An intelligent sensor architecture with fuzzy associative memory system
Authors: Yamaguchi Toru , Takagi Tomohiro , Tanabe Minoru 
Published: July 2007

AbstractIn realizing the intelligent sensor which flexibly transforms input information into the information required by the user employing such knowledge processing as fuzzy inference, the following points are especially important: (1) the representation of the knowledge as well as the acquisition of the knowledge should be easy; and (2) the inference should be executed with a high speed.This paper proposes a sensor construction which satisfies both of the forementioned requirements. The intelligent sensor proposed in this paper employs the if‐then type knowledge representation as the fuzzy rule with a high affinity to human thought. The sensor is composed of three independent neural nets: the input (if) part, the output (then part), and the input/output relation (if‐then) part.In the input part, the learning vector quantization (LVQ) network evaluates the features of the input waveform, and the result is mapped directly on the concept represented in the condition part of the fuzzy rule. LVQ executes self‐learning without a supervisor based on the features of the input waveform and automatically generates the membership function needed in the condition part of the fuzzy rule. This simplifies the knowledge acquisition process.In the input/output relation part, the fuzzy inference is executed with a high speed by the parallel processing of the associative memory network. Thus, the intelligent sensor based on the fuzzy associative memory can improve the forementioned two points (1) and (2). Furthermore, to demonstrate the high versatility of the proposed construction, this paper considers the problem in which two entirely different sample problems are realized by the same construction. The realization example is shown by a simulation.
Monolithic integrated magnetic sensor realizing omnidirectional measurement
Authors: Maenaka Kazusuke , Ohgusu Tatsuro , Nakamura Tetsuro 
Published: July 2007

AbstractA monolithic integrated magnetic sensor realizing omnidirectional measurement is presented. This monolithic integrated sensor consists of three Hall cells which detect magnetic components in x, y, and z directions and the bipolar circuit which converts the output signal of Hall cells VX, VY, and VZ into its absolute value (=(V2X + V2Y + V2Z)1/2).For the magnetic detector, a new “lateral Hall cell” is proposed to detect the magnetic components parallel to the chip surface (x, y directions). The three‐dimensional (3‐D) magnetic detection has been realized by combining two lateral Hall cells and a conventional epitaxial (lateral) Hall cell (for z direction).The signal conversion circuit uses a Gilbert multiplier for square calculation and a translinear circuit for a root circuit, with a total device count of 158 elements. The test device realized an omnidirectional magnetic measurement with a maximum error of ±4 percent, sensitivity of 14 V/T, and a temperature coefficient of 2100 ppm/°C in the magnetic flux range of −250 to +250 mT.
A high‐speed, large‐capacity BiCMOS SRAM with bipolar current switch logic
Authors: Douseki Takakuni , Ohmori Yasuo 
Published: July 2007

AbstractBiCMOS SRAM has high speed comparable to that of the bipolar ECL RAM. In the realization of the SRAM by previous technology, the useful SRAM architecture employs the bipolar current switching circuit for all the peripheral circuits and CMOS for the cell array.This paper discusses the construction of the bipolar peripheral circuit to apply the forementioned architecture to large‐capacity memory. First, the decoding scheme using the emitter‐follower is proposed for the selector circuit which contains the bipolar current switching circuit and the selection function. It is shown that the delay time and the power consumption can be suppressed even if the memory capacity is increased. The word driver which employs the current switching level converter and the CMOS converter is proposed. The relation between the current of the level converter and the inverter size is clearly indicated, and it is shown that a high‐speed operation is realized. Then the three‐stage multiplexer is proposed for the read‐out circuit. where the output buffer is provided with the selection function. The number of multiplexing in each stage is determined which minimizes the delay time of the read‐out circuit. Finally, the proposed structure is applied to the 256‐kbit SRAM and the usefulness is demonstrated.
Resistor and dielectric properties of carbon‐black epoxy resin composites
Authors: Nakamura Shuhei , Ito Atushi , Sawa Goro , Kitagawa Keiichi 
Published: July 2007

AbstractIn this paper, the change in carbon black (CB) coherence with CB loading in CB resin composites has been studied from the viewpoint of resistance characteristics (resistivity, temperature coefficient of resistance) and dielectric properties by using HS 500 as CB. Equivalent circuit parameters (Rs, Rc, and Cc) for these composites also are used for comparison.The dielectric properties have been obtained from a complex relative dielectric constant evaluated from the reflection and transmission coefficients at the frequency of 300 kHz to 3 GHz. The parameters for the equivalent circuit have been obtained from the frequency dependence of relative dielectric constant and the dc conductivity. As the CB loading increases, the dc resistivity decreases and Rs and Rc also decrease. This corresponds to the increase in the number of conductive paths formed by the CB structure bridging the electrodes.From the decrease of the positive TCR value, it is considered that a mechanically strong coherence was formed between the CB structure with an increase of the CB loading. Also, from the increase in the strength of relaxation and Cc with the CB loading, the branching of the CB structure which branches out of the conduction path bridging the electrodes has been found to increase. In this case, a parameter βd which is a measure of the distribution of the relaxation time increased.
Optical computed tomography for biomedical objects based on coherent detection imaging method
Authors: Toida Masahiro , Ichimura Tsutomu , Kondo Makoto , Inaba Humio 
Published: July 2007

AbstractThis paper summarizes a series of studies aiming at realization of computed tomography imaging (CT) by laser beam for actual in vitro biological samples, which is the first successful trial achieved in the world. The method is realized first by image reconstruction, which detects and selects only the weak transmitted light component buried in stronger multiple scattered light, using the optical heterodyne detection with a very high directivity and sensitivity. This is called coherent detection imaging (CDI).To realize the optical CT using the laser light based on the projection theorem, the following three conditions should essentially be satisfied:

(1) The direct‐transmitted light component in the biological system with multiple scattering should accurately be selected and detected.
(2) The Lambert‐Beer law should be applied to the selectively detected direct‐transmitted light component.
(3) There must exist a direct‐transmitted light component in the medium with complex distribution of refraction index as well as complex boundaries. The authors examined the medium in which the sample is buried and cannot be observed, not only by the naked eye but also by the traditional direct detection method. It was verified experimentally that the three conditions for the realization of the optical CT are applicable, and it was demonstrated that optical CT imaging is feasible for actual samples using the CDI method.
Ultrafast optical processes in DC‐field biased quantum‐well structures
Authors: Yamanishi Masamichi 
Published: July 2007

AbstractThis paper describes one of the ultrafast optical processes in the dc‐biased quantum‐well structure, ultrafast switching of light emission controlled by electric field effect, and its application for light‐emitting devices. In the fabricated device, injection current for device operation is extremely low (10 A/cm2) and high‐speed switching of light emission (switching time of 300 ps) can be achieved without the influence of a recombination life‐time.Utilizing the amplification of light emission in the microcavity, the external efficiency of the light‐emitting device can be improved, indicating that a switching time of 10 ps with an external efficiency of 10 percent can be achieved.The paper also discusses the ultrafast optical nonlinearity due to virtual charge polarization caused during optical excitation of the quantum‐well structure by nonresonant light, and the physics and applications of utlrafast electric pulse caused by the nonlinerity. In addition, the possibility is discussed of optical detection without optical detection without optical absorption using the virtual excitation.
Optical switching effects using excited state absorption of Er3+ ‐doped fibers
Authors: Maeda Yoshinobu , Migitaka Masatoshi 
Published: July 2007

AbstractWhen a 787‐nm signal light with constant optical intensity is superimposed with a control light of the same wavelength in an Er‐doped optical fiber, optical switchoff occurs. The optical intensity of the control light for switch‐off is 1.4 and 25 W/cm2. As the optical intensity increases, the optical transmission of the fiber decreases. When the optical intensity is 25 W/cm2, the optical transmission is lowest.A numerical analysis based on the four‐level double absorption model indicates that this nonlinear transmission characteristic takes place because the excited absorption due to the 2H11/2‐4I13/2 transition of Er3+ is predominating in the 4I9/24I15/2 and 2H11/2‐4H13/2 double absorptions. The optical switch‐off phenomenon is regarded as the first‐order phase transition phenomenon due to complex saturable absorbers with negative optical intensity dependence in optical transmission.
Optical fiber local‐light injection and detection coupling system for identification of fiber transmission operation lines
Authors: Shimizu Masatoshi , Kobayashi Hideo 
Published: July 2007

AbstractThe development of optical fiber cable transfer splicing systems is being advanced to increase the speed of connection of in‐use circuits to new ones, an operation that has been necessary in cable joints, branches, etc. In the construction of these systems, the conservation of the action‐objectives of the in‐use fiber between two different points must be confirmed and, therefore, the fiber identification techniques play the most important role.In this paper, considering the identification of in‐use fibers, the conditions of bent fiber light injection and detection and their coupling systems are discussed. As to the bent fiber light injection, the relations among the ray angle of incidence which results in the injected optical signal to propagate as a core mode, the bending radius, the thickness deviations of the UV coat and the refractive index of the matching material are investigated.The bent‐injection coupling efficiency in relation to the axial displacement between the identifying fiber and the injected one also is investigated. It is found that large coupling efficiencies can be achieved if the incident light beam spot‐size is reduced and the light‐source wavelength is increased. As to the condition of the bent fiber light detection system, the detection efficiency in regard to the source wavelength when the detected optical signal inside the core corresponds to the injected light is discussed. It is shown that large detection efficiency can be achieved if the optical source‐wavelength is increased and the bending radius is kept below 6 mm.
Characteristics of high‐speed bipolar RAMs under address‐skew condition
Authors: Yamaguchi Kunihiko , Homma Noriyuki 
Published: July 2007

AbstractThis paper considers a high‐speed bipolar RAM with the integration density of 4 kb, as an example. The access time and the operational margin are examined by simulation and actual measurement in representing the effect of the timing difference between address input signals (called skew) on the characteristics of the memory.First, it is shown that the access time increases by approximately 0.9 ns (17 percent) by the skew. This is due to the operation of the sense amplifier producing the differential output. As a result of the skew, the switching of the sensing current is delayed and the period is produced in which the differential sense outputs are kept at the same potential. This equipotential period lasts longer due to the skew than in the case without a skew, which produces a waveform distortion in the data output signal. This waveform distortion increases the access time. However, the increase is suppressed by optimizing the timing design of the internal circuit.Next, the memory cell potential in the transient state is considered and the relation between the skew and the operational margin is examined. It is shown as a result that when a skew exists, the circuit experiences a special transient state which is not observed when there is no skew. It is shown that the operational margin in this state is determined by the particular memory, cell with a large variation in the forward voltage VF of Schottky Barrier Diode (SBD). It has been proven useful to reduce the variation of VF and to increase the SBD capacitance to reduce the dependency on the skew.Finally, the relation between the two forementioned skew dependencies and the internal address latch function is discussed.
Ultralow‐frequency oscillator with switched capacitors
Authors: Miyazaki Tomoyuki , Lim Siew Thong , Minamitake Chikara , Takeishi Taisuke 
Published: July 2007

AbstractA very high and stable equivalent resistance can be realized if switched capacitors (SC) are used. The operating characteristics of a three‐phase SC oscillator are measured in which SCs are used in place of resistors in a low‐frequency CR oscillator. The amplitude of the phase shifter outputs is designed to be equal. From the squared sum of the instantaneous values of the outputs, a dc voltage proportional to the square of the oscillation amplitude is obtained to be used as the control voltage of the amplitude stabilizing circuit. The clock frequency of the SC and the oscillation frequency have a linear relationship. The experimental values agree well with the theoretical values.For constant circuit parameters, the oscillation frequency has been varied over more than five digits by changing only the clock frequency. A stable oscillation is observed at an extremely low frequency (10 μHz). A possibility of oscillation at frequencies lower than this value is demonstrated. The condition for steady‐state oscillation condition is given by the two sets of capacitance ratios. For the capacitors made with identical materials, the temperature coefficients are expected to be canceled. The problem of a long rise time of the oscillation at an extremely low frequency is resolved by reduction of the clock frequency after the amplitude has been stabilized within a short time by a high clock frequency. The effect of the equivalent parallel resistance on the characteristics of the ultralow‐frequency SC oscillator is discussed.
Temperature compensation methods for junction‐isolated analog integrated circuits and their applications
Authors: Otsuka Masanori , Hyogo Akira , Sekine Keitaro 
Published: July 2007

AbstractThis paper proposes temperature compensation methods used to improve circuit construction and to realize integrated circuits even at temperatures exceeding 200°C.The main purpose of a temperature compensation method is to maintain stability of dc bias in the high‐temperature range.The method is applied to the operational amplifier (OP‐AMP) to increase efficiency and to facilitate application to other circuits.A new OP‐AMP which can operate at high temperature is presented.
Three‐dimensional nonstationary calculation of Quasi‐phase‐matched guided‐wave, second‐harmonic generation using weighted‐index method
Authors: Yanagawa Kazunori , Hayata Kazuya , Koshiba Masanori 
Published: July 2007

AbstractA three‐dimensional (3‐D) nonstationary analysis method is proposed for the quasi‐phase‐matched (QPM) second‐harmonic generation in an optical waveguide with a periodic domain‐inversion structure. In this method, a 3‐D modeling of a waveguide‐type QPM is made possible by combining the mode coupling theory with the weighted‐index method (WIM) which is a highly accurate approximate analysis method for an optical channel waveguide. As an example of application, the effect of the channel dimensions on the conversion efficiency is studied for a proton‐exchanged LiNbO3 waveguide with a rectangular‐shaped inverted domain. The actual domain‐inversion shape is expected to be different, depending on the type of substrate material and inversion process. The present method is also applicable to an arbitrary inverted‐domain shape. Hence, the method is considered to be extremely useful for an actual device design.
Centralized system level redundancy scheme for large‐capacity memory systems
Authors: Sasaki Toshio , Shimohigashi Katsuhiro , Etoh Tsuyoshi , Sugano Toshio , Ozeki Tomotaka 
Published: July 2007

AbstractTo cope with the deterioration of the yield of the memory LSI due to the microstructured design, this paper considers the centralized system‐level redundancy scheme, where, by providing the spare memory chip and the rescue control circuit to the semiconductor memory system, the fault is rescued in a centralized way. In this scheme, the fault bits are memorized in the nonvolatile memory for each word/bit line, and the normal and the spare memories are switched at the I/O terminal of the system by the parallel access.As the method of access to the spare memory, this paper proposes the indirect address input method, where the external address is converted by the control circuit, and the direct address input method, where the external address is directly used. In the former, the external address is converted into the internal address and the ratio of the spare memory to the normal memory decreases with the increase of the system scale, which is favorable to low‐cost applications.The method is applied to the 20‐Mbit file memory using partially good 1 MSRAM, and it is verified that the defect word/bit lines of up to 35 line/chip can be rescued, thereby improving the yield by approximately three times.In the latter method, the addresses to the normal and the spare memories are input simultaneously in parallel, which is favorable for the high‐speed operation. This method is applied to the 4‐Mbit memory module using partially good 4 MDRAM and it is verified that the defect can be rescued while minimizing the deterioration of the access time.
Ultrahigh‐speed multiquantum well‐distributed feedback semiconductor lasers
Authors: Uomi Kazuhisa , Tsuchiya Tomonobu , Aoki Masahiro , Suzuki Makoto , Nakano Hiroyuki , Chinone Naoki 
Published: July 2007

AbstractWith regard to a 1.55‐μm InGaAsP multiquantum well (MQW) distributed feedback semiconductor laser which is promising for its applications to high‐capacity, long‐distance optical fiber communication systems with transmission rate above 10 Gb/s, the relaxation oscillation frequency and nonlinear damping phenomena determining the high‐speed capability and the amount of chirping determining the long‐distance capability are examined both theoretically and experimentally.First, by optimizing the number of wells in the MQW active layer and the barrier layer thickness, the relaxation oscillation frequency has been increased to 1.6 ∼ 1.7 GHz/√mA, which is almost twice the conventional value. A distinct xL dependence of the chirping at 10 Gb/s modulation has been clarified and explained by the spatial hole burning effect in the axis direction. A minimum chirp width of 3.4 Å has been obtained at 10 Gb/s large swing modulation, which is the world record. Furthermore, the physical mechanism of the nonlinear damping phenomenon has been considered from the dependences of the damping K factor and gain saturation coefficient on laser structure and oscillation wavelength and has been explained by the spectral hole burning theory.Finally, p‐type doping of the MQW active layer has been shown to be effective as a means to increase the maximum modulation bandwidth which is limited by the damping phenomenon, and the modulation above 40 GHz has been shown to be possible.
High‐speed InGaAs/InAlAs multiple‐quantum‐well optical modulator
Authors: Kotaka Isamu , Mitomi Osamu , Wakita Koichi , Kawamura Yuichi , Asai Hiromitsu 
Published: July 2007

AbstractAn external modulator shows promise in the large‐capacity long‐repeater‐interval optical communication system. This paper investigates the following characteristics to realize an electric‐field absorbing‐type modulator with a low‐loss 1.5μm band InGaAs/InAlAs multiple‐quantum‐well (MQW) structure with a high‐speed response.To reduce the device capacitance: (1) the separated pn structure is used in which the pn junction is separated from the MQW layers; (2) a polyimide is embedded into the bonding pad section; and (3) the dry etching method with a small side etch is used for formation of a good ridged waveguide. Also, to reduce the propagation loss, a ridged waveguide with a low mesa structure is formed.As a result, the frequency response at 3‐dB bandwidth is 40 GHz, the extinction ratio is 10 dB with the driving voltage of 6 V, and the insertion loss is 13 dB including the coupling loss (including the Fresnel loss) with the fiber. The bandwidth of the frequency response is limited by the device capacitance and the bonding wire inductance. Most of the insertion loss is found to be the coupling loss.