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排序方式: 共有859条查询结果,搜索用时 31 毫秒
91.
92.
Kishine K. Fujimoto K. Kusanagi S. Ichino H. 《Solid-State Circuits, IEEE Journal of》2004,39(5):740-750
A design technique for an over-10-Gb/s clock and data recovery (CDR) IC provides good jitter tolerance and low jitter. To design the CDR using a PLL that includes a decision circuit with a certain phase margin affecting the pull-in performance, we derived a simple expression for the pull-in range of the PLL, which we call the "limited pull-in range," and used it for the pull-in performance evaluation. The method allows us to quickly and easily compare the pull-in performance of a conventional PLL with a full-rate clock and a PLL with a half-rate clock, and we verified that the half-rate PLL is advantageous because of its wider frequency range. For verification of the method, we fabricated a half-rate CDR with a 1:16 DEMUX IC using commercially available Si bipolar technology with f/sub T/=43 GHz. The half-rate clock technique with a linear phase detector, which is adopted to avoid using the binary phase detector often used for half-rate CDR ICs, achieves good jitter characteristics. The CDR IC operates reliably up to over 15 Gb/s and achieves jitter tolerance with wide margins that surpasses the ITU-T specifications. Furthermore, the measured jitter generation is less than 0.4 ps rms, which is much lower than the ITU-T specification. In addition, the CDR IC can extract a precise clock signal under harsh conditions, such as when the bit error rate of input data is around 2/spl times/10/sup -2/ due to a low-power optical input of -24 dBm. 相似文献
93.
Toshihiro Isobe Yoshikazu Kameshima Akira Nakajima Kiyoshi Okada Yuji Hotta 《Journal of Porous Materials》2006,13(3):269-273
The effect of additives on paste rheology was investigated for preparation of porous ceramics with unidirectionally aligned
cylindrical pores. Ammonium poly-carboxylic acid (APA) used as a dispersant and it was adsorbed on alumina powder surface.
The adsorption isotherm of APA was fitted by Langmuir equation. The saturated monolayer adsorption was 5.9 mg/g. The apparent
viscosity became a minimum at 0.8 mass % of APA corresponding to 71.2 mPa⋅s. This APA amount of 5.6 mg/g, is in good agreement
with the observed APA amount. Since the nylon 66 fibers (0–35 vol. %) mixed with the alumina powder have a strong interaction
with each other, they became twisted and agglomerated. This agglomeration increased with increasing fiber content but decreased
by adding oleic acid. The pastes with added oleic acid were capable of being extruded at higher pressure. The obtained porous
alumina ceramics showed highly oriented cylindrical pores parallel to the extrusion direction. The pore orientation was higher
in the oleic acid added pastes than those without oleic acid. The added nylon 66 fibers are mostly converted to pores while
maintaining the original shape after sintering. The pore size distribution of the obtained porous ceramics measured by mercury
porosimetry method showed a peak at about 4 μm which is apparently smaller than that observed in the SEM photographs and the
obtained result is considered to be corresponding to the necks formed by fiber contacts. 相似文献
94.
A loop parameter optimization method for a phase-locked loop (PLL) used in wide area networks (WANs) is proposed as a technique for achieving good jitter characteristics. It is shown that the jitter characteristics of the PLL, especially jitter transfer and jitter generation, depend strongly on the key parameter ζωn (ζ is a damping factor and ωn is the natural angular frequency of the PLL), and that the optimization focusing on the ωn dependence of the jitter characteristics make it possible to comprehensively determine loop parameters and loop filter constants for a PLL that will fully comply with ITU-T jitter specifications. Using the optimization method with the low-jitter circuit design technique, a low-jitter and low-power 2.5-Gb/s optical receiver IC integrated with a limiting amplifier, clock and data recovery (CDR), and demultiplexer (DEMUX) is fabricated using 0.5-μm Si bipolar technology (fT = 40 GHz). The jitter characteristics of the IC meet all three types of jitter specifications given in ITU-T recommendation G.783. In particular, the measured jitter generation is 3.2 ps rms, which is lower than that of an IC integrated with only a CDR in our previous work. In addition, the pull-in range of the PLL is 50 MHz and the power consumption of the IC is only 0.68 W (limiting amplifier: 0.2 W, CDR (PLL): 0.3 W, DEMUX: 0.18 W) at a supply voltage of -3.3 V and only 0.35 W at a supply voltage of -2.5 V (without output buffers) 相似文献
95.
96.
The microstructure of spray-dried model granules, comprising silica microspheres and poly (vinylalcohol), was observed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) with an ultramicrotome technique. Disintegration of granules was characterized by a shear method for granular beds, and by a compression test for single granules. The internal structure changed significantly with the pH of the slurry from which the granules were spray-dried. Granules from pH 7 slurry showed the smallest apparent density, and were disintegrated under the smallest applied load. By analysing the relationship between microstructure, apparent density and flow behaviour of the slurries, it was possible to obtain a guideline for preparation of appropriate granules with controlled microstructure and strength. 相似文献
97.
Muneo Hori Toshihiro Kameda Kenji Oguni 《Mechanics of materials : an international journal》1995,21(4):313-323
To explore a possible mechanism of deep earthquakes, this paper analyzes the unstable propagation of a stress-induced phase transition which is initiated in a homogeneous stress field. This Stephen problem is formulated as an initial-value problem for the phase boundary, and the driving force of the boundary is computed by using the solution of the boundary-value problem for a partially transformed material. The propagation of the phase transition under uniform pressure is numerically simulated. It is shown that (1) under lower pressure, the transition is terminated at a certain size, but it can propagate unstably when an initially transformed region is sufficiently large; and (2) when the pressure attains a critical value, the propagation becomes unstable, and goes in a particular direction depending on the initial shape. These results confirm the possibility of the unstable propagation of phase transition, and provide a theoretical basis for the hypothesis that the phase transition of a mantle material can trigger a deep earthquake. 相似文献
98.
Toshihiro Ohtani 《Metallurgical and Materials Transactions A》2005,36(11):2967-2977
We studied the microstructure evolution of an austenitic stainless steel, Type 316L, subjected to tensile creep at 973 K through
the monitoring of shear-wave attenuation and velocity using electromagnetic acoustic resonance (EMAR). Contactless transduction
based on the Lorentz force mechanism is the key to establishing a monitor for microstructural change in the bulk of metals
with high sensitivity. In the short interval, 60 to 70 pct of the creep life, attenuation experiences a peak, independent
of the applied stress. A drastic change in dislocation mobility and rearrangement interrupted this novel phenomenon, as is
supported by observations using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). The EMAR
exhibited the potential for the assessment of damage advance and the prediction of the remaining creep life of metals. 相似文献
99.
Yoshifumi Ikoma Kazunori Hayano Kaveh Edalati Katsuhiko Saito Qixin Guo Zenji Horita Toshihiro Aoki David J. Smith 《Journal of Materials Science》2014,49(19):6565-6569
This paper describes fabrication of Si nanograins through allotropic phase transformation by concurrent application of high pressure and intense straining using high-pressure torsion (HPT). Single-crystalline Si(100) wafers were processed by HPT under a pressure of 24 GPa at room temperature. X-ray diffraction and Raman analysis revealed that the HPT-processed samples were composed of metastable Si-III and Si-XII phases and amorphous phases in addition to the original diamond-cubic Si-I phase. It was found that nanograins formed because the Si-I diamond phase had transformed to high-pressure phases (Si-II, Si-XI, and Si-V) having metallic nature, and it then became easier to generate a high density of dislocations to form grain boundaries. The high-pressure phases were further transformed to the Si-XII and Si-III phases via the Si-II phase upon unloading and they existed as metastable phases at ambient pressure. Subsequent annealing at 873 K gave rise to reverse transformation to Si-I but with nanograin sizes. Although no appreciable photoluminescence (PL) peak was observed from the HPT-processed sample, a broad PL peak centered around 600 nm was detected from the annealed sample due to quantum confinement in the Si-I nanograins. 相似文献
100.
Highly Oriented Polymer Semiconductor Films Compressed at the Surface of Ionic Liquids for High‐Performance Polymeric Organic Field‐Effect Transistors
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