30 GHz pulse train generation from a multiquantum well electroabsorption intensity modulator

Stable optical pulse trains with repetition rates as high as 20-30 GHz have been successfully generated at 1.55 mu m from an InGaAs/InAlAs multiquantum well electroabsorption modulator for the first time.<>     

标准与专科池:使用专科许可领导市场

解释了为什么以利润为目的的公司参与标准化活动和特别关注标准与专利的关系,并从经济学角度,使用反公共的悲剧和跨越式发展的概念分析了这个问题.反公共的悲剧解释了为什么公司交叉授权他们的专利许可以及为什么标准化组织的专利政策包含交叉授权.跨越式发展解释了为什么拥有为实施标准的必要专利的公司将他们的专利许可授予没有相关专利的公司.通过向外授予专利许可,公司在短期内可以获得经济利益,在长期可以获得影响市场发展的战略机会,并为民营公司提供一些建议.     

Penetration and stainability of modified Sato's lead staining solution.

The penetration and stainability of modified Sato's lead staining solution containing calcined lead citrate were studied. Modified Sato's lead solution was preserved for 1 week and for 2 years, each at room temperature and at 4 degrees C. Specimens were stained with these solutions to measure the stainability. After 2-min staining, specimens were stained to the depth of 1.0-1.2 microns even when there had been 2-year preservation of the staining solution. This modified solution could be preserved for a long time and good penetration and stainability could still be obtained. This solution is also suitable for the observation of semithin sections.     

Budding of fowlpox and pigeonpox viruses at the surface of infected cells

Chick embryo fibroblasts and chorioallantoic membranes infected with fowlpox virus (FWPV) or pigeonpox virus (PPV) were examined by transmission and scanning electron microscopy. Immature virus particles were observed in finely granular areas, i.e. virus factories, of the cytoplasm. These particles had various forms depending on their stages of development. Many tubular structures were also seen in these regions. Mature virus particles with ellipsoidal or brick-shaped forms enclosing electron-dense cores were detected throughout the cytoplasm. Notably, there was a high frequency of virus budding at the cell surface, but only occasional virus wrapping in the cytoplasm. Another remarkable feature of the infected cells was accumulation of many virions just beneath the plasma membrane, indicating that this phenomenon is closely related to virus budding. Based on the observed frequency of budding, this mechanism seems to be the predominant way for FWPV and PPV to exit the cell.     

Design methodology of embedded DRAM with virtual-socketarchitecture

This paper proposes the virtual-socket architecture in order to reduce the design turn-around time (TAT) of the embedded DRAM. The required memory density and the function of the embedded DRAM are system dependent. In the conventional design, the DRAM control circuitry with the DRAM memory array is handled as a hardware macro, resulting in the increase in design TAT. On the other hand, our proposed architecture provides the DRAM control circuitry as a software macro to take advantage of the automated tools based on synchronous circuit design. With array-generator technology, this architecture can achieve high quality and quick turn-around time (QTAT) of flexible embedded DRAM that is almost the same as the CMOS ASIC. We applied this virtual-socket architecture to the development of the 61-Mb synchronous DRAM core using 0.18-μm design rule and confirmed the high-speed operation, 166 MHz at CAS latency of two, and 180 MHz at that of three. The experimental results show that our proposed architecture can be applied to the development of the high-performance embedded DRAM with design QTAT     

A multigigabit DRAM technology with 6F2 open-bitlinecell, distributed overdriven sensing, and stacked-flash fuse

A multigigabit DRAM technology was developed that features a low-noise 6F² open-bitline cell with fully utilized edge arrays, distributed overdriven sensing for operation below 1 V, and a highly reliable post-packaging repair scheme using a stacked-flash fuse. This technology, which can be used to fabricate a 0,13-μm 180-mm² 1-Gb DRAM assembled in a 400-mil package, was verified using a 57.6-mm², 200-MHz array-cycle, 256-Mb test chip with 0.109-μm² cells     

1.58-μm band gain-flattened erbium-doped fiber amplifiers forWDM transmission systems

This paper describes the amplification characteristics of gain-flattened Er³⁺-doped fiber amplifiers (EDFAs) by using 0.98-μm and 1.48-μm band pumping for a 1.58-μm band WDM signal. Silica-based Er³⁺-doped fiber (S-EDF) and fluoride-based Er ³⁺-doped fiber (F-EDF) have gain-flattened wavelength ranges from 1570 to 1600 nm and from 1565 to 1600 nm, respectively, and exhibit uniform gain characteristics with gain excursions of 0.7 and 1.0 dB, and the figure of merit of the gain flatness (gain excursion/average signal gain) of 3 and 4.3%, respectively, for an eight-channel signal in the 1.58-μm band. We show that 1.48-μm band pumping has a better quantum conversion efficiency and gain coefficient, and that 0.98-μm band pumping is effective for improving the noise characteristics. We also show that the EDFAs consisting of two cascaded amplification units pumped in the 0.98-μm and 1.48-μm bands are effective in constructing low-noise and high-gain 1.58-μm band amplifiers     

An all DC-powered Josephson logic circuit

A novel DC-powered Josephson circuit is reported. An improved HUFFLE-type DC flip-flop with a parallel resistor, to prevent hang-up, is constructed by combinational circuits as well as sequential circuits. The basic device is a vertical type two-junction interferometer with only three-metal layers. The design rule is 2.5 μm. High junction-current density allows for a wide operating margin even with a low inductance load. Basic circuit function test elements have been completed. The DC flip-flop with excess gate current works as a GHz range VCO (voltage controlled oscillator) for internal clock generation. The speedup junction successfully accelerated the switching speed. The ring-oscillator showed a minimum gate delay of 11.3 ps     

A channel-erasing 1.8-V-only 32-Mb NOR flash EEPROM with a bitlinedirect sensing scheme

A 1.8-V-only 32-Mb NOR flash EEPROM has been developed based on the 0.25-μm triple-well double-metal CMOS process. A channel-erasing scheme has been implemented to realize a cell size of 0.49 μm² , the smallest yet reported for 0.25-μm CMOS technology. A block decoder circuit with a novel erase-reset sequence has been designed for the channel-erasing operation. A bitline direct sensing scheme and a wordline boosted voltage pooling method have been developed to obtain high-speed reading operation at low voltage. An access time of 90 ns at 1.8 V has been realized     

Time-resolved photoluminescence of polycrystalline GaN layers on metal substrates

The low-temperature time-resolved photoluminescence of polycrystalline GaN layers grown by molecular beam epitaxy on metal substrates (Mo and Ta) was investigated. The photoluminescence spectra observed include two emission bands in the ultraviolet spectral region. We assign one of these bands to recombination processes inside cubic nanocrystallites, which are formed in the hexagonal polycrystalline GaN host. The recombination radiation of cubic nanocrystallites is enhanced due to predominant trapping of the nonequilibrium electron-hole pairs in these crystallites.