NEC

About: NEC is a company organization based out in Tokyo, Japan. It is known for research contribution in the topics: Signal & Layer (electronics). The organization has 33269 authors who have published 57670 publications receiving 835952 citations. The organization is also known as: NEC Corporation & NEC Electronics Corporation.

Apparatus for forming a double-bump structure used for flip-chip mounting

Abstract: A bump structure has a bump constituted by a metal projection which is formed on an electrode of a substrate, and a solder which covers the metal projection but does not touch the electrode The metal projection is substantially spherical and has a projected portion at a center portion on an upper surface thereof The metal projection is made of a metal having properties of solder diffusion prevention and adhesion to solder The bump structure may have two bumps, the first bump being substantially the same as the bump described above and the second being such that its diameter is smaller than an outer diameter of the first bump and it covers the projected portion on the first bump This bump structure can be formed using a simple process, and can be applied to flip-chip mounting in semiconductor devices with high reliability and yield

Echo Canceler with Two Echo Path Models

Abstract: An adaptive echo canceler with two echo path models is proposed to overcome the false adaptation problem for double-talking. The echo canceler possesses two separate echo path models (EPMs), one (background EPM) for adaptively identifying echo path transfer characteristics and the other (foreground EPM) for synthesizing an echo replica to cancel out echo. The parameter values of the foreground EPM are refreshed by those of the background EPM, according to a transfer control logic, when the logic determines that the background EPM is giving a better approximation of echo path transfer characteristics than the foreground EPM. Completely digital hardware implementation is described. Using the hardware, it is shown that virtually complete double-talking protection is actually realizable by the new method.

Fast optical channel recovery in field demonstration of 100-Gbit/s Ethernet over OTN using real-time DSP.

Abstract: A field trial of 100-Gbit/s Ethernet over an optical transport network (OTN) is conducted using a real-time digital coherent signal processor. Error free operation with the Q-margin of 3.2 dB is confirmed at a 100 Gbit/s Ethernet analyzer by concatenating a low-density parity-check code with a OTN framer forward error correction, after 80-ch WDM transmission through 6 spans x 70 km of dispersion shifted fiber without inline-dispersion compensation. Also, the recovery time of 12 msec is observed in an optical route switching experiment, which is achieved through fast chromatic dispersion estimation functionality.

Memory system and memory card

Abstract: A memory system comprises nonvolatile memory chips (CHP1, CHP2) having memory banks (BNK1, BNK2) capable of performing memory operations independently and a memory controller (5) capable of accessing/controlling separately the nonvolatile memory chips. The memory controller can selectively instruct the memory banks of the nonvolatile memory chips to perform a simultaneous or interleave write operation. Therefore, the simultaneous write operations each requiring a write time much longer than the write set-up time can be completely parallel carried out, and the interleave write operations following the write set-up can be carried out parallel and overlapped with a write operation of another memory bank. As a result, the number of nonvolatile memory chips constituting a memory system capable of performing a high-speed write operation can be relatively small.

Density Functional Theory Calculations of Alkali Metal (Li, Na, and K) Graphite Intercalation Compounds

Abstract: First-principles calculations were done to examine the energetics of alkali metal intercalation into graphite. Calculations based on the exchange-correlation functionals that include a nonlocal correlation were found to give reasonable agreement with experiments concerning the crystal structure of graphite and LiC6, binding energy of graphene sheets, and Li intercalation potential. We found that K intercalation from KC8 to KC6 cannot be achieved through electrochemical reactions. We also found that the absence of the stage-I structures for Na graphite intercalation compounds such as NaC6 or NaC8 is linked to a relatively high redox potential of Na/Na+ compared to that of Li/Li+.