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.

Wavelength division switching system with reduced optical components using optical switches

Abstract: In a wavelength division switching system having m 1 inlet highways and m 2 outlet highways, m 1 splitters are coupled respectively to the inlet highways to split each multiplex signal into m 2 ×n output signals for coupling to respective inputs of m 2 ×n optical switches. Each optical switch is responsive to a switching control signal for coupling one of its inputs to one of m 2 ×n tunable wavelength filters capable of passing one of n different wavelengths, in response to a wavelength selecting signal, to one of m 2 ×n fixed wavelength converters which are organized into m 2 groups. These wavelength converters provide conversion of the input signals so that the converted wavelength is unique in each of the m 2 groups. An array of m 2 combiners are respectively associated with the groups of the fixed wavelength converters and with the outlet highways. Each combiner has n inputs coupled respectively to the outputs of the fixed wavelength converters of the associated group to multiplex signals appearing at the n inputs thereof for coupling to the associated outlet highway.

HF vapour selective etching method and apparatus.

Abstract: In order to study an etching rate difference of a layer formed mainly with silicon dioxide on a wafer, a thermal oxide film (113) and layers of BSG (117), BPSG (125), and PSG (129) are laminated on a wafer and are etched in a gaseous etching atmosphere consisting essentially of hydrogen fluoride or a mixture of hydrogen fluoride and water vapour. The layers are etched with various etching rates which are higher than that of the thermal oxide film. The etching rate difference is a difference between the etching rate of each layer and an etching rate of the thermal oxide film. The layers may include impurities, such as boron and phosphorus, collectively as a part of a layer material of each layer. The etching rate difference depends on the layer material. Preferably, the gaseous etching atmosphere should have a reduced pressure. Alternatively, a water vapour partial pressure should not be greater than 2000 Pa. As a further alternative, either the layer or the gaseous etching atmosphere should be heated.

Active matrix liquid crystal display substrate with island structure covering break in signal bus line and method of producing same

Abstract: In an active matrix substrate of a liquid crystal display using a TFT as a switching device for each pixel, a gate bus line and a drain bus line extending perpendicular to each other are formed simultaneously by patterning a metal film, and one of the two bus lines is broken to provide a gap across which the other extends. The gap is covered by an island structure of a gate dielectric film and a semiconductor layer formed to provide the TFT, and a supplementary bus line makes direct contact with the broken bus line on both sides of the gap to provide a bridge over the gap. The supplementary bus line is formed together with a pixel electrode by patterning a transparent conductor film. By this arrangement of bus lines, the total number of photolithography steps in the production process is decreased so that the production cost can be reduced.

Figure layout compaction method and compaction device

Abstract: A layout amendment specification section includes an input means such as a mouse and gives instructions to an section for compacting within allowable spacing, a wiring compaction section, a rewiring section, and an allowable spacing calculation section. The layout amendment specification section produces vertical ranking data for elements of terminals, via-holes, and wiring divided by each bent point of the wiring route. The allowable spacing calculation section produces vertical and horizontal sequence data that places all elements in order vertically and horizontally, and moreover, calculates the allowable spacing between terminals and via-holes. Based on the allowable spacing data, section for compacting within allowable spacing shifts the terminals and via-holes by pushing them down, and in addition, shifting the terminals and via-holes while maintaining a spacing of a gap compensation amount wherever possible that can accommodate one wire between a terminal or via-hole and an adjacent element.

A Highly Stabilized Low-Noise GaAs FET Integrated Oscillator with a Dielectric Resonator in the C Band

Abstract: A GaAs FET integrated oscillator stabilized with a BaO--TiO/sub 2/ system ceramic dielectric resonator provides a high-frequency-stabilized low-noise compact microwave power source. The newly developed ceramic has an expansion coefficient and dielectric constant temperature coefficient that offset each other and result in a small resonant frequency temperature coefficient. A stabilized oscillator output of 100 mW with a 17-percent efficiency and a frequency temperature coefficient as low as 2.3 ppm//spl deg/C are obtained at 6 GHz. FM noise level is reduced more the 30 dB by the stabilization. The dynamic properties of the oscillator and resonator are precisely measured to determine equivalent circuit representations. A large-signal design theory based on these equivalent circuit representations is presented to realize the optimal coupling condition between the oscillator and stabilizing resonator. The stabilized oscillator performance is sufficient for application to microwave communications systems.