Fast approximate analysis for token passing LAN protocol with asymmetrically distributed traffic loads

A new approximate analytical expression for the mean packet delay for a non-exhaustive token passing LAN is derived and compared with discrete event computer simulation. The computational problems associated with the exact and other approximate treatments are avoided because the need to solve a system of simultaneous equations is removed.<>     

A first-order current-steering sigma-delta modulator

A new architecture is presented for a first-order sigma-delta (ΣΔ) modulator. The system achieves a high sampling frequency, can be used as a building block for higher-order modulators, and uses circuit techniques that are largely independent of a specific technology. The key features of this implementation are that it operates in a continuous-time (as opposed to switched) mode and does not need feedback amplifiers. To test the validity of the concept, the system was realized in 2-μm, n-well, double-metal, single-poly technology. It has a measured resolution of 9 b and a linearity of 13 b at a clock frequency of 20 MHz with an oversampling ratio of 128. It operates from a power supply of ±2.5 V with a power consumption of 3 mW. The circuit occupies an area of 0.92 mm²     

45% efficient silicon photovoltaic cell under monochromatic light

Improvements in the performance of silicon photovoltaic cells for solar applications are adapted for nonsolar photovoltaic applications. Improved monochromatic light efficiencies above 45% are reported including efficiencies close to 40% for relatively long-wavelength (1.064 μm) light as produced by neodymium-doped yttrium-aluminum garnet (Nd:YAG) lasers     

Analytical investigation of factors influencing power systemstabilizers performance

Results of simulations, designed to illustrate the influence of power system stabilizers (PSS) on inter-area and local oscillations in interconnected power systems, are reported. It is shown that the PSS location and the voltage characteristics of the system loads are significant factors in the ability of a PSS to increase the damping of interarea oscillations. It is also shown that an interaction between modes in two distinct parts of a power system is possible, due to resonance, and that this might cause distortions in mode shape and participation factors     

On the coupling characteristics of coplanar waveguides andmicrostrip lines to multilayer dielectric media

The spectral-domain technique is utilized to optimize the coupling of coplanar waveguides and microstrip lines to lossy dielectric media. It is shown that to enhance the coupling, higher frequencies should be used, the dielectric constant of the substrate should be small (∈=2.56), and the width of the center conductor and gaps should be as large as possible. The dielectric constant of the superstrate should be low if a leaky-wave type of coupling is desired or large if a strong coupling by the transverse-field components is desired. It is shown that the quasi-static TEM and TM₀ modes will be excited if a superstrate is present between a high dielectric lossy media and the coplanar waveguide     

Electrical and optical feedback in an InGaAs/InP light-amplifyingoptical switch (LAOS)

A circuit model for optical and electrical feedback has been developed to investigate the cause of negative differential resistance (NDR) switching in a series connected heterojunction phototransistor (HPT) light-emitting diode (LED) device. The model considers optical feedback from the light generated in the LED, electrical feedback from the holes thermally emitted over the LED cladding layer, nonlinear gain of the HPT, the Early effect, and leakage resistance. The analysis shows that either electrical or optical feedback can be the dominant cause for the NDR, depending upon their relative strengths. The NDR observed in the devices was caused primarily by electrical feedback since the optical feedback is weak. For low input power, avalanche breakdown appears to initiate the NDR in the devices although avalanching alone cannot cause NDR     

Low-power digital radio as a ubiquitous subscriber loop

The recent growth in the use of digital radio is reviewed. The technology used to implement low-power digital radio in the local exchange loop plant is discussed. The integration of digital radio subscriber loops withnetwork intelligence is explored. The relationship between low-power digital radio loops and broadband fiber loops is briefly examined, and standards and frequency allocation activities are summarized     

Extending the power line LAN up to the neighborhood transformer

This article reports on the performance of audio, video, multimedia, and other high-data-rate in-home networking applications. The article starts by describing the problems encountered in power line communication channels in terms of frequency response and noise characteristics, and explains how in-home power line LANs can be extended to the neighborhood transformer. OFDM physical layers providing speeds of 45 Mb/s and 200 Mb/s as well as QoS and security are introduced. Finally, the results of large tests involving several thousands of nodes are described.     

The origination and optimization of Si/SiO/sub 2/ interface roughness and its effect on CMOS performance

As CMOS device dimensions scale down to 100 nm and beyond, the interface roughness between Si and SiO/sub 2/ has become critical to device performance and reliability. Si/SiO/sub 2/ interface roughness degrades channel mobility decreasing drive currents. The authors have used atomic force microscopy to study surface roughness in the processing of 0.16 /spl mu/m CMOS integrated circuits. All of the process steps that could potentially affect the interface roughness have been studied. The results show that oxidation is the major contributor to the interface roughness. The rms roughness is found to be linearly dependent on oxide thickness. Transistors with Si/SiO/sub 2/ interface rms roughness that has been reduced from 1.6 to 1.1 /spl Aring/ by reducing oxide thicknesses show improved device drive currents. This technique for interfacial smoothing and device performance improvement has the advantage of being easily implemented in today's technology.