Experimental validation of crosstalk simulations for on-chip interconnects using S-parameters

Since the design of advanced microprocessors is based on simulation tools, accurate assessments of the amount of crosstalk noise are of paramount importance to avoid logic failures and less-than-optimal designs. With increasing clock frequencies, inductive effects become more important, and the validity of assumptions commonly used in simulation tools and approaches is unclear. We compared accurate experimental S-parameters with results derived from both magneto-quasi-static and full-wave simulation tools for simple crosstalk structures with various capacitive and inductive couplings, in the presence of parallel and orthogonal conductors. Our validation approach made possible the identification of the strengths and weaknesses of both tools as a function of frequency, which provides useful guidance to designers who have to balance the tradeoffs between accuracy and computation expenses for a large variety of cases     

Comparisons of conventional, 3-D, optical, and RF interconnects for on-chip clock distribution

This paper analyzes the performance of different interconnect technologies for on-chip clock distribution, including conventional, three-dimensional, optical, and radio frequency interconnects. Skew, power, and area usage were estimated for each of these technologies based on the 2001 International Technology Roadmap for Semiconductors. Our results indicate that most of the skew and power are associated with local clock distribution. Consequently, since the alternative clock distribution approaches that have been proposed focus on global clock distribution, we have not found significant advantages over conventional clock distribution in terms of skew and power. Furthermore, it was found that low skews could be attained with conventional clock distribution schemes if the clock signals are not scaled down.     

Angular multiplexing for multichannel communication in a single fiber

A concept of angular multiplexing of several communication channels in a relatively short step-index fiber is described. The angular dependence of the outgoing light flux and the temporal impulse response are calculated for slab waveguides and round fibers in terms of the fiber's length and the excitation conditions. Calculations of the inpulse response in the presence of mode coupling are based on a simple model which is found to be adequate for short fibers. Crosstalk levels are calculated by integrating the flux over the aperture of the detectors. Measurements of angular flux distribution, temporal impulse response, and crosstalk levels agree with theoretical prediction and validate the proposed concepts. To increase light levels, parallel excitation of each channel by several light sources is suggested and tested. Also, light collection efficiency is increased by employing lenses and annular mirrors to deflect and focus the light from each channel to small-area detectors. Given a 25 m long fiber with a coupling constant of 10^-5rad²/m, it is possible to multiplex four channels with cross-talk of about -25 dB and information rates ranging from 10⁹bits/s to 10¹⁰bits/s for each channel.     

An experimental check of the quark-model relations for inclusive reactions

The quark-model relations for inclusive reactions obtained in the previous paper by two of the authors are compared with existing experimental data. The x and p_T² distributions are considered for hadrons produced as a result of fragmentation of an incident meson or nucleon, with the kinematics of the resonance decay being taken into account. The predictions of the quark model are in a reasonable agreement with experiment, both in the shape of spectra and in the absolute magnitude of cross sections. A number of predictions is obtained for cross sections of some inclusive reactions which are not yet measured.     

Quark model predictions and production of vector resonances and strange particles in the central region

The mass spectrum of 3γ states produced in π^?p collisions has been studied. A peak corresponding to ω^o→π^oγ decay in the π^?p→ω^on reaction was selected. The measurements were performed at the IHEP accelerator at momenta 21, 25, 32.5, 40 and 48 GeV/c. The reaction cross section decreases with the momentum in a power form (～P^?2.4) The differential cross section follows exponential t-dependence, exp (bt). The scattering cone shrinks slowly with the energy increase.