An Application of Volterra Series to IC Buffer Models

International audienceThis paper presents a Volterra-based method of behavioral modeling for the I/O buffers of digital ICs. While this technique brings a slight improvement in accuracy over previous ones, its main strength is a greater degree of generality. With a modeling approach less dependent on the nature of the devices and more easily extendable to include the effects of multiple inputs one may hope better meet the challenges of advancing technology. The proposed models can be obtained from device port transient responses only and can be easily implemented in any simulation environment, including SPICE-based circuit description software. Two illustrative examples conclude the paper

Versatile surrogate models for IC buffers

In previous papers [1,2] the authors have investigated the use of Volterra series in the identification of IC buffer macro-models. While the approach benefited from some of the inherent qualities of Volterra series it preserved the two-state paradigm of earlier methods (see [3] and its references) and was thus limited in its versatility. In the current paper the authors tackle the challenge of going beyond an application or device-oriented approach and build versatile surrogate models that mimic the behavior of IC buffers over a wide frequency band and for a variety of loads thus achieving an unprecedented degree of generality. This requires the use of a more general system identification paradig

Realization of a semiconductor-based cavity soliton laser

The realization of a cavity soliton laser using a vertical-cavity surface-emitting semiconductor gain structure coupled to an external cavity with a frequency-selective element is reported. All-optical control of bistable solitonic emission states representing small microlasers is demonstrated by injection of an external beam. The control scheme is phase-insensitive and hence expected to be robust for all-optical processing applications. The motility of these structures is also demonstrated

Stochastic Time-Domain Mapping for Comprehensive Uncertainty Assessment in Eye Diagrams

The eye diagram is one of the most common tools used for quality assessment in high-speed links. This article proposes a method of predicting the shape of the inner eye for a link subject to uncertainties. The approach relies on machine learning regression and is tested on the very challenging example of flexible link for smart textiles. Several sources of uncertainties are taken into account related to both manufacturing tolerances and physical deformation. The resulting model is fast and accurate. It is also extremely versatile: rather than focusing on a specific metric derived from the eye diagram, its aim is to fully reconstruct the inner eye and enable designers to use it as they see fit. This article investigates the features and convergence of three alternative machine learning algorithms, including the single-output support vector machine regression, together with its least squares variant, and the vector-valued kernel ridge regression. The latter method is arguably the most promising, resulting in an accurate, fast and robust tool enabling a complete parametric stochastic map of the eye

Continuum limit of amorphous elastic bodies (III): Three dimensional systems

Extending recent numerical studies on two dimensional amorphous bodies, we characterize the approach of elastic continuum limit in three dimensional (weakly polydisperse) Lennard-Jones systems. While performing a systematic finite-size analysis (for two different quench protocols) we investigate the non-affine displacement field under external strain, the linear response to an external delta force and the low-frequency harmonic eigenmodes and their density distribution. Qualitatively similar behavior is found as in two dimensions. We demonstrate that the classical elasticity description breaks down below an intermediate length scale $\xi$, which in our system is approximately 23 molecular sizes. This length characterizes the correlations of the non-affine displacement field, the self-averaging of external noise with distance from the source and gives the lower wave length bound for the applicability of the classical eigenfrequency calculations. We trace back the "Boson-peak" of the density of eigenfrequencies (obtained from the velocity auto-correlation function) to the inhomogeneities on wave lengths smaller than $\xi$.Comment: 27 pages, 11 figures, submitted to Phys. Rev.

Worst-Case Optimization of a Digital Link for Wearable Electronics in a Stochastic Framework

This paper demonstrates an optimization strategy for systems affected by uncertainties in the case of a textile interconnect line. Rather than simply conducting stochastic analysis at the end of the design process, tolerances are accounted for from the early stages of the flow. An unsupervised approach, used to describe the stochastic behavior of the line, isintegrated within a heuristic optimization algorithm with the aim of selecting the optimal parameters of a passive equalizer

Cosmic-ray Monte Carlo predictions for forward particle production in p-p, p-Pb, and Pb-Pb collisions at the LHC

We present and compare the predictions of various cosmic-ray Monte Carlo models for the energy (dE/deta) and particle (dN/deta) flows in p-p, p-Pb and Pb-Pb collisions at sqrt(s) = 14, 8.8, and 5.5 TeV respectively, in the range covered by forward LHC detectors like CASTOR or TOTEM (5.2<|eta|<6.6) and ZDC or LHCf (|eta|>8.1 for neutrals).Comment: 5 pages, 5 figs. Poster proceedings Quark-Matter'08, Jaipur. To appear in Indian J. of Phy

What is the probability of connecting two points ?

The two-terminal reliability, known as the pair connectedness or connectivity function in percolation theory, may actually be expressed as a product of transfer matrices in which the probability of operation of each link and site is exactly taken into account. When link and site probabilities are $p$ and $\rho$, it obeys an asymptotic power-law behavior, for which the scaling factor is the transfer matrix's eigenvalue of largest modulus. The location of the complex zeros of the two-terminal reliability polynomial exhibits structural transitions as $0 \leq \rho \leq 1$.Comment: a few critical polynomials are at the end of the .tex source fil