Noël Tanguy

Online optimization of the time scale in adaptive Laguerre-based filters

A new online method to optimize the free parameter in adaptive Laguerre-based filters is presented, it is based on the minimization of a criterion that is equivalent to an upper bound for the quadratic approximation error. The proposed technique presents a fast convergence and a good robustness.

Optimum choice of free parameter in orthonormal approximations

This correspondence investigates the choice of a free parameter, usually related to time scale, that minimizes the error energy when approximating a given signal with some widely used orthonormal basis functions. The proposed solution is the best that can be achieved with the limited required knowledge of the signal. It is appealing for experimental data for which no exact mathematical expression is available. >

Pertinent choice of parameters for discrete Kautz approximation

Kautz functions have received much attention in the recent mathematical modeling and identification literature. These functions which involve free parameters can approximate efficiently signals with strong oscillatory behavior. We consider here the choice of the free parameters in discrete (two-parameter) Kautz approximation. Using a key relationship between Kautz and Laguerre expansions we derive an upper bound for the quadratic truncation error. Minimization of this upper bound yields pertinent parameters, whose computation then requires reduced knowledge of the function to be modeled.

Laguerre-Gram reduced-order modeling

We present an efficient model reduction procedure based on the Laguerre description of the system to be approximated. Using a one-order operator defined in the Laplace domain we construct a pencil of functions and formulate the problem as the minimization of the L/sub /spl infin///sup 2/(/spl Ropf//sup +/) criterion. The use of a weight function in the inner product definition allows a control of the time-error spreading in model reduction procedure. We show how the required Gram matrix can be computed efficiently and prove that the impulse response of the reduced model is also in L/sub /spl infin///sup 2/(/spl Ropf//sup +/). The transfer function approach allows an immediate and promising application in model reduction of infinite dimensional systems. An extension to multiple-input-multiple-output systems is also given.

Improved method for optimum choice of free parameter in orthogonal approximations

We report on our investigations to choose a free parameter to minimize the error energy when approximating a given signal with orthogonal basis functions. This method requires limited knowledge of the signal to be approximated and has a low computational cost.

Fast communication: A simple algorithm for stable order reduction of z-domain Laguerre models

Discrete-time Laguerre series are a well known and efficient tool in system identification and modeling. This paper presents a simple solution for stable and accurate order reduction of systems described by a Laguerre model.

An application of Volterra series to IC buffer models

This 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.

Statically constrained nonlinear models with application to IC buffers

Volterra series are well known approaches to modeling non-linear systems. In recent works a properly weighted combination of Volterra models have been used to successfully mimic the behavior of the output port of an integrated circuit buffer. The current paper focuses on a novel mechanism for controlling the static characteristic of such models. A commercial driver example is used to illustrate the efficiency of the technique to guarantee accurate static levels during time-domain simulations.

Low Complexity Equivalent Circuit Models for VLSI Interconnects

In this paper we present a technique for generating low complexity equivalent circuit models for VLSI circuit interconnects via the Laguerre-Gram model order reduction (MOR) method developed by our team. We discuss model passivity and equivalent circuit implementation and then show the advantages of our method in preserving important signal parameters such as rise time, delay and overshoot

High-Frequency Effects of Orthogonal Interconnect Layers on Inductance in High-Speed VLSI Circuits

This communication deals with frequency behavior of orthogonal interconnect layers on inductance in high-speed VLSI circuits. The RLC parameters of the distributed model are determined by electromagnetic simulations. We evidence the error made on inductance in the range 1-50 GHz for three traditional interconnect configurations. A time-domain analysis highlights the impact of the inductance error on digital signals propagation. This analysis uses a numerical tool to take into account the frequency dependence of RLC parameters