The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Nov. 25, 2003
Filed:
Nov. 22, 1999
Nicholas L. Rethman, North Andover, MA (US);
Nevine Nassif, Arlington, MA (US);
William J. Grundmann, Westborough, MA (US);
Hewlett-Packard Development Company, L.P., Houston, TX (US);
Abstract
A method of data compression for continuous or piecewise linear curves in two variables is presented which can guarantee that any compression error is exclusively on one selected side of the curve. Limiting errors to one side is required when simulating integrated circuit performance to determine if a design will have speed-related problems. In such a simulation it is necessary to calculate both the minimum and maximum possible time delays for a logic chain of circuit elements. Data compression of the transistor or gate voltage versus time relationship is necessary to reduce the very large amount of data that is required for the simulation. Data compression may introduce errors into the data in either direction. If it is necessary to have any possible error confined to one side of the curve, the compressed data must be shifted toward the desired error side by at least the maximum possible data error. This shifting increases the total error between the compressed data and reality by more than is acceptable in current simulations. The present method approximates the data curve with piecewise linear segments all of which are on a selected side of the curve, for example the late side. This avoids increasing the error between the data curve and the stored approximation due to shifting of the stored data to ensure that all points are on the selected side.