Abstract: A method for matching patterns, based on an orthogonal sub-space projection of layout shapes using Walsh patterns, performs a preliminary density feature extraction of a circuit design layout, allows a user to define a pattern, and performs a high resolution search of the layout to locate all instances of the pattern. A sorted list of layout windows ranging from the most similar to quantitatively less similar is generated. The method for matching patterns significantly reduces false positives in comparison with the prior art and enables the same density data to be reused as a window is stepped in small increments across the layout.

Abstract: A pattern matching system, based on an orthogonal sub-space projection of layout shapes using Walsh patterns, performs a preliminary density feature extraction of a circuit design layout, allows a user to define a pattern, and performs a high resolution search of the layout to locate all instances of the pattern. A sorted list of layout windows ranging from the most similar to quantitatively less similar is generated. The pattern matching system significantly reduces false positives in comparison with the prior art and enables the same density data to be reused as a window is stepped in small increments across the layout.

Abstract: A single pattern-matching algorithm which allows both exact and inexact pattern-matching so that transistor-level design automation tools can reliably perform timing analysis, electrical rules checking, noise analysis, test pattern generation, formal design verification, and the like prior to manufacturing custom logic. The user (circuit designer) specifies which of each of the pattern external nets may be matched inexactly (attached to Vdd, attached to GND, and shorted to other external nets), with the remainder of the pattern external net connections being matched using exact isomorphism constraints. The method described herein achieves a substantial reduction in the number of patterns which circuit designers must generate, and altogether eliminates the need for an exponential number of patterns by providing an inexact pattern matcher to circuit designers.