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:
Dec. 22, 1998
Filed:
May. 20, 1997
Varadarajan Srinivasan, Los Altos Hills, CA (US);
Sandeep Khanna, Santa Clara, CA (US);
Sanjay V Gala, Sunnyvale, CA (US);
Ketan K Mehta, Sunnyvale, CA (US);
Quality Semiconductor, Inc., Santa Clara, CA (US);
Abstract
A circuit and a method for detecting the presence of multiple active match lines in a content addressable memory is disclosed. The circuit includes at least one bus group for expressing a unary-encoded address portion of an active match line and, for each match line, an encoding circuit capable of activating a single member of each bus group according to the address of that match line when that match line is active. The multiple match detection circuit advantageously uses the property that each match line has a unique address, and therefore if there is more than one active match line, at least one bus group will have at least two active members. The multiple match detection circuit further comprises, for each bus group, an bus group detection-OR circuit for computing the logical bus group detection-OR of the members of that bus group. The multiple match detection circuit further comprises an OR circuit for computing the logical OR of the outputs of the bus group detection-OR circuits, for providing a multiple match flag which is active when two or more match lines are active and which is inactive otherwise.