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:
Feb. 11, 1997
Filed:
Jun. 07, 1996
Robert L Barry, Essex Junction, VT (US);
John D Chickanosky, South Burlington, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A growable read only memory (ROM) provides improved performance over a wide range of array sizes by incorporating a localized reference bitline that accurately tracks changes in loading and variations in process parameters. The reference bitline is input into one side of a differential sense amplifier while a selected data bitline is input into the other side. The reference bitline is precharged and includes two columns, a first column includes devices that are matched to memory cell devices wherein a device of the selected word line will be selected to discharge the referenced bitline. The second column includes a recessed oxide device corresponding to each memory cell in the column. The combination of the two columns ensures that the reference bitline will discharge at a predetermined rate that tracks the rate at which a selected contact programmed memory cell discharges.