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:
Sep. 15, 2009
Filed:
Dec. 03, 2004
Applicants:
Chih-ta Star Sung, Glonn, DE;
Thomas Chang, Hsinchu, TW;
Ing-ruey Liaw, Hsinchu, TW;
Inventors:
Assignee:
Taiwan Imagingtek Corporation, Jhudong, TW;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
G11C 17/00 (2006.01); G11C 5/06 (2006.01); G11C 7/00 (2006.01);
U.S. Cl.
CPC ...
Abstract
The present invention provides a new semiconductor Read-Only Memory, ROM, which stores more than one bit per cell. The potential of multiple threshold voltages combined with the potential multiple ratios of device channel width and length makes an ROM cell store multiple bits feasible. An N-type or a P-type MOS device of the standard CMOS process or a flat-cell mask ROM process are operable devices and processes in the design of this multi layer cell ROM. The ROM cell with smaller size is implemented to represent the LSB bits, while the larger size ROM cell is to represent the MSB bits.