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:
Mar. 17, 1992
Filed:
Nov. 29, 1989
Applicant:
Inventor:
Vincent L Fong, Fremont, CA (US);
Assignee:
Rohm Corporation, San Jose, CA (US);
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
G11C / ; G11C / ;
U.S. Cl.
CPC ...
365185 ; 365184 ; 365218 ;
Abstract
The present invention provides protection against the effects of overerasure while essentially maintaining a single transistor per memory cell through the use of an additional transistor for each row of memory cells. The added transistor is a positive voltage threshold device which is coupled between the connected sources of the floating gate transistors and a read input line to limit the threshold voltage. For programming, a second transistor with a negative voltage threshold is coupled in the same manner, but is coupled to a program input line. The positive threshold transistor prevents an unselected transistor from turning on during a read operation.