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. 28, 2010
Filed:
Feb. 21, 2007
Jiankang Bu, Windham, ME (US);
William S. Belcher, Cape Elizabeth, ME (US);
David Courtney Parker, Topsham, ME (US);
Jiankang Bu, Windham, ME (US);
William S. Belcher, Cape Elizabeth, ME (US);
David Courtney Parker, Topsham, ME (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A system and method are disclosed for providing an electrically programmable read only memory (EPROM) in which each memory cell comprises an NMOS select transistor with a thick gate oxide and a PMOS breakdown transistor with a thin gate oxide. The source of the NMOS transistor and the source, drain and N well of the PMOS transistor are connected. The gate of the PMOS transistor is grounded. Under the control of the NMOS transistor, a programming voltage pulse is passed to the N well of the PMOS transistor of a selected memory cell. The magnitude of the voltage is sufficient to break the thin gate oxide of the PMOS transistor without damaging the NMOS transistor. Because the memory state of the memory cell depends on the breakdown status of the PMOS transistor, the data may be retained in the memory cell for an unlimited period of time.