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. 25, 2007
Filed:
Jun. 23, 2006
Shan Sun, Colorado Springs, CO (US);
Xiao-hong Du, Colorado Springs, CO (US);
Fan Chu, Colorado Springs, CO (US);
Bob Sommervold, Colorado Springs, CO (US);
Shan Sun, Colorado Springs, CO (US);
Xiao-Hong Du, Colorado Springs, CO (US);
Fan Chu, Colorado Springs, CO (US);
Bob Sommervold, Colorado Springs, CO (US);
Ramtron International Corporation, Colorado Springs, CO (US);
Abstract
A ferroelectric reference circuit generates a reference voltage proportional to (P+U)/2 and is automatically centered between the bit line voltages corresponding to the P term and the U term across wide temperature and voltage ranges. To avoid fatiguing the reference ferroelectric capacitors generating (P+U)/2, the reference voltage is refreshed once every millisecond. To eliminate the variation of the reference voltage due to the leakage in the ferroelectric capacitors during this period of time, the reference voltage generated from the reference ferroelectric capacitors is digitized when it is refreshed. The digital value is fixed and converted to an analog value which is then fed into sense amplifiers for resolving the data states. The reference voltage is automatically at the center of the switching (P) and non-switching (U) signals and therefore the signal margin is maximized.