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:
May. 18, 2004
Filed:
Nov. 27, 2002
Chitra K. Subramanian, Austin, TX (US);
Bradley J. Garni, Austin, TX (US);
Motorola, Inc., Schaumburg, IL (US);
Abstract
The state of a MRAM cell is detected when the magnetic tunnel junction (MTJ) of the MRAM cell has a reduced bias from the maximum voltage that is used for biasing. In one example, the MTJ of the selected cell and the MTJ of a reference cell are both biased to a first voltage. The MTJs then discharge this bias asymptotically (RC time constant based utilizing bit line capacitance and MTJ resistance) to a lower voltage such as ground but at rates that are different for the selected cell versus the reference cell due to MTJ resistance differential. At a predetermined time the voltage differential is detected. In another example, the MTJs are precharged to a low voltage then are driven asymptotically toward a higher voltage. Thus, at the time of sensing for both cases, the voltage across the MTJ is less than the bias voltage that is being used.