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:
Nov. 28, 1978
Filed:
Jun. 20, 1977
Jack I Raffel, Lexington, MA (US);
John A Yasaitis, Lexington, MA (US);
Massachusetts Institute of Technology, Cambridge, MA (US);
Abstract
An improved method for reading metal dual insulator semiconductor capacitor memories is disclosed. The memory contains a plurality of capacitor cells, each cell comprising a semiconductor substrate layer and a high conductivity layer sandwiching two insulator layers. The substrate is doped to provide avalanche breakdown in a surface depletion layer at a voltage comparable to the write voltage in the accumulation direction. According to the invention, a small variable voltage is applied across a selected cell or cells. The range of voltage includes a 'flat-band' portion of the hysteresis loop describing the voltage-capacitance relationship for the capacitor memory. The unselected cells are maintained in a depletion state in which their capacitance is a minimum. A change or the absence of a change in the current through the capacitor indicates the state of the capacitor cell.