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    High density thin film memory and method of operation
    2.
    发明授权
    High density thin film memory and method of operation 失效
    高密度薄膜存储器和操作方法

    公开(公告)号：US3573760A

    公开(公告)日：1971-04-06

    申请号：US3573760D

    申请日：1968-12-16

    Applicant: IBM

    Inventor： CHANG HSU ,  GREBE KURT R

    IPC: G09F3/06 ,  G11C5/02 ,  G11C11/14 ,  G11C11/15 ,  G11C11/155 ,  G11C11/16 ,  G11C11/56 ,  H01F10/00

    CPC classification number: G11C11/14 ,  G09F3/06 ,  G11C5/02 ,  G11C11/15 ,  G11C11/16 ,  G11C11/5607 ,  H01F10/00

    Abstract: A multilayer, multithreshold magnetic film memory element is disclosed which consists of a number of superposed magnetic storage layers which share the same word and bit-sense lines. Operation of the element is essentially in the orthogonal drive mode and requires the application of different amplitude pulses on the word line to separately energize each of the storage films of the memory element. Thus, for readout of stored information, the amplitude of a succeeding read pulse increases relative to the amplitude of the preceding read pulse. Each ascending step in the read pulses provides sufficient magnetic field to overcome the rotational switching threshold of a storage film, but insufficient magnetic field to overcome the rotational switching threshold of the next storage film. For writing, each succeeding pulse after the initial pulse is lower in amplitude than the preceding pulse and is applied in coincidence with one bit pulse. Only one layer at a time is switched; the magnetization direction thereof being determined by the polarity of each bit pulse. Several embodiments of a multilayer magnetic elements are shown all of which are capable of storing multiple bits of information at the intersection of a single word line and a single bit-sense line. The method of operating multilayer memory elements in conjunction with an array of these elements is also disclosed.

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