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Design of a Multi-Level/Analog Ferroelectric Memory DeviceIncreasing the memory density and utilizing the dove1 characteristics of ferroelectric devices is important in making ferroelectric memory devices more desirable to the consumer. This paper describes a design that allows multiple levels to be stored in a ferroelectric based memory cell. It can be used to store multiple bits or analog values in a high speed nonvolatile memory. The design utilizes the hysteresis characteristic of ferroelectric transistors to store an analog value in the memory cell. The design also compensates for the decay of the polarization of the ferroelectric material over time. This is done by utilizing a pair of ferroelectric transistors to store the data. One transistor is used as a reference to determine the amount of decay that has occurred since the pair was programmed. The second transistor stores the analog value as a polarization value between zero and saturated. The design allows digital data to be stored as multiple bits in each memory cell. The number of bits per cell that can be stored will vary with the decay rate of the ferroelectric transistors and the repeatability of polarization between transistors. It is predicted that each memory cell may be able to store 8 bits or more. The design is based on data taken from actual ferroelectric transistors. Although the circuit has not been fabricated, a prototype circuit is now under construction. The design of this circuit is different than multi-level FLASH or silicon transistor circuits. The differences between these types of circuits are described in this paper. This memory design will be useful because it allows higher memory density, compensates for the environmental and ferroelectric aging processes, allows analog values to be directly stored in memory, compensates for the thermal and radiation environments associated with space operations, and relies only on existing technologies.
Document ID
20080010083
Acquisition Source
Marshall Space Flight Center
Document Type
Conference Paper
Authors
MacLeod, Todd C.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Phillips, Thomas A.
(NASA Marshall Space Flight Center Huntsville, AL, United States)
Ho, Fat D.
(Alabama Univ. Huntsville, AL, United States)
Date Acquired
August 24, 2013
Publication Date
January 1, 2006
Subject Category
Computer Systems
Meeting Information
Meeting: International Symposium on Integrated Ferroelectrics 2006
Location: Honolulu, HI
Country: United States
Start Date: April 23, 2006
End Date: April 27, 2006
Distribution Limits
Public
Copyright
Other

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