Active solid-state devices (e.g. – transistors – solid-state diode – Thin active physical layer which is – Heterojunction
Reexamination Certificate
2002-10-23
2003-12-23
Nelms, David (Department: 2818)
Active solid-state devices (e.g., transistors, solid-state diode
Thin active physical layer which is
Heterojunction
C257S025000, C257S030000
Reexamination Certificate
active
06667490
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
This invention relates generally to digital memory and more particularly to a method and system for generating a memory cell.
BACKGROUND OF THE INVENTION
As microprocessors and other electronics applications become faster, storing and accessing data at increasingly high speeds presents more of a challenge. Generally, static random access memories (SRAMs) have been able to operate at higher speeds than dynamic random access memories (DRAMs). In addition, unlike DRAM cells, SRAM cells do not need to be refreshed. This conserves power and makes them continuously available for reading and writing data. However, DRAMs generally are less expensive than SRAMs and are available at densities several times higher than SRAMs. Therefore, conventional memory cells are unable to provide on-chip data storage that includes a combination of high speed, low power, low cost and high density characteristics.
SUMMARY OF THE INVENTION
In accordance with the present invention, a method and system for generating a memory cell are provided that substantially eliminate or reduce the disadvantages or problems associated with previously developed systems.
In one embodiment of the present invention, a negative differential resistance device is provided that includes a first barrier, a second barrier and a third barrier. A first quantum well is formed between the first and second barriers. A second quantum well is formed between the second and third barriers.
In another embodiment of the present invention, a memory cell is provided that includes a data storage operable to store a piece of data. The data storage includes a first negative differential resistance device and a second negative differential resistance device. The first and second negative differential resistance devices operate at a low current density. The memory cell includes an access device for accessing the piece of data stored in the data storage.
Technical advantages of the present invention include providing an improved method and system for generating a memory cell. In particular, a double quantum well resonant tunneling diode is included as a part of the memory cell. Accordingly, the low power characteristics of a conventional SRAM cell and the low cost and high density of a conventional DRAM cell are provided together in a new memory cell. In addition, the improved memory cell allows relaxation of transistor leakage requirements. This allows the use of faster, leakier transistors than those normally used in DRAM cells, yielding a higher speed cell.
Other technical advantages of the present invention will be readily apparent to one skilled in the art from the following figures, descriptions and claims.
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Klimeck Gerhard
Van der Wagt Jan Paul
Baker & Botts L.L.P.
Nelms David
Raytheon Company
Tran Long
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