Nonvolatile static random access memory devices
First Claim
1. A nonvolatile memory device comprising a volatile semiconductor memory cell for storing binary data, means for reading from and writing to said volatile memory cell, a nonvolatile memory means, comprising an electrically insulated floating gate conductor, for storing binary data as one of two different electric charge levels on said floating gate conductor, means for capacitively coupling said volatile memory cell to said nonvolatile memory means and for copying the memory state of said bistable memory cell to the floating gate conductor at a predetermined one of said electric charge levels, and means for capacitively coupling said floating gate conductor of said nonvolatile memory means to the said volatile memory cell for copying the memory state of said floating gate to said volatile memory cell upon application of electrical power to said volatile memory cell.
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Abstract
Nonvolatile, semiconductor random access memory cells comprising a static, RAM cell and a nonvolatile memory element which may be interconnected with the static random-access memory cell by capacitative coupling, such that the RAM cell contents may be directly copied to the nonvolatile element, and such that the nonvolatile memory cell contents will be copied to the RAM cell upon applying power to the RAM cell. The nonvolatile memory element may be a substrate-coupled floating gate cell incorporating self-regulated and asperity enhanced tunnel currents.
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13 Claims
- 1. A nonvolatile memory device comprising a volatile semiconductor memory cell for storing binary data, means for reading from and writing to said volatile memory cell, a nonvolatile memory means, comprising an electrically insulated floating gate conductor, for storing binary data as one of two different electric charge levels on said floating gate conductor, means for capacitively coupling said volatile memory cell to said nonvolatile memory means and for copying the memory state of said bistable memory cell to the floating gate conductor at a predetermined one of said electric charge levels, and means for capacitively coupling said floating gate conductor of said nonvolatile memory means to the said volatile memory cell for copying the memory state of said floating gate to said volatile memory cell upon application of electrical power to said volatile memory cell.
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11. A method for nonvolatile storage of binary information in a semiconductor integrated circuit, comprising the steps of
capacitively sensing the one of two binary memory states of a volatile semiconductor memory cell having binary information stored therein, causing a predetermined one to two electric charge levels to be created on a dielectrically isolated floating gate conductor corresponding to said one capacitively sensed memory state of said volatile memory cell without altering the memory state of said volatile memory cell, and causing said volatile memory cell to capacitively sense the current charge level of said floating gate when power is first coupled to said volatile memory cell, such that the memory state of said volatile memory cell corresponds to said charge level of said floating gate.
Specification