Analog sensing of memory cells in a solid state memory device
AssigneeMicron Technology, Inc.
InventorsVishal Sarin, Jung-Sheng Hoei, Frankie F. Roohparvar
Life of this patent
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Abstract
A memory device that includes a sample and hold circuit coupled to a bit line. The sample and hold circuit stores a target threshold voltage for a selected memory cell. The memory cell is programmed and then verified with a ramped read voltage. The read voltage that turns on the memory cell is stored in the sample and hold circuit. The target threshold voltage is compared with the read voltage by a comparator circuit. When the read voltage is at least substantially equal to (i.e., is substantially equal to and/or starts to exceed) the target threshold voltage, the comparator circuit generates an inhibit signal.
Claims25
A method for operating a selected memory cell, the method comprising:
- storing target data having a target threshold voltage into a sample and hold circuit;
- and
- increasing a threshold voltage of the selected memory cell until a representation of the threshold voltage is at least substantially equal to a representation of the target threshold voltage.
A method for analog sensing of a selected memory cell, the method comprising:
- storing a representation of a target voltage in a sample and hold circuit;
- biasing the selected memory cell with a first programming voltage;
- verifying the selected memory cell to determine a first threshold voltage;
- storing the a representation of the first threshold voltage;
- comparing the representation of the target voltage with the representation of the first threshold voltage;
- and
- if the representation of the target voltage is substantially equal to the representation of the first threshold voltage, inhibiting programming of the selected memory cell.
A method for analog sensing of a selected memory cell, the method comprising:
- storing a representation of a target voltage separate from the selected memory cell;
- programming the selected memory cell to a first threshold voltage;
- comparing a representation of the first threshold voltage to the representation of the target voltage;
- and
- inhibiting programming of the selected memory cell when the representation of the first threshold voltage is substantially equal to the representation of the target voltage.
A memory device comprising:
- an array of memory cells organized in word lines and bit lines, each cell programmable to a target threshold voltage;
- a sample and hold circuit, coupled to a bit line, for storing the target threshold voltage;
- a current sensing circuit coupled to the bit line for detecting a bit line current in response to a read threshold voltage on a word line;
- and
- a comparator circuit for generating an inhibit signal in response to a comparison between the target threshold voltage and the read voltage.
Dependencies are inferred from the claim text.