Controller for nonvolatile semiconductor memory
AssigneeToshiba Memory Corporation
InventorShinichi Kanno
Life of this patent
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Abstract
According to one embodiment, a controller for a nonvolatile semiconductor memory that stores data expressed using n levels (n is a natural number not less than 3) page by page includes an extraction unit and a conversion unit. The extraction unit extracts a second data stream shorter than a first data stream from the first data stream that includes a plurality of data written to the nonvolatile semiconductor memory. The conversion unit converts the second data stream into a third data stream longer than the second data stream, when a difference between threshold voltages of the nonvolatile semiconductor memory corresponding to adjacent two data included in the second data stream is a first level difference. The third data stream has a second level difference smaller than the first level difference.
Claims16
A controller for a nonvolatile semiconductor memory that stores data expressed using n threshold voltage levels (n is a natural number not less than 3) page by page, the controller comprising:
- an extractor configured to extract a second data stream from a first data stream, the first data stream including a plurality of data written to the nonvolatile semiconductor memory, each of the data having a corresponding threshold voltage level, wherein the second data stream includes compressed data of the first data stream, the first data stream having a first length shorter than a length of a page, and the second data stream being shorter than the first data stream;
- and
- a converter configured to convert the second data stream into a third data stream longer than the second data stream, when a difference between threshold voltages of two adjacent data included in the second data stream is a first threshold voltage level difference, the third data stream including in the place of the two adjacent data of the second data stream a data pattern, wherein each pair of adjacent data within the data pattern has a second threshold voltage level difference smaller than the first threshold level difference.
A controller for a nonvolatile semiconductor memory that stores data expressed using n threshold voltage levels (n is a natural number not less than 3) page by page, the controller comprising:
- an extractor configured to extract a second data stream from a first data stream, the first data stream including a plurality of data written to the nonvolatile semiconductor memory, each of the data having a corresponding threshold voltage level, wherein the second data stream includes compressed data of the first data stream, and the second data stream being shorter than the first data stream;
- and
- a converter configured to convert the second data stream into a third data stream longer than the second data stream, when a difference between threshold voltages of two adjacent data included in the second data stream is a first threshold voltage level difference, the third data stream including in the place of the two adjacent data of the second data stream a data pattern, wherein each pair of adjacent data within the data pattern has a second threshold voltage level difference smaller than the first threshold voltage level difference.
Dependencies are inferred from the claim text.