Multi-state memory
AssigneeSanDisk Corporation
InventorsDaniel C. Guterman, Yupin Kawing Fong
Life of this patent
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Abstract
Maximized multi-state compaction and more tolerance in memory state behavior is achieved through a flexible, self-consistent and self-adapting mode of detection, covering a wide dynamic range. For high density multi-state encoding, this approach borders on full analog treatment, dictating analog techniques including A to D type conversion to reconstruct and process the data. In accordance with the teachings of this invention, the memory array is read with high fidelity, not to provide actual final digital data, but rather to provide raw data accurately reflecting the analog storage state, which information is sent to a memory controller for analysis and detection of the actual final digital data.
Claims11
A memory comprising:
- a plurality of EEPROM memory cells organized into a plurality of sectors, each sector including at least one wear detecting cell comprising:
- a read/write path;
- a read only path;
- and
- a floating gate shared by said read/write and said read only paths;
- and
- control circuitry for detecting the difference in conduction characteristics of said read/write and read only paths during reading, to measure the amount of wear of said wear detecting cell.
A method for operating a memory comprising a plurality of EEPROM memory cells organized into a plurality of sectors, each sector including at least one wear detecting cell comprising a read/write path, a read only path, and a floating gate shared by said read/write and said read only paths, said method comprising the step of:
- during one or more read operations, detecting the difference in conduction characteristics of said read/write and read only paths, to measure the amount of wear of said wear detecting cell.
Dependencies are inferred from the claim text.