Method of operating memory device including multi-level memory cells

• US 9,613,664 B2
• Filed: 01/20/2015
• Issued: 04/04/2017
• Est. Priority Date: 01/20/2015
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Berman, Amit, Beitler, Uri, Kong, Jun Jin
• Primary Examiner(s): MCMAHON, DANIEL F
• Application Number:
  US14/600,754
• Publication Number:
  US 20160211028A1
• Time in Patent Office: 805 Days
• Field of Search: None
• CPC Class Codes: G11C 16/0483 comprising cells having several storage transistors connected in series
• CPC Class Codes: G11C 16/10 Programming or data input circuits
• CPC Class Codes: G11C 2207/102 Compression or decompression of data before storage
• CPC Class Codes: G11C 7/1006 Data managing, e.g. manipulating data before writing or reading out, data bus switches or control circuits therefor

Abstract

A method of operating a memory device is provided. The memory device includes a plurality of multi-level memory cells of which each memory cell includes L levels. Data which is expressed in a binary number is received. A P-length string is generated from the data. The P-length string is converted to a Q-length string. The Q-length string is distributed using I levels by eliminating at least one level from the L levels. P and Q represent binary bit lengths of the P-length string and the Q-length string. Q is greater than P. L represents a maximum number of levels which each multi-level memory cell has. I is smaller than L. The Q-length string is programmed into the plurality of memory cells.

Claims

1. A method of operating a memory device including a plurality of multi-level memory cells of which each multi-level memory cell includes L levels, comprising:

receiving data which is expressed in a binary number;

generating a P-length string from the data;

converting the P-length string to a Q-length string by eliminating at least one level from the L levels, wherein P and Q represent binary bit lengths of the P-length string and the Q-length string, wherein Q is greater than P and wherein L represents a maximum number of levels which each multi-level memory cell has; and

programming the Q-length string into the plurality of multi-level memory cells,

wherein the Q-length string is distributed using I levels,

wherein I is smaller than L, and

wherein P/Q is equal to or smaller than log_L I.

2. The method of claim 1,

wherein the converting of the P-length string to the Q-length string is performed using a table including information of a plurality of one-to-one mapping relationships between the P-length string and the Q-length string.

3. The method of claim 1,

wherein the converting of the P-length string to the Q-length string includes converting the P-length string expressed in a number of a base L to the Q-length string expressed in a number of a base I using a base conversion from the base L to the base I.

4. The method of claim 1, further comprising:

reading the Q-length string from the plurality of multi-level memory cells using (I−

1) reference voltages; and

decoding the Q-length string to the P-length string.

5. The method of claim 4,

wherein, the decoding of the Q-Length string is performed using a table including information of one-to-one mapping relationships between the P-length string and the Q-length string.

6. The method of claim 5,

wherein the decoding of the Q-length string includes converting the Q-length string expressed in a number of a base L to the P-length string expressed in a number of a base I using a base conversion from the base I to the base L.

7. The method of claim 1,

wherein the generating of the P-length string comprises:

compressing the data to a compressed data; and

encoding the compressed data by associating parity bits for the compressed data to generate the P-length string,

wherein the converting of the P-length string to the Q-length string is performed after the encoding of the compressed data.

8. The method of claim 1,

wherein the generating of the P-length string comprises:

compressing the data to a compressed data, and

further comprising;

generating an X-length parity bit based on the Q-length string;

encoding the X-length parity bit to a Y-length parity bit, wherein Y is greater than X, and wherein the Y-length parity bit is distributed over the I levels.

9. The method of claim 8, further comprising:

programming the Y-length parity bit into the plurality of multi-level memory cells.