Nonvolatile memory device and data write method

Patent metadata

Field	Value
Publication number	US-9355701-B2
Application number	US-201414179614-A
Country	US
Kind code	B2
Filing date	Feb 13, 2014
Priority date	Mar 15, 2013
Publication date	May 31, 2016
Grant date	May 31, 2016

Abstract

A data write method of a nonvolatile memory device is provided which includes receiving write data to be stored in selected memory cells; reading data stored in the selected memory cells; processing the write data according to a plurality of data modulation manners to generate a plurality of modulated data values; calculating the number of flip bits and the number of switching bits when the write data and the plurality of modulated data values are overwritten on the selected memory cells, each flip bit indicating that a logical value of a selected memory cell is reversed and each switching bit indicating that a logical value of a selected memory cell is switched from a first logical value to a second logical value; and selecting one of the write data and the plurality of modulated data values according to calculating the number of flip bits and the number of switching bits.

First claim

What is claimed is:

1. A data write method for a nonvolatile memory device, the method comprising:
receiving externally provided write data to be stored in selected memory cells during a write operation;
reading previous data previously stored in the selected memory cells;
modulating the write data to generate modulated write data;
counting a first number of flip bits and a first number of switching bits that result when the previous data is overwritten by the write data, and counting a second number of flip bits and a second number of switching bits that result when the previous data is overwritten by the modulated write data;
selecting one of the write data and the modulated write data to be selected data based on the first number of flip bits, the first number of switching bits, the second number of flip bits, and the second number of switching bits; and
writing the selected data to the selected memory cells.

2. The data write method of claim 1 , wherein each of the selected memory cells comprises a magnetic tunnel junction element.

3. The data write method of claim 1 , wherein selecting the one of the write data and the modulated write data to be selected data comprises:
subtracting the first number of flip bits from the second number of flip bits to generate a difference value; and
comparing the difference value to a reference value.

4. The data write method of claim 3 , further comprising:
if the difference value is greater than the reference value, selecting the write data as the selected data, else comparing the first number of switching bits to the second number of switching bits.

5. The data write method of claim 4 , further comprising:
if the first number of switching bits is greater than the second number of switching bits, selecting the modulated write data as the selected data, else selecting the write data as the selected data.

6. The data write method of claim 1 , wherein modulating the write data to generate modulated write data comprises using one of a bit reversion modulation scheme, a circular shifting modulation scheme, and a differential modulation scheme to generate the modulated write data from the write data.

7. The data write method of claim 1 , wherein the reading of the previous data stored in the selected memory cells and the modulating of the write data to generate modulated write data are performed at least in part at the same time.

8. A data write method for a nonvolatile memory device, the method comprising:
receiving externally provided write data to be stored in selected memory cells during a write operation;
reading previous data previously stored in the selected memory cells;
modulating the write data using different modulation schemes to generate corresponding sets of modulated write data;
counting respective numbers of flip bits and respective numbers of switching bits that result when the previous data is overwritten by the write data, and by each one of the sets of modulated write data;
selecting the write data or one of the sets of modulated write data as selected data based on the respective numbers of flip bits and the respective numbers of switching bits; and
writing the selected data to the selected memory cells.

9. The data write method of claim 8 , wherein each of the selected memory cells comprises a magnetic tunnel junction element.

10. The data write method of claim 9 , wherein each switching bit is a bit that corresponds to one of the selected memory cells having a magnetization direction for its magnetic tunnel junction element switched from a parallel state to an anti-parallel state when a bit of one of the sets of modulated write data is used to overwrite the memory cell.

Assignees

• Oh Eun Chu
• Kong Junjin
• Yoo Younggeon
• Lee Kijun
• Samsung Electronics Co Ltd

Inventors

• Oh Eun Chu
• Kong Junjin
• Yoo Younggeon
• Lee Kijun

Classifications

• G11C11/2275

  Writing or programming circuits or methods · CPC title

• G11C13/0007

  comprising metal oxide memory material, e.g. perovskites · CPC title

• G11C2029/0411

  Online error correction · CPC title

• G11C7/1006

  Data managing, e.g. manipulating data before writing or reading out, data bus switches or control circuits therefor · CPC title

• G11C2013/0076

  Write operation performed depending on read result · CPC title