Generating soft read values using multiple reads and/or bins

Patent metadata

Field	Value
Publication number	US-9269448-B2
Application number	US-201313747329-A
Country	US
Kind code	B2
Filing date	Jan 22, 2013
Priority date	Jan 27, 2012
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

A starting read threshold is received. A first offset and a second offset is determined. A first read is performed at the starting read threshold offset by the first offset to obtain a first hard read value and a second read is performed at the starting read threshold offset by the second offset to obtain a second hard read value. A soft read value is generated based at least in part on the first hard read value and the second hard read value.

First claim

What is claimed is:

1. A system for generating a soft read value, comprising:
a read threshold generator configured to:
receive a starting read threshold; and
determine a first offset and a second offset, wherein determining the first offset is based at least in part on the age of data associated with the first read and a second read;

a storage read interface configured to:
perform the first read at the starting read threshold offset by the first offset to obtain a first hard read value; and
perform the second read at the starting read threshold offset by the second offset to obtain a second hard read value; and

a soft information generator configured to generate a soft read value based at least in part on the first hard read value and the second hard read value.

2. The system of claim 1 , wherein the system includes a semiconductor device, including one or more of the following: an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

3. The system of claim 1 further comprising solid state storage, wherein the storage read interface is configured to read the solid state storage.

4. A system, for generating a soft read value, comprising:
a solid state storage, wherein a storage read interface is configured to read the solid state storage;
a read threshold generator configured to:
receive a starting read threshold; and
determine a first offset and a second offset, wherein determining the first offset includes one or more of the following: (1) basing the first offset at least in part on the age of the solid state storage or (2) accessing a table which includes a plurality of potential first offsets, where the table is indexed by the age of data associated with the first read and the second read and by the age of the solid state storage;

the storage read interface which is configured to:
perform a first read at the starting read threshold offset by the first offset to obtain a first hard read value; and
perform a second read at the starting read threshold offset by the second offset to obtain a second hard read value; and

a soft information generator configured to generate a soft read value based at least in part on the first hard read value and the second hard read value.

5. The system of claim 1 , wherein:
the storage read interface is further configured to read a plurality of cells at the starting read threshold offset by the first offset to obtain a measured percentage of hard read values; and
the read threshold generator is configured to determine the second offset, including by compensating based at least in part on the measured percentage of hard read values and an expected percentage of hard read values.

6. A method for generating a soft read value, comprising:
receiving a starting read threshold;
using a read threshold generator to determine a first offset and a second offset, wherein determining the first offset is based at least in part on the age of data associated with the first read and the second read;
using a storage read interface to perform a first read at the starting read threshold offset by the first offset to obtain a first hard read value;
using the storage read interface to perform a second read at the starting read threshold offset by the second offset to obtain a second hard read value; and
using a soft information generator to generate a soft read value based at least in part on the first hard read value and the second hard read value.

7. A method for generating a soft read value, comprising:
receiving a starting read threshold;
using a read threshold generator to determine a first offset and a second offset, wherein determining the first offset includes one or more of the following: (1) basing the first offset at least in part on the age of the solid state storage or (2) accessing a table which includes a plurality of potential first offsets, where the table is indexed by the age of data associated with the first read and the second read and by the age of the solid state storage;
using a storage read interface to perform a first read at the starting read threshold offset by the first offset to obtain a first hard read value;
using the storage read interface to perform a second read at the starting read threshold offset by the second offset to obtain a second hard read value; and
using a soft information generator to generate a soft read value based at least in part on the first hard read value and the second hard read value.

8. The system of claim 4 , wherein the system includes a semiconductor device, including one or more of the following: an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

9. The method of claim 6 , wherein the method is performed by a semiconductor device, including one or more of the following: an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

10. The method of claim 7 , wherein the method is performed by a semiconductor device, including one or more of the following: an application-specific integrated circuit (ASIC) or a field-programmable gate array (FPGA).

11. The system of claim 4 further comprising solid state storage, wherein the storage read interface is configured to read the solid state storage.

12. The system of claim 4 , wherein:
the storage read interface is further configured to read a plurality of cells at the starting read threshold offset by the first offset to obtain a measured percentage of hard read values; and
the read threshold generator is configured to determine the second offset, including by compensating based at least in part on the measured percentage of hard read values and an expected percentage of hard read values.

13. The method of claim 6 further comprising:
using the storage read interface to read a plurality of cells at the starting read threshold offset by the first offset to obtain a measured percentage of hard read values; and
using the read threshold generator to determine the second offset, including by compensating based at least in part on the measured percentage of hard read values and an expected percentage of hard read values.

14. The method of claim 7 further comprising:
using the storage read interface to read a plurality of cells at the starting read threshold offset by the first offset to obtain a measured percentage of hard read values; and
using the read threshold generator to determine the second offset, including by compensating based at least in part on the measured percentage of hard read values and an expected percentage of hard read values.

Assignees

• Link—A—Media Devices Corp
• Sk Hynix Memory Solutions Inc

Inventors

• Tang Xiangyu
• Lee Frederick K H
• Bellorado Jason
• Subramanian Arunkumar
• Zeng Lingqi

Classifications

• G06F11/1048

  using arrangements adapted for a specific error detection or correction feature · CPC title

• H03M13/1102

  Codes on graphs and decoding on graphs, e.g. low-density parity check [LDPC] codes · CPC title

• G11C16/3431

  Circuits or methods to detect disturbed nonvolatile memory cells, e.g. which still read as programmed but with threshold less than the program verify threshold or read as erased but with threshold greater than the erase verify threshold, and to reverse the disturbance via a refreshing programming or erasing step · CPC title

• G11C16/34

  Determination of programming status, e.g. threshold voltage, overprogramming or underprogramming, retention · CPC title

• G06F11/1072

  in multilevel memories · CPC title