Systems and methods for soft data utilization in a solid state memory system

• US 9,575,832 B2
• Filed: 12/01/2015
• Issued: 02/21/2017
• Est. Priority Date: 10/21/2013
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Wu, Yunxiang, Cai, Yu, Haratsch, Erich F.
• Primary Examiner(s): Ton, David
• Application Number:
  US14/956,162
• Publication Number:
  US 20160085623A1
• Time in Patent Office: 448 Days
• US Class Current: 1/1
• CPC Class Codes: G06F 11/1008 in individual solid state devices G06F11/1004 takes precedence
• CPC Class Codes: G06F 11/1012 using codes or arrangements adapted for a specific type of error G06F11/1048 takes precedence
• CPC Class Codes: G06F 11/1068 in sector programmable memories, e.g. flash disk G06F11/1072 takes precedence
• CPC Class Codes: H03M 13/1111 Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms
• CPC Class Codes: H03M 13/45 Soft decoding, i.e. using symbol reliability information H03M13/41 takes precedence
• CPC Class Codes: H03M 13/611 Specific encoding aspects, e.g. encoding by means of decoding

Abstract

Systems and methods relating generally to solid state memory, and more particularly to systems and methods for recovering data from a solid state memory. An example data processing system includes a first circuit operable to yield a modified soft data set from a data set accessed from a solid state memory device, and a second circuit operable to apply a data decoding algorithm to the modified soft data to yield a decoded output.

Claims

1. A data processing system, the system comprising:

a first circuit operable to yield a modified soft data set from a data set accessed from a solid state memory device, wherein the first circuit is operable to apply a non-uniform transfer function to yield the modified soft data set; and

a second circuit operable to apply a data decoding algorithm to the modified soft data to yield a decoded output.

2. The data processing system of claim 1, wherein the data decoding algorithm is a low density parity check decoding algorithm.

3. The data processing system of claim 1, wherein the non-uniform transfer function is operable to decrease a probability indicated by a first portion of an original soft data corresponding to the data set, and to increase a probability indicating by a second portion of the original soft data.

4. The data processing system of claim 3, wherein the first portion of the original soft data exhibits a lower probability than the second portion of the original soft data.

5. The data processing system of claim 1, wherein an original soft data corresponding to the data set includes a first number of bits per element, wherein the modified soft data set includes a second number of bits per element, wherein the first circuit is operable to apply a non-uniform transfer function to yield an interim data set, and wherein the first circuit is further operable to force the value of any element of the interim data set that falls outside of a range of the second number of bits per element to equal a nearest extreme of a range to yield the modified soft data set.

6. The data processing system of claim 1, wherein the data processing system is implemented in an integrated circuit.

7. The data processing system of claim 1, wherein the data processing system further comprises:

the solid state memory device operable to maintain the data set; and

wherein the data processing system including the solid state memory device is implemented on an integrated circuit.

8. The data processing system of claim 7, wherein the solid state memory device is a flash memory device.

9. The data processing system of claim 8, wherein the flash memory device is able to hold multiple bits of data in each memory cell of the flash memory device.

10. The data processing system of claim 1, wherein the first circuit comprises a soft data modification circuit, and the second circuit comprises a data decoder circuit, and the system further comprises:

a soft data generation circuit operable to generate an original soft data corresponding to the data set.

11. A method for recovering data from a memory, the method comprising:

generating a modified soft data set from an original soft data using a transfer function, the original soft data corresponding to a data set received from a memory device; and

generating a decoded output from the modified soft data set using a data decoding algorithm.

12. The method of claim 11, wherein the data decoding algorithm is a low density parity check decoding algorithm.

13. The method of claim 11, wherein the transfer function is a non-uniform transfer function.

14. The method of claim 13, wherein the non-uniform transfer function is operable to decrease a probability indicated by a first portion of the original soft data, and to increase a probability indicating by a second portion of the original soft data.

15. The method of claim 14, wherein the first portion of the original soft data exhibits a lower probability than the second portion of the original soft data.

16. The method of claim 11, wherein the original soft data includes a first number of bits per element, the modified soft data set includes a second number of bits per element, the transfer function is a non-uniform transfer function that yields an interim data set, and generating a modified soft data set comprises:

applying the non-uniform transfer function to the original soft data to generate an interim data set; and

forcing any element of the interim data set that falls outside of a range of the second number of bits per element to equal a nearest extreme of a range to yield the modified soft data set.

17. The method of claim 11, wherein the memory device is a flash memory device.

18. The method of claim 17, wherein the flash memory device is able to hold multiple bits of data in each memory cell of the flash memory device.

19. A memory system comprising:

a solid state memory device operable to maintain a data set;

a first circuit operable to generate original soft data corresponding to the data set;

a second circuit operable to generate a modified soft data set from the original soft data using a non-uniform transfer function, the original soft data corresponding to a data set received from the solid state memory device;

a third circuit operable to apply a data decoding algorithm to the modified soft data to yield a decoded output.