Systems and methods for soft decision generation in a solid state memory system

• US 10,298,264 B2
• Filed: 04/09/2018
• Issued: 05/21/2019
• Est. Priority Date: 11/16/2013
• Status: Active Grant

• Current Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Original Assignee: Seagate Technology LLC (Seagate Technology Holdings Plc)
• Inventors: Chen, Zhengang, Wu, Yunxiang, Haratsch, Erich F.
• Primary Examiner(s): Chase, Shelly A
• Application Number:
  US15/948,082
• Publication Number:
  US 20180226991A1
• Time in Patent Office: 407 Days
• 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 11/1072 in multilevel memories
• CPC Class Codes: G11C 29/52 Protection of memory contents; Detection of errors in memory contents
• CPC Class Codes: H03M 13/1111 Soft-decision decoding, e.g. by means of message passing or belief propagation algorithms
• CPC Class Codes: H03M 13/1154 Low-density parity-check convolutional codes [LDPC-CC]

Abstract

Systems and method relating generally to solid state memory, and more particularly to systems and methods for generated data from a solid state memory. A data processing system includes a solid state memory device, a soft data generation circuit operable to receive multiple instances of an element of a read data set accessed from the solid state memory device, and access a scramble compensating extended look up table using the multiple instances of the element to receive corresponding soft data, and a data decoder circuit operable to yield a decoded output from the soft data.

Claims

1. A data storage system, the system comprising:

a solid state memory device;

a soft data generation circuit operable to receive multiple instances of an element of a read data set accessed from the solid state memory device; and

access a scramble compensating extended look up table using the multiple instances of the element to receive corresponding soft data, wherein the scramble compensating extended look up table includes modified soft data values and unmodified soft data values; and

a data decoder circuit operable to yield a decoded output from the soft data.

2. The data storage system of claim 1, wherein the data decoder circuit is operable to apply a soft decoding process to the soft data to yield the decoded output.

3. The data storage system of claim 2, wherein the soft decoding process is a low density parity check decoding process.

4. The data storage system of claim 1, wherein each instance of the element is read using a different reference value.

5. The data storage system of claim 1, wherein the scramble compensating extended look up table includes a number of soft data values corresponding to different possible values for the multiple instances of the element.

6. The data storage system of claim 1, wherein the solid state memory device comprises a single bit per cell flash memory.

7. The data storage system of claim 1, further comprising:

a data de-randomizer circuit operable to de-randomize the soft data, wherein the modified soft data values correspond to soft data modified by the de-randomizer circuit, and wherein the unmodified soft data values correspond to soft data unmodified by the de-randomizer circuit.

8. The data storage system of claim 7, wherein the soft data generation circuit, the data decoder circuit, and the data de-randomizer circuit are hardware circuits.

9. The data storage system of claim 7, wherein the solid state memory device comprises a multi-bit per cell flash memory, wherein the multiple instances of the element includes a first set of instances corresponding to a first bit in a cell of the multi-bit bit per cell flash memory, and a second set of instances of the element corresponds to a second bit in the cell of the multi-bit per cell flash memory.

10. The data storage system of claim 9, wherein the scramble compensating extended look up table includes a first set of soft data values corresponding to different possible values for the first set of instances, and a second set of soft data values corresponding to different possible values for the second set of instances.

11. The data storage system of claim 10, further comprising a data de-randomizer circuit operable to de-randomize the soft data, wherein a first portion of the first set of soft data values corresponds to data unmodified by the de-randomizer circuit, and a second portion of the first set of soft data values corresponds to data modified by the de-randomizer circuit.

12. The data storage system of claim 11, wherein all of the second portion of the first set of soft data values corresponds to data modified by the de-randomizer circuit.

13. The data storage system of claim 11, wherein all of the second portion of the first set of soft data values corresponds to data unmodified by the de-randomizer circuit.

14. A method for recovering data from a solid state memory device, the method comprising:

accessing, via a soft data generation circuit, a cell of a solid state memory device to yield, in conjunction with a data decoder circuit, multiple instances of a read;

accessing, via the soft data generation circuit, a scramble compensating extended look up table using the multiple instances to receive corresponding soft data, wherein the scramble compensating extended look up table includes modified soft data values and unmodified soft data values.

15. The method of claim 14, wherein accessing the cell includes repeatedly accessing the cell using different reference values.

16. The method of claim 14, further comprising:

applying a de-randomizer process using a de-randomizer circuit to each of the multiple instances of the read to yield corresponding de-randomized instances, wherein the modified soft data values correspond to soft data modified by the de-randomizer circuit, and wherein the unmodified soft data values correspond to soft data unmodified by the de-randomizer circuit; and

accessing the scramble compensating extended look up table using the de-randomized instances.

17. The method of claim 14, the method further comprising:

applying a low density parity check decoding process to the soft data to yield a decoded output.

18. The method of claim 14, wherein the scramble compensating extended look up table includes a number of soft data values corresponding to different possible values for the multiple instances of the element.

19. A data storage system, the system comprising:

a memory device;

a soft data generation circuit operable to receive multiple instances of an element of a read data set accessed from the solid state memory device; and

access a scramble compensating extended look up table using the multiple instances of the element to receive corresponding soft data, wherein the scramble compensating extended look up table includes modified soft data values and unmodified soft data values; and

a data decoder circuit operable to yield a decoded output from the soft data, wherein the soft data generation circuit and the data decoder circuit are hardware circuits.

20. The data storage system of claim 19, wherein the data decoder circuit is operable to apply a soft decoding process to the soft data to yield the decoded output.