Granted Patent B2

US 10,580,485 · App. 15/849,572 · Granted Mar 3, 2020

Abstract

Claims (80)

1. A method comprising:

receiving a request to perform a memory access operation on a wordline of non-volatile memory;

selecting a bias equation corresponding to the wordline of the non-volatile memory from a group of bias equations;

determining a bias value based on the selected bias equation and the wordline;

adjusting a read level in the non-volatile memory based on the bias value; and

performing the memory access operation on the wordline of the non-volatile memory using the adjusted read level,

wherein the bias value is not generated or stored prior to selecting the bias equation,

wherein the group of bias equations corresponds to a plurality of wordline address zones, each bias equation of the group corresponding to a respective zone of the plurality of wordline address zones,

wherein the bias equation, for the respective zone, is one of:

a constant bias value, for the respective zone, calculated from averaging read thresholds within a respective zone of the plurality of wordline address zones;

a linear equation, for the respective zone, having a slope and an endpoint bias value; or

an equation, for the respective zone, having a higher order than the linear equation.

2. The method of claim 1 , wherein the bias equation is the linear equation.

3. The method of claim 1 , wherein selecting the bias equation further comprises determining a wordline address zone of the plurality of wordline address zones containing an address of the wordline.

4. The method of claim 3 , further comprising:

determining that a recalibration condition has been triggered;

determining endpoint bias values for each of the plurality of wordline address zones; and

adjusting the group of bias equations based on the determined endpoint bias values for each of the plurality of wordline address zones.

5. The method of claim 4 , wherein the recalibration condition comprises the non-volatile memory transitioning from a first operating temperature range into a second operating temperature range.

6. The method of claim 1 , further comprising:

selecting the group of bias equations from a plurality of groups of bias equations corresponding to a block group of the non-volatile memory containing the wordline.

7. The method of claim 1 , wherein the non-volatile memory is a NAND flash memory.

8. A non-transitory machine-readable medium including machine-executable instructions thereon that, when executed by a processor, perform a method comprising:

receiving a request to perform a memory access operation on a wordline of non-volatile memory;

selecting a bias equation corresponding to the wordline of the non-volatile memory from a group of bias equations;

determining a bias value based on the selected bias equation and the wordline;

adjusting a read level in the non-volatile memory based on the bias value; and

performing the memory access operation on the wordline of the non-volatile memory using the adjusted read level,

wherein the bias value is not generated or stored prior to selecting the bias equation,

wherein the group of bias equations corresponds to a plurality of wordline address zones,

wherein the bias equation is one of:

a constant bias value calculated based on read thresholds within a respective zone of the plurality of wordline address zones;

a linear equation having a slope and an endpoint bias value; or

an equation having a higher order than the linear equation.

9. The non-transitory machine-readable medium of claim 8 , wherein the bias equation is a linear function.

10. The non-transitory machine-readable medium of claim 8 , wherein selecting the bias equation further comprises determining a wordline address zone of the plurality of wordline address zones containing an address of the wordline.

11. The non-transitory machine-readable medium of claim 10 , wherein the method further comprises:

determining that a recalibration condition has been triggered;

determining endpoint bias values for each of the plurality of wordline address zones; and

adjusting the group of bias equations based on the determined endpoint bias values for each of the plurality of wordline address zones.

12. The non-transitory machine-readable medium of claim 11 , wherein the recalibration condition comprises the non-volatile memory transitioning from a first operating temperature range into a second operating temperature range.

13. The non-transitory machine-readable medium of claim 8 , wherein the method further comprises:

selecting the group of bias equations from a plurality of groups of bias equations corresponding to a block group of the non-volatile memory containing the wordline.

14. The non-transitory machine-readable medium of claim 8 , wherein the non-volatile memory is a NAND flash memory.

15. A system, comprising:

a processor;

a non-volatile memory;

a memory media having instructions stored thereon that, when executed by the processor, cause the processor to:

receive a request to perform a memory access operation on a wordline of the non-volatile memory;

select a bias equation corresponding to the wordline of the non-volatile memory from a group of bias equations;

determine a bias value based on the selected bias equation and the wordline;

adjust a read level in the non-volatile memory based on the bias value; and

perform the memory access operation on the wordline of the non-volatile memory using the adjusted read level,

wherein the bias value is not generated or stored in the memory media prior to selecting the bias equation,

wherein the group of bias equations corresponds to a plurality of wordline address zones,

wherein the bias equation is one of:

a constant bias value calculated based on read thresholds within a respective zone of the plurality of wordline address zones;

a linear equation having a slope and an endpoint bias value; or

an equation having a higher order than the linear equation.

16. The system of claim 15 , wherein the bias equation is a linear function.

17. The system of claim 15 , wherein selecting the bias equation further comprises determining a wordline address zone of the plurality of wordline address zones containing an address of the wordline.

18. The system of claim 17 , wherein the instructions are further configured to cause the processor to:

determine that a recalibration condition has been triggered;

determine endpoint bias values for each of the plurality of wordline address zones; and

adjust the group of bias equations based on the determined endpoint bias values for each of the plurality of wordline address zones.

19. The system of claim 18 , wherein the recalibration condition comprises the non-volatile memory transitioning from a first operating temperature range into a second operating temperature range.

20. The system of claim 15 , wherein the instructions are further configured to cause the processor to:

select the group of bias equations from a plurality of groups of bias equations corresponding to a block group of the non-volatile memory containing the wordline.

21. The system of claim 15 , wherein the non-volatile memory is a NAND flash memory.

22. A system comprising:

one or more controllers, wherein the one or more controllers comprise: means for receiving a request to perform a memory access operation on a wordline of non-volatile memory; means for selecting a bias equation corresponding to the wordline of the non-volatile memory from a group of bias equations; means for determining a bias value based on the selected bias equation and the wordline;

means for adjusting a read level in the non-volatile memory based on the bias value; and

means for performing the memory access operation on the wordline of the non-volatile memory using the adjusted read level, wherein the bias value is not generated or stored in the system prior to selecting the bias equation, wherein the group of bias equations corresponds to a plurality of wordline address zones, wherein the bias equation is one of: a constant bias value calculated based on read thresholds within a respective zone of the plurality of wordline address zones; a linear equation having a slope and an endpoint bias value; or an equation having a higher order than the linear equation.

23. The system of claim 22 , wherein the bias equation is a linear function.

24. The system of claim 22 , wherein the means for selecting the bias equation further comprises means for determining a wordline address zone of the plurality of wordline address zones containing an address of the wordline.

25. The system of claim 24 , wherein the one or more controllers further comprise: means for determining that a recalibration condition has been triggered; means for determining endpoint bias values for each of the plurality of wordline address zones; and

means for adjusting the group of bias equations based on the determined endpoint bias values for each of the plurality of wordline address zones.

26. The system of claim 25 , wherein the recalibration condition comprises the non-volatile memory transitioning from a first operating temperature range into a second operating temperature range.

27. The system of claim 22 , wherein the one or more controllers further comprise: means for selecting the group of bias equations from a plurality of groups of bias equations corresponding to a block group of the non-volatile memory containing the wordline.

28. The system of claim 22 , wherein the non-volatile memory is a NAND flash memory.

Assignments (10)