Memory with an assist determination controller and associated methods

• US 8,982,651 B2
• Filed: 03/28/2013
• Issued: 03/17/2015
• Est. Priority Date: 03/28/2013
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Inventors: Grover, Anuj, Visweswaran, Gangaikondan Subramani
• Primary Examiner(s): PHAN, TRONG Q
• Application Number:
  US13/852,222
• Publication Number:
  US 20140293723A1
• Time in Patent Office: 719 Days
• Field of Search: 365/205, 365/210.1
• US Class Current: 365/205
• CPC Class Codes: G11C 11/419 Read-write [R-W] circuits
• CPC Class Codes: G11C 17/18 Auxiliary circuits, e.g. for writing into memory
• CPC Class Codes: G11C 7/06 Sense amplifiers; Associated circuits , e.g. timing or triggering circuits
• CPC Class Codes: G11C 7/14 Dummy cell management; Sense reference voltage generators

Abstract

A memory includes an array of active memory cells arranged in rows and columns, and at least one dummy memory cell column adjacent the array of active memory cells. A sensing circuit is coupled to the at least one dummy memory cell column to sense at least one variation associated with the at least one dummy memory cell column. An assist circuit is coupled to the array of active memory cells. An assist determination controller is coupled to the sensing circuit to store a look-up table of output assist values corresponding to different variations associated with the at least one dummy memory cell column, to determine an output assist value from the look-up table based upon the at least sensed variation, and to operate the assist circuit based upon the determined output assist value.

Claims

1. A memory comprising:

an array of active memory cells arranged in rows and columns;

at least one dummy memory cell column adjacent said array of active memory cells;

a sensing circuit coupled to said at least one dummy memory cell column and configured to sense at least one variation associated with said at least one dummy memory cell column;

an assist circuit coupled to said array of active memory cells; and

an assist determination controller coupled to said sensing circuit and configured to

store a look-up table of output assist values corresponding to different variations associated with said at least one dummy memory cell column,

determine an output assist value from the look-up table based upon the at least sensed variation, and

operate said assist circuit based upon the determined output assist value.

2. The memory according to claim 1 wherein said at least one dummy memory cell column comprises:

a plurality of programmable discharge memory devices, with each programmable discharge memory device comprising at least one discharge transistor; and

a plurality of programmable load memory devices, with each programmable load memory device comprising at least one load transistor.

3. The memory according to claim 2 wherein said at least one dummy memory cell column comprises:

at least one sense line coupled to said plurality of programmable discharge memory devices and to said plurality of programmable load memory devices;

at least one activation line coupled to said plurality of programmable discharge memory devices;

at least one programmable discharge programming line coupled to said plurality of programmable discharge memory devices; and

at least one programmable load programming line coupled to said plurality of programmable load memory devices.

4. The memory according to claim 3 wherein said at least one sense line is coupled to said plurality of programmable discharge memory devices via said respective discharge transistors, and to said plurality of programmable load memory devices via said respective load transistors.

5. The memory according to claim 3 wherein said assist determination controller is configured to:

program said plurality of programmable discharge memory devices via said at least one programmable discharge programming line; and

program said plurality of programmable load memory devices via said at least one programmable load programming line.

6. The memory according to claim 3 wherein said assist determination controller is configured to:

activate said plurality of programmable discharge memory devices; and

activate said sensing circuit at a set time after activation of said plurality programmable discharge memory devices to sense the at least one variation associated with said at least one dummy memory cell column.

7. The memory according to claim 2 wherein each programmable discharge memory device comprises at least one memory transistor;

and wherein said at least one discharge transistor is configured as an access transistor coupled to said at least one memory transistor.

8. The memory according to claim 2 wherein each programmable discharge memory device comprises at least one additional transistor;

and wherein said at least one discharge transistor is coupled to said at least one additional transistor to define a pair of pull-up devices.

9. The memory according to claim 2 wherein said at least one discharge transistor is configured as a pull-down device.

10. The memory according to claim 1 wherein the at least one variation comprises at least one of a process variation, a voltage variation, a temperature variation, and a leakage current variation.

11. The memory according to claim 1 wherein said assist determination controller is configured to periodically determine the output assist value, and to periodically operate said assist circuit based upon the determined output assist value.

12. The memory according to claim 1 wherein said assist determination controller is configured to store the look-up table of output assist values further based on different operating voltages.

13. The memory according to claim 1 wherein said array of active memory cells is configured so that the memory is a static memory.

14. A static memory comprising:

an array of active memory cells arranged in rows and columns;

at least one dummy memory cell column adjacent said array of active memory cells and comprising

a plurality of programmable discharge memory devices, with each programmable discharge memory device comprising at least one discharge transistor, and

a plurality of programmable load memory devices, with each load memory device comprising at least one load transistor;

a sensing circuit coupled to said at least one dummy memory cell column and configured to sense at least one variation associated with said at least one dummy memory cell column;

an assist circuit coupled to said array of active memory cells; and

an assist determination controller coupled to said sensing circuit and configured to

store a look-up table of output assist values corresponding to different variations associated with said at least one dummy memory cell column,

determine an output assist value from the look-up table based upon the at least sensed variation, and

operate said assist circuit based upon the determined output assist value.

15. The static memory according to claim 14 wherein said at least one dummy memory cell column comprises:

at least one sense line coupled to said plurality of programmable discharge memory devices and to said plurality of programmable load memory devices;

at least one activation line coupled to said plurality of programmable discharge memory devices;

at least one programmable discharge programming line coupled to said plurality of programmable discharge memory devices; and

at least one programmable load programming line coupled to said plurality of programmable load memory devices.

16. The static memory according to claim 15 wherein said at least one sense line is coupled to said plurality of programmable discharge memory devices via said respective discharge transistors, and to said plurality of programmable load memory devices via said respective load transistors.

17. The static memory according to claim 15 wherein said assist determination controller is configured to:

activate said plurality of programmable discharge memory devices; and

activate said sensing circuit at a set time after activation of said plurality programmable discharge memory devices to sense the at least one variation associated with said at least one dummy memory cell column.

18. The static memory according to claim 14 wherein the at least one variation comprises at least one of a process variation, a voltage variation, a temperature variation, and a leakage current variation.

19. A method for operating a memory comprising an array of active memory cells arranged in rows and columns;

at least one dummy memory cell column adjacent the array of active memory cells;

a sensing circuit coupled to the at least one dummy memory cell column;

an assist circuit coupled to the array of active memory cells; and

an assist determination controller coupled to the sensing circuit and configured to store a look-up table of output assist values corresponding to different variations associated with the at least one dummy memory cell column, the method comprising;

operating the sensing circuit to sense at least one variation associated with the at least one dummy memory cell column; and

operating the assist determination controller to

determine an output assist value from the look-up table based upon the at least sensed variation, and

operate the assist circuit based upon the determined output assist value.

20. The method according to claim 19 wherein the at least one dummy memory cell column comprises a plurality of programmable discharge memory devices, with each programmable discharge memory device comprising at least one discharge transistor;

and a plurality of programmable load memory devices, with each programmable load memory device comprising at least one load transistor.

21. The method according to claim 20 wherein the at least one dummy memory cell column comprises:

at least one sense line coupled to the plurality of programmable discharge memory devices and to the plurality of programmable load memory devices;

at least one activation line coupled to the plurality of programmable discharge memory devices;

at least one programmable discharge programming line coupled to the plurality of programmable discharge memory devices; and

at least one programmable load programming line coupled to the plurality of programmable load memory devices.

22. The method according to claim 21 wherein the at least one sense line is coupled to the plurality of programmable discharge memory devices via the respective discharge transistors, and to the plurality of programmable load memory devices via the respective load transistors.

23. The method according to claim 21 wherein operating the assist determination controller further comprises:

programming the plurality of programmable discharge memory devices via the at least one programmable discharge programming line; and

programming the plurality of programmable load memory devices via the at least one programmable load programming line.

24. The method according to claim 21 wherein operating the assist determination controller further comprises:

activating the plurality of programmable discharge memory devices; and

activating the sensing circuit at a set time after activation of the plurality programmable discharge memory devices to sense the at least one variation associated with the at least one dummy memory cell column.

25. The method according to claim 19 wherein the at least one variation comprises at least one of a process variation, a voltage variation, a temperature variation, and a leakage current variation.

26. The method according to claim 19 wherein the assist determination controller is operated to periodically determine the output assist value, and to periodically operate the assist circuit based upon the determined output assist value.