Magnetic Memory and Method for Using the Same

• US 20200135250A1
• Filed: 10/31/2018
• Published: 04/30/2020
• Est. Priority Date: 10/31/2018
• Status: Active Grant

• Current Assignee: Avalanche Technology Incorporated
• Original Assignee: Avalanche Technology Incorporated
• Inventors: Nobunaga, Dean K., Abedifard, Ebrahim
• Granted Patent: US 10,832,751 B2
• Time in Patent Office: Days
• CPC Class Codes: G11C 11/00 Digital stores characterised by the use of particular electric or magnetic storage elements; Storage elements therefor G11C14/00 - G11C21/00 take precedence
• CPC Class Codes: G11C 11/161 details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell
• CPC Class Codes: G11C 11/1659 Cell access
• CPC Class Codes: G11C 11/1673 Reading or sensing circuits or methods
• CPC Class Codes: G11C 11/1675 Writing or programming circuits or methods
• CPC Class Codes: G11C 11/1677 Verifying circuits or methods
• CPC Class Codes: G11C 11/1693 Timing circuits or methods
• CPC Class Codes: G11C 11/1697 Power supply circuits
• CPC Class Codes: G11C 13/003 Cell access
• CPC Class Codes: G11C 13/004 Reading or sensing circuits or methods
• CPC Class Codes: G11C 13/0061 Timing circuits or methods
• CPC Class Codes: G11C 13/0064 Verifying circuits or methods
• CPC Class Codes: G11C 2013/0054 Read is performed on a reference element, e.g. cell, and the reference sensed value is used to compare the sensed value of the selected cell
• CPC Class Codes: G11C 2013/0076 Write operation performed depending on read result
• CPC Class Codes: G11C 2213/76 Array using an access device for each cell which being not a transistor and not a diode

Abstract

The present invention is directed to a memory circuitry that includes a magnetic memory element and a selector coupled in series between a first conductive line and a second conductive line; a current detector coupled to the second conductive line; and a means for supplying a sufficiently high voltage to the first conductive line for turning on the selector. When the selector turns on, the current detector detects a current flowing across the selector and effectuates a current limiter to reduce the current while maintaining the selector on. The memory circuitry may be operated by applying a sufficiently high voltage to the first conductive line for turning on the selector; reducing a current flowing through the selector while maintaining the sufficiently high voltage on the first conductive line; and determining a resistance state of the magnetic memory element.

Claims

1. A memory circuit including:

a magnetic memory element and a selector coupled in series between a first conductive line and a second conductive line;

a current detector coupled to the second conductive line; and

a means for supplying a sufficiently high voltage to the first conductive line for turning on the selector,

wherein when the selector turns on, the current detector detects a current flowing across the selector and effectuates a current limiter to reduce the current to prevent switching of the magnetic memory element while the selector remains on.

2. The memory circuit of claim 1, wherein the current detector includes a current mirror.

3. The memory circuit of claim 1, wherein the current detector includes a latch.

4. The memory circuit of claim 1, wherein the current limiter is coupled to the first conductive line.

5. The memory circuit of claim 1, wherein the current limiter is a current source.

6. The memory circuit of claim 1, wherein the magnetic memory element includes a magnetic reference layer and a magnetic free layer with an insulating tunnel junction layer interposed therebetween.

19. The memory circuit of claim 1, wherein the selector is a volatile threshold-switching device.

7. A method for operating a magnetic memory element and a selector coupled in series between a first conductive line and a second conductive line, the method comprising the steps of:

applying a sufficiently high voltage to the first conductive line for turning on the selector without switching the magnetic memory element;

reducing a current flowing through the selector to further prevent switching of the magnetic memory element while maintaining the selector on; and

determining a resistance state of the magnetic memory element after reducing the current,

wherein the selector is a volatile threshold-switching device.

8. The method of claim 7, wherein the magnetic memory element includes a magnetic reference layer and a magnetic free layer with an insulating tunnel junction layer interposed therebetween.

9. The method of claim 7, wherein the step of determining the resistance state of the magnetic memory element is carried out by measuring a voltage of the second conductive line.

10. The method of claim 7, wherein the step of reducing the current flowing through the selector is accomplished by a current limiter.

11. The method of claim 10, wherein the current limiter is a current source.

12. The method of claim 7 further comprising the step of switching the resistance state of the magnetic memory element by maintaining the sufficiently high voltage on the first conductive line without limiting the current after determining the resistance state of the magnetic memory element.

13. The method of claim 12 further comprising the steps of reducing the current flowing through the selector and determining the resistance state of the magnetic memory element after switching the resistance state of the magnetic memory element.

14. A method for operating a magnetic memory element and a selector coupled in series between a first conductive line and a second conductive line, the method comprising the steps of:

applying a sufficiently high voltage to the first conductive line for turning on the selector and switching a resistance state of the magnetic memory element;

reducing a current flowing through the selector while maintaining the selector on after switching the resistance state of the magnetic memory element; and

determining the resistance state of the magnetic memory element after reducing the current.

15. The method of claim 14, wherein the magnetic memory element includes a magnetic reference layer and a magnetic free layer with an insulating tunnel junction layer interposed therebetween.

16. The method of claim 14, wherein the step of determining the resistance state of the magnetic memory element is carried out by measuring a voltage of the second conductive line.

17. The method of claim 14, wherein the step of reducing the current flowing through the selector is accomplished by a current limiter coupled to the first conductive line.

18. The method of claim 14, wherein the current limiter is a current source.