Compact implementation of neuron and synapse with spin switches

Patent metadata

Field	Value
Publication number	US-9864950-B2
Application number	US-201514609359-A
Country	US
Kind code	B2
Filing date	Jan 29, 2015
Priority date	Jan 29, 2014
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A neuron and synapse implementation is disclosed which incorporates a circuit element that includes first and second nanomagnets and first and second fixed magnets. The first nanomagnet is inductively coupled to a first current carrying element, and is configured to change polarity responsive to current in the first current carrying element. In one example, the first current carrying element includes a spin Hall effect substrate. The second nanomagnet is magnetically coupled to the first nanomagnet, and is inductively coupled to a second current carrying element. The first fixed magnet is disposed on the second nanomagnet and has a first fixed polarity, and second fixed magnet disposed on the second nanomagnet and has a second fixed polarity.

First claim

We claim:

1. A circuit element, comprising:
a first nanomagnet inductively coupled to a first current carrying element, the first nanomagnet configured to change polarity responsive to current in the first current carrying element;
a second nanomagnet magnetically coupled to the first nanomagnet and inductively coupled to a second current carrying element;
a first fixed magnet disposed on the second nanomagnet and having a first fixed magnetic polarity;
a second fixed magnet disposed on the second nanomagnet and having a second fixed magnetic polarity opposite to the first fixed magnetic polarity; and
a weighting circuit operably coupled to the first fixed magnet and the second fixed magnet to provide a first voltage to the first fixed magnet and a second voltage to the second fixed magnet, the first and second voltages having opposite electrical polarities.

2. The circuit element of claim 1 , wherein the weighting circuit includes a floating gate voltage regulator.

3. The circuit element of claim 1 , wherein the weighting circuit is formed in a semiconductor layer of a device, and the first nanomagnet and second nanomagnet are formed in a metallization layer of the device.

4. The circuit element of claim 1 , further comprising an input coupled to the first current carrying element, and an output coupled to the second current carrying element.

5. The circuit element of claim 1 , wherein the first current carrying element comprises a giant spin Hall effect material.

6. The circuit element of claim 1 , wherein the first nanomagnet is constructed of CoFeB.

7. The circuit element of claim 1 , further comprising an oxide layer disposed between the first fixed magnet and the second nanomagnet, the oxide layer being further disposed between the second fixed magnet and the second nanomagnet.

8. The circuit element of claim 7 , wherein the first fixed magnet and the oxide layer cooperate to form a first magnetic tunnel junction when the first voltage is applied to the first fixed magnet, and wherein the second fixed magnet and the oxide layer cooperate to form a second magnetic tunnel junction when the second voltage is applied to the second fixed magnet.

9. The circuit element of claim 1 , wherein the second current carrying element is disposed at least in part between the first nanomagnet and the second nanomagnet, and further comprising an insulating layer disposed between the second current carrying element and the first nanomagnet.

10. A plurality of circuit elements including a first circuit element and a first group of at least two circuit elements, each circuit element comprising:
at least a first nanomagnet inductively coupled to a first current carrying element, the first nanomagnet configured to change polarity responsive to current in the first current carrying element;
at least a second nanomagnet magnetically coupled to the first nanomagnet and inductively coupled to a second current carrying element;
at least a first fixed magnet disposed on the second nanomagnet and having a first fixed magnetic polarity; and
at least a second fixed magnet disposed on the second nanomagnet and having a second fixed magnetic polarity opposite to the first fixed magnetic polarity;
wherein the first circuit element includes an input coupled to its first current carrying element, each of the first group of circuit elements includes an output coupled to its respective second current carrying element, each output operably coupled to the input of the first circuit element.

11. The plurality of circuit elements of claim 10 , wherein the first circuit element includes a plurality of first nanomagnets magnetically coupled to a plurality of second nanomagnets.

12. The plurality of circuit elements of claim 11 , wherein at least some of the plurality of first nanomagnets are operably coupled to receive different weighted currents from the output of a first of the first group of circuit elements.

13. The plurality of circuit elements of claim 10 , wherein each of the first group of circuit elements includes a plurality of first nanomagnets magnetically coupled to a plurality of second nanomagnets.

14. The plurality of circuit elements of claim 10 , further comprising a weighting circuit operably coupled to the first fixed magnet and the second fixed magnet to provide a first voltage to the first fixed magnet and a second voltage to the second fixed magnet, the first and second voltages having opposite electrical polarities.

15. The plurality of circuit elements of claim 14 , wherein the weighting circuit includes a floating gate voltage regulator.

16. The plurality of circuit elements of claim 10 , wherein the second current carrying element of each circuit element further comprises a current carrying layer disposed between the first nanomagnet and the second nanomagnet, and each circuit element further comprises an insulating layer disposed between the current carrying layer and the first nanomagnet.

17. The plurality of circuit elements of claim 16 , wherein each circuit element further comprises an oxide layer disposed between the first fixed magnet and the second nanomagnet, the oxide layer being further disposed between the second fixed magnet and the second nanomagnet.

18. The plurality of circuit elements of claim 17 , wherein the first fixed magnet and the oxide layer cooperate to form a first magnetic tunnel junction when a first voltage is applied to the first fixed magnet, and wherein the second fixed magnet and the oxide layer cooperate to form a second magnetic tunnel junction when a second voltage is applied to the second fixed magnet.

19. The plurality of circuit elements of claim 16 , wherein the first current carrying element comprises a giant spin Hall effect material.

20. The plurality of circuit elements of claim 14 , wherein the weighting circuit is formed in a semiconductor layer of a device, and the first nanomagnet and second nanomagnet are formed in a metallization layer of the device.

Assignees

• Purdue Research Foundation

Inventors

• Datta Supriyo
• Sutton Brian
• Diep Vinh Quang
• Behin-Aein Behtash

Classifications

• G11C11/1673

  Reading or sensing circuits or methods · CPC title

• G11C11/161

  details concerning the memory cell structure, e.g. the layers of the ferromagnetic memory cell · CPC title

• G11C11/18

  using Hall-effect devices · CPC title

• G11C11/54

  using elements simulating biological cells, e.g. neuron · CPC title

• G11C11/1675

  Writing or programming circuits or methods · CPC title