RESISTIVE PROCESSING UNIT WITH MULTIPLE WEIGHT READERS

• US 20190325291A1
• Filed: 04/20/2018
• Published: 10/24/2019
• Est. Priority Date: 04/20/2018
• Status: Active Grant

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Gokmen, Tayfun, Haensch, Wilfried, Kim, Seyoung
• Granted Patent: US 11,087,204 B2
• Time in Patent Office: Days
• CPC Class Codes: G06N 3/044 Recurrent networks, e.g. Hopfield networks
• CPC Class Codes: G06N 3/045 Combinations of networks
• CPC Class Codes: G06N 3/063 using electronic means
• CPC Class Codes: G06N 3/08 Learning methods
• CPC Class Codes: G06N 3/084 Backpropagation, e.g. using gradient descent
• CPC Class Codes: G06N 3/088 Non-supervised learning, e.g. competitive learning

Abstract

Embodiments of the present invention include a crossbar array that includes a resistive processing unit (RPU) device at each crosspoint in the crossbar array. The RPU device includes a single weight storage element, and multiple weight reader elements. A first weight reader element is coupled with a first row wire to compute a first matrix product value using a first value and a stored value, the first value being transmitted via the first row wire and the stored value being stored in the single weight storage element. A second weight reader element is coupled with a second row wire to compute a second matrix product value of a second value and said stored value, the second value being transmitted via the second row wire.

Claims

1. A crossbar array comprising:

a resistive processing unit (RPU) device at each of a plurality of crosspoints, the RPU device comprising;

a single weight storage element; and

a plurality of weight reader elements comprising;

a first weight reader element that is coupled with a first row wire, the first weight reader configured to compute a first matrix product value using a first value and a stored value, the first value being transmitted via the first row wire and the stored value being stored in the single weight storage element; and

a second weight reader element that is coupled with a second row wire to compute a second matrix product value of a second value and said stored value, the second value being transmitted via the second row wire.

2. The crossbar array of claim 1, wherein the first weight reader element is further coupled to a first column wire, the first matrix product value being transmitted via the first column wire.

3. The crossbar array of claim 2, the first weight reader element configured to compute the first matrix product value by multiplying the first value and the stored value, and adding a sum value being transmitted via the first column wire.

4. The crossbar array of claim 3, wherein the second weight reader element is further coupled to a second column wire, the second matrix product value being transmitted via the second column wire.

5. The crossbar array of claim 4, wherein the second weight reader element is configured to compute the second matrix product value by:

multiplying the second value and the stored value; and

adding a sum value being transmitted via the second column wire.

6. The crossbar array of claim 1, wherein the RPU devices compute corresponding matrix product values concurrently.

7. The crossbar array of claim 1, wherein the RPU devices:

receives column vectors of a first matrix via corresponding row wires; and

stores values of a second matrix that is to be multiplied with the first matrix.

8. A system comprising:

a controller; and

a crossbar array coupled with the controller, the crossbar array configured to perform a matrix-matrix multiplication, the crossbar array receives a first input matrix and a second input matrix from the controller, the crossbar array comprising;

a resistive processing unit (RPU) device at each of a plurality of crosspoints, the RPU device comprising;

a single weight storage element; and

a plurality of weight reader elements comprising;

a first weight reader element that is coupled with a first row wire, the first weight reader configured to compute a first matrix product value using a first value and a stored value, the first value being transmitted via the first row wire and the stored value being stored in the single weight storage element; and

a second weight reader element that is coupled with a second row wire to compute a second matrix product value of a second value and said stored value, the second value being transmitted via the second row wire.

9. The system of claim 8, wherein the first weight reader element is further coupled to a first column wire, the first matrix product value being transmitted via the first column wire.

10. The system of claim 9, the first weight reader element configured to compute the first matrix product value by multiplying the first value and the stored value, and adding a sum value being transmitted via the first column wire.

11. The system of claim 10, wherein the second weight reader element is further coupled to a second column wire, the second matrix product value being transmitted via the second column wire.

12. The system of claim 11, wherein the second weight reader element configured to compute the second matrix product value by:

multiplying the second value and the stored value; and

adding a sum value being transmitted via the second column wire.

13. The system of claim 8, wherein the RPU device computes corresponding matrix product values concurrently.

14. The system of claim 8, wherein the RPU device:

receives column vectors of the first input matrix via corresponding row wires; and

stores values of the second input matrix that is to be multiplied with the first input matrix.

15. A method for performing matrix-matrix multiplication, the method comprising:

receiving, by a crossbar array, a first input matrix and a second input matrix for performing the matrix-matrix multiplication; and

performing the matrix-matrix multiplication by the crossbar array in parallel using a resistive processing unit (RPU) device at each of a plurality of crosspoints, the RPU device comprising;

a single weight storage element; and

a plurality of weight reader elements;

wherein performing the matrix-matrix multiplication comprises;

computing, by a first weight reader element from the plurality of weight readers, the first weight reader element is coupled with a first row wire, a first matrix product value using a first value and a stored value, the first value being transmitted via the first row wire and the stored value being stored in the single weight storage element; and

computing, by a second weight reader element from the plurality of weight readers, the second weight reader element is coupled with a second row wire, a second matrix product value of a second value and said stored value, the second value being transmitted via the second row wire.

16. The method of claim 15, wherein the first weight reader element is further coupled to a first column wire, the first matrix product value being transmitted via the first column wire.

17. The method of claim 16, wherein computing the first matrix product value by the first weight reader element comprises multiplying the first value and the stored value, and adding a sum value being transmitted via the first column wire.

18. The method of claim 17, wherein the second weight reader element is further coupled to a second column wire, the second matrix product value being transmitted via the second column wire.

19. The method of claim 18, wherein computing the second matrix product value by the second weight reader element comprises:

multiplying the second value and the stored value; and

adding a sum value being transmitted via the second column wire.

20. The method of claim 15, wherein the RPU device:

receives column vectors of the first input matrix via corresponding row wires; and

stores values of the second input matrix.