Methods for efficient 3D SRAM-based compute-in-memory

1. A computing device, comprising:

a first array of compute units arranged on a first substrate, the first array of compute units including a first plurality of compute-in-memory (CIM) modules;

a first array of routers configured to route information horizontally among the first array of compute units on the first substrate;

a second array of compute units arranged on a second substrate, the second array of compute units including a second plurality of CIM modules, wherein the second substrate is disposed vertically from the first substrate; and

a second array of routers configured to route the information horizontally among the second array of compute units on the second substrate;

wherein the first array of routers and the second array of routers send the information vertically between the first substrate and the second substrate.

2. The computing device of claim 1 , wherein each of the first array of routers includes an in-plane portion having plurality of horizontal routing connections coupled with a portion of the first plurality of CIM modules and an out-of-plane portion.

3. The computing device of claim 2 , wherein the out-of-plane portion includes at least one inductive coupling interface.

4. The computing device of claim 3 , wherein the out-of-plane portion further includes a serializer/deserializer and a modulator/demodulator for sending and receiving the information.

5. The computing device of claim 3 , wherein the out-of-plane portion is coupled between a compute unit of the first array of compute units and the in-plane portion.

6. The computing device of claim 3 , wherein the plurality of horizontal routing connections includes not more than five horizontal routing connections.

7. The computing device of claim 1 , wherein each router of the first array of routers and the second array of routers includes an in-plane portion having plurality of horizontal routing connections and an out-of-plane portion, the out-of-plane portion including at least one inductive coupling interface.

8. The computing device of claim 1 , wherein a portion of the first array of routers includes an in-plane portion having plurality of horizontal routing connections coupled with a portion of the first plurality of CIM modules and an out-of-plane portion, the out-of-plane portion including at least one inductive coupling interface.

9. The computing device of claim 1 , wherein a CIM module of the first plurality of CIM modules includes a plurality of storage cells storing data corresponding to a matrix and logic for performing a vector-matrix multiplication (VMM) of the matrix.

10. The computing device of claim 9 , wherein the plurality of storage cells includes a plurality of SRAM cells.

11. The computing device of claim 1 , wherein each of the first array of compute units includes a tile having a general purpose processor and a portion of the plurality of CIM modules.

12. The computing device of claim 1 , further comprising:

a third array of compute units arranged on a third substrate, wherein the third substrate is disposed vertically from the first substrate and from the second substrate; and

a third array of routers configured to route the information horizontally among the third array of compute units on the third substrate;

wherein the first array of routers, the second array of routers, and the third array of routers send information vertically between the first substrate, the second substrate, and the third substrate.

13. A computing system, comprising:

a plurality of layers, each of the plurality of layers including a plurality of compute units and a plurality of routers arranged on a substrate, the plurality of compute units including a plurality of compute-in-memory (CIM) modules, the plurality of routers configured to route information horizontally among the plurality of compute units on the substrate, at least a portion of the plurality of routers being configured to wirelessly send the information vertically between the plurality of layers.

14. The computing system of claim 13 , wherein the at least the portion of the plurality of routers are configured to inductively send the information vertically between the plurality of layers.

15. The computing system of claim 14 , wherein each of the at least the portion of the plurality of routers includes at least one inductive coupling interface.

16. The computing system of claim 15 , wherein each of the at least the portion of the plurality of routers includes an in-plane portion having plurality of horizontal routing connections coupled with a portion of the plurality of CIM modules.

17. A method comprising:

transmitting information from a first compute unit of a first array of compute units to a first router of a first array of routers, the first array of compute units and the first array of routers being arranged on a first substrate, the first array of compute units including a first plurality of compute-in-memory (CIM) modules; and

wirelessly sending the information from the first router to a second router of a second array of routers, the second array of routers and a second array of compute units being arranged on a second substrate, the second array of compute units including a second plurality of CIM modules, wherein the second substrate is disposed vertically from the first substrate,

wherein the first array of routers horizontally between the first array of compute units and the second array of routers are configured to send data horizontally between the second array of compute units.

18. The method of claim 17 , further comprising:

sending the information from the second router to a second compute unit in the second array of compute units.

19. The method of claim 17 , further comprising:

serializing, by the first router, the information from the first compute unit to provide serialized information; and

modulating, by the first router, the serialized information to provide modulated, serialized information;

wherein the wirelessly sending the information includes wirelessly sending the modulated, serialized information by the first router, the first router being inductively coupled with the second router.

20. The method of claim 19 , further comprising

demodulating, by the second router, the modulated, serialized information to provide the serialized information at the second router; and

deserializing, by the second router, the serialized information.