3D Stacked Memory ASIC for Neural Network Data Access

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Solution Overview

Problem

Complex artificial neural networks require fast and efficient access to high-performance memory for both training and inference, but existing architectures often suffer from inefficiencies in connection distances and communication between processing elements and memory, limiting performance and efficiency.

Innovation Solution

The proposed solution involves an application-specific integrated circuit (ASIC) with an architecture that minimizes connection distances between processing elements and memory, supporting concurrent forward and back propagation through a systolic array architecture with interconnected processing tiles and staging buffers, enabling efficient communication and data flow for neural network operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If existing memory architectures are used with neural networks, then memory capacity is provided, but connection distances between processing elements and memory are long causing inefficiency

Engineering Contradiction:
Improvememory access speedVSAvoidconnection distance
Core Design Contradiction:
SpeedVSLength of moving object

Solution Approach 1:

The patent transitions from planar 2D memory architecture to 3D stacked memory architecture, adding a vertical dimension to the system. Memory stacks are positioned directly above processing elements, creating short vertical connections through through-silicon vias (TSVs). This dimensional change reduces connection distance dramatically while maintaining high memory capacity, directly resolving the contradiction between fast access and long connection distances.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If complex neural networks are implemented, then computational capability increases, but communication efficiency between processing elements and memory decreases

Engineering Contradiction:
Improvecomputational capabilityVSAvoidcommunication efficiency
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The system is segmented into multiple processing elements (PEs) arranged in a mesh network, each with dedicated local memory stacks. This segmentation allows parallel processing of neural network computations while each PE communicates only with nearby memory, reducing communication overhead and energy loss. The mesh network further segments communication paths, enabling efficient data exchange between PEs without bottlenecks.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

By stacking memory vertically above each PE and using TSVs for inter-layer communication, the architecture creates short vertical communication paths. This 3D arrangement enables complex neural network computations to proceed efficiently, as each PE can access its required memory data through short vertical connections rather than long horizontal traces, significantly improving communication efficiency and reducing energy loss.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Productivity

If conventional architectures are used, then system simplicity is maintained, but idle time increases reducing overall efficiency

Engineering Contradiction:
Improveoverall efficiencyVSAvoididle time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The architecture pre-positions multiple memory stacks directly above each processing element, so that all required data for computation is immediately accessible when needed. This preliminary arrangement eliminates idle time by ensuring that processing elements never wait for data fetches from distant memory locations. The systolic array architecture further enables continuous data flow through the network, keeping all elements actively computing without idle periods.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentUS20220335283A1Systems and methods for accelerated neural-network convolution and training
Publication Date: 2022.10.20 RAMBUS INC
  • US20220335283A1 patent drawing
  • US20220335283A1 patent drawing
  • US20220335283A1 patent drawing

AI summary

An application-specific integrated circuit for an artificial neural network is integrated with a high-bandwidth memory. The neural network includes a systolic array of interconnected processing elements, including upstream processing elements and downstream processing elements. Each processing element includes input/output port pairs for concurrent forward and back propagation. The processing elements can be used for convolution, in which case the input/output port pairs can support the fast and efficient scanning of kernels relative to activations.