In-Memory Computation Device with Segmented Memory Tiles

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Solution Overview

Problem

In-memory computation devices face significant challenges in reducing data storage demand and power consumption, particularly in large-scale multiply-add operations for deep neural networks, which are essential for AIoT applications.

Innovation Solution

The device divides the memory array into p×q memory tiles with bit line selection switches and analog-to-digital converters (ADCs) to generate sub-output signals, which are then processed by a ladder adder for calculation, allowing for adjustable bit numbers and reduced data storage needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a large-scale memory array is used for multiply-add operations in deep neural networks, then computation capability is improved, but data storage demand and power consumption increase significantly

Engineering Contradiction:
Improvecomputation capabilityVSAvoiddata storage demand
Core Design Contradiction:
ProductivityVSQuantity of substance

Solution Approach 1:

The memory array is divided into multiple sub-memory arrays, each handling a portion of the multiply-add operations. This segmentation allows the system to process large-scale computations while using smaller, more manageable memory units, thereby reducing the data storage demand of any single memory unit while maintaining overall computation capability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a third dimension by stacking multiple sub-memory arrays vertically. This 3D architecture enables the system to perform large-scale multiply-add operations across multiple layers, effectively increasing computation capability without proportionally increasing the data storage demand in any single layer.

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

2Productivity

If a large-scale memory array is used for multiply-add operations, then computation capability is improved, but power consumption increases

Engineering Contradiction:
Improvecomputation capabilityVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by stationary object

Solution Approach 1:

By dividing the memory array into multiple sub-memory arrays, the total power consumption is distributed across multiple smaller units. Each sub-memory array consumes less power individually, and the segmented architecture allows for more efficient power management while maintaining high computation capability through parallel operations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The vertical stacking of sub-memory arrays in 3D enables computation to be distributed across multiple layers, reducing the power consumption burden on any single layer while maintaining high overall computation capability through layered parallel processing.

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

3Quantity of substance

If the memory array is divided into multiple memory tiles with bit line selection switches, then data storage demand is reduced, but device complexity increases

Engineering Contradiction:
Improvedata storage demandVSAvoiddevice complexity
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The bit line selection switches are designed to serve multiple functions: they select which bit lines are active for computation, enable or disable specific memory tiles, and control the flow of data between sub-memory arrays. This multi-functionality reduces the need for separate control mechanisms, thereby managing device complexity while enabling data storage reduction through selective activation.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The bit line selection switches provide dynamic control over the active memory tiles and bit lines based on computation requirements. This dynamic configuration allows the system to adaptively reduce data storage demand by activating only the necessary memory portions, while the reconfigurability manages complexity through software-controlled flexibility rather than hardwired complexity.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentUS11221827B1In-memory computation device
Publication Date: 2022.01.11 MACRONIX INTERNATIONAL CO LTD
  • US11221827B1 patent drawing
  • US11221827B1 patent drawing
  • US11221827B1 patent drawing

AI summary

An in-memory computation device including a memory array, p×q analog to digital converters (ADCs) and a ladder adder is provided. The memory array is divided into p×q memory tiles, where p and q are positive integers larger than 1. Each of the memory tiles has a plurality local bit lines coupled to a global bit line respectively through a plurality of bit line selection switches. The bit line selection switches are turned on or cur off according to a plurality of control signals. The memory array receives a plurality of input signals. The ADCs are respectively coupled to a plurality of global bit lines of the memory tiles. The ADCs respectively convert electrical signals on the global bit lines to generate a plurality of sub-output signals. The ladder adder is coupled to the ADCs, and performs an addition operation on the sub-output signals to generate a calculation result.