Memory System Aging Compensation via Block Segmentation

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Solution Overview

Problem

Computing-in-memory (CiM) operations performed by non-volatile memory devices suffer from accuracy degradation due to aging, requiring calibration to maintain computation accuracy.

Innovation Solution

A memory system with a control circuit that divides the memory array into multiple blocks, enabling or disabling blocks based on aging conditions to compensate for drifted weights by adding or cutting memory blocks, thereby maintaining computation accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If computing-in-memory operations are performed by non-volatile memory devices, then computation speed is accelerated, but accuracy degrades due to aging

Engineering Contradiction:
Improvecomputation speedVSAvoidcomputation accuracy
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent applies preliminary action by training backup neurons in advance to compensate for expected weight drifts caused by aging. Before the memory device is fully deployed, multiple backup neurons are trained with different compensation parameters. When aging occurs, the pre-trained backup neurons can be activated to compensate for the drifted weights without requiring real-time retraining or calibration, thus maintaining computation accuracy while preserving the speed benefits of CiM operations.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If calibration is performed to maintain computation accuracy, then accuracy is maintained, but additional time and complexity are required

Engineering Contradiction:
Improvecomputation accuracyVSAvoidcalibration time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs calibration in advance during the training phase, where multiple backup neurons are trained with different compensation parameters before deployment. This preliminary calibration eliminates the need for time-consuming calibration operations during actual computation, as the compensation mechanisms are already prepared and can be activated instantly when aging effects are detected.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent creates copies of neurons (backup neurons) that replicate the functionality of original neurons but with compensated weights. These backup neurons serve as pre-prepared alternatives that can replace drifted neurons without requiring complex real-time calibration procedures, thus maintaining accuracy while minimizing time loss.

Inventive Principle:
Principle #26Copying

3Reliability

If backup neurons are added to compensate for aging, then accuracy is maintained, but device complexity increases

Engineering Contradiction:
Improvecomputation accuracyVSAvoidneural network complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the neural network into original neurons and separate backup neurons, allowing independent management and activation. This segmentation enables the system to use only the necessary components (original neurons when fresh, backup neurons when aging occurs) rather than maintaining all components active simultaneously, thus managing complexity more effectively while maintaining accuracy through selective activation of compensation mechanisms.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentUS20230229922A1Training method, operating method and memory system
Publication Date: 2023.07.20 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD
  • US20230229922A1 patent drawing
  • US20230229922A1 patent drawing
  • US20230229922A1 patent drawing

AI summary

A training method, an operating method and a memory system are provided. The operating method comprises using a first memory block of the memory system for computation; obtaining an aging condition of the memory system; determining whether the aging condition meets a predetermined aging condition; and when it is determined that the aging condition meets the predetermined aging condition, enabling the second memory block and using the first memory block and the second memory block for computation.