Resistive Memory Cells with Variable Data Retention

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Solution Overview

Problem

Existing non-volatile memory devices face challenges in achieving power efficiency during write operations, as longer data retention times require more energy-consuming write operations, and existing solutions do not effectively balance data retention and power consumption.

Innovation Solution

A memory device comprising two types of resistive non-volatile data storage elements with different data retention times, allowing selection based on the retention time needed for stored data, coupled with a read-write circuit for efficient data transfer and storage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If non-volatile resistive elements with longer data retention periods are used, then data reliability is improved, but energy consumption during write operations increases

Engineering Contradiction:
Improvedata retentionVSAvoidwrite energy consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The memory device is divided into multiple memory cells, each containing resistive elements with different retention characteristics. This segmentation allows the system to select appropriate retention elements based on data requirements, avoiding the energy penalty of programming all elements to maximum retention.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically selects which resistive elements to program based on the retention requirements of the data being stored. By adapting the programming operation to the actual retention needs, the system avoids unnecessary energy consumption while maintaining data reliability.

Inventive Principle:
Principle #15Dynamics

2Device complexity

If uniform resistive elements are used in all memory cells, then device simplicity is maintained, but energy efficiency for different retention requirements cannot be optimized

Engineering Contradiction:
Improvememory cell uniformityVSAvoidwrite energy consumption
Core Design Contradiction:
Device complexityVSUse of energy by moving object

Solution Approach 1:

Different memory cells are equipped with resistive elements having different retention characteristics based on their specific requirements. This local differentiation allows energy-efficient storage by matching retention properties to data importance, while the overall device structure remains relatively simple.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system varies the retention parameter of resistive elements across different memory cells to optimize energy consumption. By changing the retention parameter according to data requirements, the system achieves energy efficiency without requiring complex control mechanisms.

Inventive Principle:
Principle #35Parameter changes

3Use of energy by moving object

If resistive elements with different retention times are used, then energy efficiency is improved, but device complexity increases

Engineering Contradiction:
Improvewrite energy consumptionVSAvoidmemory cell variability
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The memory device is divided into multiple memory cells, each containing resistive elements with different retention characteristics. This segmentation allows the system to select appropriate retention elements based on data requirements, avoiding the energy penalty of programming all elements to maximum retention.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The memory device provides multiple retention options within a single unified structure, allowing it to serve different retention requirements using the same basic memory cell architecture and control mechanisms.

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

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enables energy-efficient data storage by selecting the resistive element with the appropriate retention time for the data, reducing power consumption while maintaining reliable data retention.

Implementation Method 1

programmable resistive elements in memory cells to ensure non-volatile data storage. Such resistive elements are programmable to assume one of a plurality of different resistive states.

Methodology Applied
Scientific EffectResistive switching: Electrical Resistance

Implementation Method 2

each of the first and second memory cells is coupled to a read-write circuit allowing data to be read and written into the first and second memory cells

Methodology Applied
Scientific EffectElectrical signal transmission: Conduction (electrical)

Data Source

PatentEP2821998B1Non-volatile memory device
Publication Date: 2021.03.24 COMMISSARIAT A LENERGIE ATOMIQUE ET AUX ENERGIES ALTERNATIVES
  • EP2821998B1 patent drawingFigure 1A~2
  • EP2821998B1 patent drawingFigure 3A~4B
  • EP2821998B1 patent drawingFigure 5~7B

AI summary

The invention relates to a memory device comprising: a first memory cell (102) comprising a first non-volatile resistive data storage element (106A) programmable to store a first bit of data; and a second memory cell (104) comprising a second non-volatile resistive data storage element (106B) programmable to store a second bit of data; in which the first resistive element is arranged to have a first data retention time, and the second resistive element is arranged to have a second data retention time different from the first data retention time.