Phase Change Memory Current Control via Temperature Sensing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Phase change memory cells experience data storage errors due to inconsistent resistance values of phase change materials, which vary with temperature, leading to unreliable program efficiency and increased error rates.

Innovation Solution

A current control apparatus for phase change memory that includes a temperature sensing block generating an output voltage proportional to temperature, and a write driver providing current inversely proportional to temperature, ensuring consistent current delivery across varying temperatures through a reset control unit and set control unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a phase change material is used as a variable resistor element, then the resistance value changes significantly at high temperature, but the resistance value becomes inconsistent at different temperatures leading to data storage errors

Engineering Contradiction:

Improvedata storage reliabilityVSAvoidresistance value consistency

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the program current magnitude based on temperature conditions. The temperature sensing block detects internal circuit temperature and the write driver modifies the program current accordingly - providing lower current at high temperatures and higher current at low temperatures - to maintain consistent resistance changes and eliminate data storage errors across different temperature conditions

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements feedback through a temperature sensing block that continuously monitors the internal circuit temperature and feeds this information back to the write driver. This closed-loop feedback mechanism enables the write driver to adjust the program current in real-time based on detected temperature conditions, ensuring reliable data storage regardless of temperature variations

Inventive Principle:

Principle #23Feedback

2Reliability

If program current is increased to ensure sufficient current at low temperatures, then data storage reliability improves, but over-driving issues occur at high temperatures

Engineering Contradiction:

Improveprogram efficiencyVSAvoidover-driving at high temperature

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the program current dynamic rather than fixed. The write driver adjusts the program current magnitude based on real-time temperature conditions detected by the temperature sensing block - using lower current at high temperatures to prevent over-driving and higher current at low temperatures to ensure sufficient programming, thereby eliminating the need for a fixed conservative current level

Inventive Principle:

Principle #15Dynamics

3Object-affected harmful factors

If program current is decreased to prevent over-driving at high temperatures, then harmful effects are reduced, but insufficient current at low temperatures causes data storage errors

Engineering Contradiction:

Improveover-driving preventionVSAvoiddata storage accuracy

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent applies dynamics by making the program current adaptive rather than static. The temperature sensing block and write driver work together to dynamically adjust current magnitude based on actual temperature conditions - providing reduced current at high temperatures to prevent over-driving and increased current at low temperatures to ensure adequate programming, thereby solving the dilemma of fixed current selection

Inventive Principle:

Principle #15Dynamics

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

The solution effectively controls set/reset currents based on temperature, reducing over-driving issues at high temperatures and minimizing unnecessary current consumption and errors at low temperatures, thereby enhancing data storage reliability.

Implementation Method 1

a temperature sensing block having an output node whose voltage level varies depending on temperature of an internal circuit

Methodology Applied

Scientific EffectTemperature sensing:

Implementation Method 2

the phase change material used as the variable resistor element of the phase change memory cell is characterized in that the resistance value changes with temperature

Methodology Applied

Scientific EffectPhase change: Phase Change

Data Source

PatentUS8526226B2Current control apparatus and phase change memory having the same

Publication Date: 2013.09.03 SK HYNIX INC

AI summary

A current control apparatus of a phase change memory includes a temperature sensing block having an output voltage level which varies depending on temperature of an internal circuit and a write driver configured to control an amount of program current provided to a memory cell in response to the output voltage level of the temperature sensing block.