DRAM Self Refresh Cycle Control via Temperature Sensing

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Solution Overview

Problem

Conventional memory devices rely on user-programmed EMRS code settings for Temperature Compensated Self Refresh (TCSR) cycles, which are inadequate for varying temperatures, leading to potential DRAM operation failures when temperatures are outside the specified range.

Innovation Solution

A memory device with a self refresh cycle control function that includes a temperature sensing unit generating independent and temperature-dependent voltages, a comparing unit for producing a comparison result signal, and a self refresh signal generating unit that adjusts the self refresh cycle based on this signal to compensate for temperature variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If user-programmed EMRS code settings are used for TCSR cycles, then the device can operate within specified temperature ranges, but the device fails to operate reliably when temperatures are outside the specified range

Engineering Contradiction:

ImproveDRAM operation reliabilityVSAvoidtemperature range adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The temperature sensing unit automatically detects ambient temperature and the comparing unit autonomously generates control signals based on temperature thresholds, eliminating the need for user-programmed EMRS code settings. The system serves itself by continuously monitoring temperature and adjusting refresh cycles without external intervention, enabling reliable operation across extended temperature ranges.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The patent dynamically changes the self-refresh cycle period based on detected temperature conditions. When temperature exceeds thresholds, the system modifies refresh timing parameters to compensate for increased leakage current, thereby maintaining data integrity across varying temperatures without requiring manual configuration.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If the self refresh cycle is set to be longer at low temperature, then energy consumption is reduced, but data preservation reliability decreases

Engineering Contradiction:

Improveenergy consumptionVSAvoiddata preservation reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The system dynamically adjusts the self-refresh cycle period based on real-time temperature detection rather than using a fixed cycle. At lower temperatures, the system can extend refresh intervals to reduce power consumption, while automatically shortening intervals when temperature increases to maintain data reliability, creating an adaptive balance between energy efficiency and data preservation.

Inventive Principle:

Principle #15Dynamics

3Reliability

If the self refresh cycle is set to be shorter at high temperature, then data preservation reliability is improved, but energy consumption increases

Engineering Contradiction:

Improvedata preservation reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The system changes the refresh cycle period parameter based on detected temperature conditions. At high temperatures, the comparing unit generates control signals that shorten the refresh interval to compensate for doubled leakage current, thereby maintaining data integrity. When temperature decreases, the system automatically extends the refresh interval to reduce unnecessary power consumption.

Inventive Principle:

Principle #35Parameter changes

4Device complexity

If conventional EMRS code setting is used, then device complexity is reduced, but the device cannot operate outside specified temperature specifications

Engineering Contradiction:

Improvecontrol mechanism complexityVSAvoidtemperature range

Core Design Contradiction:

Device complexityVSAdaptability or versatility

Solution Approach 1:

The patent introduces a temperature sensing unit and comparing unit as intermediary components between the temperature environment and the refresh control logic. These intermediaries automatically translate temperature conditions into appropriate refresh cycle adjustments, extending operational temperature range while adding minimal complexity compared to manual EMRS configuration.

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enables automatic and temperature-compensated self refresh cycle control, ensuring stable DRAM operation across a range of temperatures without the need for user-set EMRS code variations, thereby enhancing the reliability of DRAM performance.

Implementation Method 1

a temperature sensing unit for generating a first voltage independent of a temperature variation and a second voltage dependent upon a temperature variation

Methodology Applied

Scientific EffectTemperature sensing:

Data Source

PatentUS7701796B2Memory device with self refresh cycle control function

Publication Date: 2010.04.20 SK HYNIX INC

AI summary

Provided is a memory device capable of automatically controlling a self refresh cycle by sensing an ambient temperature, rather than setting Extended Mode Register Set (EMRS) code. The memory device includes a temperature sensing unit for generating a first voltage independent of a temperature variation and a second voltage dependent upon a temperature variation, a comparing unit for comparing the first voltage with the second voltage to provide a comparison result signal, and a self refresh signal generating unit for receiving a self refresh entry signal and generating a self refresh signal of temperature compensated cycle under the control of the comparison result signal.