Fine Granularity Refresh Mode Extension for DRAM Power Reduction

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Solution Overview

Problem

Dynamic random-access memory (DRAM) devices consume excessive power due to redundant refresh operations caused by premature exit from the Fine Granularity Refresh (FGR) mode, leading to incomplete memory bank refreshes.

Innovation Solution

The memory device extends the FGR mode to ensure an even number of refresh operations are completed before exiting, thereby reducing redundant refreshes and power consumption by internally managing the duration to finish any remaining refresh operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the memory device exits the Fine Granularity Refresh (FGR) mode prematurely, then the operational responsiveness is improved, but redundant refresh operations occur causing excessive power consumption

Engineering Contradiction:

Improveoperational responsivenessVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The memory device performs preliminary actions by extending the FGR mode duration to complete a predetermined even number of refresh operations before exiting the mode. This preliminary completion of refresh operations prevents the need for redundant refresh operations that would otherwise occur after premature exit, thereby reducing power consumption while maintaining operational responsiveness.

Inventive Principle:

Principle #10Preliminary action

2Use of energy by moving object

If the memory device completes all refresh operations in FGR mode before exiting, then power consumption is reduced by eliminating redundant refreshes, but the exit timing is delayed

Engineering Contradiction:

Improvepower consumptionVSAvoidexit timing delay

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The memory device changes the temporal parameter of FGR mode by extending its duration dynamically. The mode is extended just long enough to complete a predetermined even number of refresh operations, optimizing the balance between power consumption reduction and exit timing. This parameter adjustment ensures that the mode extension is minimal while still achieving the power savings from eliminating redundant refresh operations.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the memory device performs an odd number of refresh operations in FGR mode, then the refresh coverage is maximized, but uneven refresh distribution across memory banks occurs

Engineering Contradiction:

Improverefresh coverageVSAvoidrefresh distribution uniformity

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The memory device performs preliminary action by determining whether an odd or even number of refresh operations have been completed and proactively extending the FGR mode if an odd number is detected. This preliminary detection and correction ensures that the predetermined even number of refresh operations is achieved before mode exit, maintaining uniform refresh distribution across memory banks while maximizing refresh coverage.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS11011217B1Selective extension of a fine granularity mode for memory refresh operations

Publication Date: 2021.05.18 MICRON TECHNOLOGY INC

AI summary

Control circuitry may operate to refresh memory banks and determine that a memory bank was not refreshed within a threshold time duration from the current time. The control circuitry may extend a duration of an operational mode in response to determining that the memory bank was not refreshed within the threshold time duration. In response to extending the duration of the operational mode, the control circuitry may refresh the second memory bank without refreshing the first memory bank.