Memory DLL Lock Control During Auto-Refresh Updating

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Solution Overview

Problem

Synchronous semiconductor memory devices face errors due to reduced data valid windows when operating at high frequencies, and existing DLL circuits struggle to maintain a locked state during auto-refresh operations, leading to power consumption issues and noise generation.

Innovation Solution

A semiconductor memory device with a control unit that manages a delay-locked loop circuit to maintain a locked state during the updating period of the auto-refresh operation by using AND gates to generate control signals based on auto-refresh request and end signals, ensuring synchronization and reducing power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the DLL circuit performs locking operation continuously during auto-refresh, then synchronization is maintained, but power consumption increases

Engineering Contradiction:

Improvesynchronization stabilityVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The DLL circuit performs locking operation periodically rather than continuously. The control unit generates a locking operation control signal only during specific periods (when auto-refresh is not performed), allowing the DLL to maintain synchronization through periodic updates instead of continuous operation, thereby reducing power consumption while preserving synchronization stability.

Inventive Principle:

Principle #19Periodic action

2Use of energy by moving object

If the DLL circuit stops locking operation during auto-refresh, then power consumption is reduced, but synchronization is lost

Engineering Contradiction:

Improvepower consumptionVSAvoidsynchronization stability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The control unit predicts when auto-refresh operations will occur based on refresh timing signals and proactively controls the DLL circuit to maintain locking operation during periods when auto-refresh is not performed. This preliminary control ensures synchronization is maintained in advance before potential disruption occurs, preventing synchronization loss while managing power consumption.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If auto-refresh operation is performed, then memory banks are refreshed, but noise is generated due to ground voltage variation

Engineering Contradiction:

Improvememory refresh reliabilityVSAvoidnoise

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent separates the auto-refresh operation from the DLL locking operation in time. The control unit extracts or isolates the noise-generating auto-refresh period by controlling the DLL to perform locking operations only during updating periods when auto-refresh is not active. This temporal separation removes the harmful noise interaction while preserving the necessary memory refresh function.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8730751B2Semiconductor memory device for controlling operation of delay-locked loop circuit

Publication Date: 2014.05.20 SAMSUNG ELECTRONICS CO LTD

AI summary

A semiconductor memory device for controlling an operation of a delay-locked loop (DLL) circuit is provided. The semiconductor memory device includes a DLL circuit that receives an external clock signal and that performs a locking operation on the external clock signal and an internal clock signal, thereby obtaining a locked state. A control unit controls the DLL circuit to constantly maintain the locked state during an updating period of an auto-refresh period of an auto-refresh operation for refreshing memory banks.