Dynamic Self-Refresh Period Adjustment in Semiconductor Memory
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Solution Overview
Problem
Semiconductor memory devices, such as DRAM, face challenges in optimizing refresh periods to balance data reliability and power consumption, as fixed refresh periods can lead to unnecessary power consumption and data degradation due to finite data retention characteristics.
Innovation Solution
A method and system for dynamically varying the self-refresh period of semiconductor memory devices based on temperature codes and error information, where the refresh period is adjusted by combining temperature codes and error flags to extend the refresh period as long as no errors occur, and reducing it when errors are detected, thereby optimizing retention characteristics and minimizing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed refresh period is used to ensure data reliability, then data retention is improved, but power consumption increases due to unnecessary refresh operations
Solution Approach 1:
The refresh period is changed from a fixed value to a dynamic value that adjusts based on real-time temperature conditions and error detection results. The refresh controller modifies the refresh period length according to actual device state, allowing the system to optimize between data reliability and power consumption by refreshing only when necessary.
Solution Approach 2:
The refresh period parameter is changed based on temperature codes and error flag states. When temperature increases or errors are detected, the refresh period is shortened to ensure data reliability. When temperature is stable and no errors occur, the refresh period is extended to reduce power consumption, thus dynamically optimizing the parameter for different operating conditions.
2Reliability
If a shorter refresh period is used to account for data leakage, then data retention is improved, but power consumption increases due to more frequent refresh operations
Solution Approach 1:
The refresh period transitions from a static short interval to a dynamic interval that adapts to actual data retention needs. By monitoring temperature and error conditions, the system determines the minimum necessary refresh frequency, extending the period when conditions permit to reduce power consumption while maintaining adequate data retention.
Solution Approach 2:
The system uses feedback from error detection circuits and temperature sensors to adjust the refresh period. Error flags generated during refresh operations provide information about actual data retention characteristics, allowing the controller to optimize the refresh period length and avoid unnecessarily frequent refreshes that waste power.
3Ease of manufacture
If a fixed refresh period is programmed in advance, then manufacturing simplicity is maintained, but adaptability to different temperature conditions deteriorates
Solution Approach 1:
The refresh period becomes dynamic and adaptive to temperature conditions while maintaining a relatively simple overall structure. Temperature sensors provide real-time data that automatically adjusts the refresh period without requiring complex manufacturing changes, thus achieving temperature adaptability with minimal impact on manufacturing simplicity.
Solution Approach 2:
The memory device performs self-adjustment of the refresh period based on its own temperature conditions and error detection results. The device monitors its own state and automatically modifies refresh operations accordingly, eliminating the need for external control or complex manufacturing configurations while achieving temperature adaptability.
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 maximizes data retention characteristics while minimizing power consumption by dynamically adjusting the refresh period according to real-time temperature and error conditions, ensuring data reliability without wasteful energy expenditure.
Implementation Method 1
a temperature sensor configured to detect an operation temperature of the semiconductor memory device and generate a temperature code
Data Source
AI summary
Disclosed is a self-refresh method of a semiconductor memory device, including generating a temperature code indicative of a temperature of the semiconductor memory device; generating a first error flag indicative of any data errors in a memory area of the semiconductor memory device; performing a first self-refresh operation for the memory area within a first refresh period based on the temperature code and the first error flag; generating a second error flag indicative of any data errors in the memory area during the first self-refresh operation; and performing a second self-refresh operation for the memory area within a second refresh period based on the temperature code and the second error flag, wherein the second refresh period is longer than the first refresh period if the second error flag is indicative of no data errors in the memory area during the first self-refresh operation.