DRAM Refresh Controller Selective Bank Management
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Solution Overview
Problem
Current DRAM devices consume high current due to frequent refresh operations, which is a significant drawback in terms of power efficiency.
Innovation Solution
The semiconductor device incorporates a refresh controller with a refresh bank counter and selectors that manage refresh operations across multiple memory banks, optimizing the refresh process to avoid duplicate operations and reduce current consumption by skipping refreshes on banks that have recently been refreshed, using a combination of all-bank-refresh and per-bank-refresh signals to manage the refresh address and prevent duplicate operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed frequently on all memory banks, then data retention reliability is improved, but current consumption increases
Solution Approach 1:
The patent applies partial action by performing refresh operations selectively on only those memory banks that require refreshing, rather than refreshing all banks uniformly. The refresh controller monitors each bank's refresh status and skips banks that have been recently refreshed, thereby reducing the total number of refresh operations while maintaining data retention reliability.
Solution Approach 2:
The patent implements local quality by treating different memory banks differently based on their individual refresh needs. Each memory bank is monitored independently, and refresh operations are applied locally only to banks that require them, rather than applying a uniform refresh policy to all banks. This localized approach reduces overall current consumption while maintaining reliability.
2Reliability
If refresh operations are performed on all memory banks uniformly, then data retention is ensured, but duplicate refresh operations increase current consumption
Solution Approach 1:
The patent employs feedback mechanisms where the refresh controller continuously monitors the refresh status of each memory bank. Based on this feedback information about which banks have been recently refreshed, the controller intelligently decides whether to perform a refresh operation on each bank, thereby avoiding duplicate operations and reducing energy waste.
Solution Approach 2:
The refresh controller performs self-service by autonomously monitoring and managing the refresh status of memory banks without requiring external intervention. It automatically identifies which banks need refreshing and executes refresh operations accordingly, eliminating the need for external control and preventing duplicate operations.
3Use of energy by moving object
If refresh operations are skipped on recently refreshed banks, then current consumption is reduced, but data retention reliability may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-monitoring and tracking the refresh status of each memory bank before deciding whether to perform a refresh operation. The refresh controller maintains information about recent refresh operations, allowing it to make informed decisions about which banks need refreshing, thus ensuring reliability while reducing unnecessary operations.
Data Source
AI summary
Disclosed herein is an apparatus that includes a plurality of memory banks and a refresh controller configured to perform a refresh operation on one or more of the plurality of memory banks having a first state without performing the refresh operation on one or more of the plurality of memory banks having a second state responsive to a first refresh command, and perform the refresh operation on a selected one of the plurality of memory banks responsive to a second refresh command. The refresh controller is configured to bring the selected one of the plurality of memory banks into the second state when the refresh operation is performed responsive to the second refresh command.