Memory Control Circuit Row Hammer Refresh Logic
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Solution Overview
Problem
The row hammer phenomenon in memory devices leads to decreased retention time of memory cells when continuously refreshed, causing delays in refreshing other memory cells and resulting in potential data loss and redundant refreshing operations.
Innovation Solution
A memory device with a memory control circuit that counts access and refreshing commands to identify row hammer events, performing targeted refreshing operations to prevent data loss and reduce redundant refreshes by latching specific bank and row addresses when the count values are equal, and resetting counts appropriately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional refreshing operations are performed to eliminate the row hammer phenomenon, then data loss is prevented, but the retention time of memory cells decreases and refreshing of other memory cells is delayed
Solution Approach 1:
The patent segments the refreshing operation into two distinct modes: normal refreshing and row hammer refreshing. By separating these operations and using different address selection mechanisms (normal address vs. inverted address for adjacent rows), the system can perform targeted row hammer refreshing without unnecessarily delaying other memory cell refreshes. This segmentation allows selective intervention only when row hammer phenomenon is detected.
Solution Approach 2:
The patent applies local quality by performing row hammer refreshing operations specifically on adjacent memory rows that are susceptible to the row hammer phenomenon, rather than universally refreshing all memory rows. The memory control circuit identifies specific victim rows based on activation patterns and applies refreshing operations only to those affected rows, thereby preventing data loss in vulnerable areas without causing widespread refreshing delays.
2Reliability
If continuous refreshing is performed on selected word line, then row hammer phenomenon is mitigated, but retention time of memory cells decreases
Solution Approach 1:
The patent implements periodic action by using a timer to monitor the interval between consecutive refreshing operations on the same word line. When the timer detects that a predetermined time has elapsed since the last refresh, it enables row hammer refreshing operations. This periodic mechanism ensures that refreshing is performed at appropriate intervals to mitigate row hammer effects without excessive frequency that would degrade retention time.
Solution Approach 2:
The patent applies preliminary action by proactively refreshing adjacent memory rows before data loss occurs. The memory control circuit monitors activation commands and identifies potential victim rows that are susceptible to row hammer effects. By performing refreshing operations on these identified rows in advance, the system prevents data loss before it happens, rather than waiting for actual data degradation to occur.
3Reliability
If row hammer refreshing operations are performed, then data loss is prevented, but redundant refreshing operations occur
Solution Approach 1:
The patent implements feedback mechanisms through multiple counters that track the number of refreshing operations performed on different word lines. The memory control circuit continuously monitors these counter values and compares them against predetermined thresholds. This feedback system enables the circuit to identify when row hammer phenomenon is actually occurring versus when normal operation is occurring, thereby activating row hammer refreshing operations only when necessary and avoiding redundant refreshing that would reduce productivity.
Solution Approach 2:
The patent applies dynamics by making the refreshing operation mode adaptive based on real-time conditions. The memory control circuit dynamically switches between normal refreshing and row hammer refreshing modes depending on the detected activation patterns and counter values. This dynamic adaptation allows the system to optimize refreshing efficiency by using the appropriate mode for each situation, avoiding redundant operations while maintaining data integrity.
Data Source
AI summary
A memory device and a data refreshing method of the memory device are provided. The memory device includes a memory array and a memory control circuit. The memory control circuit counts the number of access commands to generate a first count value and counts the number of refreshing commands to generate a second count value. If the first count value is equal to the second count value, the memory control circuit latches a memory bank address and a memory row address corresponding to the access commands to obtain a row hammer refreshing bank address and a row hammer refreshing row address. The memory control circuit performs a row hammer refreshing operation on a memory bank according to the row hammer refreshing bank address and the row hammer refreshing row address.