Row Hammer Handler for DRAM Refresh Address Generation
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Solution Overview
Problem
Volatile memory devices, such as DRAM, face issues with charge leakage over time, leading to the need for frequent refresh operations. Additionally, as memory devices are scaled down, the row hammer phenomenon occurs due to voltage fluctuations, causing data loss in adjacent memory cells.
Innovation Solution
A semiconductor memory device with a row hammer handler that generates a refresh address to perform a refresh operation on memory cell rows. The row hammer handler includes a weight distributor that assigns weights to row addresses, an aggress address generator that determines an aggress address based on the weight data, and a refresh address generator that generates a refresh address for adjacent memory cell rows.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If memory devices are scaled down to reduce size, then device dimensions are reduced, but row hammer phenomenon occurs due to increased voltage fluctuation influence between adjacent word lines
Solution Approach 1:
The patent performs preliminary detection of row hammer attacks by monitoring access patterns to word lines. When repeated accesses to a specific word line are detected, the system proactively activates adjacent word lines before data loss occurs, preventing the harmful effect rather than reacting after damage is done.
Solution Approach 2:
The patent applies preliminary anti-action by detecting aggressive access patterns to specific word lines and counteracting the voltage fluctuation influence by activating adjacent word lines in advance. This creates a protective effect that neutralizes the row hammer phenomenon before it can corrupt data in adjacent memory cells.
2Reliability
If refresh operations are performed frequently to prevent charge leakage, then data retention is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent implements dynamic refresh operations that adapt to actual memory access patterns. Instead of performing uniform frequent refreshes across all memory rows, the system dynamically identifies rows that need protection from row hammer attacks and performs refresh operations selectively on those specific rows, reducing overall complexity and power consumption.
Solution Approach 2:
The patent applies local quality by performing refresh operations only on specific memory rows that are vulnerable to row hammer attacks, rather than uniformly refreshing all rows. The system identifies affected rows based on access patterns and applies refresh operations locally to those specific areas, optimizing resource usage.
3Reliability
If refresh operations are performed frequently to counteract row hammer effects, then data loss is reduced, but power consumption increases
Solution Approach 1:
The patent implements dynamic refresh operations that adapt to actual memory access patterns. Instead of performing uniform frequent refreshes across all memory rows, the system dynamically identifies rows that need protection from row hammer attacks and performs refresh operations selectively on those specific rows, reducing overall power consumption.
Solution Approach 2:
The patent applies local quality by performing refresh operations only on specific memory rows that are vulnerable to row hammer attacks, rather than uniformly refreshing all rows. The system identifies affected rows based on access patterns and applies refresh operations locally to those specific areas, optimizing power usage.
Data Source
AI summary
A semiconductor memory device includes a memory cell array having a plurality of rows of memory cells therein, and a row hammer handler configured to generate a refresh address when performing a refresh operation on the plurality rows of memory cells. The row hammer handler (RHH) includes a weight distributor configured to: receive a plurality of row addresses, assign a weight to each of the plurality of row addresses thus received, and to generate weight data corresponding to each of the plurality of row addresses. The RHH also includes an aggress address generator configured to determine an aggress address of a row of memory cells based on the weight data, and a refresh address generator configured to receive the aggress address and to generate the refresh address, which includes address information of a memory cell row adjacent the aggress address.