Refresh Control Device for Memory Data Reliability
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Solution Overview
Problem
In semiconductor devices, memory cells experience data degradation due to the discharge of capacitors over time and interference from adjacent word lines, leading to issues like row hammering, which requires additional refresh operations to maintain data reliability.
Innovation Solution
A refresh control device that divides input addresses into partial addresses, generates updated counts for these addresses, and performs targeted refresh operations on specific word lines to mitigate data loss and interference, thereby extending the refresh cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional target refresh operations are performed on frequently accessed word lines to prevent row hammering, then data reliability is improved, but refresh cycle time increases and productivity decreases
Solution Approach 1:
The refresh operation is segmented into two distinct types: normal refresh operations that systematically cover all word lines, and target refresh operations that specifically address frequently accessed word lines. This segmentation allows the system to maintain data reliability for high-access word lines through targeted refreshes without requiring all word lines to undergo frequent refresh cycles, thereby improving overall refresh operation efficiency while preventing row hammering effects
Solution Approach 2:
Instead of performing exhaustive refresh operations on all word lines at maximum frequency, the system applies partial refresh actions only to the specific word lines that require it (those with high access frequency). This partial action approach maintains sufficient data reliability for critical word lines while reducing the total refresh burden on the memory system, thus balancing reliability improvement with productivity maintenance
2Productivity
If the refresh cycle is extended to improve productivity, then refresh operation efficiency increases, but data reliability may deteriorate due to increased discharge time
Solution Approach 1:
The system implements self-service monitoring where the address processing circuit automatically tracks and counts access frequencies of different word lines. Based on this self-collected information, the system autonomously determines which word lines require target refresh operations and generates appropriate target refresh addresses, eliminating the need for external intervention while maintaining data reliability even with extended refresh cycles
3Reliability
If frequent refresh operations are performed on all word lines to maintain data reliability, then data loss is prevented, but device complexity and energy consumption increase
Solution Approach 1:
The address processing circuit serves multiple functions: it processes normal refresh addresses, monitors access frequencies of word lines, counts access patterns, and generates target refresh addresses for frequently accessed lines. By making this single circuit multi-functional, the system maintains data retention through comprehensive monitoring and targeted refreshes without requiring separate complex control circuits for each function, thus managing device complexity effectively while ensuring data reliability
Data Source
AI summary
A refresh control device may include, an address processing circuit configured to divide an input address into a plurality of partial addresses, and generate an updated partial address input count based on an input count for each partial address value. The refresh control device also includes a target refresh address generation circuit configured to generate a target refresh address based on the updated partial address input count, and a target refresh circuit configured to perform a refresh operation on a word line corresponding to the target refresh address.