Semiconductor Memory Refresh Control via Address Comparison
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Solution Overview
Problem
Semiconductor memory devices face data loss due to charge leakage and unwanted charging/discharging in memory cells, exacerbated by increased integration and reduced distances between word lines, which necessitates efficient refresh operations to maintain charge levels without deteriorating device efficiency.
Innovation Solution
A semiconductor memory device with an address latch unit, address comparison unit, refresh control unit, and refresh operation unit that selectively performs normal and smart refresh operations based on address comparisons and refresh command signals, optimizing refresh operations to prevent data loss while maintaining efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operations are performed frequently to prevent charge leakage and data loss, then data reliability is improved, but device operating efficiency deteriorates
Solution Approach 1:
The patent changes the refresh operation parameters by introducing two distinct modes: normal refresh operation and smart refresh operation. The refresh control unit selectively switches between these modes based on address comparison results, thereby optimizing the refresh frequency and timing to prevent charge leakage while minimizing impact on operating efficiency
Solution Approach 2:
The patent implements dynamic refresh control where the refresh operation mode is not fixed but adapts based on real-time address comparison results. The refresh control unit dynamically selects between normal and smart refresh operations, making the refresh strategy flexible and responsive to actual memory access patterns, thus balancing data reliability and operating efficiency
2Manufacturing precision
If the distance between word lines is reduced to increase integration density, then manufacturing precision is improved, but electrical coupling effects between adjacent word lines intensify
Solution Approach 1:
The patent addresses electrical coupling effects by changing the operational parameters of memory cell activation. When address comparison indicates potential coupling issues (same address consecutively activated), the system switches to smart refresh operation that adjusts activation timing and sequencing, thereby mitigating the harmful electrical coupling effects while maintaining high integration density
3Reliability
If normal refresh operations are performed on all memory cells, then charge levels are maintained, but operating efficiency deteriorates due to unnecessary refresh operations
Solution Approach 1:
The patent applies local quality by differentiating refresh operations based on specific memory cell addresses. The address comparison unit identifies which memory cells actually need refreshing by comparing consecutive addresses, and the refresh control unit applies appropriate refresh operations only to those specific locations, rather than uniformly refreshing all memory cells, thus maintaining charge levels efficiently
Solution Approach 2:
The patent implements partial action by performing smart refresh operations only when address comparison results indicate it is necessary, rather than performing full normal refresh operations on all memory cells continuously. This selective approach performs just enough refresh action to maintain data reliability while avoiding excessive operations that would degrade operating efficiency
Data Source
AI summary
A semiconductor memory device includes an address latch unit suitable for consecutively latching first refresh addresses, which correspond to successively-activated word lines, from consecutively received addresses for word lines to be activated in response to word line hit signals identifying the successively-activated word lines; an address comparison unit suitable for generating a comparison result signal by comparing the previously latched first address with the currently latched first address; a refresh control unit suitable for selecting a first refresh operation corresponding to the currently latched first address, and a second refresh operation corresponding to a second address in response to the comparison result signal, and a refresh command signal; and a refresh operation unit suitable for performing the first and second refresh operations on memory cells therein according to the selection of the refresh control unit.