Memory Refresh Division Control for External Access Period Reduction
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Solution Overview
Problem
Conventional DRAMs perform refresh operations that prolong the external access operation period due to continuous read and rewrite operations synchronized with an internal clock, leading to increased external clock cycles and longer access times.
Innovation Solution
A memory system with a refresh division control portion that separates the refresh operation into read and rewrite operations, performing these either before or after internal access operations, allowing for reduced external access periods and improved data transfer rates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If refresh operation is performed by continuously performing read and rewrite operations in synchronization with internal clock, then refresh operation can be performed without hindering internal access operation, but cycle of external clock must be increased resulting in long period of external access operation
Solution Approach 1:
The refresh operation is segmented into read operation and rewrite operation that can be performed independently and asynchronously. The read operation and rewrite operation are divided into separate processing stages, allowing them to be executed at different times rather than continuously, thereby reducing the impact on external access operation timing while still achieving complete refresh functionality.
2Productivity
If internal clock cycle is shorter than external clock cycle, then more internal clocks are generated in constant period enabling refresh operation, but external access operation period increases
Solution Approach 1:
The read operation of the refresh is performed in advance before the external access operation completes, and the rewrite operation is performed after the external access operation. This preliminary action allows the refresh process to overlap with external access operations rather than extending them, maintaining high refresh frequency without increasing external access period.
Data Source
AI summary
A memory allowing reduction of the period of an external access operation is provided. This memory comprises an access control portion performing an internal access operation on the basis of an external access operation, a refresh control portion performing a refresh operation and a refresh division control portion dividing the refresh operation into a read operation RFRD and rewrite operations RFRS1 and RFRS2. The memory performs the read operation RFRD and the rewrite operations RFRS1 and RFRS2 at least either before or after different internal access operations corresponding to different external access operations respectively.