Word Driver Signal Control for DRAM Refresh Power Reduction
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Solution Overview
Problem
The refresh operations in semiconductor memory devices, such as DRAM, consume significant current due to the need to drive main word lines and word driver lines between active and inactive states, leading to high power consumption.
Innovation Solution
By maintaining one of the main word drivers or word drivers in an active state during refresh operations and alternating the other between active and inactive states, reducing the number of signal transitions and thus the current draw.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If main word lines and word driver lines are driven between active and inactive states during refresh operations, then subword lines can be selected and refreshed, but current consumption increases significantly
Solution Approach 1:
The patent applies periodic action by selectively activating only the necessary word driver lines corresponding to the refresh address, rather than periodically activating all word driver lines. The refresh controller activates specific word driver lines in a periodic refresh cycle, but only for the addressed subword lines, reducing unnecessary signal transitions and current consumption during refresh operations
Solution Approach 2:
The patent implements local quality by applying different activation states to different word driver lines based on their relevance to the refresh operation. Specifically, word driver lines corresponding to the refresh address are activated while others remain inactive, creating a localized activation pattern that reduces overall current consumption while maintaining refresh functionality
2Productivity
If all word driver lines are activated during refresh operations, then all subword lines can be refreshed, but power consumption increases
Solution Approach 1:
The patent applies local quality by differentiating between relevant and irrelevant word driver lines during refresh operations. The refresh controller selectively activates only those word driver lines that correspond to the refresh address, while keeping other word driver lines inactive. This localized activation approach maintains the ability to refresh specific subword lines while significantly reducing overall power consumption compared to activating all word driver lines
Data Source
AI summary
Apparatuses and methods for maintaining an active state of a word driver signal are described. The word driver may be included in a memory device including a hierarchical structured main word lines and subword lines. The subword lines may be driven by subword drivers that are activated by main word drivers and word drivers. During an operation such as a refresh operation, a driving signal provided by a word driver to a subword driver may be held in an active state while the driving signal provided by a main word driver to the subword driver transitions between active and inactive states. In some examples, the word driver may include a latch for latching an activation signal at an initiation of a refresh operation to maintain a state of the driving signal.