Memory Controller Pass Voltage Segmentation for Operation Stability
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Solution Overview
Problem
Memory systems face operation errors and normal operation challenges due to changes in threshold voltages and distributions of memory cells, particularly during read, program, and erase operations, where existing technologies fail to differentially supply pass voltages based on the state of memory cells.
Innovation Solution
A memory system that includes a memory device with multiple word lines and bit lines, where different pass voltages are applied to unselected word lines based on whether they correspond to programmed or erased memory cells, using a memory controller to transmit pass voltage control information and control circuits to manage these voltages, ensuring stable operations by distinguishing between programmed and erased states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pass voltage is applied to all unselected word lines, then the device complexity is reduced, but operation errors occur due to threshold voltage changes in memory cells
Solution Approach 1:
The patent segments the unselected word lines into two groups: first word lines corresponding to programmed memory cells and second word lines corresponding to erased memory cells. Different pass voltages are applied to each group, resolving the operation stability issue caused by threshold voltage changes while maintaining manageable device complexity through systematic classification.
Solution Approach 2:
The patent applies local quality by providing different pass voltage levels to different groups of word lines based on their specific requirements. Programmed memory cells receive one pass voltage level while erased memory cells receive another, allowing each region to operate under optimal voltage conditions for its state, thereby preventing operation errors.
2Reliability
If different pass voltages are applied to first and second word lines based on memory cell state, then operation errors are prevented, but the device complexity increases
Solution Approach 1:
The patent divides unselected word lines into distinct segments (first and second word lines) based on the state of corresponding memory cells. This segmentation enables targeted voltage application, improving reliability while the systematic classification approach keeps the increased complexity manageable through clear organizational structure.
Solution Approach 2:
The patent changes the voltage parameter differently for different word line groups based on memory cell state. By adjusting pass voltage levels according to whether memory cells are programmed or erased, the system achieves superior operation stability while the parameter changes are systematically managed through state-based classification.
3Reliability
If pass voltage is increased to ensure normal operation, then operation stability improves, but energy consumption increases
Solution Approach 1:
The patent applies local quality by providing different pass voltage levels to different word line groups. First word lines corresponding to programmed memory cells receive one voltage level while second word lines corresponding to erased memory cells receive another level, ensuring each group operates stably without unnecessarily increasing energy consumption across the entire device.
Solution Approach 2:
The patent optimizes energy consumption by changing voltage parameters selectively based on memory cell state. Instead of uniformly increasing pass voltage for all unselected word lines, the system adjusts voltage levels according to whether cells are programmed or erased, maintaining operation stability while minimizing overall energy usage.
Data Source
AI summary
A memory system, a memory controller and a memory device. In a set operation, by applying different pass voltages to at least one first word line and at least one second word line among the plurality of word lines excluding a selected target word line, an operation error of the memory device may be prevented.