Non-volatile Memory Drain Selector Circuit for Leakage Prevention
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Solution Overview
Problem
Conventional non-volatile memory systems face the risk of erroneous writing due to voltage leakage between unselected memory cells, leading to potential data corruption during the writing process.
Innovation Solution
The implementation of a four-drain selection route system with alternating drain selectors and a source selector to isolate non-selected memory cells, ensuring that only the intended memory cell receives the write voltage, thereby minimizing potential differences between drain and source electrodes and preventing current flow in unselected cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If one drain electrode is selected to apply write voltage while the other remains open, then the write operation can be performed, but voltage leakage occurs causing erroneous writing in non-selected memory cells
Solution Approach 1:
The drain selection function is divided into two separate selectors (first drain selector and second drain selector), each handling different sets of drain electrodes. This segmentation allows independent control of voltage application to different memory cell groups, preventing voltage leakage to non-selected cells while maintaining efficient write operations.
Solution Approach 2:
The patent introduces intermediate control circuits (first and second drain selectors) that act as mediators between the write voltage source and the drain electrodes. These intermediaries precisely control voltage distribution, ensuring voltage is applied only to selected memory cells and isolated from non-selected cells, thus preventing erroneous writing.
2Ease of operation
If the non-selected drain electrode is left in open state, then the selected memory cell can be written, but potential difference of (CDV-Vt)/2 appears causing current flow in unselected cells
Solution Approach 1:
The drain electrode set is divided into two groups controlled by separate drain selectors. Each selector independently manages its group, allowing one group to be in high-impedance state while the other receives write voltage, eliminating voltage leakage to unselected cells.
Solution Approach 2:
The drain selectors dynamically switch between different drain electrode groups based on write operations. During write operations, one selector actively drives selected drains while the other maintains high-impedance state, dynamically preventing voltage leakage without complicating the overall write operation procedure.
Data Source
AI summary
A memory cell array circuit of a non-volatile memory selects the drain electrodes of the memory cells, interconnected to word lines and bit lines, by two drain selectors, adapted for selecting the drain electrodes in two selection routes, so that the memory cell array circuit will select the drain electrodes in four selection routes. In writing in the memory cells, the drain electrodes of the memory cells are selected at a rate of one out of four drain electrodes and the voltage CDV is applied to the so selected drain electrode. This decreases the potential difference between the drain and source electrodes of the non-selected memory cells to prevent the erroneous writing in the non-selected memory cells. A method for writing in the memory is also provided.