Flash Memory Block Continuous-Write Verification via Free Word Line
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Solution Overview
Problem
Conventional flash memory devices require multiple command invocations to determine if a block continuous-write operation is possible across multiple pages, leading to increased time and efficiency losses due to the need to verify the erase state of each page individually.
Innovation Solution
The implementation of a flash memory system that uses a free word line connected to both programmed and erased memory cells, allowing for the verification of erase states across multiple pages during a single busy signal period using a free word line checker, thereby determining the feasibility of a block continuous-write operation with a single command invocation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the conventional flash memory performs read operation and data output operation for each page individually, then the block continuous-write operation can be performed with complete verification, but the time required for the operation increases due to multiple command invocations
Solution Approach 1:
The memory block is divided into multiple pages, each with its own verification status. The patent segments the verification process by maintaining individual verification states for different pages within a block, allowing the system to track which pages have been verified without re-verifyring them, thus reducing redundant command invocations
Solution Approach 2:
The patent performs verification of erase states in advance during initial page operations. By verifying pages beforehand and storing their verification status, the system avoids repeated verification commands during subsequent block continuous-write operations, thereby reducing overall operation time while maintaining reliability
2Measurement precision
If the flash memory requires multiple command invocations to determine block continuous-write possibility, then thorough verification is achieved, but the operational efficiency decreases
Solution Approach 1:
The memory device maintains internal verification status information for each page within a block. This self-service mechanism allows the device to automatically track which pages have been verified without requiring external controller commands, enabling efficient block continuous-write determination while maintaining thorough verification through stored verification states
3Measurement precision
If the conventional system verifies erase state of each page individually, then accurate determination is possible, but the number of command invocations increases
Solution Approach 1:
The patent implements a universal verification status register that serves multiple pages within a block. This single data structure tracks the verification state of all pages, allowing the system to determine block continuous-write possibility for multiple pages through a unified mechanism rather than separate command sequences for each page, thereby reducing overall command complexity while maintaining determination accuracy
Data Source
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AI summary
Disclosed is a storage device which includes a first word line (WL6 - WL8) connected with memory cells (MC6 - MC8) being in a program state, a second word line (WL1 - WL3) connected with memory cells (MC1 - MC3) being in an erase state, and a free word line (WL5, WL4) between the first and second word lines (WL1 - WL3, WL6 - WL8) and connected with memory cells (MC5, MC4) being in the erase state. Whether a block continuous-write is possible with respect to the memory cells (MC1 - MC3) connected with the second word line (WL1 - WL3) is determined by verifying the erase state of the memory cells (MC5, MC4) connected with the free word (WL5, WL4) line during one busy signal period. According to the present disclosure, because whether a block continuous-write is possible is determined with respect to a plurality of free pages during one busy signal period, a time taken to perform the block continuous-write operation may decrease.