Hybrid Dynamic Word Line Start Voltage Offset Storage
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Solution Overview
Problem
Current memory systems face inefficiencies in programming time and system performance due to limitations in storing and retrieving offset voltages for dynamic word line start voltage (DWLSV) in NAND devices, particularly with auto-DWLSV's limited storage capacity and manual-DWLSV's increased command overhead.
Innovation Solution
A hybrid-DWLSV approach is introduced, where the NAND die determines the lowest DWLSV for a block and stores offsets by block types, allowing for efficient retrieval and use of offset voltages without the need for additional registers or extensive command exchanges, thereby reducing programming time and firmware overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If auto-DWLSV is used to store offset voltages in the NAND die, then programming time is reduced, but storage capacity is limited
Solution Approach 1:
The patent segments the offset voltage storage function into two parts: the NAND die stores only the current offset voltage value (minimal storage), while the host system stores the mapping between block addresses and offset voltages. This segmentation resolves the contradiction by eliminating the need for large storage capacity in the NAND die while maintaining the programming time benefits of DWLSV.
Solution Approach 2:
The patent introduces the host system as an intermediary that manages the offset voltage data. Instead of requiring the NAND die to store all offset voltage information, the host acts as an external storage intermediary, allowing the NAND die to use minimal internal storage while still enabling DWLSV functionality through coordinated operation.
2Adaptability or versatility
If manual-DWLSV is used to manage offset voltages externally, then storage flexibility is improved, but command overhead increases
Solution Approach 1:
The patent applies preliminary action by having the host system pre-calculate and store the mapping between block addresses and offset voltages before programming operations. This pre-computation eliminates the need for complex runtime command exchanges between host and NAND, reducing command overhead while maintaining external storage flexibility.
Solution Approach 2:
The NAND die performs self-service by autonomously determining the current offset voltage and applying it to programming operations without requiring complex host intervention. This self-service capability reduces the command overhead associated with manual-DWLSV while the host maintains flexible external storage of offset voltage mappings.
3Quantity of substance
If additional registers are added to the NAND die for offset voltage storage, then storage capacity is improved, but device complexity increases
Solution Approach 1:
The patent extracts the offset voltage storage function from the NAND die and relocates it to the host system. This extraction eliminates the need for additional registers in the NAND die, maintaining storage capacity requirements without increasing device complexity. The host system, being external, provides the necessary storage without affecting NAND die complexity.
Data Source
AI summary
Methods, systems, and devices for hybrid DWLSV are described. One or more controllers may communicate one or more program commands to a NAND memory device. The memory device may perform program operations that correspond to the program commands communicated by the controller. The memory device may perform the program operations using a word line start voltage. Once the programming operations are complete, the memory device may communicate the lowest word line starting voltage offset associated with performing the program operations to the one or more controllers.