NAND Flash Page Buffer Layout for Signal Routing
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Solution Overview
Problem
The layout of page buffers in NAND flash memory devices faces challenges due to space constraints, making it impractical to position read/program units directly under bit lines, leading to complex signal routing and parasitic capacitance issues that affect the accuracy of read and program operations.
Innovation Solution
The solution involves organizing read/program units into groups aligned in a specific direction, with shared signal tracks and column-selection transistors to equalize parasitic capacitance effects, allowing for efficient data transfer and operation despite space constraints.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If read/program units are positioned directly under bit lines, then signal routing is simplified, but space constraints make this layout impractical
Solution Approach 1:
The patent positions read/program units in groups along a first direction (parallel to bit lines) rather than directly under them, and arranges multiple groups along a second direction (transverse to bit lines). This dimensional reorganization allows signal tracks to be shared among units in the same group, reducing routing complexity while accommodating space constraints through systematic spatial distribution.
Solution Approach 2:
Multiple read/program units within the same group share common signal tracks for data input and output. This merging of signal paths reduces the total number of tracks required and simplifies the overall routing architecture, directly addressing the space and complexity trade-off.
2Area of stationary object
If read/program units are grouped and share signal tracks, then space is optimized, but parasitic capacitance effects increase
Solution Approach 1:
The patent introduces column-selection transistors at each read/program unit to provide localized control over signal track connections. This allows precise management of parasitic capacitance effects by enabling selective activation of units, thereby isolating active units from capacitive coupling with inactive neighboring units sharing the same signal tracks.
Solution Approach 2:
The signal tracks are effectively segmented through the use of column-selection transistors that act as switches. This segmentation isolates the electrical paths for different read/program units, reducing mutual parasitic capacitance interference while maintaining the space-efficient shared track architecture.
3Ease of operation
If more signal tracks are provided for each read/program unit, then signal routing is simplified, but device area increases
Solution Approach 1:
The patent merges signal tracks by having multiple read/program units within the same group share common data input and output tracks. This consolidation reduces the total number of tracks required compared to providing dedicated tracks for each unit, thereby optimizing device area while maintaining functional capability through shared resources.
Solution Approach 2:
Shared signal tracks serve multiple read/program units simultaneously, making the tracks universal rather than dedicated. This multi-functionality allows the same physical infrastructure to support multiple operational units, reducing overall device area while preserving routing simplicity through systematic sharing arrangements.
Data Source
AI summary
A memory device is provided. The memory device includes a matrix of memory cells adapted to store data and arranged in a plurality of bit lines, the bit lines extending along a first direction; a page buffer adapted to interface the matrix with a downstream circuitry, the page buffer comprising a plurality of read/program units. Each read/program unit is associated with at least one bit line. The memory device further includes at least two groups each including at least two respective read/program units, wherein the read/program units of a generic one of said groups are generically aligned along the first direction. Each group comprises at least one signal track shared by the at least two read/program units of the group.