Current Control Circuit for Limiting String Current in NAND Flash Memory
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Solution Overview
Problem
High-density memory architectures, such as NAND flash memories, face increased power consumption due to elevated string current during memory access operations, limiting efficiency and potentially preventing certain operations.
Innovation Solution
A current control circuit is implemented to limit the maximum string current by controlling the source select gate voltage, thereby restricting the current flow through memory cell strings, ensuring power consumption remains within specified limits while allowing all-bitline testing without exceeding performance specifications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If memory access operations are performed across multiple memory cell strings to improve efficiency, then productivity increases, but string current increases causing power consumption to exceed specifications
Solution Approach 1:
The patent changes the voltage parameter of the source select gate to control and limit the string current. By adjusting the source select gate voltage, the system can perform memory access operations while keeping power consumption within specifications, thus resolving the contradiction between productivity and energy use
2Productivity
If the number of memory cell strings used for memory access operations is increased to improve efficiency, then productivity increases, but the string current exceeds maximum limits
Solution Approach 1:
The patent applies parameter changes by modifying the source select gate voltage to control string current. This allows multiple memory cell strings to be accessed efficiently while maintaining current within maximum limits, resolving the contradiction between productivity and harmful current levels
3Measurement precision
If certain testing operations are performed, then measurement precision improves, but power consumption exceeds specifications due to increased string current
Solution Approach 1:
The patent uses parameter changes in the source select gate voltage to enable testing operations with improved measurement precision while constraining power consumption to remain within specifications, thus resolving the contradiction between measurement quality and energy consumption
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The current control circuit effectively reduces power consumption during memory access operations, enabling efficient performance without exceeding performance limits, including the ability to perform all-bitline tests.
Implementation Method 1
a source select gate voltage to activate the source select gates (130(0-Y)) and limit string current magnitudes
Data Source
AI summary
Apparatuses, current control circuits, and methods for limiting string current in a memory are described. An example apparatus includes a memory cell string including a memory cell. The example apparatus further includes a sense circuit configured to sense a current through the memory cell string, and a select gate configured to couple the memory cell string to a source based on a select gate voltage. The example apparatus further includes a current control circuit coupled to the select gate. The current control circuit is configured to limit current through the memory cell string during a memory access operation based on a reference current.