Semiconductor Memory Page Buffer Current Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional semiconductor memory devices face limitations in performing fine sense operations due to the inability to accurately measure shifts in current levels of nano amperes, which affects the reliability of read and verification operations.
Innovation Solution
The semiconductor memory device employs a page buffer that compares an analog signal based on the threshold voltage of a selected memory cell with a reference current, allowing for precise sensing and outputting digital sense data, thereby enhancing the accuracy of the sense operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional sense operation using voltage control is used, then the operation is simple, but the measurement precision of fine current levels is insufficient
Solution Approach 1:
The patent replaces the conventional voltage-based sense operation with a current-based sense operation. Specifically, it substitutes the mechanical/electrical voltage control system with a current comparison system that uses a sense amplifier to directly measure and compare bit line current against a reference current, enabling precise measurement of fine current levels in the nanoampere range.
Solution Approach 2:
The patent introduces a sense amplifier as an intermediary component between the bit line and the read circuitry. This sense amplifier acts as a mediator that converts the small current variations on the bit line into measurable voltage signals that can be processed by subsequent logic circuits, thereby enabling precise current measurement without directly complicating the overall system architecture.
2Reliability
If voltage control method is used for sense operation, then the control is easy, but the reliability of fine sense operation is insufficient
Solution Approach 1:
The patent replaces the voltage control method with a current comparison method. Instead of controlling and measuring voltage levels, the system now directly controls and measures current levels using a sense amplifier that compares the bit line current with a reference current, thereby improving the reliability of fine sense operations while maintaining operational simplicity through automated current comparison.
3Measurement precision
If conventional sense method is used, then the device structure is simple, but the ability to measure nanoampere current shifts is insufficient
Solution Approach 1:
The patent introduces a sense amplifier as an intermediary device that specifically targets the measurement of nanoampere current shifts. This sense amplifier serves as a specialized mediator between the memory cell array and the read circuitry, providing the necessary current measurement capability without requiring a complete redesign of the entire memory device structure.
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
This approach enables a more reliable sense operation by accurately measuring the threshold voltage of the selected memory cell, improving the reliability of read and verification operations.
Implementation Method 1
the voltage level of a precharged bit line shifts or remains intact depending on the level of a threshold voltage of the selected memory cell
Data Source
AI summary
A semiconductor memory device includes a memory cell array including cell strings each including a plurality of memory cells, bit lines coupled to the respective cell strings, and page buffers configured to compare a reference current and currents of the respective bit line and output sense data corresponding to a level of a threshold voltage of a selected memory cell based on a result of the comparison, in a sense operation.