Page Buffer Current Mirror Testing for Virtual Cell Sensing
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Solution Overview
Problem
Existing nonvolatile memory devices face challenges in verifying the robustness of current sensing operations in peripheral circuits without the memory cell array, which is crucial for improving productivity and efficiency.
Innovation Solution
The nonvolatile memory device incorporates a page buffer, a control signal generator, and a current mirror to replicate a cell current in a virtual cell mode, allowing for robust current sensing without an actual memory cell by using a current mirror to generate a control voltage and replicate the current through page buffers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a memory cell array is used to verify current sensing operation, then sensing robustness can be confirmed, but productivity and efficiency are reduced due to the complexity of integrating and testing the full memory structure
Solution Approach 1:
The patent creates a virtual cell mode that replicates the electrical characteristics of an actual memory cell without requiring the physical memory cell array. A test circuit generates a test current that mimics the cell current flowing through the page buffer, allowing sensing verification through a simplified copy of the original system.
Solution Approach 2:
The invention extracts the essential current sensing function from the complete memory system by isolating the page buffer and providing an external current source. This separates the sensing verification from the memory cell array, allowing independent testing of the sensing circuitry without the overhead of the full memory structure.
2Productivity
If the memory cell array is removed for peripheral circuit testing, then productivity improves, but the ability to verify current sensing operation deteriorates
Solution Approach 1:
The patent introduces a current mirror circuit as an intermediary between the external current source and the page buffer. This current mirror replicates the test current to match the characteristics of actual cell current, serving as a mediator that enables accurate sensing verification without the memory cell array.
Solution Approach 2:
The invention changes the parameter control approach by using control signals (first and second control signals) to regulate the page buffer operation in virtual cell mode. The control signal generator adjusts these signals to match the electrical characteristics of normal memory operation, enabling realistic sensing verification through parameter adjustment rather than physical 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 consistent replication of cell current in the subthreshold region, verifying the robustness of current sensing operations and confirming the sensing method's reliability, even in the absence of a memory cell, thereby enhancing productivity and efficiency.
Implementation Method 1
The current mirror may output, in a virtual cell mode, a control voltage corresponding to a bias current
Data Source
AI summary
A nonvolatile memory device may include a page buffer, a control signal generator, and a current mirror. The page buffer may be connected to a bitline and may allow a replicated current to flow through a ground terminal in response to a first control signal and a second control signal. The control signal generator may output the first control signal and the second control signal to the page buffer. The current mirror may output, in a virtual cell mode, a control voltage corresponding to a bias current. The control voltage may correspond to the first control signal.