Flash Memory Word Line Voltage Feedback for Read Accuracy
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Solution Overview
Problem
The existing methods for regulating word line voltage in flash memories are inadequate, leading to a reduced sensing window as technology advances, making it difficult to accurately read data due to misjudgment of memory cell values.
Innovation Solution
A voltage regulating method that adjusts the word line voltage based on the difference between written and read data amounts, using a counter to determine a delta voltage and applying it to the word line voltage, thereby ensuring accurate data reading by optimizing the voltage level.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional word line voltage regulation methods are used, then the flash memory can operate with basic reading functionality, but the sensing window size is reduced and data reading accuracy deteriorates due to misjudgment of memory cell values
Solution Approach 1:
The patent implements a feedback mechanism by counting the number of memory cells read as a specific value (e.g., 0 or 1) and comparing this count against expected values. Based on this feedback, the system dynamically adjusts the word line voltage to optimize the sensing window and improve reading accuracy. The counter records read results and feeds this information back to the voltage regulator, which modifies the word line voltage accordingly.
Solution Approach 2:
The patent changes the electrical parameter (word line voltage level) based on the counted data distribution. By adjusting the voltage parameter dynamically according to the actual data distribution in the memory array, the system expands the sensing window and improves the distinction between different data states, thereby enhancing measurement precision.
2Reliability
If the word line voltage level is not properly regulated, then the circuit operation is simple, but the sensing window is reduced leading to increased reading errors
Solution Approach 1:
The system performs self-diagnosis and self-adjustment by automatically counting its own read results and using this information to regulate its own operating voltage. The memory system monitors its own performance through the counter and autonomously adjusts the word line voltage without requiring external intervention, thereby improving reliability while keeping the control mechanism relatively simple.
Solution Approach 2:
The counter acts as an intermediary element that bridges the reading operation and the voltage regulation. Instead of directly monitoring complex voltage levels or sensing window characteristics, the system uses the counter to indirectly measure reading accuracy and translate this into voltage adjustment commands, simplifying the overall control architecture.
3Measurement precision
If dynamic word line voltage adjustment is implemented to expand sensing window, then data reading accuracy improves, but the operation time increases due to voltage regulation steps
Solution Approach 1:
The system performs preliminary counting of read data during the normal read operation, accumulating statistical information about data distribution. This preliminary action allows the system to prepare voltage adjustment decisions based on aggregated data rather than making frequent small adjustments, reducing the overall time penalty while maintaining improved accuracy.
Solution Approach 2:
The patent applies partial adjustment by making voltage changes only when the counted data distribution indicates a need for optimization. Rather than continuously adjusting the voltage, the system performs adjustments selectively based on the counter feedback, thereby reducing the time overhead while still achieving the benefits of expanded sensing window when needed.
Data Source
AI summary
A voltage regulating method applied to a memory to regulate a word line voltage corresponding to a set of memory cells of the memory comprises the following steps. Firstly, a first value, which is for indicating an amount of data having a specific data value in a set of written data, is counted, wherein the set of written data is written into the set of memory cells. Next, a second value, which is for indicating an amount of data having the specific data value in a set of read data, is counted, wherein the set of read data is obtained by reading the set of written data. Then, a regulating voltage is determined according to a difference between the first and second values. After that, the word line voltage is regulated to be a sum of the word line voltage and the regulating voltage.