Memory Sense Voltage Calibration for Read Accuracy
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Solution Overview
Problem
Existing memory technologies face read process errors due to varying output voltages from storage units, especially in multi-level cell memories, where sense amplifiers may incorrectly identify bit values when using a fixed set of sense voltages, leading to inaccurate data retrieval.
Innovation Solution
A data read method that involves storing a training sequence and pilot sequences in storage units, allowing the controller to adjust the sense voltage based on the accuracy of these sequences to ensure correct data identification, by comparing read-out sequences with predetermined patterns and adjusting the voltage until accurate readings are obtained.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed set of sense voltages is used to read data from storage units, then the read operation is simple and fast, but read errors occur when storage units output different voltages due to location or neighboring data
Solution Approach 1:
The patent applies preliminary action by storing training sequences in advance in the storage units during manufacturing or initialization. These training sequences serve as reference data that enable the sense amplifier to determine optimal sense voltages before actual data reading operations begin, thereby eliminating the need for complex real-time voltage adjustments during normal read operations.
Solution Approach 2:
The patent implements self-service by enabling the sense amplifier to automatically determine the appropriate sense voltage by comparing the output voltage of storage units with the predetermined training sequences. This self-adjustment mechanism allows the system to adapt to variations in storage unit output voltages without requiring external intervention or complex control circuits.
2Reliability
If sense voltage is adjusted for each storage unit to ensure accurate reading, then read accuracy improves, but the read process becomes more complex and time-consuming
Solution Approach 1:
The patent resolves this contradiction by performing the voltage calibration action in advance through the pre-stored training sequences. The optimal sense voltages are determined before normal operation begins, allowing fast data reading without repeated voltage adjustments. This preliminary calibration eliminates the time penalty that would otherwise accompany accurate voltage matching for each read operation.
Solution Approach 2:
The patent applies parameter changes by using different sense voltages corresponding to different voltage output levels of storage units. The system dynamically selects appropriate sense voltages based on the comparison between output voltages and training sequences, enabling accurate reading of storage units with varying output characteristics without requiring time-consuming iterative adjustments.
3Productivity
If the same sense voltage is used for all storage units, then the read operation is efficient, but storage units with different output voltage characteristics produce read errors
Solution Approach 1:
The patent applies local quality by assigning different sense voltages to different storage units or groups of storage units based on their output voltage characteristics. By comparing each storage unit's output with locally stored training sequences, the system determines the appropriate sense voltage for that specific storage unit, thereby maintaining high read speed while achieving accurate voltage measurement for each unit.
Solution Approach 2:
The patent implements parameter changes by dynamically selecting sense voltage levels based on the output characteristics of storage units. The system changes the sense voltage parameter to match the voltage output level of the storage unit being read, whether it corresponds to logic 0 or logic 1 states, thereby maintaining both reading efficiency and measurement precision.
Data Source
AI summary
The invention provides a data read method. First, a training sequence stored in a storage unit of a memory is read according to at least one sense voltage to obtain a read-out training sequence. Whether the read-out training sequence is correct is then determined. When the read-out training sequence is not correct, the sense voltage is adjusted.