Memory Cell Read Operation Voltage Phase Adjustment
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Solution Overview
Problem
Existing memory devices face increased latency in read operations due to threshold voltage drift over time, requiring more voltage steps to accurately determine logic states in multi-level memory cells.
Innovation Solution
A memory device implements a two-phase read operation where the starting voltage for the second phase is determined based on the ending voltage of the first phase, rather than being the negative of the first phase's starting voltage, allowing for fewer voltage steps and reduced latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a traditional two-phase read operation is used with symmetric voltage sequences, then the read operation can determine logic states in multi-level memory cells, but the read latency increases due to threshold voltage drift requiring more voltage steps
Solution Approach 1:
The patent changes the voltage parameters by determining the second starting voltage based on the first ending voltage plus an offset, rather than using a fixed symmetric relationship. This dynamic parameter adjustment allows the voltage sequence to adapt to threshold voltage drift, maintaining measurement precision while reducing the number of voltage steps required and thus reducing read latency
Solution Approach 2:
The patent introduces dynamics into the previously static symmetric voltage sequence by making the second starting voltage dependent on the first ending voltage. This dynamic relationship allows the read operation to adapt to changing threshold voltages over time, reducing the number of steps needed while maintaining accuracy
2Measurement precision
If more voltage steps are applied to compensate for threshold voltage drift, then the accuracy of determining logic states is maintained, but the read operation latency increases
Solution Approach 1:
By changing how the voltage parameters are determined - specifically making the second starting voltage dependent on the first ending voltage - the patent achieves both accuracy and speed. This parameter change allows for fewer voltage steps while maintaining detection accuracy, thus improving productivity
Data Source
AI summary
Methods, systems, and devices for memory cell read operation techniques are described. A memory device may determine a starting voltage for a second phase of a read operation for a set of memory cells which may have a different magnitude than a magnitude of a starting voltage of a first phase of the read operation. For example, the memory device may use an ending voltage of the first phase to determine the starting voltage for the second phase. In some cases, the starting voltage for the second phase may correspond to a difference of a voltage offset and the ending voltage of the first phase. As part of the second phase of the read operation, the memory device may apply a sequence of voltages to the set of memory cells in accordance with the determined starting voltage of the second phase.