Semiconductor Memory Sense Circuit Dynamic Pull-Up Current Adjustment
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Solution Overview
Problem
Existing semiconductor memory devices face challenges in maintaining a sufficient margin between the threshold distributions of memory cells storing different data types, leading to potential overlap due to variations in temperature and voltage, which affects data retention and write operations.
Innovation Solution
The semiconductor memory device adjusts the driving force of the pull-up current in the sense circuit based on the data being written, varying the pull-up current values to increase the margin between threshold distributions without altering the word line electrical potential, thereby enhancing data retention and write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the word line electrical potential is changed to increase the margin between threshold distributions, then data retention is improved, but the write verification process becomes less stringent and threshold distributions may overlap
Solution Approach 1:
The patent applies dynamics by making the pull-up current driving force adjustable based on the data type being written. The sense circuit dynamically changes the pull-up current magnitude according to whether 0 or 1 is being written, allowing the verification process to adapt to different threshold distribution characteristics without changing the word line electrical potential.
Solution Approach 2:
The patent changes the parameter of pull-up current driving force in the sense circuit based on the data type. By varying the pull-up current magnitude according to the write data (0 or 1), the system creates different verification conditions for each data type, thereby maintaining sufficient margin between threshold distributions while ensuring reliable data retention.
2Manufacturing precision
If the pull-up current driving force is increased to make verification more stringent, then threshold distribution margin is improved, but data retention may be compromised
Solution Approach 1:
The sense circuit dynamically adjusts the pull-up current driving force based on the specific data type being written. For data type 0, a stronger pull-up current is applied to ensure sufficient margin, while for data type 1, a weaker pull-up current is used to maintain retention. This dynamic adjustment resolves the contradiction between verification stringency and data retention.
Solution Approach 2:
The patent changes the pull-up current parameter according to the write data type. By selecting different pull-up current magnitudes based on whether 0 or 1 is being written, the system optimizes both threshold distribution margin and data retention without compromising either aspect.
3Device complexity
If a fixed pull-up current is used for all data types, then the circuit is simple, but threshold distributions overlap due to temperature and voltage variations
Solution Approach 1:
The sense circuit transitions from a fixed configuration to a dynamic one that adapts to the data type being written. The pull-up current driving force is automatically adjusted based on the write data, providing different verification conditions for 0 and 1 without requiring complex external control circuits.
Solution Approach 2:
The sense circuit performs self-adjustment based on the write data type. The control circuit automatically selects the appropriate pull-up current magnitude without requiring external intervention, making the system self-adaptive to different storage conditions while maintaining simplicity.
Data Source
AI summary
According to one embodiment, semiconductor memory device includes a first circuit that determines data stored in a memory cell; and a second circuit that controls the first circuit, wherein in a sequence in which the second circuit writes first data in the memory cell, the first circuit generates a first current of a first current value, and determines data stored in the memory cell based on the first current and a second current flowing in the memory cell, and in a sequence in which the second circuit writes second data different from the first data in the memory cell, the first circuit generates a third current of a second current value different from the first current value, and determines data stored in the memory cell based on the third current and the second current.