Sense Amplifier Circuit with Dynamic Current Mirror for Memory Read Accuracy
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Solution Overview
Problem
Non-volatile memory sense amplifiers face errors due to increased programming cycles, which cause the cell current to become closer to the reference current, making it difficult to accurately differentiate between logic 1 and logic 0 data bits.
Innovation Solution
A sense amplifier circuit with a current mirror that amplifies the cell current based on the erase count of the memory cell, using a pre-charge circuit, enable circuit, comparator, and buffer to generate and compare reference and charge voltages, ensuring accurate data bit interpretation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the number of programming cycles increases, then the memory cell can store more data, but the cell current value approaches the reference current value making accurate sensing difficult
Solution Approach 1:
The patent implements dynamic adjustment of the reference current based on the number of programming cycles. The reference current is scaled by a factor that increases with programming cycles, maintaining a sufficient difference between cell current and reference current for accurate sensing even after many programming operations.
Solution Approach 2:
The patent changes the reference current parameter dynamically according to the programming cycle count. By adjusting the reference current magnitude based on erase/program history, the system adapts to maintain measurement precision despite the degrading signal conditions from repeated programming.
2Measurement precision
If the cell current and reference current are kept close for high precision sensing, then measurement precision improves, but the ability to differentiate logic 1 and logic 0 deteriorates
Solution Approach 1:
The system dynamically adjusts the reference current based on programming cycle history. This dynamic adaptation allows the reference current to scale appropriately, maintaining both measurement precision and reliable data differentiation across the memory's operational lifetime.
Solution Approach 2:
The patent uses feedback from the programming cycle count to adjust the reference current. This feedback mechanism ensures that the reference current is continuously optimized based on the memory cell's programming history, maintaining accurate sensing and reliable differentiation throughout the device lifecycle.
3Device complexity
If a fixed reference current is used, then device complexity is reduced, but measurement precision deteriorates with increased programming cycles
Solution Approach 1:
The reference circuit is made dynamic by introducing programming cycle-dependent scaling. This adds moderate complexity to the reference circuit but significantly improves measurement precision, as the adaptive reference current compensates for signal degradation from repeated programming operations.
Solution Approach 2:
The reference current parameter is changed dynamically based on programming history. This parameter adaptation transforms the simple fixed reference circuit into an adaptive system that maintains high measurement precision without requiring complex circuitry.
Data Source
AI summary
A sense amplifier circuit may be used for read operation of a non-volatile memory. The sense amplifier circuit includes of a first pre-charge circuit, a second pre-charge circuit, a bias circuit, an enable circuit, a current mirror, a first comparator, a second comparator, a buffer and a counter. The current mirror is able to amplify a cell current of a memory cell to prevent error and shorten or maintain access time as erase count of the memory cell increases.