Non-Volatile Memory Built-In Self-Trim Mechanism
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Solution Overview
Problem
Non-volatile memory devices face issues with reference current drift due to environmental factors and data retention errors, lacking a mechanism for in-field adjustment or re-trimming, which affects their reliability and requires costly initial trimming procedures.
Innovation Solution
A built-in self-trim mechanism using an analog-to-digital converter to compare the reference current with a stored target value and adjust it by applying program or erase pulses, incorporating environmental factors like temperature to maintain the reference current within an acceptable range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If initial trimming is performed using external equipment, then reference cell stability is improved, but production cost increases and production volume decreases
Solution Approach 1:
The patent implements a self-trimming mechanism where the memory device automatically adjusts its own reference cell parameters using built-in circuitry. The device measures its own reference current drift and applies corrective program/erase pulses to the reference cell without requiring external trimming equipment, thereby eliminating the need for costly external trimming operations while maintaining reference cell stability.
Solution Approach 2:
The patent performs preliminary self-trimming operations during manufacturing or initialization to establish the reference cell at its optimal operating point. By pre-configuring the reference cell with self-trimming capability and performing initial calibration before deployment, the system avoids the need for repeated external trimming operations throughout the product lifecycle, reducing overall production costs.
2Measurement precision
If initial trimming is performed using external equipment, then reference cell accuracy is improved, but production time increases
Solution Approach 1:
The memory device performs self-trimming operations autonomously using integrated circuitry that measures reference current and automatically applies corrective pulses to the reference cell. This eliminates the time-consuming external trimming process while maintaining high accuracy, as the self-trimming can be performed rapidly within the device without requiring external equipment setup and operation.
Solution Approach 2:
The system performs preliminary self-trimming during manufacturing or initialization to establish accurate reference cell operation before the product is deployed. This preliminary self-calibration ensures high measurement precision for subsequent operations without requiring time-consuming external trimming equipment during production, thereby reducing overall production time.
3Adaptability or versatility
If reference cell is subject to environmental effects, then device adaptability is improved, but reference current drift increases
Solution Approach 1:
The patent implements a feedback mechanism where the memory device continuously monitors its reference current for drift caused by environmental effects such as temperature changes, data retention errors, or read disturb errors. When drift is detected, the system automatically applies corrective program or erase pulses to the reference cell to restore it to its target operating point, thereby maintaining reference current stability while operating in varying environmental conditions.
Solution Approach 2:
The reference cell system is made dynamic through the self-trimming mechanism, which allows the reference cell parameters to be adjusted in real-time in response to environmental changes. Rather than being a static, fixed reference cell, the system can adapt its reference current level dynamically by applying corrective pulses when drift is detected, enabling the device to maintain stability across different environmental conditions.
Data Source
AI summary
A non-volatile memory built-in self-trim mechanism is provided by which product reliability can be improved by minimizing drift of reference current used for accessing the non-volatile memory and for performing initial trimming of the reference current. Embodiments perform these tasks by using an analog-to-digital converter to provide a digital representation of the reference current (Iref) and then comparing that digital representation to a stored target range value for Iref and then adjusting a source of Iref accordingly. For a reference current generated by a NVM reference bitcell, program or erase pulses are applied to the reference cell as part of the trimming procedure. For a reference current generated by a bandgap-based circuit, the comparison results can be used to adjust the reference current circuit. In addition, environmental factors, such as temperature, can be used to adjust the measured value for the reference current or the target range value.