Adaptive Read Voltage Circuit for Non-Volatile Memory Temperature Compensation
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Solution Overview
Problem
Non-volatile memory devices face read errors due to changes in threshold voltage distributions caused by temperature variations, leading to misreading of data when the program and read operations are performed at different temperatures.
Innovation Solution
A circuit that generates a read voltage adaptable to ambient temperature and program state by using multiple voltage generating circuits and a comparison amplifying circuit, which adjusts the output voltage based on resistance rates and temperature shifts, ensuring accurate data reading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed read voltage is applied to memory cells, then the circuit operation is simple, but read errors occur due to threshold voltage changes with temperature
Solution Approach 1:
The read voltage is changed dynamically according to temperature conditions. The voltage generation circuit selects different read voltages (e.g., first read voltage at high temperature, second read voltage at low temperature) based on detected temperature, making the system adaptive rather than static. This resolves the contradiction by allowing simple fixed-voltage operation under normal conditions while enabling complex adaptive voltage adjustment only when temperature variations cause read errors.
Solution Approach 2:
The read voltage parameter is changed based on temperature conditions to maintain optimal read margins. The system adjusts the voltage level parameter according to environmental temperature, using higher read voltages at low temperatures where threshold voltages are higher, and lower read voltages at high temperatures where threshold voltages are lower. This parameter adaptation resolves the contradiction between simple fixed-voltage operation and reliable reading across temperature ranges.
2Reliability
If the read voltage is adjusted according to temperature, then read accuracy is improved, but the circuit complexity increases
Solution Approach 1:
The temperature range is segmented into multiple regions (e.g., high temperature range, low temperature range), and different read voltages are assigned to each segment. The voltage generation circuit includes multiple voltage generation paths, each optimized for specific temperature segments. This segmentation allows the system to maintain high read margin stability in each temperature segment while avoiding the need for continuously complex voltage adjustment mechanisms.
Solution Approach 2:
A temperature detection circuit acts as an intermediary between the environment and the voltage generation circuit. This intermediary detects temperature conditions and triggers appropriate voltage selection, mediating the complex temperature-voltage relationship through a simple detection-and-select mechanism. This reduces overall circuit complexity by separating the temperature sensing function from the voltage generation function.
3Adaptability or versatility
If multiple voltage generation circuits are used to adapt to temperature variations, then read accuracy across temperatures is improved, but the device complexity increases
Solution Approach 1:
The voltage generation circuit is designed with multi-functionality to handle multiple temperature conditions. Rather than using completely separate circuits for different temperature ranges, the system uses a unified voltage generation circuit that can generate different read voltages based on temperature conditions. This universal circuit approach provides temperature adaptability while minimizing the increase in device complexity compared to multiple dedicated circuits.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution reduces data read errors by maintaining a stable read margin across varying temperatures, ensuring accurate data retrieval by adjusting the read voltage in accordance with temperature and threshold voltage changes.
Implementation Method 1
a first voltage generating circuit for outputting a first voltage by dividing an input voltage on the basis of a resistance rate which is varied in accordance with a first control signal
Implementation Method 2
a second voltage generating circuit for outputting a second voltage, wherein the second voltage is shifted in accordance with a temperature
Implementation Method 3
a third voltage generating circuit for changing the third voltage by using voltage shift rate which is setted respectively in accordance with level of an operation voltage to be outputted at the temperature, thereby outputting a fourth voltage
Implementation Method 4
a comparison amplifying circuit for outputting the operation voltage in accordance with the first voltage, the fourth voltage and resistance rate
Data Source
AI summary
A circuit for providing a voltage, which includes a first voltage generating circuit to output a first voltage generated by dividing an input voltage on the basis of resistance rate varied in accordance with a first control signal, a second voltage generating circuit to output a third voltage by using a second voltage, where the third voltage is shifted in accordance with a temperature, a third voltage generating circuit to change the third voltage by using a voltage shift rate set in accordance with a level of an operation voltage to be outputted at the temperature, thereby outputting a fourth voltage, and a comparison amplifying circuit configured to output the operation voltage in accordance with the first voltage, the fourth voltage and resistance rate.