Flash Memory Read Voltage Compensation for Temperature Drift
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Solution Overview
Problem
Flash memory devices experience variations in threshold voltages of memory cells due to temperature fluctuations during programming and reading, leading to inaccurate data retrieval.
Innovation Solution
A nonvolatile memory device equipped with temperature sensors and a temperature compensation circuit that adjusts read voltages based on measured program and read temperatures, ensuring accurate data retrieval by generating compensation read voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed read voltage is used for reading memory cells, then the device operation is simple, but the data reading accuracy deteriorates due to temperature-induced threshold voltage variations
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the read voltage based on temperature variations. The read voltage is modified according to the threshold voltage drift caused by temperature changes, ensuring accurate data reading across different temperature conditions. This is achieved by changing the voltage parameter in response to temperature sensor feedback.
Solution Approach 2:
The patent implements feedback control by using temperature sensors to monitor the actual temperature of the memory device and adjusting the read voltage accordingly. The threshold voltage information derived from temperature data is fed back to the read control circuit, which then modifies the read voltage to compensate for temperature-induced variations, creating a closed-loop control system.
2Reliability
If temperature compensation circuitry is added to adjust read voltages, then data reading accuracy is improved, but the device complexity increases
Solution Approach 1:
The patent introduces temperature sensors as intermediary components that bridge the gap between the physical temperature environment and the electrical read operation. These sensors convert temperature information into electrical signals that can be processed by the control circuit, enabling indirect compensation for temperature effects without directly controlling thermal conditions.
Solution Approach 2:
The patent changes the electrical parameters of the read operation based on temperature compensation calculations. By adjusting the read voltage level according to the relationship between temperature and threshold voltage, the system maintains reliable data retrieval while using relatively simple voltage adjustment mechanisms rather than complex structural modifications.
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 ensures accurate data reading by compensating for temperature-induced voltage variations, thereby improving the reliability of flash memory devices.
Implementation Method 1
a first temperature sensor that measures a read temperature
Implementation Method 2
a second temperature sensor that measures a program temperature of first memory cells
Implementation Method 3
a temperature compensation circuit that calculates a read level offset based on the read temperature and a program temperature
Data Source
AI summary
Disclosed is a nonvolatile memory device which include a memory cell array including a plurality of memory cells connected to a plurality of word lines, an address decoder that controls a selected word line among the plurality of word lines based on an address received from an external device including a first temperature sensor, a second temperature sensor that measures a read temperature of first memory cells connected to the selected word line from among the plurality of memory cells, and a temperature compensation circuit that calculates a read level offset based on the read temperature and a program temperature of the first memory cells measured by the first temperature sensor and generates a compensation read voltage based on the read level offset. The address decoder is further configured to provide the compensation read voltage to the selected word line.