Non-Volatile Memory Read Compensation via Temperature-Adaptive Bit Line Voltage
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Solution Overview
Problem
Non-volatile memory devices face challenges in maintaining accurate data reading and verification due to changes in temperature, which affect the threshold voltage of memory cells, leading to reduced read margins and incorrect state determination.
Innovation Solution
A method that involves sensing the temperature of memory cells and adjusting the voltage levels of bit line sensing signals, with a difference between precharge and sensing voltages increasing as temperature rises, to ensure consistent data reading and verification results across temperature changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature changes occur during operation, then the threshold voltage of memory cells changes, but the read margin is reduced and reading accuracy deteriorates
Solution Approach 1:
The patent adjusts the bit line sensing signal voltage levels dynamically based on detected temperature changes. Specifically, it modifies the first voltage (precharge voltage) and second voltage (sensing voltage) of the bit line sensing signal in response to temperature variations, ensuring that the voltage difference between programmed and erased states remains sufficient for accurate reading across different temperature conditions.
2Measurement precision
If the threshold voltage changes with temperature, then the memory cell state determination becomes inaccurate, but maintaining fixed voltage levels simplifies the reading operation
Solution Approach 1:
The patent implements a feedback mechanism where the operating temperature is detected and used to control the voltage levels of the bit line sensing signal. The detector monitors temperature, and based on the detected temperature, the controller adjusts the first and second voltages of the bit line sensing signal to maintain optimal reading conditions despite temperature variations.
3Reliability
If voltage levels are adjusted to compensate for temperature, then reading accuracy is maintained, but the device complexity increases due to additional control circuitry
Solution Approach 1:
The patent employs a self-service approach where the memory device automatically detects its own operating temperature and adjusts its own bit line sensing signal voltage levels in response. This self-regulation eliminates the need for external temperature compensation circuits while maintaining stable reading performance across varying temperature conditions.
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
This approach allows for constant and accurate data reading and verification, compensating for temperature-induced changes in memory cell states, thereby maintaining the desired read margin and preventing misinterpretation of programmed or erased states.
Implementation Method 1
sensing a temperature of a memory cell
Data Source
AI summary
A method of reading data in a non-volatile memory device compensates for a change in a reading/verifying result in accordance with a change of temperature. The method includes sensing a temperature of a memory cell, setting a first voltage and a second voltage of a bit line sensing signal in accordance with the sensed temperature so that a difference of the first voltage and the second voltage is increased as the temperature increases, precharging a bit line in accordance with the set first voltage, and sensing data of the memory cell in accordance with the set second voltage. The method may read/verify data constantly even though a temperature is changed.