NAND Memory Read Voltage Compensation Across Write Temperatures
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Solution Overview
Problem
Existing memory sub-systems fail to accurately account for temperature variations during both write and read operations in non-volatile memory devices, leading to increased raw bit error rates (RBER) that exceed error correction capabilities, resulting in poor performance and high trigger rates for data recovery.
Innovation Solution
The memory sub-system controller stores and retrieves temperature data during write operations, calculates a read offset voltage to adjust read voltages based on temperature differences, using a temperature-measuring device and data structures to ensure accurate cross-temperature compensation, thereby reducing RBER and improving performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If temperature variations during write and read operations are not compensated, then device complexity is reduced, but raw bit error rate increases exceeding error correction capabilities
Solution Approach 1:
The patent applies preliminary action by measuring and storing the temperature at the time of data write operation. This temperature information is saved in a temperature register before the actual data storage, enabling later compensation during read operations without adding complex real-time temperature monitoring hardware.
Solution Approach 2:
The patent implements feedback by using the stored temperature information to dynamically adjust read offset voltages. The system continuously monitors temperature differences between write and read operations and applies compensatory voltage adjustments accordingly, creating a closed-loop error prevention mechanism.
2Reliability
If temperature data is stored and read offset voltage values are calculated for every operation, then data integrity is maintained, but processing time increases
Solution Approach 1:
Temperature measurement and storage are performed in advance during the write operation, so that when the read operation occurs, the temperature compensation data is already available in registers, eliminating the need for real-time temperature measurement and reducing processing delay.
Solution Approach 2:
The patent uses temperature register copies to store temperature information. Instead of repeatedly measuring temperature or accessing complex lookup tables, the system uses pre-stored temperature values in registers that can be quickly retrieved and applied during read operations.
3Productivity
If cross-temperature compensation is implemented, then trigger rate for data recovery is reduced, but device complexity increases
Solution Approach 1:
By pre-measuring and storing temperature data during write operations, the system avoids the need for complex real-time temperature monitoring and adjustment mechanisms during read operations, simplifying the overall system while maintaining effective compensation.
Solution Approach 2:
The patent changes the voltage parameter (read offset voltage) based on temperature differences. Instead of implementing complex hardware adjustments, the system dynamically modifies voltage levels according to stored temperature information, achieving compensation through simple parameter adjustment.
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 reduces the trigger rate for data recovery, enhancing the reliability and operational life of memory sub-systems by accurately compensating for temperature-induced errors during read operations.
Implementation Method 1
using temperature-measuring devices like thermocouples or infrared sensors
Implementation Method 2
it has been discovered that voltage distributions, such as threshold voltage distributions, of the memory device can shift based on a change in temperature of the memory device
Data Source
AI summary
Systems and methods are disclosed including a memory device and a processing device operatively coupled to the memory device. The processing device can perform operations comprising performing a first read operation on the memory device to retrieve first data; determining, from the first data, second data indicative of a write temperature associated with the first data, wherein the write temperature is indicative of a temperature measured during a write operation; determining a read voltage value based on the second data; and performing a second read operation on the memory device using the read voltage value to obtain the first data.