MRAM Preprogrammed Data Recovery Using ECC and Majority Voting
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Solution Overview
Problem
Preprogrammed data stored in nonvolatile memory devices, such as magnetoresistive memory devices, is susceptible to degradation due to exposure to high temperatures during manufacturing processes like solder reflow, leading to data loss and errors.
Innovation Solution
Implementing distributed redundant data storage and utilizing majority voting schemes combined with error correction codes (ECC) to recover preprogrammed data by storing multiple copies of data in different memory locations and correcting errors using ECC information, ensuring reliable data retrieval even after adverse conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If preprogrammed data is stored in nonvolatile memory during manufacturing, then data can be utilized for startup or initialization operations, but the preprogrammed data can be corrupted by elevated temperatures during subsequent manufacturing operations such as reflow soldering
Solution Approach 1:
The patent applies preliminary action by preprogramming data into nonvolatile memory during manufacturing operations such as wafer probe or burn-in testing, before the device undergoes subsequent manufacturing processes. This allows the data to be available for startup or initialization operations, while the patent subsequently addresses the vulnerability to temperature exposure through error correction mechanisms
Solution Approach 2:
The patent implements beforehand cushioning by storing multiple redundant copies of the preprogrammed data in different memory locations and implementing error correction code (ECC) mechanisms prior to potential data corruption. This cushioning protects against data loss from temperature exposure during reflow soldering or other manufacturing operations, ensuring data integrity can be recovered even if some copies are corrupted
2Reliability
If multiple redundant copies of data are stored in different memory locations, then data recovery reliability is improved, but memory resource consumption increases
Solution Approach 1:
The patent applies copying by storing multiple redundant copies of the preprogrammed data in different memory locations within the nonvolatile memory device. This allows the system to retrieve and compare multiple copies to recover the original data even if some copies are corrupted by temperature exposure. The copying approach balances reliability improvement with acceptable memory resource consumption by using a manageable number of redundant copies
3Measurement precision
If error correction code mechanisms are implemented, then data retrieval accuracy is improved, but processing complexity increases
Solution Approach 1:
The patent implements feedback through error correction code (ECC) mechanisms that detect and correct errors in the preprogrammed data during retrieval. The system reads the data, applies ECC algorithms to detect and correct bit errors, and verifies the corrected data before use. This feedback loop significantly improves data retrieval accuracy while managing processing complexity through efficient ECC implementation
Data Source
AI summary
Techniques for recovering preprogrammed data from non-volatile memory are provided that include majority voting and/or use of one or more levels of ECC correction. Embodiments include storage of multiple copies of the data where ECC correction is performed before and after majority voting with respect to the multiple copies. Multiple levels of ECC correction can also be performed where one level of ECC is performed at the local level (e.g. on-chip), whereas another level of ECC correction is performed at a system level.