Non-Volatile Memory ECC Recovery During Interrupted Writes
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Solution Overview
Problem
Conventional non-volatile memory devices may not include an embedded Error Correction Code (ECC) encoder circuit, and those that do may malfunction when power is suddenly removed, leading to potential data corruption during write operations.
Innovation Solution
A method for operating non-volatile memory devices that involves writing a portion of a new codeword to an address storing an old codeword, detecting interruptions, and generating error correction bits by combining the old and new codewords, which are then written in response to power loss signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If power is abruptly removed during a write operation, then the write operation is interrupted, but data corruption occurs because the codeword is incomplete
Solution Approach 1:
The patent performs a pre-read operation before the write operation to read the old codeword from the memory address. This preliminary action stores the old codeword in a buffer, so that if power is lost during the write operation, the old codeword is already available for combination with the partially written new codeword to generate valid error correction bits.
Solution Approach 2:
The patent introduces a buffer as an intermediary component that temporarily stores the old codeword. This buffer acts as a mediator between the memory address and the ECC encoder, allowing the system to combine old and new codeword portions even when power is lost during the write operation, thus preventing data corruption.
2Reliability
If an ECC encoder circuit is not included, then device complexity is reduced, but data integrity cannot be maintained during power loss
Solution Approach 1:
The patent makes the ECC encoder circuit multi-functional by using it for both normal error correction operations and for generating error correction bits during interrupted write operations. The same ECC encoder that corrects read errors is also used to generate protection bits for partially written codewords, eliminating the need for separate dedicated circuits.
Solution Approach 2:
The system uses its own existing ECC encoder circuit to generate the error correction bits needed during power loss recovery, rather than requiring external assistance or additional dedicated hardware. The ECC encoder serves the dual purpose of normal operation and interruption recovery.
3Manufacturing precision
If the write operation continues until the portion of the new codeword comprises an integer number of words, then manufacturing precision is improved, but data integrity is compromised during interruption
Solution Approach 1:
The patent implements a feedback mechanism where the system detects whether a write operation was interrupted by checking if the number of written words is an integer. Based on this feedback, the system determines whether to perform the pre-read operation and combine old and new codewords. This feedback-driven approach allows the system to adapt its behavior based on the write operation status.
Data Source
AI summary
A non-volatile memory device may operate by writing a portion of a new codeword to an address in the device that stores an old codeword, as part of a write operation. An interruption of the write operation can be detected before completion, which indicates that the address stores the portion of the new codeword and a portion of the old codeword. The portion of the old codeword can be combined with the portion of the new codeword to provide an updated codeword. Error correction bits can be generated using the updated codeword and the error correction bits can be written to the address.