NAND Page Buffer ECC and De-Randomization for Faster Reads
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Solution Overview
Problem
Nonvolatile semiconductor memory devices face performance slowdowns due to error detection and correction operations, which hinder read and write speeds.
Innovation Solution
Incorporating an on-chip error correcting circuit (ECC) and an on-chip randomizer within the nonvolatile memory device, where data is stored in a page buffer, error decoding is performed, and data is de-randomized using a seed after error correction, optimizing read and write operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If error detection and correction operations are performed in the nonvolatile memory device, then data reliability is improved, but read and write speed deteriorates
Solution Approach 1:
The patent applies preliminary action by performing de-randomization of error correction data before storing it in the page buffer. This preprocessing step ensures that when error correction operations are needed, the data is already in the correct format, reducing the time penalty during actual read/write operations. The randomizer/de-randomizer circuit processes data in advance to minimize overhead during critical error correction operations.
2Speed
If de-randomization operation is performed after error correction, then read speed is improved, but operation complexity increases
Solution Approach 1:
The patent merges the randomizer and de-randomizer functions into a single integrated circuit block that works closely with the error correction circuit. This consolidation allows the randomization and error correction operations to be coordinated efficiently, reducing the overall complexity compared to having separate, independent circuits. The merged design shares resources and control logic between these functions.
Solution Approach 2:
The page buffer serves as an intermediary structure between the error correction circuit and the randomizer/de-randomizer. It temporarily stores error correction data and facilitates the coordinated operation of multiple circuits, simplifying the control logic by providing a centralized storage point that mediates data flow between different functional blocks.
3Reliability
If error correction data is stored in the page buffer, then data integrity is improved, but buffer management complexity increases
Solution Approach 1:
The patent implements dynamic buffer management where the page buffer's content and state change based on operational needs. The buffer selectively stores either normal data or error correction data depending on the operation mode, and the control logic dynamically adjusts buffer usage patterns. This dynamic approach optimizes buffer utilization while maintaining data integrity without requiring complex static management structures.
Data Source
AI summary
A read method of a nonvolatile memory device is provided. The method includes storing data sensed from selected memory cells of the nonvolatile memory device into a page buffer, performing an error decoding operation by performing error detection on the sensed data to detect and error, correcting the detected error if the error is detected, and overwriting the page buffer with the corrected data, and de-randomizing data stored in the page buffer by using a seed after the error decoding operation has completed.