Flash Memory ECC Controller with Dual Mode Error Correction
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Solution Overview
Problem
Conventional flash memory systems face challenges in maintaining data retention characteristics due to electron trap-induced deterioration, especially with miniaturization and multi-valued recording, which also compromise high-speed transmission and low power consumption requirements, particularly in applications like business-grade memory cards.
Innovation Solution
An information recording and reproducing apparatus that employs a dual ECC mode: a first mode for reading user data without parity data to prevent transmission speed and power consumption degradation, and a second mode for reading and correcting parity data to enhance error durability, using a (5,4) ECC code and Reed-Solomon error correction codes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If parity data is always read to correct errors, then error durability is improved, but transmission speed and power consumption deteriorate
Solution Approach 1:
The patent implements dynamic switching between two reproducing modes: a first mode that reads only user data for high-speed transmission, and a second mode that reads both user data and parity data for error correction. The system dynamically selects the appropriate mode based on whether errors are detected, thereby optimizing both transmission speed and error durability as needed.
Solution Approach 2:
The patent changes the reading parameter (whether to read parity data or not) based on error detection results. When no errors are detected, the system uses the first reproducing mode with parameter set to read only user data. When errors are detected, it switches to the second reproducing mode with parameter set to read both user data and parity data for correction.
2Reliability
If parity data is always read to correct errors, then error durability is improved, but power consumption increases
Solution Approach 1:
The system dynamically adjusts power consumption by switching between reproducing modes. The first mode consumes less power by reading only user data, while the second mode consumes more power by reading both user data and parity data. The system optimizes power usage by selecting the first mode when errors are not detected and only switching to the second mode when error correction is actually needed.
Solution Approach 2:
Instead of always performing the full action of reading parity data for error correction, the system applies partial action by reading parity data only when necessary (when errors are detected). This reduces overall power consumption while maintaining error durability when needed.
3Quantity of substance
If multi-valued recording is implemented to enlarge capacity, then recording capacity is improved, but data retaining characteristics deteriorate due to electron traps
Solution Approach 1:
The patent applies error correction codes (ECC) as a beforehand cushioning mechanism to protect against data retention deterioration. By generating and storing parity data in advance, the system creates a protective buffer that can compensate for errors that may occur due to electron trap formation in multi-valued flash memory, thereby maintaining data reliability despite capacity enlargement.
Solution Approach 2:
The patent converts the harmful effect of electron traps and deterioration into a manageable issue by using ECC. Instead of trying to prevent all deterioration, the system uses parity data to detect and correct errors caused by electron traps, thereby turning the potential harm of multi-valued recording into an acceptable risk with built-in correction capabilities.
Data Source
AI summary
An information recording and reproducing apparatus writes user data received from an external device into a recording medium and reads the user data from the recording medium so as to transmit the user data to the external terminal. The information recording and reproducing apparatus includes an external interface unit operable to transmit and receive the user data to and from the external device, a first ECC generator operable to generate parity data corresponding to the user data, an access unit operable to control recording and reading of the user data or the parity data to and from the recording medium, a recording controller operable to record the user data and the first parity data to the recording medium via the access unit, an ECC correcting unit operable to correct an error of the user data read from the recording medium using the parity data read from a nonvolatile memory via the access unit, and a reproducing controller having a first reproducing mode for reading and reproducing the user data without reading the parity data from the recording medium at the time of reproducing data and a second reproducing mode for reading and reproducing at least the parity data from the recording medium, the reproducing controller operable to detect presence or non-presence of an error of the user data read from the recording medium during execution of the first reproducing mode and executing the second reproducing mode when the presence of an error is detected.