Memory Apparatus Dual Sensing Error Correction
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Solution Overview
Problem
Conventional memory apparatuses face increased bit error rates due to threshold voltage shifts over time, limiting the correction scope of existing ECC algorithms, which can only correct single bit errors effectively.
Innovation Solution
A dual sensing technology is employed, using two reference voltages to distinguish memory cell states and gradually changing bit values to calculate syndromes, allowing for reverse error checking and correction of read data, thereby enhancing the correction capability beyond single bit errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single reference voltage sensing is used, then the reading operation is simple, but the correction scope of ECC algorithm is limited to single bit errors
Solution Approach 1:
The patent divides the sensing operation into two separate sensing steps with different reference voltages (first reference voltage and second reference voltage). This segmentation allows the system to identify multiple error bits by comparing the results of two sensing operations, thereby extending the error correction capability beyond single bit errors while maintaining manageable operational complexity through structured division of the sensing task.
Solution Approach 2:
The patent introduces a second dimension of sensing by using two different reference voltages instead of a single reference voltage. This dimensional change enables the system to detect and correct multiple bit errors simultaneously. The first sensing operation uses a first reference voltage and the second sensing operation uses a second reference voltage, creating an additional degree of freedom that enhances error detection and correction capability.
2Reliability
If dual sensing with two reference voltages is used, then multiple bit errors can be corrected, but the sensing operation becomes more complex
Solution Approach 1:
The patent employs feedback by comparing the sensing results from the first and second sensing operations. The result of the first sensing operation (using first reference voltage) is fed back to the second sensing operation (using second reference voltage), and the comparison between these feedback results enables the system to identify error bits. This feedback mechanism maintains operational simplicity by automating the error identification process through systematic comparison of sensing results.
3Reliability
If ECC algorithm is extended to correct multiple bit errors, then the correction scope increases, but the calculation complexity increases
Solution Approach 1:
The patent performs preliminary action by conducting two sensing operations before the ECC correction process. The first sensing operation uses a first reference voltage and the second sensing operation uses a second reference voltage, establishing the sensing results in advance. This preliminary action simplifies the subsequent ECC calculation by providing pre-computed sensing data that can be directly compared to identify error bits, thereby reducing the overall calculation complexity required for multi-bit error correction.
Data Source
AI summary
A memory apparatus and a data reading method thereof are provided. In the method, a plurality of memory cells of the memory apparatus are read to obtain read data, in which a threshold voltage of each memory cell is sensed and respectively compared with a first reference voltage and a second reference voltage to determine bit values. The first reference voltage and the second reference voltage are used to distinguish different states of the memory cell and the second reference voltage is larger than the first reference voltage. The bit values of the memory cells having the threshold voltage between the first reference voltage and the second reference voltage in the read data are gradually changed and syndromes of the changed read data are calculated. The read data is corrected according to values of the syndromes.