NAND flash memory ECC based on QC-LDPC for space CCD image

In order to improve the reliability of NAND flash for the application of space CCD camera, an error correction coding (ECC) algorithm based on quasi-cyclic low-density parity-check (QC-LDPC) for NAND flash memory is presented in this paper. First, this paper presents a deep analysis of the NAND flash memory channel model. Then, according to the built channel model, a QC-LPDC (1056, 1024)-based error correction coding algorithm is proposed. In order to improve the coding efficiency, a constructing method of the check matrix and efficient coding method are developed. The designed check matrix has 0 or 1 only, which can only be implemented by shift and addition operations. This characteristic is very suitable for the hard implementation. Finally, the verification experiments of the proposed NAND error correction coding algorithm are carried out using the ground test device. The experimental results show that the proposed error correction coding algorithm can operate fast, efficiently, reliably, and stably. The complexity of the proposed algorithm is very low, which is only O (N). The proposed algorithm has great correction ability, and the encoding gain is improved by 0.47 dB than RS method when the BER is 10^-6. In a 65 nm CMOS process, the QC-LDPC code designed as a prototype provides a decoding throughput of 7.2 Gbit/s. The proposed algorithm has low error-floor, and the error-floor does not exist when the BER is 10^-8. The proposed error correction coding algorithm can satisfy the space camera data storage requirements of the reliability.