BCH and LDPC error correction codes for NAND flash memories

Abstract

Because NAND devices can’t be manufactured without defects, the use of Error Correction Codes (ECCs) has always been a common practice. While BCH (Bose-Chaudhuri-Hocquenghem) is a de facto standard for consumer applications, LDPC (Low-Density-Parity-Check) codes are a typical choice in the enterprise world. This is especially true when looking at planar (2D) ultra-scaled (e.g. 15nm) NAND. Generally speaking, LDPC offers higher correction capabilities, but BCH remains a good solution when bandwidth requirements are very stringent. This chapter provides an overview of both BCH and LDPC state-of-the-art solutions.