Row weight adjustment in two-level low-density parity-check (ldpc) error correction

Abstract

A method for error correction includes reading, by a memory controller, a first-level codeword from a memory device, the first-level codeword having user data and first-level parity data. The method includes decoding, by the memory controller responsive to determining the first-level codeword contains errors, the first-level codeword using a first-level low-density parity-check (LDPC) decoder employing a first-level H matrix having a portion with reduced column weights to reduce an average row weight for the first-level H matrix. Responsive to the first-level LDPC decoder failing to correct the errors in the first-level codeword, the memory controller decodes a second-level codeword using a second-level LDPC decoder employing a second-level H matrix that includes a portion with increased column weights to increase an average row weight of a second-level of the second-level H matrix. The second-level codeword having the user data, the first-level parity data and second-level parity data.