Adaptive dsp generation of read thresholds for gaussian and non-gaussian distributions in solid state storage using cumulative observed counts

Abstract

A next read threshold is determined based on a level count disparity which is based on an expected count and an observed count. It is determined whether to switch from a hard to a soft error correction decoder. If so, read data at increments of Δ are received where reads are performed on the solid state storage at integer increments of Δ to obtain the read data at increments of Δ and Δ is a smallest voltage increment. Adjacent difference counts are determined based on the read data at increments of Δ. A second read threshold is determined based on an inversely weighted average and the adjacent difference counts. Second read data is obtained by reading using the second next read threshold. The soft error correction decoder performs error correction decoding on the second read data.