Adjusting log likelihood ratio values to compensate misplacement of read voltages

摘要

An apparatus having a circuit and an interface to a nonvolatile memory is disclosed. The circuit is configured to (i) perform one or more attempts of a soft-decision decode of data stored in the nonvolatile memory, where soft-decision decode uses a plurality of log likelihood ratio values stored in a table, (ii) generate one or more adjusted log likelihood ratio values by adding a constant value to one or more of the log likelihood ratio values in response to a failure to decode the data using the log likelihood ratio values and (iii) re-decode the data using the adjusted log likelihood ratio values.

主权项

1. An apparatus comprising:
a memory configured to store data; and a controller configured to process a plurality of input/output requests to read/write to/from the memory, calculate a plurality of log likelihood ratio values over a range of a plurality of read voltages of the memory, store a portion less than all of the plurality of log likelihood ratio values that correspond to a portion less than all of the plurality of read voltages in one or more tables in the controller, perform one or more attempts of a soft-decision decode of the data stored in the memory using the log likelihood ratio values stored in the one or more tables, generate one or more adjusted log likelihood ratio values by adding a constant value to one or more of the log likelihood ratio values stored in the one or more tables in response to a failure to decode the data using the log likelihood ratio values, and perform one or more attempts to re-decode the data using the one or more adjusted log likelihood ratio values.