US 11,538,534 B1 · Soft bit reference level calibration using decoded data

Abstract

Calibration of soft bit reference levels in a non-volatile memory system is disclosed. When the soft bit reference levels are to be calibrated, encoded data is read from a group of the memory cells. The encoded data is decoded and error corrected. Therefore, the original data that was programmed into the memory cells is recovered. The group of memory cells are sensed at candidate soft bit reference levels, and possibly other reference levels. For each candidate soft bit reference level, mutual information between the original programmed data and the data for that candidate soft bit reference level is determined. The mutual information serves as a good measure for how well the candidate soft bit reference level will aid in decoding the data. In an aspect, a soft bit reference level having the highest mutual information out of several candidates is selected as the calibrated soft bit reference level.

Claims20

Dependent claims

An apparatus comprising:

a memory controller interface;
and
one or more control circuits configured to connect to a memory structure comprising non-volatile memory cells, wherein the one or more control circuits are configured to:
read encoded data from a group of the non-volatile memory cells, including sense the group at one or more hard bit reference levels;
provide the encoded data to a data decoder;
receive error corrected data from the data decoder to recover original data that was programmed into the group;
sense the group at candidate soft bit reference levels associated with the one or more hard bit reference levels, thereby generating data for each respective candidate soft bit reference level;
calculate, for each candidate soft bit reference level, mutual information between the error corrected data and the data for the respective candidate soft bit reference level;
and
establish, based on the mutual information, a soft bit reference level for sensing non-volatile memory cells in the memory structure.

7 more elements

A method of operating non-volatile storage, the method comprising:

sensing a group of non-volatile memory cells at one or more hard bit reference voltages to generate encoded data;
decoding and error correcting the encoded data to recover data that was programmed into the group;
sensing the group at lower candidate soft bit reference voltages and upper candidate soft bit reference voltages for each of the one or more hard bit reference voltages;
calculating, for each lower candidate soft bit reference voltage and for each upper candidate soft bit reference voltage, mutual information between the error corrected data and the data sensed based on the candidate soft bit reference voltage;
selecting, for each hard bit reference voltage, a lower candidate soft bit reference voltage that has the highest mutual information as a calibrated lower soft bit reference voltage;
and
selecting, for each hard bit reference voltage, an upper candidate soft bit reference voltage that has the highest mutual information as a calibrated upper soft bit reference voltage.

4 more elements

A non-volatile memory system, comprising:

a memory structure comprising non-volatile memory cells;
sensing means for reading a codeword from a group of the non-volatile memory cells based on one or more hard bit reference levels, the sensing means further for sensing the group at candidate soft bit reference voltages, thereby generating data for each respective candidate soft bit reference voltage based on sensing at the respective candidate soft bit reference voltage and a hard bit reference voltage associated with the respective candidate soft bit reference voltage;
decoding means for decoding and error correcting the codeword to recover original data that was programmed into the group;
and
soft bit calibration means for selecting calibrated soft bit reference voltages based on highest mutual information between the original data and the data for each candidate soft bit reference voltage.

2 more elements

Dependencies are inferred from the claim text.

Soft bit reference level calibration using decoded data

Life of this patent

Soft bit reference level calibration using decoded data

Life of this patent

Abstract

Claims20