Patent ID: 9607710
Date: 2017-03-28
CPC Classifications: G11C

Claim:
1. A read-threshold calibration method in a solid state storage system, comprising: measuring, with a controller, a threshold voltage distribution of solid state storage elements; locating, with the controller, a first minimum point of the threshold voltage distribution; estimating, with the controller, a first optimal read threshold based on the located first minimum point; decoding, with the controller, data using the estimated first optimal read threshold; if decoding fails: removing, with the controller, an excessive number of minimum points from the threshold voltage distribution by filtering the threshold voltage distribution of the solid state storage elements; locating, with the controller, a subsequent minimum point of the filtered threshold voltage distribution; estimating, with the controller, a subsequent optimal read threshold based on the located subsequent minimum point; and decoding, with the controller, the data that previously failed to decode using the estimated subsequent optimal read threshold.