Data clustering system and read voltage determination apparatus for memory device using the data clustering system

A read voltage determination apparatus comprising:

• a test circuit configured to change threshold voltage distributions of memory cells coupled to a plurality of word lines and bit lines for each word line;
• a data acquisition circuit configured to select a plurality of word lines for each bit data level stored in the memory cells as a plurality of samples and generate an observed data set including the plurality of samples, wherein a data value of the sample is a read offset for each bit data level stored in each of the plurality of samples;
• and
• a read retry table generation circuit configured to receive the observed data set, determine at least a part of initial centroids based on frequency of the data value, and determine a read retry voltage by grouping the plurality of samples based on a distance between the data value corresponding to each of the samples and each of centroids.